Using the RTL-SDR as a Panadapter for a Kenwood TS-570D
Over on YouTube user SA6 HAM has uploaded a video showing how to modify a Kenwood TS-570D so that an RTL-SDR dongle can be connected to its first IF stage in order to create a low cost panadapter. A panadapter is a device that allows you to visually view RF signals with an FFT or waterfall display on a regular analogue hardware radio. Some radios have IF output ports on the case, but older radios tend to need internal modification to expose the IF as a port.
In the video SA6 HAM opens up his Kenwood TS-570D radio and shows exactly where to connect the RTL-SDR dongle’s antenna connector on the inside.
There is a problem with this mod. The SDR antenna input and the used koax cable have 50 Ohm impedance.This impedance is connected in parallel of the normal circuit and “eats” energy away from the receiver, which results in lower receive signal and impedance missmatching. The correct solution would be to connect a signal amp with high impedance input and 50 ohm output to the sampling point before sending the signal to the SDR.
Got everything working. Some trial and error on some software settings.
I like SDR-RADIO.COM V3. Seems to work good.
I have made this modification, and while I hear something, it sounds like my vfo is set low, and out of adjustment. Using the dongle as a receiver, the unit sounds fine. Is there some way to adjust this?
Yaesu FT-920
first IF being 68.985 MHz (68985000 Hz)
Kenwood TS-570
Intermediate Frequency: 1st IF 73.05 MHz (73050000 Hz)
In HDSDR under ExtIO, I have tried “Disabled”, “I input”, and “Q input”. I have tried all relevant settings. I should also mention that I have 2 of the same dongles and have switched them with the same results.
As far as Direct Sampling mode, I’m not sure how to set that. However, I just came across this link as I write this so I will try that tomorrow.
https://www.rtl-sdr.com/direct-sampling-mode-hardware-modifcations/
As mentioned before, using the dongles as a regular SDR with a good antenna everything works as it should. Shortwave/HF ham through VHF/UHF with no issues. Only issue is when trying to use as a panadapter it does not work.
68 MHz is above 24 MHz, so you’ll need to stay in the normal quadrature mode (not direct sampling), which is set just by selecting Disabled in the ExtIO settings under direct sampling.
Hmm so first I would try just to tune directly to 68.985 MHz in HDSDR, and NOT set any offsets/IF frequencies in HDSDR just yet.
I’m going to try again tomorrow and see what happens.
I have not been able to get my RTL-SDR R820T2 RTL2832U Version 3 dongle to work as a panadapter with either my Kenwood TS-570DG or my Yaesu FT-920..
The dongle I bought from Amazon is https://smile.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0129EBDS2/ref=sr_1_4?s=electronics&ie=UTF8&qid=1513624240&sr=1-4&keywords=sdr
The dongle works fine otherwise as a ham/shortwave/police monitor. I have tapped the proper location for the 1st IF in both radios and inputted the proper 1st IF frequencies in HDSDR. I can control radios with OmniRig , but my panadapter display shows nothing but a few random lines. Just does not work! Maybe it is the particular dongle I am using. Also, my computer is plenty fast …I7 32gb ram, etc…..
Any ideas?
What frequency is the IF output at? And if it’s below 24 MHz, did you enable the direct sampling mode?
When you say direct sampling, you mean I or Q sampling?
Yep, choosing the I or Q branch is enabling direct sampling mode.