[Elecraft] K3 (S) Weird Main RX issue

[Udo Langenohl - DK5YA]

Thanks to all so many who replied, also off list.

I found the K1 relay on the SUBIN board to be faulty. Ordered a new one 
and will see what happens after.

73 Udo, DK5YA

hashtag: #cantwaituntilmyK4arrives

Am 08.05.2021 um 10:55 schrieb Udo Langenohl - DK5YA:
> Gentleman,
> 
> I have a problem with the main receiver on one of my K3s. The main 
> receiver is between 6 and 8dB worse than the second receiver. The stupid 
> thing about it: it is not always like that, but the poor sensitivity 
> comes sometimes creeping or sometimes suddenly. It seems to have 
> something to do with the transmit / receive switching. I checked this 
> very carefully with an HP8664A signal generator and a spectrum analyzer. 
> Sometimes both receivers are exactly the same, then the main receiver 
> slowly gets worse and worse (within a minute the amplification drops by 
> 6-8dB) sometimes it happens immediately after switching from RX to TX 
> and back. Then it happens that after switching from RX to TX and back 
> again, both receivers are the same again. It can also happen that the 
> main receiver is initially 8dB worse than the second receiver, but 
> without RX / TX switching the missing 6-8dB are suddenly there again - 
> in the middle of receiving mode, without switching. So it's intermittent 
> and it drives me crazy not to find out what's going on. Is that another 
> bad pin diode somewhere in the main receiver and if so: which one? Maybe 
> someone has an idea? Help is very much appreciated.
> 
> This is a K3 #56xx with all features and all upgrades so its more or 
> less a K3S rather than an K3.
> 
> 73 Udo, DK5YA
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