Kenwood TS-2000: 1st IF, tap for Panadapter
I’ve bought on Ebay a cheap DVB-T dongle that can be easily used as a wideband receiver with HDSDR, SDR#, gqrx and other SDR softwares for Linux and Windows systems. The coverage is about 24 to 1700 MHz and bandwidth up to 2.4 MHz
I was inerested to connect the dongle as a panadapter for the Kenwood TS-2000, the rig that I use when in remote.
Googling around I’ve found only info about HF SDR connected to the lower IF of that rig at 10.695 MHz. This frequency is outside the range of the rtl-sdr dongle and the detected spectrum at 10.695 is narrow only few kHz.
For a good panoramic receiver the solution is to tap the IF at the first conversion just after the mixer and before the roofing filter.
Looking the schematic one can see that the designer had already added this possibility, same way of IC-756, and the connector CN6 on TX-RX1 board (bottom of the rig) can do the job.
The signal is tapped with a small capacitor, C118 of 2 pF. I’ve connected directly to the dongle without a buffer and I did not detect any reduction in sensitivity anyway is a good practice to insert an high impedance amplifier between the CN6 and the dongle.
On the back of the rig no free holes to fit a coaxial connector, so I took out the cable using the space around the REMOTE socket, unused in my shack.
The TS-2000 has 2 different IFs depending on the selected band, so we must insert different values in the “IF-frequency” box of HDSDR-Options-RF Front End + Calibration window.
For receiving 30m, 20m, 12m and 6m 69085000 Hz must be inserted.
Other HF frequencies use a 75925000 Hz IF
Everything works very well.
All this description is only for HF/6m bands. VHF and UHF have a different conversion path.