[Elecraft] Re: RF Coupleing

[Stewart Baker]

David,
A very good point. Although the space is rather restricted for 
RG58/U it should be possible to fit some of the smaller diameter 
cable such as that used to connect between VHF/UHF PCB's.
I have some silver braided coax that would be suitable. 

It would have little adverse effect over such a small length, but 
might provide additional isolation.

Food for thought...

73
Stewart G3RXQ
On Wed, 16 Jul 2008 12:14:03 -0400, David Robertson wrote:
> Stewart,
> Your posting is good information however one of the factors of 
isolation between ANT 1
> and 2 can be how the pigtail leads from the 2
> SO239 connectors and the antenna coupler board are dressed.  It 
would seem easy to have
> these nonshielded wires crossing or near each other. The space 
seems too tight to use
> rg58/U cable. this could mean that depending how those wires 
were dressed the coupling
> would be different between all K3's.
>
> 73
>
> Dave KD1NA
>
>
> From: Stewart Baker <stewart at baker.nildram.co.uk>
> Subject: Re: [Elecraft] Re: KAT3 ATU and SPE Expert 1K-FA 
Amplifier
> To: Dave G4AON <elecraft at astromag.co.uk>, 
<elecraft at mailman.qth.net>
> Message-ID: <2008715195354.766566 at shack>
> Content-Type: text/plain; charset="ISO-8859-1"
>
> I made some measurements of the isolation between ANT 1 & ANT 2 
on
> my K3.
>
> There is little difference between ATU & BYPASS. Unable to do
> 50MHz.
>
> 1.9MHz 58.1dB
> 3.7MHz 51.9dB
> 5.1MHz 49.2dB
> 7.0MHz 47.1dB
> 10MHz 44.7dB
> 14MHz 42.5dB
> 18MHz 40.8dB
> 21MHz 39.2dB
> 24MHz 37.1dB
> 28MHz 35.7dB
>
> So on 60m for 100W from ANT 1 there will be 1mW from ANT 2.
>
> 73
> Stewart G3RXQ