[Milsurplus] Hey Bob, W9RAN

[sbjohnston at aol.com]

One-tube power-oscillator transmitters can definitely kill FT-243 crystals.  I know this from sad personal experience.  
I think the crystal-controlled power-oscillator designs originated in the 1930s when the crystals in use had a much larger "chunk" of quartz inside. High crystal current did not matter so much in that case.  The designs persisted over the decades but the quartz mass in the contemporary crystals declined greatly.
In my business AF4K Crystals, many of my sales are of vintage crystals re-stuffed with HC-49 crystals.  They are perfectly fine in multi-stage tube equipment, but I do caution users about the one-tube transmitters. 
Interestingly quite a few customers report success with the power-oscillators.  The factors involved seem to be (A) limiting crystal current with a series resistor and (B) not trying to get absolute maximum power out of the single stage.   If you are satisfied to consider it a QRP rig you have a much better experience.
I much prefer to build a two-stage MOPA rig.  For example:
https://www.wd8das.net/TTTTT.html
or
https://www.wd8das.net/dream.html
or even splurge on three tubes:
https://www.wd8das.net/Raider/Raider.html

73   Steve  WD8DAS   

sbjohnston at aol.com   
http://www.wd8das.net/   http://af4k-crystals.com/   
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Mein Ohr ganz nah am Weltempfänger...



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