Strange K2 Behaviour - KAT100 Antenna Isolation

[Mike Walkington-3]

Hi All,

Continuing the theme of describing strange K2 behaviour!  My KAT100 is
remotely installed in an EC2.  I use ANT1 with nothing connected to the 2nd
antenna socket.  Recently I noticed that having tuned in a relatively strong
station on ANT 1 and switching to the 2nd antenna (ie by pressing ANT1/ANT2
switch) that I could still hear the station even though there is no antenna
connected to ANT2.  This made me wonder what the isolation is between the
two antenna sockets and if anyone has measured it or whether I have a
problem that I need to locate and fix.  Sorry, but I haven't yet swapped the
antenna to see if the behaviour reciprocates.

Mike
VK1KCK
K2 #2599


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[Geoffrey Mackenzie-Kennedy-2]

Hi Mike,

I have the same thing here even with a dummy load on the ANT 2 connection
(default in case anything goes ape). It is something that I would expect,
how much isolation depends on the type of relay used, the frequency, how
well the relay coil is by-passed , the crosstalk between external circuits,
leakage through the box, etc etc etc. I would hope that when you switch to
ANT 2, the signal drops a lot. I have not measured anything to do with this,
but I would GUESS that at 7.1 MHz the isolation is around 50 - 60db. Hope
this helps.

73,

Geoff.
GM4ESD


----- Original Message -----
From: "Mike Walkington" <[hidden email]>
To: "Elecraft-Reflector" <[hidden email]>
Sent: Monday, January 24, 2005 11:17 AM
Subject: [Elecraft] Strange K2 Behaviour - KAT100 Antenna Isolation


> Hi All,
>
> Continuing the theme of describing strange K2 behaviour!  My KAT100 is
> remotely installed in an EC2.  I use ANT1 with nothing connected to the
2nd
> antenna socket.  Recently I noticed that having tuned in a relatively
strong
> station on ANT 1 and switching to the 2nd antenna (ie by pressing
ANT1/ANT2
> switch) that I could still hear the station even though there is no
antenna
> connected to ANT2.  This made me wonder what the isolation is between the
> two antenna sockets and if anyone has measured it or whether I have a
> problem that I need to locate and fix.  Sorry, but I haven't yet swapped
the
> antenna to see if the behaviour reciprocates.
>
> Mike
> VK1KCK
> K2 #2599
>
>

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[S55M]

Hello!

There will always be a cross-talk between antenna ports on KAT100.
If u put on unused antenna port some 50 ohm dummy the crosstalk will be
lower.
I did measure crosstalk between ports on my KAT100 now aprox results are:

28Mhz 35 dB with unterminated ANT 2 port and around 40dB with terminated...

I suppose the crosstalk on lower bands is better!

73's
Adi -K2-3204

----- Original Message -----
From: "Mike Walkington" <[hidden email]>
To: "Elecraft-Reflector" <[hidden email]>
Sent: Monday, January 24, 2005 12:17 PM
Subject: [Elecraft] Strange K2 Behaviour - KAT100 Antenna Isolation


> Hi All,
>
> Continuing the theme of describing strange K2 behaviour!  My KAT100 is
> remotely installed in an EC2.  I use ANT1 with nothing connected to the
2nd
> antenna socket.  Recently I noticed that having tuned in a relatively
strong
> station on ANT 1 and switching to the 2nd antenna (ie by pressing
ANT1/ANT2
> switch) that I could still hear the station even though there is no
antenna
> connected to ANT2.  This made me wonder what the isolation is between the
> two antenna sockets and if anyone has measured it or whether I have a
> problem that I need to locate and fix.  Sorry, but I haven't yet swapped
the

> antenna to see if the behaviour reciprocates.
>
> Mike
> VK1KCK
> K2 #2599
>
>
> _______________________________________________
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> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

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[Brian Mury-3]

On Mon, 2005-24-01 at 22:17 +1100, Mike Walkington wrote:
> Recently I noticed that having tuned in a relatively strong
> station on ANT 1 and switching to the 2nd antenna (ie by pressing
> ANT1/ANT2
> switch) that I could still hear the station even though there is no
> antenna
> connected to ANT2.

What happens if you then disconnect the antenna from ANT 1? It's
probably a long shot, but if a signal is strong enough, it is possible
to hear it with no antenna hooked up at all. I have observed this many
times. Sometimes just having the end of the coax near the rig's antenna
connector will allow me to receive a signal - sometimes I don't even
need that.

--
73, Brian
VE7NGR

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