On Dec 16, 9:58*am, "Rick" wrote:
A few years ago someone gave me a box of tube sockets and some 5763s. *I
always wondered if they were any good. *So I built up a sloppy little
oscillator, running on 7038 and 22 out of 23 of them oscillated. *It takes
17 seconds for a filament to warm up and the circuit to start putting out
power.
Ok so what next? *I notice in the tube manual, ARRL handbook 1966, that it
has 13 watts plate dissipation. *Wow that seems like a lot for a little 9
pin tube. *So I built another stage next to the oscillator and a little pi
network output and drove the heck out of it. *Only got 3 watts. *Then double
checked the voltages since I was running on a variac and lo and behold I
only had 5 volts on the filament so cranked her up where she should be and
now getting 9 watts into 50 ohms.
Then checked the great W8JI website and see where he put some shaping into
his DX60 to clean up the clicks so I looked at my output with a scope with
my keyer banging away at the thing and ye Gads, a square wave. *So now
working on values of a grid block keyer circuit to round off the edges.
Fun stuff.
Added a socket for an 807. *Wow, got plenty of drive !! 55 watts out with
600 volts on the plate. *2nd harmonic 45 db down, not too bad. *Total money
expended to date - $zero.
Anyone like to do something similar? *If you need a 5763 and socket just let
me know. *All I ask is you to really use it, not just throw it in the drawer
for some day in the future.
Oh by the way. *This is just posted to homebrew, don't need to cross post it
to the other newsgroups, too much of that going on. *Pick the group that it
belongs in and they will find it if they are interested.
73,
Rick *K2XT

About 5 or 6 years ago I think the government must have dumped its
supply of 5763s since they started showing up by the thousands, 1980s
manufacture. Since as a kid I had seen lots of articles that used
them, I quickly bought Too Many. I think everybody I know has at
least 25 and often 100. Since then I've donated some and sold some
and used some. It's a very nice little tube, and should last forever
(+/-) in oscillator or QRP service.

Very interesting to hear how much difference the lower heater voltage
made. It's tempting these days to just make up a 6.3VDC regulator and
be done with it.

73,
Mike, KK6GM