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Re: [TenTec] OMNI6 PLUS Alignment procedure needed

To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] OMNI6 PLUS Alignment procedure needed
From: "Bob McGraw - K4TAX" <RMcGraw@Blomand.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 29 Dec 2007 20:23:11 -0600
List-post: <mailto:tentec@contesting.com>
Jerry's point is correct.  The manual clearly states that the BFO alignment 
procedure should be repeated until no interaction is observed.  Most often I 
find that the alignment is incorrect due to poorly calibrated test equipment 
or measurement procedure.

Additionally, I find that occasionally one may say "I'll skip the FSK 
alignment because I don't intend to operate FSK".   WRONG....... there is 
interaction within these circuits.

Bob, K4TAX

> I may be out in left field look the wrong way without ever seeing the
> Omni circuits or manual. But there could be some weird interactions
> around the BFO/carrier generator frequency settings.
> As I recall, the CW BFO crystal is shifted in frequency for transmit. No
> doubt it has separate trimmer capacitors for each frequency and probably
> the manual says trimmer A sets receive and trimmer B sets transmit.
> Trouble is that in one mode both trimmer A and trimmer B affect the
> crystal and if you set one trimmer with both in the circuit, then set
> the other mode, the first setting is now off and you go back and forth
> for a while because of the excessive interaction. What's needed is to
> set the trimmer that is alone for its mode, then change mode and set the
> other. There might not be much interaction, but there could be some
> capacitive coupling in the trimmer switch. To require a couple repeats.
> Otherwise I can't think of any other place for there to be significant
> interaction so long as the alignment proceeds from amplifier chain input
> to output. If the loads aren't exactly the same when a tuned circuit is
> switched between transmit and receive, it may be necessary to optimize
> one and accept the lack of optimization on the other or to try for some
> sort of compromise.
> 73, Jerry, K0CQ
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