[HomeBrew] Chirpy 6V6 osc/filtering solution?

[Eric M Hughes]

kwylow zinjanthropus wrote:

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>All:
>Just wanted to know how I should eliminate/mitigate a chirpy 6V6 (AC-1 type) oscillator. I took a look at WA6VVL's book, "Vintage Anthology, Book 1" and he basically detuned the plate to lessen the chirp on the AC-1's signal. I have been doing that practice but would like to try and eliminate the problem electrically. I have been toying with the idea of canning my present filtering system and basically put in a 470 uF/450 VDC electrolytic I have. I'm currently using two 22 uF/350 VDC caps and a single 2H choke in pi configuration but somehow that doesn't seem to be doing anything with the chirp problem. Any comments? Thanks. Cal, N6KYR. 
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Hello, I had a friend who tried to use that tube and Im sure some guys 
on the list could advise you  on how to tame that tube, However my buddy 
never did and gave up. My experience has always been to use metal 6ag7 
tubes in vintage equipment designs. In
my opinion that would be a better choice in a oscillator design than the 
6v6. The tube is extremely stable and with a vr-150 controling the 
screen, you can even feed the antenna
directly with a pi-network without chirp. That was my first homebrew rig 
back in my novice days. You can find reference to these rigs in many of 
the old 1960 handbooks. With the vr -150 on the screen of the single 
tube 6ag7 oscillator put out about 5 watts, and you could re-insert a 
vr-75 and reduce the output to less than half a watt!!. I worked the 
west coast on a dipole at 7mhz running that little half watt monster. 
(In the novice band of coarse!) It had plug in coils, one each for 80,40 
and 15 meters. Standard power supply of
about 300 volts was built using only a isolation transfrormer and a 
voltage doubler circuit.
Both the transmitter and power supply was built on thin plywood chasis 
with aluminum foil
glued to the bottom for a ground conection. Was quite a setup!
In any event, I hope you can work out the problem you have and just 
thought I would add my
two cents and my experience with the beloved 6ag7 tube.( I have at least 
6 of them in my junk box at all times!) I am currently reworking my 
grandfathers old vfo and turning it into a 5 watt vfo exciter. This time 
the VR tubes are gone and I will use super regulated power supply for 
stability.  A 6sk7 and a 6l6 will regulate the screen.
Anway good luck and hope to hear that AC1 soon! 73, eric- W4CHQ