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Re: Slightly OT. IC970 70CM PLL Problem



Thanks; I have been studying the manual to understand the multi-loop PLL
theory of operation. I know what goes in (30.2) and what comes out (first LO
injection), but the DDS VCO operating freq's are a bit of a mystery.
(Terrible service manual). I like to figure these things out before opening
the case. Often you can sniff the PLL with a spectrum analyser or receiver
and determine which section is out of lock. This one is kinda tuff to figure
out. I will start with the C121 and go from there.

Has anyone seen a actual theory of operation manual for the IC-970?

Fred Kennedy wrote:

> Hi Joe,
>           Same thing on my 970 back in 1994.  Repair invoice quotes
> adjustment of C 121 - same as John Knight's finding.  Been OK
> ever since.
> Rgds
> Fred
>
> Date sent:              Sat, 16 Dec 2000 13:15:23 -0500
> From:                   Joe Leikhim <jleikhim@nettally.com>
> Organization:           AMSAT
> Copies to:              amsat-bb@AMSAT.Org
> Subject:                [amsat-bb] Slightly OT. IC970 70CM PLL Problem
>
> > Well as luck would have it I cannot listen for the AO-40 beacon on
> > 70CM as that portion of my IC970 is suddenly displaying "---------"
> > after a few seconds, and the audio is muted. So this is most certainly
> > a PLL problem. I have some service notes and other information that
> > suggests this is the dreaded "blue trimmer capacitor" sysndrome. Has
> > anyone had this same failure on an IC-970? Was it in fact the LPL loop
> > C121? Are there other similar trimmer capacitors inside that I should
> > change while I am at it. I will be fixing this myself as usual.
> >
> >
> > ---
> > Joe Leikhim K4SAT
> > Jleikhim@nettally.com
> >
> > "tv dinner by the pool,
> > i'm so glad i finished school" -F.Zappa 1967
> >
> > "The Revolution will NOT be televised" -Gil Scott Heron
> >
> > "Whats he building in there?"- Tom Waits
> >
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--
Joe Leikhim K4SAT
Jleikhim@nettally.com

"tv dinner by the pool,
i'm so glad i finished school" -F.Zappa 1967

"The Revolution will NOT be televised" -Gil Scott Heron

"Whats he building in there?"- Tom Waits

WARNING TO UNSOLICITED SPAMMERS!!!

Pursuant to U.S. Code, title 47, Chapter 5, Subchapter II,
"Any and all non-solicited commercial E-mail (SPAM) sent to
this address is subject to a download and archival fee of
$500.00 U.S."! E-mailing denotes acceptance of these terms.


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