[Elecraft] Balanced AT

[d.cutter at ntlworld.com]

If I had a doublet I would seriously consider feeding it like the W5DXP which uses switched ladder line for matching .  Looks cheap, low loss and easy to do: any residual mismatch should be compensated by the K2/K3 auto-matching system.

http://www.w5dxp.com/notuner.htm

David
G3UNA

> 
> From: "Geoffrey Mackenzie-Kennedy" <gmk at gm4esd.fsworld.co.uk>
> Date: 2007/09/10 Mon AM 05:09:13 BST
> To: "Ron D'Eau Claire" <ron at cobi.biz>
> CC: Elecraft Discussion List <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] Balanced AT
> 
> Ron AC7AC wrote:
> 
> 
> Another issue with a balanced AT is that they tend to be used in multiband
> systems fed with open wire line where high SWRs are expected. High SWRs mean
> very, very high RF voltages at a current "loop", demanding relays, etc.,
> that can safely deal with thousands of volts of RF at any power level much
> above QRP.
> 
> ---------------------------------------------------------------
> 
> A timely warning Ron. This is one reason why commercial remote antenna 
> matching units designed to handle such high voltages and / or currents 
> without going up in smoke tend to be expensive. Fortunately for those of us 
> who homebrewed in ancient times suitable vacuum relays and and Mil Spec wide 
> spaced air variable capacitors were available at bargin basement prices.
> 
> 73,
> Geoff
> GM4ESD
> 
> 
> 
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