To search the FAQs, press "Ctrl" on PC, or "⌘ Comand" on MAC, and press "F" at the same time to call the search function. Then type the keyword and the various topics will be highlighted.
Can I purchase FACTORY STOCK RADIOS from the Asymod web site?
Yes, we offer a wide variety of new, stock CB and 10 meter radios at great prices.
We Sell New Stock Transceivers. Optional Hi-Fi mods, such as, frequency expansion, alignment, tune/peak and basic Hi Fi upgrades can be selected before check out. Simply go to the PRODUCTS link at the top of the page or select from the following:
Where can I purchase Asymod products?
On this site which is the Asymod home and official site dedicated to wideband AM and eSSB, on www.asymod.am and on eBay by eBay member "Myspin".
I would like to send MY radio in to get the Asymod installed in it, how much does this cost?
OPTION 1 (recommended):
Mail In Instructions
Please note turnaround time is typically 1 to 2 weeks if not sooner. More complex installs may take longer.
Please note before committing, all sales are final and there are no returns due to the nature of the customerization.
Make sure to pack your unit well and that it is double boxed with prepaid return label. The unit will be returned in the same packaging once work is completed.
Please provide name, email, return address, phone number and detailed description of work to be performed and settings (desired dead key, mod % or max PEP – Only applies to internal installations) in the package or email with these details.
You will be invoiced after all work is complete. Send PayPal payments to email@example.com via friends and family.
You will be notified by email or phone at the time all work is completed. Payment is due once all work is completed and prior to return shipping to customer.
Please ship to the service address below:
2777 SW 32 Court
Miami, FL. 33133
Asymod Installation on SSB transceivers is $175, AM only transceivers is $150. Turnaround is about 2-3 days, excluding shipping time. Please include prepaid return USPS shipping label or add $19.50 for mobile radios and $49.50 for base station radios to the total for shipping. For installation prices on HF rigs, please or call us at (786)-554-8077.
Once you decide to proceed, submit the settings and information required to firstname.lastname@example.org, or call us at (786)-554-8077. A listing will then be created for you at www.asymod.am. At that point you will be notified. Once notified, follow the instructions or simply go to www.asymod.am and purchase the installation package that was created for you. Once check out is completed, you will receive an email with the shipping instructions.
Alternatively, send PayPal payment to email@example.com and submit the settings requirements to firstname.lastname@example.org or via PayPal. Once payment is completed, you will receive an email with the shipping instructions.
How does the connection between laptop running Pro Tools interface with the Asymod ready transceiver? Is the Asymod unit connected via USB port to USB port or some other adapted way? Is there a video showing the chain; radio to laptop to boom mike?
Setting up your Asymod transceiver is easy, you can choose from simple to more complete and elaborate setups as seen bellow. For those who prefer standalone audio processing units instead of computer based audio processing such as Pro Tools, below are two possible setup configurations using the Behringer DEQ2496 processor. The DEQ2496 requires a mic pre amp. Additional information regarding the AM Hi-Fi audio process visit the NU9N page at the following link: http://www.nu9n.com/am.html
Bellow is a simple Pro Tools Hi-Fi setup. A more complete Pro Tools setup can be put together in the same manner as the above complete Hi-Fi setup.
What other mods are included when I send my radio in for the Asymod installation?
A typical Asymod installation includes:
- RF and IF stage upgrades
- RX and TX audio stage upgrades
- New 6 kHz bandwidth / 455 kHz IF AM filter
- Demodulator/Detector, Noise Blanker and S Meter upgrades
- New Asymod board (6, HP or TA)
- Line-In Jack - Rear panel 1/8”
- PTT jack - Rear panel 1/4”
- Amplifier Keying – (optional) Rear panel RCA jack.
- Low / High power switch (some high power units only)
- Other mods (specific to different radios)
Do you guys repair radios other than Asymod radios?
Yes we do, we service and repair HF rigs, CB radios and 10 meter radios. Simply CONTACT US and we will provide you with the mail in instructions or follow the instructions above.
What is the link address to the Asymod YouTube channel?
To what PayPal address can I send payment to?
How can I contact Asymod support if I have any questions?
What radios does Asymod work the best in?
Few things to consider. The Asymod works on all solid state high level modulation AM transceivers. The choice is really up to the radio operator. Once the Asymod is in place most of the transceiver’s factory transmit functions, such as the microphone preamp, transmit audio control, limiters, and modulator sections are disabled and replaced by the Asymod. Receive functions remain as per factory specs unless the unit is upgraded for Hi-Fi receive.
From the modes of operation point of view, typically an AM only transceiver is best. Multimode transceivers (SSB/AM/FM) require a bit more work but work just as well.
The ideal transceiver to use with the Asymod, is a dual final, single mode, AM only transceiver. Class C bias or close to it should be employed in multimode transceivers RF final stages to allow for -100% modulation peaks and achieve the correct asymmetry. Because modes such as SSB requires higher bias levels, such as, class AB, some modifications and/or adjustments may need to be performed on multimode (SSB, CW, etc.) transceivers.
A perfect example of a Class C biased RF final stage is where the bases of the driver and final RF transistors are pulled far down and the Q-point is set some way below the cut-off point in the DC load line. As a result the transistors will start conducting only after the input signal amplitude has risen above the base emitter voltage (Vbe~0.7V). This is what allows for the maximum negative modulation peaks.
A Galaxy DX-29HP is a great choice as it has dual finals, therefore, only the RF driver transistor is modulated and the dual finals are configured to function as a linear amplifier, this allows for the Asymod to run much cooler.
Can you give me a discount?
All prices are lower here at www.asymod.am on all Asymod products. Www.asymod.am is the Asymod home and official site dedicated to wideband AM and eSSB. When buying from asymod.am you are buying directly from the manufacturer and is easy. Simply select the item you want and check out via PayPal. All major credit cards are accepted.
What the does the expand, tune and alignment consist of?
What type of microphones are you using?
The Asymod equipped transceivers are mostly used in conjunction with some type of audio processing scheme, whether computer based or rack gear... Your choice. The processed audio is fed to the Line-In ¼” TS connector. The recommended microphone is a high quality studio cardioid dynamic microphone. First choice is the Electro Voice RE20, following the lower cost Sure SM7B, SM58 or similar. In the case where audio processing is not possible, and as a last resort, a hand microphone can be used. A dynamic microphone with tone controls, such as the Astatic 575-M6 or similar is recommended, but this somewhat defeats the purpose of the Hi-Fi functionality of the Asymod. KEEP IN MIND PROCESSED AUDIO GIVES YOU THE PUNCH, DEPTH, QUALITY AND BANDWIDTH THAT MAKE IT STAND OUT FROM THE REST.
To achieve optimum results and to make the most of the Asymod, an adequate AM audio process chain catered to emphasize on your natural voice is necessary.
Audio processing and a high quality microphone is REQUIRED for optimum performance. Audio processing for mobile operation is possible with the use of the iRig PRE or iRig PRO interface using its companion IK Multimedia's VocalLive Vocal Processor and Recording Studio app on your iOS device. More elaborate and sophisticated detailed third party apps are available that provide more intricate adjustments. Audio processing for base station operation is possible with the use of rack pro-audio processing gear or computer based processing such as ProTools for PC or Mac along with its companion interface such as the Mbox 2 Mini or newer.
Do you have any Hi-Fi radios that have a variable dead key?
All Asymod radios have variable dead key (carrier level) at the Asymod board’s “CAR” control potentiometer. The dead key is adjustable via the Asymod onboard CAR control. The modulation (LEVEL) and Asymmetry (ASY) controls require readjustment whenever the carrier level (CAR) is changed to maintain the correct modulation envelope pattern. Four small holes can be drilled on the radio’s cover directly aligned over the Asymod board adjustment locations. It is possible, upon request to mount these controls externally. Optionally, external units, such as, the or the can be installed. These provide front panel on the fly tuning.
Are class AB biased transistor amps the only reasonable choice for running the
Asymod? Can a class B amplifier be used?
AB is the best choice considering efficiency and performance. Class B reproduces only over half of the RF cycle, unless is a class B amp designed in a push-pull configuration which is capable of reproducing the entire RF cycle depending how it is configured. Many even use class C which reproduces less than half the cycle but this creates distortion. Class B will work but AB will work much better.
What is the best way to measure my modulation?
An oscilloscope is a real time, instantaneous RF measuring tool that can show details about a signal that a watt meter will never show. The use of an oscilloscope using an RF coupler or RF pickup device is recommended. Learn more on the NU9N site at this link: http://www.nu9n.com/scope_your_audio.html. You can make your own PC based oscilloscope by following the instructions in the following manual:
Is there a procedure to adjust the Asymod without the use of an oscilloscope?
