[Milsurplus] mechanical modulator

[Thomas Adams]

At 02:15 PM 9/13/2008, Marty Reynolds wrote:


>Clete, you're gonna know this
>
>The 2/42 Radio News defense edition says the localizer has 90 & 150 hz fm
>a mechanical modulator
>
>Is that a deal that switches back 'n forth between dummy load & antenna at
>those rates?
>
>   Tnx!
>
>      Marty
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That's ONE way to do it. An easier way is the "wobbulator".

A wobbulator is essentially a speaker with a metal cone. It acts as 
one plate of
a capacitor. The cap's other plate (fixed plate) turns this critter 
into a device that
will directly vary in capacitance at an audio rate.

In at least one radio altimeter design, a wobbulator was directly 
coupled to the tuned
plate and grid lines of a free running UHF oscillator. Early TV 
service guys wanted that
altimeter to convert into a sweep generator.


Mr. T., W9LBB