It's all about the Software

Having problems with AM & SSB reception with an RSP-1a whenever I reduce the RF gain below 6: very distorted or no audio. It sounds just like a biasing problem with an op amp when the DC bias point shifts toward one of the supply rails. Everything looks normal to me in the screen shot. I have the same problem with the RX-888, though kind of backwards: if I set the HF attn. to -20 dB reception is OK, at -10 it's very distorted & at 0 the audio fades away after a couple seconds of severe distortion. The RSP-1a works perfectly in SDRuno at all RF/IF gain combos. The problem is in the MW band I have to turn the RF gain in SDRC way down to avoid overload, & at those RF gains the demoded audio goes away.

Also attaching a short video that shows what happens as the RF gain is changed.

Bob NO6B

Turn on the AGC!
The one in the DSP panel.
You don’t use your ‘old school’ HF rig with he AGC off? If you did, the strong signals would be distorted too.

Typically I use RF gain of 5 to 7, -30 or -35 of Manual (not automatic) IF gain an 10 to 15 dab visual gain.
With IF gain in automatic, the AGC pumps wildly if a strong pulsing signal i.e. CW is in the operating bandwidth.

73 Kriss KA1GJU

Thanks Kriss. I knew it had to be something simple but I couldn't find it, maybe because I use FM 98% of the time. I also missed the manual gain slider that's present when AGC is off; adjusting that fixes it too.

Bob NO6B

I also suggest using the RSP's AGC gains rather than setting the RF/IF but that's really just me being lazy