Yes, the adjustment procedure may be done without an oscilloscope with the use of an accurate PEP meter and by following the chart seen in Fig.1 above. Note that there are differences in the direction of the controls between the Asymod III and the Asymod IIIs and you must refer to their respective Operation & Troubleshooting Guide for the correct direction to raise or lower the levels.
For the Asymod III, the Gain goes up CW, the LEVEL, CAR and ASY go up CCW.
For the Asymod IIIs, all controls go up in the CW direction.
- Turn all controls down, GAIN, LEVEL, CAR, and ASY refer to the Operation & Troubleshooting Guides.
- Set the dead key where desired by raising the CAR control.
- Raise the Level control while injecting a 1 kHz tone or by speaking into the microphone at a normal level until you see 4 times the power of the dead key on the meter. For example, if you set a 2 watt dead key, you should see 8 watts of PEP.
- Raise the Asymmetry control (ASY) to the desired modulation percentage desired according to the chart seen on Fig.1 above. For example, if you want 200% modulation, the chart says 200% modulation is 8 x the carrier power, so here you would raise the asymmetry control until you see 16 watts of PEP on the meter. Hence 8 x 2 watts of carrier = 16 watts PEP. And there. You’re done!
How can I quickly set the adjustments on the Asymod board without an oscilloscope?
Take a look at the guide at the following link or follow the instructions below:
Asymod Quick Settings (using PEP meter)
· Turn all settings counterclockwise.
· Raise carrier to desired power. For example, let’s say we want a 1 watt carrier.
· Feed 800 hertz tone or steady voice tone into line in.
· Raise the level control till you get 4 times the carrier in PEP, in this case, 4 watts PEP.
· You should now see 4 watts PEP on a true PEP meter, this is 100 % modulation.
· Last, for example, if you want 250% pos. modulation bring up the asymmetry till you get 11 watts PEP.
· Use the Modulation Percentage chart below to adjust the asymmetry (ASY) potentiometer to control the positive modulation level.
Can you explain modulation percentage in relation to headroom?
Due to headroom restrictions, the maximum dead key setting is limited by the percentage of modulation desired for a given transceiver. For example, for a single final transceiver such as a stock Cobra 29 (no MOSFET upgrade) which is rated a 16 watts PEP, to achieve 300% modulation the dead key can be no more than 1 watt. Being that the multiplication factor for 300% modulation is 15 (15 times the carrier power), we can say that 15 x 1W = 15W PEP, this leaves us with 1 watt of remaining headroom. The higher the dead key the less room available for the modulation envelope excursion to fully expand itself within the headroom barriers. Any peaks looking to go above 16W PEP will be distortion.
If a higher dead key is needed, say 2 watts, then the maximum modulation percentage is limited and will max out at about 200% on the positive peaks, let’s take a look:
We now know the multiplication factor for 300% modulation is 15 (15 times the carrier power), so we can say that 15 x 2W = 30W PEP, we can see that to achieve 300% modulation with a 2 watt carrier we need a transceiver capable of producing a minimum of 30 watts PEP and clearly a stock Cobra 29 can only produce 16W PEP.
To accommodate the 2 watt carrier, we have to reduce the modulation percentage to be well within the 16W PEP range of the Cobra 29. To do this we look at the Carrier to Peak-Envelope-Power Modulation Percentage Index Chart below where we can see that 200% modulation is 8 times the carrier power. So, 8 x 2W = 16W PEP. We can now see that to accommodate the 2 watt dead key and to stay within the 16 watt range and the headroom limits of the Cobra 29 the modulation had to decrease to 200%.
The level of dead key is inversely proportional as the modulation percentage (AM depth) increases in relation to headroom; the higher the dead key the less headroom is left for the modulation envelope. Refer to the Carrier to Peak-Envelope-Power Modulation Percentage Index Chart (Fig.1) below for more details.
Dual final transceivers such as the Galaxy DX-29HP which is rated at about 40 watts PEP can produce upwards of 200% modulation (8 times the carrier power) even at a 4 watt dead key and still have plenty of headroom left. A 4 watt dead key at 200% modulation can be expressed as 8 x 4W = 32W PEP, this leaves us with a remaining 8 watts of headroom. Remember, every time the dead key (carrier/CAR) level is changed, the modulation (LEVEL) and Asymmetry (ASY) controls have to be readjusted to maintain the correct modulation envelope pattern.
Maximum use of headroom and transmitter performance can be achieved by using the most of the headroom available without pinching at the troughs or clipping at the crests of the modulation envelope. The following Carrier to Peak-Envelope-Power Modulation Percentage Index Chart (Fig.1) provides the ratios to calculate the operating levels for a particular transmitter while staying within the headroom limitations:
To solve for the maximum dead key that can be set for a given transmitter, take the Stryker SR-955 HPC which is rated at 60 watts PEP for example, and let’s say 250% modulation is desired. By looking at the chart we can see that 250% modulation is 11 times the carrier power. So, we divide 60 watts by 11, this gives us 5.5 watts of carrier/dead key. We now see that the maximum dead key that can be used to stay within the headroom of 60 watts when modulating at 250% is a 5.5 watt dead key.
In the case where amplifier drive requirements must be met, for example, take the RM Italy HLA 300V Plus. This amplifier input is rated at 2 – 15 W.
To solve for the maximum modulation percentage allowed, and not to exceed, in this case 15W input rating, and to make the most of the amplifiers available headroom useful while sustaining a perfect modulation envelope, we need to solve for allowed carrier/dead key power and maximum modulation percentage possible without pinching at the troughs or clipping at the crests of the modulation envelope. As a starting point, let’s take 200% modulation, which is 8 x the carrier power (W). Next, divide the maximum PEP that the amplifier is able to handle by 8 to arrive at our dead key: 15W PEP/ 8 = 1.87W (round off to 2W). We now see that the maximum modulation level that we can use not to exceed the 15W input rating of the amplifier is 200% modulation with a 2 watt dead key.
Ok just so I get this correct, the Asymod will work in my Stryker SR-955HPC on SSB for 6k of bandwidth transmit and receive but not the 300 % modulation correct?
Just to clarify,
Regarding SSB, only the Hi-Fi audio from one of the audio buffer stages within the Asymod is applied directly to the balance modulator. This method allows for a SSB transmission with maximum bandwidth and provides for the Hi-Fi transmit functionality on SSB. As for SSB reception, the product detector, receive audio control section and audio amplifier have been upgraded to pass the maximum amount of audio bandwidth (~14 kHz). This allows to make the most of the SSB signal bandwidth beyond the +/-2.9 kHz stopband of the 10.695 MHz SSB filter (approaching 50 Hz ~ 4.05 kHz – eSSB Medium 1). The asymmetrical modulation function does not apply to SSB due to its suppressed-carrier characteristics. Unlike AM, where AM-Depth (modulation percentage) is the carrier to peak ratio (the relationship between the amplitude of the modulating signal and the amplitude of the carrier signal) where in regards to asymmetrical modulation the negative peaks are limited and gain is applied to the positive peaks to produce the modulation percentage desired beyond +100%. In contrast, SSB is measured in terms of peak envelope power (PEP) where the signal’s actual power is dependent upon the level of the modulating signal.
Regarding AM, during transmit, the Asymod takes over the entire transmit function. The transceiver is merely used as a frequency generator that produces the TX carrier frequency. On AM receive, the factory 3 kHz AM filter has been replaced by a 6 kHz wideband filter, the AM detector, receive audio control section and audio amplifier have been upgraded to pass the maximum amount of audio bandwidth (~14 kHz).
Q. (1 – 7 below)
I found your Asymod modulator board and I'm interested in it but I have some questions that I haven't been able to find in the documentation.
None of the Asymod radios I’ve seen have SSB. Will the Asymod work in an AM/SSB CB Radio? If it does, how wide will the SSB TX be?
Yes. There are a few multimode, AM/SSB & AM/SSB/FM radios available such as the Stryker-SR-955HPC and the Galaxy DX-955 that are not only equipped to transmit and receive Hi-Fi in AM with the Asymod, but also transmit and receive Hi-Fi in SSB, also known as eSSB.
These units are Hi-Fi capable and fully functional on both AM & SSB modes. Solid state switching is used to switch between modes (no relays or switches involved).
The asymmetrical modulation functionality does not apply to SSB due to its suppressed-carrier properties and characteristics. Only the Hi-Fi audio from one of the buffer stages within the Asymod is applied directly to the balanced modulator. This method overrides factory limitations and allows for maximum bandwidth SSB transmission and provides for the Hi-Fi transmit functionality on SSB. As for SSB reception, the product detector, receive audio control sections and audio amplifier have been upgraded to pass the maximum amount of audio bandwidth (~14+ kHz). This allows to make the most of the SSB signal’s bandwidth beyond the -3dB +/-2.9 kHz stopband of the 10.695 MHz SSB filter approaching 50 Hz ~ 4.05 kHz – eSSB Medium-1 (Fig.2).
