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Greetings - and issue with CW buzz

Posted: Sun May 26, 2019 12:01 am
by PatInDetroit
Hi all,

Really enjoying the RSP2pro. For the price it does quite well in terms of not getting overloaded in HF, and yet also pulling out some weaker signals like VHF/UHF CW beacons, even without external filters or preamps. Plus, in addition to being a good "appliance", it also exposes enough of the inner workings to allow some insight into the theory behind SDR which is another reason I was interested by it.

One issue I have noticed though: When listening to CW, it is always accompanied by some kind of 50-60ish Hz buzz. You can see it here:

Any idea why this might be happening? It is not there on any other radios or SDRs. It seems to be louder in proportion with the amplitude of the signal, and while it's most noticable on CW (maybe related to switching, or to the narrow bandwidth) I've also noticed it on stronger FT8 or BPSK31 type signals where the amplitude is generally constant. I do not think I'm seeing/hearing it on FM.

Thanks for any advice!

Re: Greetings - and issue with CW buzz

Posted: Sun May 26, 2019 4:12 am
by Mike2459
If you have an AC voltmeter measure the AC between the chassis of your SDR (when it's connected to the PC and the PC is running) and (with the antenna disconnected from the SDR) the shield of your antenna cable. You may be surprised what you find. I was. I measured 60 Volts AC