Date: Tue, 5 Apr 2005 20:13:30 -0700
From: wayne burdick 
Subject: [QRP-L] N5ESE's T1 review -- excellent, but one correction
To: QRP-L 
Cc: Elecraft Reflector 


Thanks for comprehensive review of our T1 ATU 
( I'm glad it worked well 
for you in field tests. We may make a few assembly and owner's manual 
tweaks based on your feedback. (We could have used you as a field 
tester :)

One important comment: There is definitely no need to use stacked cores 
for both transformers in the SWR bridge. Balance is excellent even with 
a stacked core at transformer T2 only, because the characteristics of 
the bridge are set strictly by the turns ratio, which is the same on 
both transformers (8:1). There is also no need for a stacked core at 
transformer T1 for power dissipation reasons, since only T2 sees the 
effect of the voltage step-up and corresponding core heating. We have 
fully tested the unit at its maximum rated power with just the one 
stacked core.

We did send out an incorrect version of the errata sheet to a few 
builders that claimed 7 turns were required on T2. Hopefully you got 
the word to use 8!