[ARC5] [Milsurplus] Radio on the Frontlines: WWI and WWII | DPLA

[Tom Lee]

I visited the Deutsches Museum in Munich a year or so ago (one of my 
favorite museums on the planet), and had a chance to speak with one of 
the docents who manned their amateur radio display. He claimed that 
their quartz-free WWII radios were stable to about 0.1% over 
temperatures encountered in the field (whatever that means). He could 
not cite any source for this claim, but offered plausible explanations. 
He said that the main bit of magic was pre-stressed inductor windings on 
low-TC coil forms (the coils were wound with heated wires which 
contracted upon cooling, so that the overall inductor TC was that of the 
form, not of the wire). Not as good as quartz, he admitted, but it 
mainly got the job done. I've heard of this pre-stressing method before, 
but this gentleman seemed to imply that it was a German innovation. I 
have no idea if that is in fact the case.

--Tom

-- 
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 3/9/2020 16:02, Hubert Miller wrote:
> Germany in the 1930s on had a limited supply of quartz. That didn't hobble their military communications; they compensated for this
> with mechanical precision. I would say quartz frequency control didn't really become a requirement until most communications
> migrated to VHF.
> -Hue
>
>> I don't know where I read it, but I read that the use of crystals to control the transmitter's exact frequency (hence, you could have a
> radio "channel") was what made radio go from an option for battlefield communications to a tactical advantage and communications
> necessity. Someone please correct me if I am wrong, but I believe that was in the 1930's for military communications.
> 73, Gordon KJ6IKT
>
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