[Elecraft] K3 Ant2 Issue With KPA500

[Harry Yingst via Elecraft]

Here is something I did out of curiosity...

I hooked my RX antenna to the input of a wattmeter and the output of the wattmeter into a dummy load.
I then then observed how much power was being sent back to me through the RX antenna.

It may not be accurate, but it was enough for me to install a front end protector. (I got an AS_RXFEP from Array Solutions)


      From: James Bennett <w6jhb at me.com>
 To: Elecraft Reflector Reflector <elecraft at mailman.qth.net> 
 Sent: Monday, May 4, 2015 11:57 PM
 Subject: [Elecraft] K3 Ant2 Issue With KPA500
   
The situation: I've got an 88 foot long doublet at 45 feet, fed with 110 feet of ladder line, a 4:1 balun, and six feet of RG8-X connected to ANT1. Also got a Hustler 6BTV mounted on the ground in the back yard with 75 feet of RG8 running to the ANT2 connector. 

When running the K3 on low power I have no problem using diversity mode. However, when the power is increased, the internal relays start chattering in the K3. I understand that this the K3's way of protecting itself from too much RF on ANT2 - it temporarily disconnects ANT2. The amount of K3 output needed to cause the relay chatter depends on the band I'm on. Sometimes 20 watts will do it, other times I'm good at 100 watts - depends on the band. When I turn on the KPA500 it'll chatter on EVERY band. Obviously it's because the vertical (ANT2) is less than 50 feet from the doublet - I get that.

My question(s) - can I assume that this relay chatter is not good, that it will cause problems if I continue running QRO in diversity mode? 

If this in fact is a bad thing, how do others run QRO and diversity? Are there devices on the market that can be put in the ANT2 line that can handle the RF? I could do it with a manual coax switch but that kinda puts a crimp in QSK operating.

Jim / W6JHB
Folsom, CA
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