Documentation regarding installation on multimode transceivers using the Asymod IIIs solid state switching via the REM control can be found in the Asymod IIIs Installation Manual starting on page 32. Additional installation instructions regarding multimode transceivers using relays and switches starting on page 21.
Will the Asymod work in any of the AM/FM/SSB Export Radios and in HF rigs? Examples: Galaxy DX-99V (Original model), Galaxy DX-98VHP, Stryker SR-955HPC, Yaesu, Icom, Kenwood?
Yes it will work on all AM high level modulation transceivers except for those that use vacuum tubes in the final RF amplifier stages. The Asymod is compatible with the majority of all CB and 10 meter transceivers even if they employ low level modulation methods. Low level modulation HF multiband transceivers, such as, Yaesu, Icom, Kenwood, Ten Tec, etc. require more work, but nevertheless can be done. The Asymod has been installed in multiband HF rigs such as the Icom IC-720A, IC-718 & IC-7300, Kenwood TS-930 & TS-480, and Yaesu FTdx-1200 & FT-757GX with great success.
Do the finals need to be changed in any of these radios to optimize the Asymod?
The finals do not necessarily need to be changed to MOSFETs if it is a transistor final radio, although MOSFETs are more efficient and operate significantly cooler in some cases and generally provide a bit more headroom.
Since the Asymod only works on AM, can it play well with a Top Gun CP-1 installed in the radio as well? For instance, can the Asymod be used in AM and be turned off by using an external switch and then using another switch to turn on the Top Gun CP-1? Perhaps a SPST On/Off/On switch configured as such: Asymod (On) / All processors (Off) / Top Gun CP-1 (On).Using this type of switch may ensure that the Asymod is never turned on while say a Top Gun CP-1 is also installed in the radio? Can this configuration work?
The Top Gun CP-1, could be installed aside the Asymod with some kind of alternate switch over scheme. Once the Asymod is installed, the factory TX audio and modulator circuits are completely disabled, literately completely taken out of the circuit and the Asymod takes over. At this point the radio is only used to generate the transmitting frequency and as a receiver, in contrast, the Top Gun CP-1 is an add-on to the factory modulator. Installing both with the switch over functionality will certainly take some extra work but can be done.
What would you charge to set up my Galaxy DX-98VHP radio with the Asymod and a Top Gun CP-1 installed in it? I'm asking because the CP-1 works in AM, FM, and SSB so this would be the best of both worlds.
The Asymod Installation on SSB transceivers is $175 (Installation on AM only radios is $150). Top Gun CP-1: $20 and installation $40.
If finals need to be upgraded in these radios, exactly what needs to change and what would it cost for you to swap them out?
There is no need to replace the finals unless is a transistorized single final radio to increase headroom. MOSFET upgrade for Cobra 29s is $45. We do MOSFET upgrades as per customer request.
Can you provide any additional information about the Asymod in most popular older and new CB and 10 Meter radios? Please let me know.
Pertinent Asymod information and the radios it is installed in can be found in the installation manuals. Installation manuals are created as the Asymod is installed into different models of transceivers. You can find installation instructions for the Stryker SR-955HPC on page 32, 34 and 7 and for the Cobra 2000GTL on page 41 of the Asymod installation manual. Installation instructions can be requested for specific transceivers after Asymod purchases. For all downloadable manuals available, go to our DOWNLOADS section.
Can you reduce the price on one of your Asymod and Galaxy DX-29HP unit on Ebay?
All prices are lower at www.asymod.am on all Asymod products since we are the manufacturer. Asymod prices on eBay can’t be reduced further due to the imposed high eBay seller fees. Asymod.am is the Asymod home and official site dedicated to wideband AM and eSSB.
Will the Asymod work on a RCI 2950 in SSB mode??
The asymmetrical modulation functionality does not apply to SSB due to its suppressed-carrier characteristics. Only the Hi-Fi audio from one of the audio buffer stages within the Asymod is applied directly to the balance modulator. This method allows for a SSB transmission with maximum bandwidth and provides for the Hi-Fi transmit functionality for eSSB. As for SSB reception, the product detector, receive audio control section and audio amplifier are upgraded to pass the maximum amount of audio bandwidth (~14 kHz). This allows to make the most of the SSB signal bandwidth beyond the +/-2.9 kHz stopband of the 10.695 MHz SSB filter (approaching 50 Hz ~ 4.05 kHz – eSSB Medium-1).
What are we looking at installed turnkey if I send you my Ranger RCI-2950? I'm in Huston, Texas.
Asymod Installation on SSB transceivers is $175, AM only transceivers is $150. Turnaround is about 2-3 days, excluding shipping time. Please include prepaid return USPS shipping label or add $19.50 for mobile radios or $49.40 for base station radios to the total for shipping.
Once you decide to proceed, submit the settings required to email@example.com, then a listing will be created for you at www.asymod.am. At that point you would simply sign up and log in at www.asymod.am and purchase your installation package for your transceiver that was created for you. Once check out is completed, you will receive an email with the shipping instructions.
Alternatively, send payment to and submit the settings requirements to or via PayPal. Once payment is completed, you will receive an email with the shipping instructions.
Any updates on the Asymod TS an Asymod HP?
The Asymod TS, Asymod HP and are currently available as of July 2019.
Can you share some info yet about your Asymod 6? I am currently using your Cobra 29 Classic LTD with external rack gear. Can’t wait for an Asymod radio with more headroom.
The new Asymod 6 will be more versatile in the sense of compatibility and ease of installation on multimode as well as on AM only transceivers. It has all the same features as its predecessor, the Asymod IIIs, with features such as: solid-state-switching control mainly for use on multimode transceivers, a more simplified internal voltage source design for the positive and negative rails and an onboard preamp. It will also include input and output filter networks and added RF suppression making it less susceptible to free running currents and RF interference. It will also have a better high voltage source rated at 4 amps.
The new Asymod 6 improvements and functionality include: Better carrier stability under high temperature conditions, enhanced RF suppression, zero cross-over distortion and audio jumpers for quick configuration. Also, a Balanced Modulator auto mute function has been added. The Balanced Modulator auto mute function is needed in HF multi-band / multi-mode transceiver installations to remove the TX audio at the input of the Balanced Modulator while on AM, and allow audio to flow while on eSSB.
Why should I choose the over the Asymod 6?
In addition to all of the Asymod 6 features, the Asymod ES is fully loaded including an on-board compressor, limiter, 3 band equalizer, noise gate, a 6 kHz active second-order 40dB/decade (12dB/octave) stop band roll-off filter and accepts balanced and unbalanced microphone inputs as well as a line input that both can be used simultaneously in mix mode. Now you can have that great sound without external computer based or rack gear audio processors!
Hate using a dirty class C amplifier as a driver, can I use a class AB amplifier?
Absolutely yes, a class AB push-pull amplifier will reproduce your original signal more linearly and your audio will sound a lot cleaner. For Hi-Fi audio a class AB is a better choice and is much better than a class C that only conduces less than 50% of the input signal and the distortion at the output is high.
I would like to order a radio with the Asymod installed that you don’t have listed. How can I go about this and how much is it?
You may order any transceiver you like and we will install the Asymod in it. Send the request with transceiver brand, model number, your name, phone number and email to and a listing will be created for you at www.asymod.am. Once the listing with your transceiver of choice is listed in www.asymod.am, you can log in and purchase it. At that point your transceiver of choice will be ordered and the Asymod will be installed in it. Please allow about a week to prep the unit.
I see all the Asymod products here on Facebook but where can I buy them?
Can you tell me what is it that makes the Asymod more practical over other AM modulators and its predecessor the Asymod III?
The Asymod, being a self-contained compact designed unit, only requires only a 12 volt supply and very simple installation without the need for external power supplies and other external connections prone to RF interference. This allows for internal installation in the transceivers, making this unit very practical for mobile operation using audio processing, such as the iRig PRE & iRig PRO interfaces using the companion IK Multimedia's VocalLive Vocal Processor and Recording Studio app on your iOS device that allows use of iOS devices such as the iPhone, iPads and iPad Mini as audio processors.
You may review the for additional information.
To watch Asymod , .
Quick question, does the Cobra 29 LX BT receive or only transmit in Hi-Fi? This unit will be around a lot of RF. Is there a way to shield it better?
The Cobra 29 LX BT equipped with the Asymod transmits and receives, both, in Hi-Fi. The receiver is equipped with a 6 kHz wideband AM filter and audio section has been upgraded to pass all the frequencies within the 6 kHz bandwidth. A good quality full range external speaker is recommended for best results. The COBRA 29 LX BT & Asymod setup is already configured to withstand harsh RF environments and include RF suppression, low pass filters at input and output and RF bypass capacitors at all Vcc junctions and audio paths. No RF interference related issues have been reported. A good rule of thumb is to make sure if you are using an RF power amplifier that is well grounded and use ferrites on all audio and USB wires.
