[Milsurplus] WW II Morale Amp

[J. Forster]

Hi Konrad,

It looks to be of the correct vintage, but I think the RBO connector is an
Input, not an Output. I think that jack took the balanced 600 Ohm audio
output of the RBO and amplified it to drive the speaker.

The amps I'm interested in were apparently mounted to the stateroom
bulkheads (walls) and received 3 channels of audio via armored cable, no
less.

Best,

-John

===================



> I think they may have used this type of phonograph for the RBO speaker
> system:
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rt=nc&nma=true&item=330513646160&si=16iJvh3ru8NoeFno6zjp02Cqck8%253D&viewitem=&sspagename=STRK%3AMEWAX%3AIT
> This Navy phonograph has an actual "RBO" output jack if you look very
> closely in the photo.  This amp uses loctal tubes and uses a power
> transformer.  Price was a little high for my liking, though I may start
> looking for this one for our RBO system hookup.
>
> Konrad
>
> On Mon, Jan 17, 2011 at 3:19 PM, J. Forster <jfor at quik.com> wrote:
>
>> Opinions please:
>>
>> The more I look at a 1 tube Morale Amp from the MASSACHUSETTS the more I
>> believe it was a modified cheap phonograph. The design is AC/DC with a
>> single 117N7 tube; input and output transformers, and very little else.
>> The purpose was to amplify audio from a 600 Ohm bus to drive a small
>> speaker in the officers' staterooms. The buses were driven by RBOs in
>> Radio 2.
>>
>> I suspect some of the crew went into Boston to Radio Shack and bought a
>> few record players. This would have been in 1941-42.
>>
>> A cheap phonograph could have had a high output, crystal cartridge and a
>> simple, very low parts count amp, probably built on an "L" shaped plated
>> steel chassis.
>>
>> The crew would have bought a couple, pulled the chassis and speaker and
>> added the input transformer and possibly changed the volume control.
>>
>> Does this seem plausible?
>>
>> Best,
>>
>> -John
>>
>> =============
>>
>>
>>
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