[Elecraft] K3 with KSYN3A 100Hz spurious

[Dave]

My old K3 (serial #80) with dual RX and KSYN3A upgrade synths, has
developed a fault.

A “tune up” carrier, CW transmission, AM transmission, all exhibit 100Hz
“modulation” with spurious carriers every 100Hz each side of the centre
frequency. They start around 10dB down and drop off in a similar manner to
SSB IMD products. Receive sounds fine.

The issue is not always present when the K3 is cold, it is not related to
external connections (removed all except power), nor to a power supply
(swapped it and the power lead). It is also present on low power and on all
bands.

I’ve asked Elecraft Support, no reply so far. Any ideas as to what might be
the problem?

Thanks
Dave G4AON
-- 
Sent from my iPhone SE