VK4ZXI

I have added some notes and portions of the circuit and block diagram to my post on a 1st IF tap on my IC-7410. Further, the design of the 7410 suggests it is a hydrid software defined receiver (SDR), as modulation/demodulation, noise control and the main filtering for different modes, are all done in a firmware-programmed digital signal processor. I bought the 7410 as it seemed the most advanced design of the available TRX in my price range. It is more so than I first thought. In reading the circuit diagram, I wonder if it is possible to tap where the Rx and Tx separate from the shared antenna. If there is such a point, the sdr and TRX Rx may be able to share an antenna at the frontend of the TRX and operate as two separate Rx.

Note: I take no responsibility for any attempts at doing what is described here. I am not an expert with these radios and am following my own interpretation of how this is done. It is shared on the basis of the philosophy of amateur radio. The main advantage of a 1st IF tap is avoiding the problem of sharing one antenna with a RTX and SDR; not simple. As mentioned in an earlier post, I have installed a tap into the 1st IF of my IC-7410. The tap is made into the TRX’s first IF (64,455 kHz), above the roofing filters (the key to a good RX). The ICOM even have a socketed test point to do it (some hesitation playing inside a new $2000 TRX! Much reading of circuit diagrams). With the plug (hard to get but only $1.50 and are used on all main brands of RTX), isolation amplifier- http://www.cliftonlaboratories.com/z10000_buffer_amp.htm (gives details of how it is done), preferably through a bandpass filter (obtained but not installed) then to Funcube. I have it running, but not perma...

Software Defined Radio (SDR), mainly receivers are what really got me back into amateur radio earlier this year, after a 40 year absence.   I had a brief revisit to radio 10 years ago, when I was medically retired, but was disappointed that so little seemed to have changed. So I went and played (when I was able) with computers, audio, video, home cinema and satellite TV (and sport cars) instead. But once I had done about all I could do there, I was after something new. Then I re-discovered radio starting with the TV dongle software defined radio, rtlsdr. While I am still annoyed that mainstream transceivers (that I could afford; or justify) are still little changed, SDRs really are a hoot; you can see what is out there- lots of really weird stuff and no dial twirling hoping to find anything of interest. I started with the TV dongles; they are not to be dismissed lightly, a couple of MHz bandwidth, 60 MHz-1200GHz range, all for $20. I bought a discone ...