RX ANT input reception issue

Petr Ourednik

Hi all,

I would like to ask kindly for ideas, tips or opinion please.

Simply I have problem with RX ANT input reception. I lost reception from external Beverages
on that input during last contest event > it worked well most of the time but Sunday evening
I realized that noise from Beverages is going down, some time later I realized that even sigs
lower and lower and finally after some time (15-20min) I realized that I am deaf from RX ANT input.
When I switched to receive back from ANT1 main all looked ok with receiver sensitivity etc.
It happened not instantly but gradually!

When I disconnected BNC from KXV3 board on read panel of K3 and put it back it received instantly OK.
So my first though was > well I have bad contact on the coaxial cable/BNC. Unfortunately
when I switched RX ANT input OFF then ON I lost sigs immediately again.
I tried to shaking with BNC on rear panel and randomly I got it back to work but
when switched on front panel the RX ANT again I lost reception from external Beverages again.

So something is wrong in my K3 and have no idea what to do at this moment BUT...
... it can be also linked to the "Phenomenon" from the Sunday earlier morning.
I noticed in the morning that during transmitting I had strong audio feedback into QSK which
sounded to me at first like short echo from myself > propagation Phenomenon.
I made short vid here: https://youtu.be/cV3rzlsZbA4

When I talked to other people they routed my mind to idea that it can be linked to RX ANT issue then after in the evening...

I am using always Front-end antenna Saver circuit which is grounding receiver input on RX ANT
port when TXing by fast relays (0.5ms) and I used only K3 at 100W out without any power amplifier!
So I do not believe/hope that I damaged it by TXing to Inverted V antenna by induced energy back thru Beverages...
See the FES circuit used here:

I will be happy to get some idea, advise or hint what I should check and replace or how I could solve it.

73 - Petr, OK1RP

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