Hello,
I built a softrock RXTX some years ago. I think it was around 2012. It worked at the time. Never actually made a contact with it - 1W just wasn't enough power.
I rediscovered it while I was poking around in my junk for another project.
First challenge was the power connector - it's a different size than all the other 12V stuff in the shack. I scrounged a 12V socket out of a defunct wifi router and replaced it. Now the softrock has its 12V.
But it doesn't work. I downloaded the drivers and software off fivedash.com, and the gorgeous SDR display is running....but no actual signals.
I remember I had gotten a high-zoot usb audio adapter to use with the softrock, but now I cannot find it. I did locate a couple of generic green "jellybean" usb adapters, and they seem to work as far as hearing hum and scratches off the input cable.
But the displayed spectrum is all noise, and does not change when I unplug the 12V. Also doesn't change when I unplug the antenna.
I don't remember which band I built it for - but figure 40M or 20M would be a good bet. Whups, that's verified - L2 and L3 are
16 turns on a yellow core. So I built it for 40-30-20.
How to get started troubleshooting?
Just for yuks, I scoped the si570 clock chip and saw a 3V p-p signal at 56.428MHz. It does change when tune with the HDSDR program.
I tried feeding a fairly robust signal into the input from a tinySA. When I did this, it behaved like there was a short at the input transformer. Plug the tinySA directly into the scope - big signal. Plug it into the transceiver input, scope across the
input connect - zilch.
I see there's a broadband transformer at the input, followed by a pi-network LPF. I would expect some modification of the input signal, but not zilch.
Yet I seem to remember it working when I built it.
- Jerry KF6VB
