[Milsurplus] WW II Morale Amp

[Bruce Gentry]

J. Forster 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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>   
 From a technical feasibility standpoint, YES!  How Naval bureaucracy 
would react to homebrew is another matter.  Many cheap phonos used a 
crystal cartridge capable of producing 3-5 volts with a 45 or 78 disc.  
In the 50's, there was an even cheaper design using a selenium rectifier 
for B+, and a  specially designed 85 volt motor drawing 300 MA.  A 
single 35L6 was the amplifier tube, with the motor dropping the rest of 
the 120 volts. It worked surprisingly well with a loud rock-n-roll 78, 
just DON'T try to operate it on DC!    Bruce Gentry ,  KA2IVY