VK4ZXI

RF tap for panadaptor/second SDR after IC-7300 bandpass filters (First draft) Introduction It is possible to tap into the IC-7300 after the bandpass filters, just before the ADC. There is a coax connector that allows an SDR tap to receive the filtered RX signal. It is shared with the low-level TX path, but the levels are low, giving a TX monitor too. Using CAT controls, the SDR can be controlled by the TRX. It can also operate as a second RX in the operating band. The RF tap is an alternative to the INRAD RX7300-receive antenna cable, with some advantages and disadvantages. Finding the RF tap In an SDR-based TRX there is no IF tap point, but on the IC-7300, there is a RF tap point after the band pass filter and RF amplifier, where an SDR has the good filtering of the IC-7300, but can access the whole operating band. The RF tap point J1431 is shown in a portion of the RF unit schematic from the service manual. The schematic shows the RX, TX and power paths in green, brown and ...

Red Pitaya: arrived and working My Red Pitaya has arrived and was working with a minimum of fuss. Simply type in the device's unique MAC address on the connect page http://discovery.redpitaya.com/  and hit connect. The instrument functions are web applications. Just click which instrument you want and it comes up in a web page. I was curious how they could get it to work on any computer, tablet or operating system, but the web access is the answer. I am not sure what consequences that has for performance, but it works and it is still early days. The Red Pipaya connected to give some idea of size. It gets pretty hot, maybe too hot for a warm climate like northern Australia; we shall see. The device is working as an oscilloscope and signal generator, with an output connected to an input. A sine wave at 20 MHz. Many of the adjustments are manual and take a bit of getting used to. However, it works. Not the cleanest sine wave; not sure if it is the signal generator or os...

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...