[Milsurplus] FT-241s again

[Bob kb8tq]

Hi

For the typical blank designed for plated electrodes, a pressed contact is unlikely to work. It will mass load the blank way more than that really thin plating did. If you look closely at some “pressure plate” crystals, the metal electrodes are set back from the center of the blank by just a tiny amount. That “non-contact” eliminates the mass loading issue. It also adds another element to the circuit model ( a series C). The do contact out at the corners of the blank and the blank is designed to be “dead” in that area. 

That’s all from memory of a classroom lecture ~50 years ago. Don’t take it as a 100% perfect answer to the question. 

Bob

> On Nov 30, 2023, at 10:13 PM, Hubert Miller <Kargo_cult at msn.com> wrote:
> 
> 
> Those FT-241 crystals for the tank radios, is there a way to "repair" them ? I know one of their major fail modes is that contacts come unplated. Will a small contact, not a plate like FT-243  and such, but a smallish contact pressed againsy where the plated contact was, with the just right pressure, will that resume piezo activity ? Lord knows, with a defective rate now of 75% or more, i have a lot of candidates to experiment with.
> -Hue Miller
> 
> 
> Sent from my Verizon, Samsung Galaxy smartphone
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