• Asymod™ Standalone Unit


    Asymod Asymmetrical Hi-Fi AM modulator Standalone

    Asymod Standalone Asymmetrical Hi-Fi AM Modulator, for use with mobile or base CB & HAM radio transmitters and transceivers. Transceiver of choice must be wired and configured. The Asymod Standalone unit provides front panel access to the controls allowing for on-the-fly adjustments. This can be very useful to adjust the transceiver's output to match the amplifier's drive requirement. 

    Now you can connect this standalone unit to your transceiver of choice.

    Be sure to see the Icom IC-7300 & Asymod Standalone, the Yaesu FTdx-1200 & Asymod Standalone and the Ranger RCI-2970N4 videos.

    Got questions? Visit the new Asymod related FAQs and get answers to the most frequently asked questions and lots of valuable information related to Hi-Fi communications.

    Sound Pro mobile or base with the Asymod Standalone Asymmetrical Hi-Fi AM Modulator. Get the Hi-Fi audio you want with this compact unit. With this setup you will save in time to come as there will never be the need to upgrade again.

    The Asymod Standalone unit makes it ideal for mobile and base operation and allows for external and simple installation and only requires a 12 Volt supply. The Asymod expands the transmitter’s audio bandwidth from the stock 3 kHz to well over 10 kHz. On board preset active and passive low pass filters can be set to 6, 8 or 10 kHz roll offs.

    The asymmetrical functionality controls the audio loudness level and provides for amplitudes in excess of +300% modulation while not exceeding the negative peaks at -100% without the use of negative peak limiting or clipping methods which produce squaring of the modulation envelope and provides for increased spectral density. The Asymod is compatible with most transceivers and it is fully adjustable front panel controls and accepts microphone and line level inputs. It offers the flexibility to use a stock hand mic when properly installed to the transceiver to a high end processing audio chain using a broadcast microphone via the Line In connector. This unit will work with all High Level Modulation transceivers by direct coupling to the driver and final’s collectors via the existing transceiver's onboard RF chokeswithout the need for a heavy, costly and large modulation transformer. Low Level Modulation transceivers will require some modification. Instructions for specific multiband HF transceivers is available upon request.

    This unit can be configured for your transceiver of choice. The one shown here has been configured to the Stryker SR-955HPC as a Plug-N-Play device. Other configurations with external power supply, modulator out, remote, microphone in, audio in and audio out for eSSB connections are available upon request.

    The Asymod IIIs produces modulation levels well above the norm and broadcast levels without distortion, allowing for your station to sound loud and clean. With the Asymod connected to your audio processing chain and a transceiver of your choice, your mobile or base station will sound just as or better than commercial broadcast stations. To achieve optimum results and to make the most of the Asymod, adequate audio processing catered to emphasize on your natural voice is necessary.


    Read through all related documents, including the Asymod FAQs and manuals to see the requirements for an effective Hi-Fi setup before committing to purchase. All sales are final and there are no returns. If the unit breaks, please send it back for repair. All repairs are free within the first two months after the sale.

     The transceiver/radio is only the exciter and should not be expected to generate high levels of RF power, it should be expected, however, to generate a clean, perfectly modulated wide-band Hi-Fi audio RF signal well within the limits of the headroom available without pinching or clipping at the crest or troughs of the modulation envelope which can be later amplified with a class AB, RF power amplifier and is best heard or monitored on a good quality receiver equipped with a 6 kHz AM wideband filter and monitored on an oscilloscope.

    The Asymod IIIs is not an audio processor, but it does allow for full bandwidth control with the use of Pro Tools, a combination of rack gear, or a broadcast multi band compressor / limiter.

    Audio processing and a high quality microphone is necessary for optimum performance.

    Audio processing for mobile or base operation is possible with the use of the iRig PRE or iRig PRO interface using the companion IK Multimedia's VocalLive Vocal Processor app (not the free version) on your iOS device.

    Audio processing for base operation is possible with the use of rack audio processing gear or computer based processing such as Pro Tools for PC or Mac along with its companion interface such as the Mbox 2 Mini or newer. Pro Tools is the best choice and is highly recommended. Pro Tools sessions are free and available for download.

     Absolute maximum ratings:  

    •Audio input: +4 dBu, 1.74 VPK or1.23 VRMS

    •+15 volt supply @ 5A Remote control sensitivity:

    •+8V ~ +12 V Audio Input Range:

    •Audio input: -30 dBu to +4 dBu Frequency response:

    •Input: 20 Hz – 11 kHz.Expandable to 20 kHz.

    •Output: 20 Hz – 11 kHz.Expandable to 20 kHz.

    Input & Output Passive Low Pass Filter:  

    Selectable: 5 kHz, 8 kHz & 11 kHz Rolloff Presets

    Preamplifier Active Low Pass Filter:

    Selectable: 8 kHz, 16 kHz