[Milsurplus] FT-241 surplus LF crystals chan - freq list ?

[Bob Camp]

Hi

If you are going to build a lattice filter, first step is to see what the biggest pile of crystals is (frequency wise).
Next step is to set up a simple sort process to “bin” them by frequency. Once you have all that, you design 
the filter around what you happen to have. If this sounds bizarre ….. you haven’t been in the crystal filter business .
“Enhancing” even a simple test set to get reasonable motional parameters is easier than you might think ….

The bottom line is that in this day and age of fancy computer analysis software, it is easier to fiddle the design 
than to fiddle the crystals. 

Bob

> On Nov 12, 2017, at 9:27 PM, Hubert Miller <Kargo_cult at msn.com> wrote:
> 
> I appreciate your effort, but...this chart is not useful, I think, because the LF frequencies are rounded off the whole kHz.
> I am actually sort of rethinking the whole idea of picking out any 'good' freqs anyway. Considering the halflife of the group
> at around 70 years, it seems to me the failures will proceed steadily. I do not recall any of the early 'conversion' articles 
> mentioning the high failure rate, so it has a time factor. I certainly at this time wouldn't attempt one of the conversion book
> lattice filters, even if I wanted to replicate the circuit; I'd worry too much about one of the 4 to 6 crystals quitting on the job.
> I was kinda thinking of crystals around 455 or 465 ( or is it 470 ?  ) for add-on single crystal filters, or replacement use for same,
> for receivers. But the high failure rate has me thinking now, maybe I should just not bother with these.
> I read online some suggestion to refasten the wires plated to the quartz with some kind of conductive glue, but no one had 
> apparently actually tried this. Dunno if I want to spend time on that effort. Oh well...at one time, I thought these crystals were
> really a swell thing. 
> -H 
> 
>> Hue, 
> Here's and old surplus ad that I depend upon:
> .................
> Regards,
> Al
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