Portsdown 2020 stuck on 4m and not transmitting.

[M0YDH]

Hi Dave
Voltage across pins 40 and 39 remains 0 when going from rx to tx and back. Plain test card appears. Nothing on the spectrum analyser. Pin 2 is at 5.6v. Supply says 5.5v

I connected the Lime with just an antenna to the Portsdown 4 using a grotty USB2 extension lead to access it in the case. I saw a 437MHz signal - calibration then actual on the analyser. It's repeatable but varies greatly in amplitude by a factor of 2. So the expensive SDR is working outside the 2020 unit.

73
David M0YDH

[G8GKQ]

David

5.6v is too high. Should be no higher than 5.3V. Try winding the supply volts down.

Dave

[M0YDH]

I did try. But being clumsy decided to probe ground at the easy to clip on main -ve terminal. And saw -13.7v applied to pin 40. Pi isn't displaying at all. Now I'm feeling wretched.

I could make a Portsdown 4 with a 4 port switch and cables to the the band select board in my rx tx relay changeover unit provided the Lime is ok. Best of 3 units.
Sorry.
David

[G8GKQ]

Hi David

Very sorry to hear this. Hope that the Lime survived. It would be good if you could get something together for the contest.

Dave

[M0YDH]

Hello Dave

I've made a lash up of my older Portsdown running Stretch 201922100 and the Lime mini and large buck converter from the 2020. I found a powered USB2 hub to use instead of the USB3 hub in the 2020 unit. I've band select and 4 band switch card so can run my rack.

I can get sustained tx of test card and contest number on 2 and 70 in S and S2 but only with the Lime mini setting. Reception is to Portsdown 4 pictured.

I'm somewhat relieved ! I'll try the SD card from the 2020 next and see if that makes matters better or worse.
Hopefully I'll get the special firmware then.

Thank you very much for helping me. I'm back to blundering.

David M0YDH

[G8GKQ]

Hi David

Well done! If it's working, I would be tempted to leave it as is. There's no need to use the LimeDVB firmware - I don't most of the time.

73

Dave

[M0YDH]

Yes the newer card did start but it's no better. I'll stick with Stretch and Lime mini mode. I've a bracket for the buck converter to make and then screw the loose parts to some plywood. I think a fan for the Pi might be prudent. I recall my switchgear doesn't like heat either.

David M0YDH