[Milsurplus] Morale Audio on Ships

[J. Forster]

> The NT-49620 amp/skr schematic shows the input running into a 600 ohm
> pad feeding what appears to be a 600 ohm input transformer to a pair
> of 35L6's (with a 35Z5 making up the AC/DC design).

OK. The pad means that each load looks like a constant load impedance to
the bus and other users joining or leaving a bus, will not alter the bus
level.

> I don't know about the WW2 ships, but from 1946-on the AM-215/U
> distribution amp was used (pair of 6AQ5's) with 600 ohm in (again 6
> mW) and 600 ohm out (10 W max).
> http://www.navy-radio.com/rcvrs/am215.htm
> I think I have seen reference to a similar WW2 amp design but can't
> place it now.

OK. I just sent you the print I have, off-list.

> I think all the shipboard AF hookups I have seen so far just run X
> loads (all 600 ohms) off the 600 ohm output - given the "run any
> output to any input" nature of the system (via WW2 patch boards and
> later SB-82/SRR transfer switchboards) I guess they really couldn't do
> much else. Operationally I don't know what effect the load changes
> had, but would like to learn more.

Well, they could have a bus with a 600 Ohm source impedance, and then
"bridge" high impedance amps across the pair. If the inputs were 300KOhm,
you could have 50 loads and the bus level would only drop 3 dB. That's be
a carrier, at least. LoL.

> Darn it, Mr. Peabody, we need a time machine, not just a bunch of
> manuals......
>
> cheers,
> Nick K4NYW

Yup.

Thanks,

-John

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