[Milsurplus] [Glowbugs] LF & HF Crystal Tester prelim comments

[Glen Zook]

I got one of those crystal testers several months ago.  Instead of the HC-49/U socket I installed one for FT-243 crystals that will work for HC-6/U crystals and for the wire lead types.  I don't have any problems with the unit reading all types of crystals.

Glen, K9STH 
Website: https://k9sth.net 

    On Friday, August 23, 2019, 04:06:02 PM CDT, Hubert Miller <Kargo_cult at msn.com> wrote:  
 
  
So I bought online for very little money one of those LF, HF crystal testers with readout.
 
It arrived remarkably quickly. It is quite a small unit and arrives in a little mailing bag. In fact, when I received the bag,
 
I thought it only would contain a couple transistors I had ordered elsewhere.
 
The thing is really only intended for tiny crystals with wire leads.
To test anything else, I think we need to attach the smallest alligator clips to very short leads and wire to the tester's
 
tiny crystal test socket. 
 
I found: 
 
It does not at all like any test leads to your crystal that are anything long. It will not "read" the crystal.
 
I think it needs good, strongly active crystals. I seem to recall that some that my dipmeter resonated, when tested on
 
this machine, did not show anything.
Maybe it has trouble with crystals with a higher than usual series resistance?
 
  
 
It did however measure a couple of those WWII FT-241  LF crystals.
 
  
 
It also proved its worth to me in short order. I had a bunch of crystals marked  453.5 that I bought from some boat – radio
 
surplus lot. Oh boy, I thought, a bunch of 453.5 kHz rocks I can use either with a mechanical filter or as single – crystal
 
selectivity near the common IF freq. Well, they all tested on this device as in the 16 MHz range. I don't get the 453.5 marking
 
and I'm pretty sure they weren't intended for 453.5 MHz use, but I'm not positive. More likely I think they were for 1970s –
 
1980s crystal controlled SSB boat radios. Now one less thing to save.
 
  
 
However, the ( gradual ) search for the ideal crystal tester goes on.
 
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