I am new to the Hi-Fi. What else do I need to buy to get this operating? I was thinking REA AMM-SD1 Series - Amplitude Modulation Monitor / oscilloscope into my Laptop. Do you have any setups with ProTools? Is this program free? And as far as a microphone what would u suggest? I guess if u could put together a starter kit list that would be great. That way I'm ready to go.
At the moment there is no complete starter kit available. A typical complete Hi-Fi setup requires the following:
1- A high quality microphone, such as, an Electro Voice RE20 or similar with shock mount and desk boom.
2- Audio processing gear, could be computer based like ProTools or the iRig PRE or iRig PRO interface using its companion IK Multimedia's VocalLive Vocal Processor app on your iOS device or studio rack mount audio processing gear.
3- An RF power PEP meter with a low scale, say, 20 ~ 50 watts to monitor the transceiver power output.
4- An oscilloscope to monitor your modulation envelope and assure you are not pinching or clipping and an RF coupler which is a device that takes a sample of the RF signal from your transmission line to supply the oscilloscope, otherwise you can simply use a RF Sampler Element for Bird 43 watt meters such as a Bird 4274-025 or a Coaxial Dynamics CDI 87005 (seen on page 3, FIG 8B in the . The PC based REA AMM-SD1 Series - Amplitude Modulation Monitor would be a good choice since it has negative & positive modulation percentage meters, oscilloscope and it comes with its RF pickup unit.
5- A good AM receiver with a 6 kHz bandwidth along with a good set of headphones to monitor yourself.
6- An HF, RF power amplifier (Class AB preferred, class C can be used but is not as clean as it passes less than 50% of the signal).
7- If using computer audio processing with Protools, the ProTool sessions are free and available for download at the following link:
The latest ProTools and its most current interface are available and are not free. The most widely used version of ProTools for this application is ProTools LE version 8.0.5 which is an older version and it can be downloaded from the Avid website and requires the Mbox 2 Mini external interface that can be found on eBay. The microphone connects to the Mbox 2 Mini, the audio output of the Mbox 2 Mini is then connected to the transceiver’s rear Line In connector, the Mbox 2 Mini connects and is powered via a USB connector to your computer and controlled by ProTools.
You can always just use a good microphone like an EV RE20 connected to the microphone front panel input and it will give you the Hi-Fi asymmetrical modulation and quality, but it is always best to have some type of audio processing to bring out the best in the voice. It makes a big difference.
I will ordered a Asymod Galaxy DX-939 and soon need to see what my driver amp can take power wise as it is a low drive amp. Does the 939 have MOSFET finals?, also, once its preset can the carrier be set from inside?
The Asymod ready transceivers are sent out per customer requirement specs and amp drive requirements. The Asymod can be set to any carrier level required, but the audio Level and Asymmetry controls have to be adjusted to match the carrier set to render the desired modulation level and PEP power which requires an oscilloscope to do it correctly. So, yes, it can be done from the inside. In some cases customers have requested the or the .
Can I send you my radio for installation of the Asymod? How much would you charge to do it and how long will it take? Thanks.
Asymod Installation on SSB transceivers is $75, AM only transceivers is $50. Turnaround is about 2-3 days, excluding shipping time.
Once you decide to proceed, submit the settings required and your PayPal email address to and you will receive a PayPal payment request. Once payment posts, you will receive an email with the shipping instructions.
Alternatively, send a PayPal payment to firstname.lastname@example.org and submit the settings requirements to or via PayPal. Once payment posts, you will receive an email with the shipping instructions.
NOTE: Please include prepaid return USPS shipping label or add $19.50 to the total for shipping.
I’m having trouble installing ProTools 8.0.1 and the update 8.0.5 on Windows 10, any suggestions?
ProTools 8.0.5 runs on Windows 10 with no issues. If you have partially installed anything related to ProTools, uninstall it using the uninstaller or Revo Uninstaller and start fresh. First install version 8.0.1, when done install the 8.0.5 update, and last, install the plugins.
Can you please provide the link for the ProTools sessions?
I’m currently using an electret/condenser microphone and I can’t get rid of the feedback when I monitor myself on a receiver with my headphones.
The first thing is to adjust the gate threshold levels in the multiband dynamics, specially targeting and attenuating those frequencies that are feeding back as seen on the spectrum analyzer and use headphones with close fitted snug muffs and are well acoustically insulated. Most electret microphones are very rich in highs and are easily prone to generating feedback. A better choice would be a dynamic cardioid microphone with a more flat response.
For help with eliminating feedback go to page 11 on the .
Can I use a condenser microphone with the ProTools interface?
Yes you can. The Mbox2 Mini and other ProTools interface devices provide phantom power which is required for condenser/electret microphones.
I think I’ve got the hang of this. I just saw a video gate out from a local operator of me and I’m not sure if the very low carrier is supposed to be like this. But I’ll tell you, it sounds killer. The only thing is I’m using my amplifier’s power supply to power the radio and it is giving me a humm. Should I use a separate supply for just the radio?
If you hear a low humm while you monitor yourself on a receiver it doesn’t necessarily mean it presents a problem. In most cases the quality of the receiver or the close proximity of transmitter/receiver causes this effect the majority of the time and is not likely to be heard by other stations at a distance. If you know for sure you have a power supply induced humm, use a linear well filtered supply just for the transceiver. If running an amplifier, use large enough ferrites where you can wind 2 or 3 turns on all audio and data/USB cables to avoid software crashes and audio hum, and of course, always use a very good ground.
Looking at a video gate from a local operator of me while I was using the Cobra 29 LX BT with my two amplifiers, I noticed his S meter is only showing a swing but no carrier. Not sure if the very low carrier is supposed to be like this. But sounds great. Let me know thanks.
Transmitter and amplifier matching is very important. It looks like you are not driving your amp sufficiently, or if the amp has an input attenuator (a variable control) most of the time the 1 watt dead key/carrier is mostly dissipated in the amplifier’s input attenuation network and doesn’t allow for proper drive. If you are running cascading amplifiers, or one amp driving the next, monitor the output of the first amp in line. Make sure the radio’s 1 or 1.5 watts of carrier is driving it enough to get a nominal carrier out of the amp. Start with a simple setup and work yourself up to a more complex setup once you’ve got all the right settings, this will simplify things and eliminate the guess work. To do this correctly an oscilloscope is required. Refer to the NU9N page “Scope Your SSB and AM Audio Modulation, Amplifier and System Linearity” at http://www.nu9n.com/scope_your_audio.html.
Run the radio by itself first, make sure you have 1.5 watts carrier peaking to 10 watts (about 160% modulation) and audio is right. Then, install the first amp, make sure when you dead key a 1.5 watt carrier out of your radio you are getting a proportional carrier out of the amp, modulate and check for headroom. Maxing out your amplifier will degrade modulation quality. Once this setup is perfect and it all checks out on the oscilloscope, you may move on to installing your final amplifier and repeat the same previous steps, check carrier level, modulation and make sure to maintain sufficient reserved headroom for each individual amplifier. Make sure all amplifiers are operating within their headroom range with ease and no one amplifier is overdriving the next stage.
For best audio use class AB biased amplifiers, class C amplifiers merely pass 50% of your signal and distortion is high.
Where can I find Asymod related information?
Click on the "Downloads" button on the main menu at the top of the page.
I love the Galaxy DX-959 with the Asymod III I purchased from you. Can you do a RCI-2970N2?
Yes, the Asymod can be installed in the RCI-2970N2 and in any high-level modulation radio with ease. Low-level modulation radios require more work such as most HF multiband transceivers, from the oldest and lower cost such as a Yaesu FT-757GX to and Icom IC-720A to the high end such as the Yaesu FT-9000, Icom IC-7851, etc. The only true exceptions are hybrids with vacuum tube PA’s, vacuum tube transceivers where Plate, Grid, or Cathode modulation methods are employed.
I can’t seem to download the ProTools session files, the links are not clickable.
If the links are not clickable or hyperlinking to the download page, simply copy each link and paste it in your internet browser address bar and press enter. This will take you to the download page where you will see a message that says "Whoops! There was a problem with the preview". Ignore that and click on the blue download button. Then it will say "Goggle Drive can't scan this file for viruses". Ignore that too and click on the Download Anyway blue button. Then you'll be prompted to save it. Click on the down arrow next to "Save" and select "Save As", then save it to a dedicated folder, you can call it ProTools. Do the same for the other links and save them all in this same folder.
I love the Asymod ready Galaxy DX-959 I purchased from you. Can you do a RCI-2970N2?
