[Milsurplus] FT-241 LF Crystals as a Long - Term Investment Instrument

[Jack Antonio]

On 11/5/2019 10:23 PM, Hubert Miller wrote:
> I had this bag of those WW2 FT-241 LF crystals,
> 
> I realized I needed to finally make an executive decision on it, so I 
> tested them all. 
> 
> Result: 74 defective, 13 working = 85% fail rate.

I was gathering up some of the FT-241s for a project, both
the ones around 300 to 500kc used in BC-683 family of transmitters,
and some around 900kc used in AN/TRC-1. And the ones I found were also
generally bad. Would not oscillate, or pass RF from a signal generator.
Didn't keep exact notes, but more than half were bad.

I opened a few up, and was surprised at how small the crystals are,
quite thin, and maybe a 1/4" square, I was expecting a fairly
substantial chunk of quartz in there. Did not see any mechanical
or obvious defects.

The project was (and still is) to get a VRC-2 on 10 meters.
(918.75 kc is the target crystal frequency for 29.4)
When I find the time, I'm looking at using some of the
QRP Labs Prog rocks as crystal substitutes.

Jack Antonio
WA7DIA