Message-ID: <001501c29ba2$de4eab20$1c076c0a@arenanet.fi>
From: "Matti Niemela" <mattis.niemela@kolumbus.fi>
To: rsgb_lf_group@blacksheep.org
References: <5.1.0.14.0.20021202175331.027c0670@gemini.herts.ac.uk>
Date: Wed, 4 Dec 2002 16:38:53 +0200
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Subject: Re: LF: W-G SPM-19 trouble
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Dear Jim,

I have SPM-19 too but without any manuals. Could you plase check what kind
of input  impedance is in "unbal 75" but selected without termination
(infinite). Instrument works great if not gone to couple of error states
caused by impurity in relay contacts (my guess).

73 de Matti/OH2ZT
----- Original Message -----
From: "James Moritz" <j.r.moritz@herts.ac.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: Monday, December 02, 2002 8:14 PM
Subject: Re: LF: W-G SPM-19 trouble


> Dear Dex,
>
> There are only 2 frequency conversions in the SPM19 - one to the 40MHz
> first IF (which is what the 40-65MHz LO signal does), and the second to
the
> 10kHz final IF. You could include a third conversion to get the demod
audio
> out at 2kHz as I recall - but I don't think you could be using the audio
> output for level measurement because it has permanently-on AGC. So I guess
> the problem you have must lie in the 40MHz to 10kHz conversion oscillator
>
> I have the circuit diagrams for the SPM19, so I will take a look and can
> send the relevant diagrams if neccessary. BTW, when you say the frequency
> is wrong by 1.792kHz, how are you measuring this? is it high or low? One
of
> the manuals also contains a list of error messages, but they usually are
> not very helpful - 100 ways to tell you it isn't working!
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>