RF tap for panadaptor/second SDR after IC-7300 bandpass filters
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 ...