Glad that you are happy with your Asymod ready Galaxy DX-959. Yes, we can put a Asymod ready RCI-2970N2 or a Stryker SR955HPC together for you if you like. The only exceptions are hybrids and other tube final HF multiband transceivers, such as, the Yaesu FT-101 series, FT-102, Kenwood TS-820S, and even then it is possible, it just takes a lot more work.
Can you install the Asymod on any radio?
The Asymod can be installed internally in any radio as long as it has the space, otherwise it has to be mounted externally. There are very few exceptions.
I need the Asymod installed in a 10 Meter radio as I talk below channel 40 aka the basement with my local people.
Currently the two most popular 10 Meter radios and are readily available with the Asymod are the Galaxy DX-29HP, RCI-2970N4 and the Stryker SR-955HPC, but you can choose any radio you like and it will be ordered and set up with the Asymod for you. Simply, send your request to with the details and a listing will be created for you. You would then purchase your listing. At that point, the radio will be ordered and set up with the Asymod within a week and a half.
Can you put extra channels in the Cobra 29 LX BT or any radios you offer? If not can you install the Asymod on a radio I have already installed the expansion board? And how much is that cost?
Yes, extra channels can be added to the Cobra 29 LX BT or any other radio of your choice. The channel expansion board and the Asymod will be installed for you. To send in your radio see the Mail In Instructions above,
Hi there, I cannot find your PayPal account email address. Can you let me know your PayPal account email address so I can send payment?
I am located in Austria. Is a longer broadcast with your Stryker SR-955HPC possible (heating)?
Does it work with any HF amplifier (12/10m band) or do you recommend one?
Nominal settings for the Asymod and the Stryker SR-955HPC on AM are 3.5 watts of carrier power and modulation at 250% which produces ~32 watts of peak envelope power. This unit is rated at 60 - 70 watts PEP, so that leaves plenty of headroom to operate it on longer than long winded, two way conversation typical duty cycles. 100% transmit duty cycle is possible with an external cooling fan at this setting.
You can order any combination of carrier level and modulation percentage. Max recommended carrier level is 5 watts for long duty cycles, but can go as high as 10 watts (not recommended for long duty cycles). Each carrier/modulation percentage combination setting has a directly proportional PEP output. Modulation percentage factor multiplied by carrier equals peak envelope power output. The factors and ratios are listed in the item description and in Fig.1 above.
A class AB amplifier operating in the rage of 12/10m band or any broadband 1.8 to 30 MHz amplifier will do. Headroom on the amplifier is also very important to maintain clarity and avoid distortion. If you already have an amplifier, provide make and model and the best settings for the Asymod and the Stryker SR-955HPC will be recommended. Otherwise with these settings it would work well with a 600 to 1000 Watt tube amplifier. If using a solid state amplifier, the drive requirements will very important since these amplifiers are less forgiving than tube amplifiers. Levels on the Asymod must be set accordingly to stay within the amplifier’s operating limits while preserving headroom. You can always adjust the Asymod yourself to match any amplifier drive requirements.
How can I send you more information including some PDF files regarding my setup since eBay doesn't allow exchanging email addresses through their message system?
You can contact us at email@example.com. This is the customer support email for all Asymod products and is displayed at the end of all demo video presentations.
I have a small problem. I’m running the Asymod III, not the newer Asymod 6. Is there a way to turn up the dead key? I'm having trouble activating (keeping the relay open on) my amplifier? Help!!
Yes there is. The right way to do this is with an oscilloscope. If you have a good ear, you are welcome to try without one. The dead key can be raised by turning the CAR control counterclockwise on the Asymod III. Once the dead key is raised to the desired setting, the audio has to be raised accordingly to achieve 99% negative peaks. The audio can be raised by turning the Level control counterclockwise (Asymod III). If the Level control is maxed out (counter clockwise position), then you can either raise the audio level from your audio gear or you can slightly raise the Gain control on the Asymod III. Last, you set the asymmetry level to render the modulation percentage desired. The ASY control increases in the counterclockwise direction, you will notice as more counterclockwise, the higher the peaks, don't overdo it because you don't want to exceed ~250 % modulation. Whenever the carrier is raised the asymmetry has to come down. (Don't move it too far from where it is at now, take a picture of the controls in case you go too far off you'll know how to set them back.) Recommend from 200% to 250% for voice. For audio with music content 120% to 130% (MAX) is recommended.
I’m running the Asymod 6, how can I turn up the dead key? I can’t seem to key my amplifier?
Refer to the starting on page 11.
Still evaluating the Stryker SR-955HPC with the Asymod. It is all good, but I’m thinking of raising the dead key.
If you raise the dead key, the audio level will have to be raised just a bit to reach very close to the negative 100% modulation peaks and the asymmetry control adjusted to reach the positive modulation peaks desired. Follow the instructions in the .
What are the recommended Asymod asymmetrical modulation levels for playing audio content with music?
Recommended settings for audio content with music is no more than 125% positive modulation (MAX) is recommended. For voice 100% and up, however, 200% to 250% is a good range.
Asymod: We are almost done with your Asymod Stryker SR-955HPC. We would like for the unit to arrive with the correct settings to match your setup and amplifier drive requirements. To avoid future issues, please provide the level of carrier and modulation percentage you would like so that we can make all the final adjustments before sending it out.
1.5 watt carrier and all you can get I guess 250%?
With a 1.5 Watt carrier at 250% modulation the PEP is only going to be 15 watts. Unless the amplifier drive requirements call for 1.5 watt carrier, it is suggested to get the most out of it since the Stryker SR-955HPC is a high power radio and offers plenty of headroom. Carrier can be as high as 5.5 watts @ 250% mod / 55 watts PEP. At the moment it is set conservatively at a 4 watt carrier, 250 % mod producing about 33 watts PEP.
The reason why I ask is because operators sometimes have the need to raise the carrier after they receive their units and the Asymod requires audio and asymmetry level adjustments every time the carrier is changed that are best done with an oscilloscope. Please confirm you still want the 1.5 watt carrier.
Leave it at a 4 watt carrier, 250 % mod at 33 watts PEP. I will use the amplifier’s variable attenuator to set it where is best.
To run the Asymod radio in a mobile how will I get my audio processing? Will I have to use a laptop and download ProTools?
Not necessarily, bellow are related links to some YouTube videos where other portable audio processor methods are implemented well suited for mobile operation .
iRig YouTube links
Can I use a good quality microphone connected to the front mic jack with no processing?
You can always just use a good microphone like an EV RE20 connected to the microphone front panel input jack and it will give you the Hi-Fi asymmetrical modulation and quality but very flat, however, not only does this defeat the purpose of a Hi-Fi setup but should only be used in this manner as a last resort and in case there is no audio process gear available at that moment. It is always best to have processed audio fed at the Line-In ¼” TS connector for this system to sound as it is meant to. This will enhance the voice, giving it depth and significant dynamics which makes it stand out and makes a very significant improvement in audio quality.
Once the Asymod is preset, can the carrier be set from inside?
All Asymod ready transceivers are set to the customer’s required specs. The Asymod can be set to any carrier level required, however, the audio Level and Asymmetry controls will require readjustment whenever the carrier level is changed. This requires an oscilloscope to ensure the modulation envelope is correct. So yes, it can be done from the inside. In some cases external Asymod controls have been requested.
Where can I download the ProTools sessions?
By clicking on the "Sessions" button on the main menu at the top of the page.
Where can I find the Asymod manuals?
By clicking on the "Manuals" icon under the home page slider.
I would like the AM carrier on my Stryker SR-955HPC to be 15W max swinging to the maximum possible to drive my amps. I have 2 custom 6 pill, 2879 amps and 2 ICOM ham amps. 150 to 200% modulation or your best recommendation with this equipment. Wide open on SSB also please. Looking forward to this and thanks for the info. Also, what would be the best voltage for the Stryker SR-955HPC? I can run up to 15 volts. Thanks again.
Let’s take 200% modulation as a starting point. 200% modulation is 8 times the carrier power. This radio is rated at 60 watts PEP max. (Although some claim it does a bit more, perhaps with higher voltage. The Stryker SR955 is designed to work on a 13.8 volt DC supply, I wouldn't recommend anything more.)
To calculate the highest carrier possible and to still be able to achieve 200% modulation within the available headroom we have to divide the maximum PEP power available (total headroom PEP watts) by 8 (multiplication factor for 200% modulation). Available headroom is 60 watts PEP.
60 divided by 8 = 7.5 watts
So this tells us the maximum carrier level that we can use to preserve the headroom needed for the 200% modulation, in this case is 7.5 watts of carrier power. At this setting you will have peaks of 60 watts with a 200% clean modulated signal. This setting will work best for you in sight of your high drive amplifiers as the Icom IC-2KL, IC-4KL, IC-PW1 which can handle ~80 – 100 watts PEP of drive and your straight 6 x 2SC2879 that can handle ~60 watts PEP of drive.
