[R-390] R-390 Digest, Vol 64, Issue 21

[Richard Green]

I thought that version of the R390A was called the R 1247. I have one that was done by Manson Labs and it has the most linear PTO of ANY Collins radio I have ever owned. I would like a copy of the docs on this version and certainly would pay for copying and postage. I do not have the synthesizer but it might be interesting to hook one up. My main question is how did they activate the relays? It appears that one of my relays is flaky as sometimes the Rx works FB and then it suddenly loses interest in RF! Usually I can wiggle the coax cables and coax it back to life so it is either a relay or connector issue.
Skip

--- On Fri, 8/14/09, r-390-request at mailman.qth.net <r-390-request at mailman.qth.net> wrote:

From: r-390-request at mailman.qth.net <r-390-request at mailman.qth.net>
Subject: R-390 Digest, Vol 64, Issue 21
To: r-390 at mailman.qth.net
Date: Friday, August 14, 2009, 11:00 AM

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Today's Topics:

   1. Frequency Synthesis on the R-390/A using the SBM-1102
      (Tisha Hayes)
   2. Re: Frequency Synthesis on the R-390/A using the SBM-1102
      (Tom Frobase)


----------------------------------------------------------------------

Message: 1
Date: Thu, 13 Aug 2009 14:11:23 -0500
From: Tisha Hayes <tisha.hayes at gmail.com>
Subject: [R-390] Frequency Synthesis on the R-390/A using the SBM-1102
To: r-390 at mailman.qth.net
Message-ID:
    <8534c9e80908131211t2119739du49cc8c76c34680a3 at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

I ran across a document explaining the setup of the FFR-41 and how the
SBM-1102 would provide precision frequency synthesis to a pair of R-390A's.
(document MM03276).

It appears that the connections to the receivers would be to the 1st mixer
with an external 17 MHz reference, the 2nd mixer with an external 9-17 MHz
reference and to the VFO with an external 2.455 - 3.455 MHz oscillator.

All of it is locked to a single 1 MHz crystal and there are provisions to
support the CV-1597 sideband converter for receiver tuning.

It is a neat idea and I can see the application for diversity reception of
RTTY where the receivers would have a single frequency reference.

This looks sort of 1967'ish and knowing that many list subscribers were in
far away, hot, sticky environments at the time I wonder if anyone had
experience with this lashup. I would think that the R-390A's would require
some modification (additional jacks and cabling) to bring the 1st and 2nd
mixers and the VFO connections to the back panel. Has anyone seen a rig
modified in this manner?

I know that NASA (and probably NoSuchAgency) had R-390A's modified so they
could adjust for doppler shift from space vehicles. This was also done with
an external reference and the R-390A was rebranded as a different model.

-- 
Ms. Tisha Hayes

----------------
"I will not recant the truth. I am corn, not chaff; I will not be blown away
with the wind or burst by the flail. I will survive both."
-Walter Milne, 1558


------------------------------

Message: 2
Date: Thu, 13 Aug 2009 20:12:49 -0500
From: Tom Frobase <tfrobase at gmail.com>
Subject: Re: [R-390] Frequency Synthesis on the R-390/A using the
    SBM-1102
To: Tisha Hayes <tisha.hayes at gmail.com>
Cc: r-390 at mailman.qth.net
Message-ID: <4A84BA11.5020204 at gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

I bought a mid 50's Motorola R-390A recently with these modifications 
installed.  Each of the effected sections have a plug in module housing 
a relay and cable assembly wired to the back of the radio.  This radio 
was not re-branded.

My intent is to restore the radio to its original mode and pass the 
modules on.  I would enjoy reading the document.  If anyone is 
interested I can take a couple of pictures. if you don't mind a very 
dirty R-390A

tom, N3LLL

Tisha Hayes wrote:
> I ran across a document explaining the setup of the FFR-41 and how the
> SBM-1102 would provide precision frequency synthesis to a pair of R-390A's.
> (document MM03276).
>
>   



------------------------------

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End of R-390 Digest, Vol 64, Issue 21
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