FT-241 measurements: a correction

[Brian Carling]

I still have a bunch more of the FT241 crystals available
that are excess to my needs...
If anyone would like some, I will supply you all you can use 
for $1.00 each!

> I made a mistake when measuring the parameters of FT-241 crystals (reported
> here a number of weeks ago).
> 
> Corrected results for crystals of two different frequencies:
> 
> 389.123kHz:
>   - delta-f with 10pF series C = 0.149kHz
>   - computed Cm, Lm = 7.66E-15F, 21.85H
>   - measured Rs, approx = 10k
>   - computed Q, approx = 5300
> 
> 500kHz:
>   - delta-f with 10pF series C = 0.132kHz
>   - computed Cm, Lm = 5.28E-15F, 19.19H
>   - measured Rs, approx = 8k
>   - computed Q, approx = 7500
> 
> Simulating a simple 1-crystal filter (phase-splitter transformer,
> 'neutralizing' capacitor, 15k load) with the 500kHz values shows a 135Hz 3dB
> bandwidth and a 4kHz 30dB bandwidth. So far, I don't have a good design for
> a ladder filter using these parameters.
> 
> YMMV: I have only measured two specimens, and given the typical age of these
> crystals one can expect large variations.
> 
> 73, ian K3IMW
> 
> 
> 
> 
> 
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