[GreenKeys] TUs I have known

[David and Joyce Meier]

My first TU was a homebrew simple one with toroid filters and two amplifier 
transistors.  It only had a 36 volt loop supply, but worked really well for 
all its simplicity.  I even added an autostart circuit.

I built an ST-3 all on a big PC board from the Ham Radio (?) magazine 
article in 1972.  It used a GE PA238 OP amp which was hard to find.  I wrote 
to Irv about it and he wrote back to express his dissatisfaction with that 
choice of device and provide an alternative using the ubiquitous 741 OP amp. 
The modified ST-3 worked great.

I later built an OA-5 TU from a kit I bought in Dayton in 1973.  This was 
the circuit of the ST-6 and AFSK generator all on one board.  It worked fine 
as well.

When computers arrived in the shack, I wrote a BASIC program to convert the 
RTTY data stream for display on the monitor.  The program was listed in the 
very first QEX magazine.

Later, my wife and I built the Heathkit HK-232 version of the AEA PK-232 
multimode controller, which we still have.

I'm back metal now with a Flesher TU-170 and a model 15.

Dave Meier N4MW
New Kent, VA
www.n4mw.com