A bit more contemporaneous... it's too long a story to relate here, but I
discovered that the internal speaker, as well as my voice, tapping on the case,
etc would FM the VCO in the synthesizer in my Elecraft K3 transceiver. This was
a birth defect that affected every one of them. They used my radio (never
figured out why they didn't use one of their own) to come up with a fix that
entailed bonding a 1/8" thick aluminum stiffener to the circuit card. This
found it's way into production and a retrofit kit was offered for others.
Wes N7WS
On 4/1/2021 11:16 AM, Richard (Rick) Karlquist wrote:
On 4/1/2021 10:32 AM, Lux, Jim wrote:
And for what it's worth DROs have their microphonic problems too. We had a
breadboard deep space transponder and you could demodulate your voice
(poorly) using the spectrum analyzer's FM demod feature. Very cool.
Unimpressive to the folks who wanted to push the technology. We were
Back around 1970, as LM radio switched from AM to FM, the HP 608
signal generator was losing market share because it couldn't
do FM. Believe it or not, there was actually an Ap Note describing
how to obtain FM by bolting a 4" loud speaker to the 608 cabinet
and driving it with an audio signal generator. Those were the days ...
Rick N6RK
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