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Topband: FAR Circuits K9AY Loop Preamp/Bandpass filter

To: "topband@contesting.com" <topband@contesting.com>
Subject: Topband: FAR Circuits K9AY Loop Preamp/Bandpass filter
From: Pete Smith <n4zr@contesting.com>
Reply-to: n4zr@contesting.com
Date: Wed, 06 Jan 2010 06:10:21 -0500
List-post: <topband@contesting.com">mailto:topband@contesting.com>
I picked up a FAR Circuits kit for a complete K9AY loop system at 
Dayton, and am building it now. I have a separate ARR wideband preamp 
here, which I have used with K9AY loops in the past with some success, 
but wonder if the FAR Circuits design would be better for 160 and maybe 
80.  If not, I'll just bypass that part of the circuit.

Typical FAR, I guess - next to no information about the circuit is 
available.  The bandpass filter uses three inductors to ground with 
series caps and three in series with caps to ground.  The preamp has a 
center-tapped bi-filar matching transformer on the input, with the 
output signal fed from the collector through half of the transformer to 
the output jack, and an RC network from that center tap back to the base 
(negative feedback?).

Does this sound familiar to anyone?  Does the BPF cover both 160 and 80? 
  If you need a schematic to comment, I'll be glad to put one up on the web.

-- 
73, Pete N4ZR
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