What is the most frequently and highest requested dead key settings for the Stryker SR-955HPC?
1.5 watts @ 250% mod, 16.5 watts PEP is the most popular setting, and the highest carrier that has been ordered is 4 watts at 250% modulation which renders 44 watts PEP.
Hi there! I have been following your new product with interest! I had a couple of questions for you.
I have a Stryker 955 and I wanted to add the Asymod to it. Can I pay to have it installed and set up by you or would I need a third party to do this for me? Do I leave it as set up when it's installed in my radio or can I turn it down from the mic gain up front if needed? Lastly what is the warranty on your product?
You can send your Stryker in and the Asymod will be installed for you.
Asymod Installation on SSB transceivers is $75, AM only transceivers is $50. Turnaround is about 2-3 days, excluding shipping time. Please include prepaid return USPS shipping label or add $19.50 to the total for shipping.
Simply submit the request with all the details; brand, model, etc. to firstname.lastname@example.org and we will respond with the total. At that point you may send the PayPal payment to email@example.com. Once payment is completed, you will receive an email with the shipping instructions.
All of the adjustments on the Asymod board are strictly for AM only, except the “PRE” control potentiometer when used for eSSB. You can request specific dead key/carrier and modulation levels required to match your setup. Line level audio from a preamp, mixer or audio processor can be fed via the rear Line-In connector. Microphone level input using the hand mic or other mic can be fed via the front mic connector. The Mic Gain control is ONLY active when using the front mic connector. Internal adjustments to the Asymod unit can be done by you, however, it is recommended to use an oscilloscope following the instructions on the downloadable Asymod Operation & Troubleshooting Guide and Installation Manual. Here is the download link:
As for SSB, you can use the Mic Gain if using a mic connected to the front mic jack, otherwise if using the Line-In there are two internal adjustments, SSB Limit and SSB Input Gain.
The Asymod is warrantied for life. Any damage or repairs directly to the Asymod board are fully covered. Shipping both ways is not covered.
Hi, curious on how much to have the Asymod installed in a CRE8900/ ALINCO DX10 (same radio) or Ranger 2950DX both new in box. Both radios are the V3 version. Any difference in price for install? Quote for both installs? Another quick question, what do you do with the variable power output knob on the radio? Would these now be obsolete or would they still be operational? Thanks Dave.
Installation on multimode radios is $175, on AM only radios is $150. The variable power output knob on the radio will be functional for FM mode if applicable and depending on how the radio is factory wired which varies from model to model, but not for AM, as all the AM settings are on the Asymod board.
Where can I find and download Asymod manuals and related information?
All manuals can be found and downloaded by clicking on the “” link at the footer of the www.asymod.am home page.
Direct link to all manuals:
Can you provide a complete list of the items it would take to make your Asymod ready radios to work properly, like for instance, you say it would work well with the Electro Voice RE20, and how about the other equipment that goes in-line with that. And, if you would, let me know where I can get these items.
A- For audio processing get the Mbox 2 Mini, about $50 on eBay. (This is the Audio interface Pro Tools requires).
B- Download Pro Tools 8.0.1, Pro Tools 8.0.5 Updater, plugins & Pro Tool sessions.
Option 1 - Best deal, best quality
- Electro-Voice RE20 Microphone Kit with Shock Mount & Two-Section Broadcast Arm complete package deal. (eBay)
Option 2 – Cheap but good quality, need desk boom, etc.
- Shure SM58-LC Dynamic Unidirectional Wired XLR Professional vocal Microphone. (eBay)
Option 3 - Good but expensive, mic only, no boom, shock mount, or cables, etc.
- Shure SM7B (Cardioid Dynamic Vocal Mic). (eBay)
D- Headphones with close fitted snug muffs and are well acoustically insulated so they don’t feedback to monitor yourself on a receiver while you transmit.
- PIONEER HDJ-1500-S PROFESSIONAL PRO DJ HEADPHONES. (eBay)
E- A Hi-Fi wideband receiver
- Drake R8 Shortwave AM SSB Ham Radio Receiver eBay item number: 391535838952 (Or similar, Icom, Kenwood, etc). (eBay)
F- Oscilloscope at least 30 MHz
- TEKTRONIX 2236A 100MHz (Will do the job, cheap and working). (eBay)
H- Coupler for oscilloscope
- Variable RF Sampler Model RF-S2K or similar. (eBay)
Otherwise you can simply use a RF Sampler Element for Bird 43 watt meters such as a Bird 4274-025 or a Coaxial Dynamics CDI 87005.
- Bird 43 Wattmeter Sampler Coupler Element 25-1000 MHz. (eBay)
Make your own as seen on page 3 on Fig 8 of the Asymod Operation and Troubleshooting guide.
Hope this helps
Do you mean I will have to have my computer inline for all of this to work properly? And what you are saying, Pro Tools controls all of this? Do you think CBers will understand all of this? Not hardly.
All radio operators doing Hi-Fi use one form of audio processing or another and knows audio processing gives you the punch, depth, quality and bandwidth that make it stand out from the rest. Whether it is computer based or a standalone unit.
If you don't want to use a computer, you can use something as simple as a Behringer Eurorack MX602A mixer console that contains the basic equalizer and level controls that goes for about $40 on eBay with the Sure SM58 microphone but this leaves you without out compression and multiband limiting, etc.
A complete standalone processor that provides Proper Balancing of Audio Amplitude Equalization is the Behringer DEQ-2496. Read about it regarding AM processing in the following link:
Another way you can process your audio is by using the iRig PRO. Take a look how others use it in the following videos:
Most of the CBers that are into Hi-Fi radio today did not known the details of the setup until they got into it. They learned and applied themselves because they are interested in sounding great.
And, yes, Pro Tools controls your audio levels and audio processes.
Would it be possible to order the Stryker SR-955HPC with the Asymod installed in a separate enclosure so I can control the Asymod? Also I run all my processed audio thru the regular mic jack. Can you set this radio up like that? Thanks.
Yes we can. Take a look at the optional external units, such as, the or the can be installed. These provide front panel on the fly tuning.
Otherwise, setting up the Asymod externally in any other manner other than the HDMI approach currently used, will require quite a bit of external wiring that can be prone to RF interference and ground noises. Wiring for audio out, audio in, modulator out, SSB audio in, SSB audio out, mode control wires (AM, SSB, FM), TX 8V, PTT and +12V would have to be installed at the rear panel. As you can see the Stryker SR-955 HPC is somewhat limited in space at the rear panel.
May I suggest drilling 4 small holes on the bottom cover aligned with the 4 adjustment VRs on the Asymod board if the Standalone Unit is not at your reach. This way you have access to all the controls with the use of a tuning wand without all the external connections. Another alternative would be to have only the control VRs mounted in an external enclosure.
Is the Stryker SR-955HPC the radio to go with as far as the receiver or would you recommend a different radio. I would really like to have the Asymod in the separate enclosure due to the place the radio will be mounted. I don't talk sideband so that's not an issue to me. I talk only AM. Suggestions?
The best option is the Stryker SR-955HPC with the or the . As far as the receiver, The Stryker 955 is super stable and better built than most other similar radios. Most SSB users use this radio because of its frequency stability.
Also can you put a 9 kHz filter in it?
I can put a 7.5 kHz filter in it. That is the widest we have at the moment. That bandwidth is actually 7.5 kHz UP and 7.5 kHz DOWN, a total of 15 kHz. Anything wider you will be hearing the adjacent channels.
Can I still use the front mic jack to inject my audio into the radio? How much to put the VR's in a separate enclosure and use the 7.5 kHz filter? Total?
Yes you can, however, the rear Line-In should be used for Hi-Fi applications as it is a direct feed to the Asymod. The front mic jack audio passes through the transceivers mic preamp, and although the transceivers mic preamp has been upgraded to pass wideband audio, it still has some factory limitations. Otherwise, you can inject your audio via the 4 pin mic jack as you might be doing with all your other radios and see if you are happy with the results before you try using the Line-In at the rear panel.
Does the Stryker SR-955HPC have a relay on the back of it to run an amplifier like an RCA jack? Also does this radio have the MARS/CAP frequencies thank you?
Yes an internal amplifier key relay may be added for an additional cost, the jack will be a RCA connector on the rear panel. The MARS/CAP frequency expansion will be done at no charge. Coverage is from 24.000 MHz to 30.0150 MHz.
Hello: I would be using the ON AIR DESIGN box for my audio inputs. Can I use their PTT instead of the mouse you have? I use a very simple set-up with a Behringer 1002 and either a Heil 781 or Shure 58 and simple 1K amplifier with 2 watts DK and 12 peak RMS. Thank you for your time.
