31 Aug
2008
31 Aug
'08
10:19 a.m.
Back to the 1951 ARRL, the device was called a 'monitone' and used
a 6SL7 with a phone jack on the one grid and the output of a
6J5 on the other grid after biasing and volume control and an
osscillator that used a neon bulb a capacator and biasing
resisters. Transmitter input was to 6J5 and effectively to side one of
6SL7 through another resister. If I could draw in ascii I'd
show this device.
bs
On Sat, 30 Aug 2008, Chuck Guzis wrote:
On 30 Aug 2008 at 7:42, William Blair wrote:
Thank you! That's the perfect tube
multivibrator lead which allowed
me to find these references using "code oscillator" and "6SN7" as
search terms:
It all was very long ago. I can tell you what I see in my mind's eye
(however accurate that is). A small chassis with a filament
transformer on one side, an interstage audio transformer on the other
and an octal tube socket in the middle. A pot on the front to vary
the pitch and a phone jack. The tube was definitely a dual triode;
it might have been a 6SL7 or 6SN7 (perhaps in the application, it
didn't matter). Construction was from either the ARRL RAH or perhaps
"The Radio Handbook" from about the same time.
I'm almost 100% certain that this was no multivibrator application;
indeed, half of the triode may have been used as a rectifier.
All of this is subject to the bit-rot that increasingly pervades my
wetware nowadays.
Cheers,
Chuck