Another HL2 hardware failure mode?

[ron.ni...@gmail.com]

Has anyone encountered this HL2 failure mode?

One of my HL2 units, in frequent use for over a year and functioning perfectly yesterday, suddenly developed what appears to be significant phase noise on receive. It operates on the higher HF bands with quiet relays, but all received CW signals exhibit several hundred Hz of phase noise or modulation, even after adding substantial (20 dB) attenuation to the antenna input.

I connected an older HL2 to the same antenna, and the older HL2 receives without issues, ruling out environmental noise.

On 160M and below, the failed unit only buzzes the relays when attempting to receive, with no signal detected. Replacing the antenna with a dummy load yields the same result—relay buzzing on 160M and below. Swapping the N2ADR filter board with one from the working HL2 did not resolve the issue; the relays still buzz on any attempt to receive at 160M and below, even with a dummy load. This should rule out the failure being in the N2ADR filter board. On higher bands with a dummy load, the relays and received signal remain quiet.

Discovery works, and reports back gateware version 73.

Any suggestions on where to investigate the cause of this failure?

Should I try reloading the gateware?

Thanks and 73,
Ron, N6YWU

[Steve Haynal]

Hi Ron,

I'd start with a finger test. Apply gentle finger pressure to various components and see if that makes any difference. This can help identify cold solder joints which may have failed over time. Also, if you have a scope, we can walk through what the signal chain should be at various points. Finally, please ensure all the power voltages are as seen on this wiki page.

https://github.com/softerhardware/Hermes-Lite2/wiki/Hardware

73,

Steve

kf7o