"Uwe" wrote in message
...

The dips in plate current are nearly imperceptible and they are not aided
by
my 250mA full scale meter. They may be 2 or 3 mA.
I tune with the help of my scope.

The pi network should be able to match a wide range of impedances but it
would help to connect a known resistive load. Five, 2-watt, 270-ohm
resistors in parallel would be close enough. If you're getting a dip in
plate current the circuit is resonating somewhere, and you say you've worked
people, so it's putting some rf on the band.

See if you're getting two dips. A lot of those pi networks would resonate on
the operating band with the plate tuning cap almost completely meshed, but
there was enough range in the cap that it would also tune to the second
harmonic. If your LC meter is right you may be dipping at a harmonic, not
the fundamental.

OTOH, if your calculation of what the original coil was is correct, the
plate tuning capacitor should resonate when its value is about 20 pF -- for
a 22-uH coil. That doesn't mesh with the range of your plate tuning cap. A
2.7 uH coil would resonate with the plate tuning cap at about 185 pF, which
seems more reasonable.

This is one of those rare occasions when a grid-dip meter is handy. Is there
a ham club in your area? Someone may have one to lend. Meanwhile, hook it up
to a dummy load and see what you get.

There's something else you could try, but I don't know how well it would
work. With the AC-1 unplugged you could connect your receiver antenna to the
top of the plate tuning cap and adjust the plate tuning cap while listening
for a peak in the noise level. That would tell you the circuit was
resonating at 7 MHz. If NG, try 20 meters and 10 meters.

In the olden days I had a 6BE6 connected inside my Viking Valiant, such that
it turned on and bridged the receiver antenna input when transmitted rf
appeared at the grid. When the key was up, rf from the antenna passed into
the receiver. This allowed for full break-in CW, and I could dip the plate
tuning cap just by listening to the noise level. Real handy when moving
around the band in a contest. You would probably pop the front end of a
solid-state receiver doing this, so don't try it. The circuit was in an old
Radio Handbook, which was edited by Bill Orr, W6SAI. That's what made me
think that you could try this with your receiver, but exercise appropriate
caution.

You know, I think you can get coil forms to fit your rig from Antique Radio
Supply, and also maybe Ocean State Electronics (oselectronics.com). You
could even make one for 30 meters. Ocean State has a power transformer in
their catalog that may do for a power supply for your rig, too. Or look for
an old tube-type hi-fi receiver in a thrift shop or at a tag sale. If you're
going to do, you may as well do it! :

73,

"PM"