[Milsurplus] NOS ART-13

[sbjohnston at aol.com]

It can be done (single-stage transmitter with small crystals).  But it seems like the minute guys try to optimize everything for max output power it has a good chance of going off the rails.
I suggest several tens of ohms of resistance in series with the crystal if you suspect the circuit might be working it too hard.  You might need to adjust the value to find the sweet spot where the crystal starts reliably but also does not yoop or drift on keydown.  If memory serves, in my experiments I ended up around 22 - 33 ohms most of the time.
One of my favorite minimalist projects was a two-stage breadboard transmitter with a 6AG7 oscillator and two 807s in parallel for the PA.  I remember that on a long key-down I could hear the frequency drifting a bit, so I figured the 6AG7 was causing a little crystal heating - so I added resistance in series with the crystal.  Checking the schematic just now I see ten ohms.
https://www.wd8das.net/dream.html
I've also seen people put a panel lamp in series with the crystal for current reduction.  I'm not sure if the shifting resistance of a lamp would be an advantage or disadvantage.  

The night I first got on the air with that transmitter I was on 40m CW, and my first contact was with a station on Mauritius Island in the Indian Ocean!  I think the output was just under 100 watts.  I lived in Pennsylvania then I think and would have been using a low inverted vee dipole.  My best DX on 40 I'm sure.  


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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