Strange Military Thingie.

Steve Harrison ko0u at OS.COM
Sun May 2 19:15:04 EDT 1999

At 05:06 PM 5/2/99 -0500, David Stinson wrote:
>Anyone know what this transmitter did?

Looks to me like it's probably VLF, maybe 550 kHz or whatever they used
(those are massive IF or RF transformers/coils!). The 6L6s and a couple of
12SN7s are probably a push-pull modulator, phase inverter and mike
amplifier for the 1625 final which is driven by the 12A6 and 6J5; but 1st
and 2nd Doublers?? Looks like the final coil is underchassis and not all
that large. Can't see how it could have been VLF or even 3105 kHz with two
doubler stages. Assuming the 1625 B+ was around 500V, and considering the
plate current meter range, looks like the 1625 could have run 50 watts
plate input for maybe 30 watts output. That would fit neatly with a pair of
6L6 modulator tubes.

Front panel says "Sidetone" and "Volume". "Volume" *could* be for the
sidetone (which, in modern-day aviation radios, isn't CW sidetone but
instead is just feeding the modulated audio back into the headphones so you
can hear what you're saying over the plane's racket). Kinda looks like it
might have a receiver, perhaps TRF; if so, those 6L6s might have been the
RX audio, and man alive... where would one need THAT much RX audio power??!
OTOH, prehaps the 12A6 was the RX audio. Note the screwdriver Volume
control, though: one didn't adjust the volume very often, obviously.

One switch looks like it says "Dyn" which could be to turn the dynamotor on
and off, meaning the filaments were allowed to run all the time with HV
off. So it wouldn't have been for monitoring a frequency.

And it looks "aircraft" to me with that relatively-small size, front rack
locking tabs, and handles. Perhaps for an early sub-hunter plane? Couldn't
have been for a fighter, too large. But there doesn't seem to be much of
any high-power antenna matcher although it definitely fed a long wire with
that Antenna Current meter.

Sure are a nice-looking set of meters, too!

Never heard of Doolittle, though. Could not pull out the operating voltage
or weight from the front panel labels, but sorta looks like the weight
might be saying 35 lbs. But the seller says the weight is around 20 lbs.

73, Steve K0XP

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