Topband: Post contest season: TX antenna vs RXantenna cros-stalk. What do you do?

Mark van Wijk, PA5MW pa5mw at
Thu Mar 24 08:18:45 EDT 2016

Hi Terry,

I have no access to the K3's as they belong to  someone else.
But I learned there  is no such thing as  total  isolation.
Not even with the Frond end savers, unless they incorporate several relays 
in series.

But I did check my TT ORION using the Elecraft XG3 generator; isolation is 
abt 65dB
You do the math when you have 9+40 signals on a large antenna like a 
fullsize TX deltaloop on 40 & 80m

73 Mark, PA5MW

-----Original Message----- 
From: Terry Posey
Sent: Thursday, March 24, 2016 12:04 PM
To: 'Mark van Wijk, PA5MW' ; 'william radice' ; topband at ; 
Eric Swartz -WA6HHQ, Elecraft
Subject: Re: Topband: Post contest season: TX antenna vs RXantenna 
cros-stalk. What do you do?

Hi Mark -

I have not experienced K3 TX/RX antenna isolation problems with my station
configuration.  I expect that if there is an isolation problem with your
rig's TX and external RX antenna routing/switching, that problem would be
nearly impossible to quantify using your station's TX and RX antennas.  The
rig's TX/RX isolation would need to be measured on the bench, using good
laboratory grade equipment.

Perhaps, Elecraft can provide a list of expected isolation values that were
measured for each of the TX and external RX antenna routing/switching
configurations possible with the K3 and K3S.  Those measurements would
surely have been done during the rigs' design performance verification


Terry K4RX

Hi Bill,

I think this is not what I meant here; I also do use BPF's and the Front End

The problem is that while listening to your receiving antennas, there is
also some signal from the transmit antenna getting through thanks to the
internal cross-talk of your rig's TX/RX relay.

I was wondering what people do besides the obvious 'kill the TX antenna
input during RX mode' ?

73 Mark, PA5MW

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