Yes you can. As it applies to the Stryker SR-955HPC, simply feed the audio from the On Air Design box into the Line-In at the rear panel of the radio and key the radio by the front mic jack or the rear panel with the PTT signal coming out of the On Air Design box. You might need to split the output of the On Air Design box into audio and PTT. The rear Line-In should be used for Hi-Fi applications as the front mic jack audio passes through the transceivers audio preamp, and although it has been upgraded to pass wideband audio, it still has some factory limitations. Otherwise, you can simply connect the On Air Design box directly to the 4 pin mic jack as you do with all your other radios and see if you are happy with the results before you try using the Line-In at the rear panel.
I would like the carrier on my Stryker SR 955HPC to be set at 50W max, swinging to 100W to drive my amps. I have 2 custom 6 pill 2879 amps and 2 ICOM ham amps. 150 to 200% modulation or your best recommendation with this equipment. Wide open on SSB also please. Looking forward to this and thanks for the info. Also, what would be the best voltage for this rig? I can run up to 15 volts. Thanks again, Bob.
200% modulation is 8 times the carrier power. This radio is rated at 60 Watts PEP max (although some claim it does a bit more, perhaps with higher voltage. The Stryker SR955 is designed to work on any 13.8 volt DC supply, I wouldn't recommend anything more.
To calculate the highest carrier possible to still be able to achieve 200% modulation we have to divide the maximum PEP power by 8.
60 divided by 8 = 7.5 Watts
So this tells us the maximum carrier level that we can use to preserve the headroom needed for the 200% modulation, in this case is 7.5 Watts of carrier power. At this setting you will have peaks of 60 Watts with a 200% clean modulated signal. This is my recommended setting in sight of your many amplifiers.
Are your six pill amps 6 straight or 2 x 4? As for the Icom amps they can handle about 80 – 100 Watts of drive: IC-2KL, IC-4KL, IC-PW1,
I must tell you I have done many of these units and the highest carrier that has been ordered by customers has been 4 Watts at 250% modulation which renders 44 Watts PEP.
Refer to the carrier to PEP modulation index chart above.
As for SSB, will set to nominal output: ~60 Watts PEP.
Would a Behringer 802 and Shure SM-58 work and sound at least as nice as the Pro Tools audio processing used in making of the Asymod videos? I don't own a computer and have no intentions of purchasing one so, Pro Tools is not an option. Hypothetically, would an amp’s class adversely affect the transceiver and (bandwidth and sound) in either AM or SSB? I don't currently own a scope but as you know their cheap and readily available. I'm not sure if you could see my purchases over the past two years but if so you'd know I'm not a tire kicker or dreamer. My knowledge of wide bandwidth 11 meter transceivers is limited to what I learned from internet research. All I ask is honest answers to my questions. I'd like to own a nice sounding AM SSB transceiver without having to put it together myself. Lack of time and knowledge both being a factor. Thanks for your time. Frank.
Yes it will work, but I’m afraid not nearly as good as Pro Tools. The Behringer 802 is not a processor, therefore you will have no compression or limitation control which is essential in a Hi- Fi setup.
Amplifier bias classification will have a very significant effect when it comes to perfect reproduction of natural audio reproduction. In the since that a class “C” will not reproduce anymore and actually less than 50 % of your original signal, both in SSB and AM (more noticeable on SSB), your originally & perfectly modulated signal will be limited much in the same way as HD video is reduced from your HD TV in comparison to standard video at standard definition video broadcast quality on a standard TV. AM and eSSB are two different subjects all together.
Hello I'm interested in your product. Do you sell the parts kits unassembled for the Asymod devices? If so could you send me a quote for one?
At the moment the Asymod 6, ES, TA and HP are available. Currently all Asymod boards and products come assembled and tested. You can browse through the at our site. The Asymod boards are sold separately or preinstalled in all Asymod ready transceivers. You can, however, install the Asymod board yourself.
The installation instruction for a Galaxy DX-2517 can be downloaded
at the bellow link which is very similar to the RCI 2995. Instructions will be
provided for your transceiver of choice upon request.
The Aymod ES is an Asymmetrical Hi-Fi AM Modulator with Noise Gate,
Compressor / Limiter, 3 band graphic EQ, accepts balanced or unbalanced
microphone input connection and offers two pole active low pass filters.
You can send in your transceiver and we can install the Asymod on your transceiver of choice except for tube and tube hybrids transceivers.
To order Asymod boards on kit form, please with the details.
Hey, wanted to say thanks. My Stryker SR-955HPC arrived safe and
sound and all is good. I’m going to bring the SSB power down. Should I set the
radio to max TX power to do it, and does it matter if I adjust the W13, or the
pre on the board, or if I adjust both? Alright so I opened the radio up and
before adjusting, put it on a meter to check things out. The am dead key is
1watt but only swings to about 3 watts. When I turn my amp on, there is a
squeal and the needle deflects full power, but shows no indication of any power
on the radio display. I moved the AM power pot and it made no difference on any
meter. Any ideas?
Pardon the Dosy, the radio does the same on my Bird. What do you think?
On AM, yes, your SR-955 was set to 1 watt, (at 100% modulation a 1 watt carrier will give you 4 WPEP) this is perfect to drive your 1 x 4. Make sure you have enough audio going into the radio if you are running audio gear bring your level up. I've come across this issue where the true PEP is not displayed on some meters with many customers. Is your Bird equipped with a PEP kit? Is the Dosy a true PEP meter, or send me the model number to find out. To read true PEP, the PEP reading circuit should be made up of active not passive components. Best I can remember you should see a 1 watt carrier and when modulating you should see about 8 to 9 WPEP which is about 250 % modulation. Do you have an oscilloscope? It would be the best way to monitor your signal. In the case that you would be reading true PEP and you are not reaching 9 W PEP, you can raise your ASY control, but be careful, it is extremely important that you have a true reading pep meter if you don't have an oscilloscope.
For SSB I would first go with W13, as it is the RF amp voltage
regulator, this will lower the gain of you RF final stage for SSB.
Cover the basics to avoid squeals and feedback, make sure all
equipment is well grounded and have individual grounds for your audio process
gear and RF sections for maximum isolation and avoid ground loops, use ferrite
beads on all audio and data wires, if necessary you can use balanced to
unbalanced audio by implementing a 1:1 600Ω audio transformer and severing the
wire shield (ground) from the audio gear XLR connector.
Asymod: Hi Jack, your Asymod Stryker SR-497 is almost done, however, can please clarify the settings you requested?
carrier and modulation or max PEP at 1 W carrier, 300% Pos. Mod,100W PEP.
SR-497 in actuality does from 80 to 90 W PEP. Now that is your MAX.
Next, you can’t have 1 watt swinging to 100 watts as this would sound like total distortion at the receiver.
If you want to use all of the radio’s available power and still be
within your headroom limits while doing 300% modulation, we do the following:
First let’s take a look at the carrier to PEP ratio chart above.
For example, here we can see starting from the right bottom that 4 times your carrier is 100% modulation, in other words, 4 is the multiplication factor for 100% modulation. Say you start off with a one watt dead key, when you modulate your carrier at 100% you should see 4 watts PEP on a true PEP RF power meter. if your carrier is 4 watts at 100% modulation you will see 16 watts PEP on a true PEP RF power meter.
Now, at 300% modulation we can see that the multiplication
factor is 15 times and lets say you start off with a one watt dead key, when
you modulate your carrier at 300% you should see 15 watts PEP on a true
PEP RF power meter. if your carrier is 4 watts at 300% modulation you will
see 60 watts PEP on a true PEP RF power meter.
Never push your Hi-Fi radio to its limits. Let’s work it at a
maximum of 80 watts.
The first thing we do is determine what modulation % we want, in your case is 300%.
Next we see that at 300% modulation our multiplication factor is 15, so we divide the total PEP power by the multiplication factor of 15.
80W PEP divided by 15 equals 5.3 watts. This tells us that we should
use a 5.3 watt carrier and when modulated at 300% we should see 80 watts PEP on
a true PEP RF power meter.
It is not recommend running more than 150% to 200% positive
So since you want a 1 watt dead key, and 200% modulation which is 8
times you power, this will put you at 8 watts PEP on a true PEP RF power meter.
So it will be a 1 watt dead key swinging to 8 watts PEP.
Would the Asymod modulator be compatible with my "Old
School" SSB radios from the 1970's?
I have a Realistic TRC-457 Navaho base station and a Realistic
TRC-449 mobile radio. Both radios utilize the Uniden 858 PLL chassis.
Do these units have to be constantly readjusted, as I have seen in
your YouTube videos or can they be setup and "left alone",
considering my radio units?
Do the Asymod units only function in AM or do they also work in SSB?
