[Motorola] 1960s Motorola Base

[Joe Walden]

Thanks Geoff,from Joe in Okla....   I appreciate the mod suggestions and am
convinced you are 100% correct.
I have one last question.... Can the tunes pipes in the receiver front end,
TU-1 thru TU-5 be padded down in frequency?
I have been told the frequency coverage is fixed with the length of the pipe
and padding them won't do any good?.  Is this correct?  Joe
All I need now is some Bomar crystals and a crane to put the radio on the
work bench...







----- Original Message ----- 
From: "Geoff Fors" <wb6nvh at mbay.net>
To: "Discussion of equipment manufactured by Motorola"
<motorola at mailman.qth.net>
Sent: Tuesday, March 21, 2006 6:02 PM
Subject: [Motorola] 1960s Motorola Base


> The old BY base station should tune down to 146.52 with just a couple of
> mods.  The receiver will have a problem, however, going too far below that
> because the cavity pipes run out of electrical length.  Unless you happen
to
> have a rare 130-150 MHz military version.
>
> The transmitters were available in several models such as the 829B model.
> Usually the transmitter will not tune properly down to the 146 range by
the
> time you get to the final amplifier.  There is a set of round disks on the
> plate lines which should be screwed close together (without shorting
them!)
> and in all likelihood you will need to add some capacity across the tuned
> lines to fully resonate it at 146.52.  This was often done with a
> couple-inch piece of RG-58 soldered across the lines, open-ended.
>
> The Sensicon-A high band receiver is a wonderful thing which will last
> virtually forever and should give you a bit better than 0.5 microvolt
> sensitivity when you are finished.  I used to use ex-radar 5654 tubes in
the
> front ends.
>
> You can find the manuals on eBay regularly, usually described as a
"Research
> Line" manual.  The base manuals show up less frequently but the Research
and
> Twin-V mobiles used the same TX and RX strips (in the older 15" cased high
> power models.)  You can also find the Motorola test sets there although
the
> BY series usually had a metering kit built-in.  I have the documentation
in
> my library but I won't be able to help anybody until after April 15th due
to
> work pressures.
>
> For anyone interested in working on "historic" tube type Motorola
equipment,
> try to get a copy of the "FM Schematic Digest" by S. Wolf.  They show up
on
> eBay from time to time and usually go begging.  This huge book has
> schematics of all the Motorola FM gear from 1942-62 including tune-up
guides
> and crystal data.  There were at least a couple editions.  The last one is
> red, and there is an earlier, slightly smaller yellow edition.  There is
> also an excellent small booklet titled "Converting Commercial FM Gear" by
> Glenn Zook, K9STH which was published in the early 1970's by 73 Magazine
and
> has lots of useful information, although today it seems very rare.  I
think
> Glenn is actually a subscriber to this list!
>
> Finally, don't worry if your unit is wideband (15 KHz deviation.)  Just
> crank the deviation down to 5 KHz.  The receiver doesn't care one way or
the
> other.
>
> Geoff Fors
> WB6NVH
>
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