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

[Tom Lee]

That agrees with what I was told at the Deutsches Museum. Does Trenkle 
talk about this in one of his books?

-- 
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 20:17, Heinz Breuer wrote:
> Hello Tom,
>
> the ceramic material either low T/C for coil forms and variable capacitors or with defined T/C for dogbone tubic style ceramic capacitors was a German innovation.
> The capacitor plates for variable capacitors were made out of milled brass and silver plated.
>
> Tuned circuits were temperature compensated by dogbone tubic style ceramic capacitors available with different negative T/C specs.
>
> vy 73 Heinz DH2FA, KM5VT
>
> Von meinem iPhone gesendet
>
>> Am 10.03.2020 um 00:27 schrieb Tom Lee <tomlee at ee.stanford.edu>:
>>
>> 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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