Are the Asymod units compatible with the use of amplified
Thanks, in advance, for your help!
Yes the Asymod modulator units are compatible with good oldies like
the Navaho TRC-457 and such similar chassis type.
These units are set it and leave it unless you have a need to change
your carrier frequently due to amplifier drive requirements or so, in such
case the Modulation level and Asymmetry controls should be
readjusted. There is a simple procedure for adjustment using only an accurate
PEP watt meter. The adjustment procedure can be found in the guide.
When factory installed by us, the Asymod is configured so that it’s on board SSB preamp turns ON while on SSB mode and provides the correct levels, audio bandwidth and roll off with adjustable level control to properly drive the balanced modulator and ensure maximum bandwidth.
The Asymod ES accepts balanced and unbalanced for microphone levels
in as well as Line In levels. The Asymod 6 audio input is unbalanced and
accepts Line In levels but can be configured for higher gain for microphone
In a typical Asymod 6 installation, the transceiver’s on board mic
pre amp is slightly modified for greater bandwidth. This way the audio bandwidth
at the input of the Asymod 6 board are the same whether from the rear Line In
connector or from the front mic connector.
So, whether you want to connect your mic directly to the Asymod 6 board, through the rear Line In connector or via front mic connector via the radio’s microphone pre amp to the Asymod 6, all three configurations are possible.
Is it possible to put the Asymod in a TRC-433 realistic Navaho CB
Yes it is possible.
I was told I can install your board in a cobra 29 that has the
MOSFET upgrade. I like the new Asymod ES model with the on-board EQ. What are
my chances of getting the board set correctly without software? I do have a
power meter to adjust carrier but I don’t have modulation monitoring
equipment. Or can I send the radio to
The Asymod IIIs is compatible with Cobra 29’s, 25’s and all others radios
with the IRF-520 and 13n10 MOSFET mods.
The chances of you getting the board tuned correctly directly
depends on you being able to follow the instructions, you don’t need any
software. The Asymod ES will be set to your required specs, however, to
properly adjust the Asymod ES settings yourself all you need is a true PEP RF
power meter and use the carrier to modulation index chart found
as a guide line. Comp/Lim, Gate & EQ is user preference, however it has to
be in accordance with the Gain, Level, CAR and ASY levels settings selected.
All you need is a steady tone preferably within 800 Hz and 1 kHz generated from
a Signal Generator weather computer generated or a standalone unit, rack gear
or otherwise, an outstandingly steady voice tone within 600 Hz and 1 kHz.
NOTE: For best performance it is best to use a NON - Cobra radio due to the low gain on the final stages of the transceiver, this includes all Cobra radios for the exception of few, most have metal chassis (non-aluminum) which makes it really difficult to cool off components for optimal performance. Cobras are OK for low power use such as a 1 to 2 watt carrier.
Asymod works best with non-modulation transformer radios, such as
most Galaxy, Ranger, Stryker, etc. which have aluminum chassis and provides
much better heat dissipation of the components and have higher gain at their 3
stage; pre-driver/driver/final which allows for cooler operation of the Asymod.
Cobra radios use modulation transformers rather than a transformer-less
driven stage via audio-amp-modulator-stage with an extra RF pre-driver stage to
make up for gain. Cobra radios use the HV via the modulation transformer which
provides for ~+25VAC to modulate the finals from the audio amp AC output added
to the dc on the modulated primary of the transformer which is sufficient to
drive it’s low gain 2 stage driver/final and the secondary is used for PA and
I received the Stryker SR-955 radio with the Asymod IIIs module. First impressions,
I can’t monitor my modulation. FM does not work. Echo and Roger beep only work with
the factory microphone when the plug on the back is disconnected from the Line
In jack on the rear panel.
In the front panel, the variable RF Power can only be set for SSB. The front
panel RF Power potentiometer does not affect the AM carrier.
The RF power coming out of the radio is too high. I would like to reduce the level of drive to the final tube amplifier. Can I follow the instructions from the manual which is available on your website? 2.5 Watt carrier @ 250% modulation, 25 Watts PEP
W10 AM ANL: Fully counter Clockwise
What I miss the most is the ability to listen to my own modulation.
Robert, Your unit was factory set to a 3 W carrier at 200% modulation, which
produces 8 times your carrier power in PEP power.
Here we can see 3W x 8 = 24WPEP.
This setting will produce ~24 W PEP. Make sure to use a true PEP meter. While speaking normally into the mic or generating an 800 Hz tone, raise the audio on your mic pre-amp or audio chain, audio processor etc. until you see slight peaks of 24 watts PEP on your PEP power meter. This is the correct setting for your factory presets.
Monitor your transmitted audio on another radio using headphones and
adjust its receiver audio as to not produce feedback.
When using the rear Line-In connector (front mic audio is
disabled, only PTT available at front jack), make sure to have sufficient
audio level coming out of your mic pre-amp or audio chain, audio processor
etc. to drive the factory preset audio Level In on the Asymod
IIIs board. You should see peaks of 24 WPEP max, anything higher will create
distortion with these presets.
If using the hand mic (rear Line-In connector unplugged), the
mic gain should be OK around 1 O’clock position. Make sure not to exceed peaks
of 24 WPEP max, anything higher will create distortion with these presets.
If your audio level coming out of your mic pre-amp or audio chain,
audio processor etc. is not high enough change the settings on the Asymod IIIs
board. To change your Asymod IIIs factory presets and set your own audio levels
on your Asymod IIIs board, remove the bottom of the radio and adjust the levels
as desired (follow the procedure in the manual). You can change your Carrier
Level (CAR), the audio level (LEVEL) or your asymmetry level (ASY). You can
find the Quick Settings procedure using a PEP power meter on the following
If you have an Oscilloscope all the better, you can find the
procedure beginning on page 5 of the following manual:
FM is only supposed to work using the front mic jack. FM is not
altered in TX or RX, and is as it comes from factory.
Echo and Roger beep is supposed to work only when feeding audio via
the front mic jack with the factory microphone, other aftermarket microphone or
from a mic pre-amp or audio chain, audio processor etc. and the Jack / plug on
the back of the housing must be disconnected.
It is normal operation when, as you mentioned: “In the front panel RF power can only be set in SSB modulation.”
When in SSB mode, SSB audio can be controlled via the mic gain
control in front of the radio when using the front mic jack.
When using the rear Line In connector in the rear / back of the
housing SSB audio can be controlled via the mic pre-amp or audio chain, audio
The (carrier) potentiometers in
front of the radio is not supposed to affect the carrier AM. This setting is
now done via the carrier (CAR) potentiometer on the Asymod IIIs board.
Yes you may reduce the level of control (carrier level) to drive the
final tube amplifier. Yes, you may follow those instructions on the manual as
well as the ones listed above.
Regarding the following: “W10 AM ANL: Fully counter Clockwise (Fig.
1)”, I wouldn’t change the factory ANL as this acts as an audio limiter to
Regarding: “What I miss the most is the ability to listen to my own
modulation”, take a look at page 10, line #6 of the
It is essential to monitor
yourself on a good AM receiver with a 6 kHz bandwidth along with a good set of
You can find all the other Asymod IIIs manuals here:
Robert: Hi, I
have a question. How do you set the last of the potentiometers on the plate
labeled PRF? I have to reduce the parameters because it distorts the
modulations in the lower frequencies. Regardless of the level and signal from
the compressor. Advise me please, what settings will be best to get rid of
distortions in the lower band? (Compatible opinion of correspondents regardless
of your radio) the level coming from my terminal before the radio is × 4dB or
first thing I would do, after you set the Asymod IIIs board to your desired
settings and since you are running an amp is bring the Asymmetry potentiometer
all the way down (counterclockwise).
Second, make sure set your mid and low frequencies at very low levels and are being limited by audio processor (it helps to use a multiband audio processor such as the DEQ-2496 if you are not using Pro Tools) then you can start bringing them up as desired while monitoring yourself.
Third and last, if you want more AM TX loudness, very slowly raise the asymmetry (ASY) potentiometer up while monitoring yourself to just before it starts to sound distorted in the receiver.
I would like to know what I need to do
to initially set up my station and can I use a condenser mic?
Before anything else, as you may know, when it comes to Hi-Fi AM
audio… all adjustments must be perfect to sound beautiful.
Thank you for the feedback, I would gladly help you to adjust your station to sound great.
Audio limits and RF headroom are very important. I hope you have had a chance to read through the available material and manuals.
At the end of the day it’s all about the combination you find to make it sound perfect, however some levels must be careful looked after.
My opinion only…. Condenser mics tend to be tinny (sound metallically) unlike a wide ceramic diaphragm mics that sounds more natural with exception of few condensers and well processed at that. A good mic is a industry standard RE-20. But I know there are few condensers that sound natural.