Jim, after my calculation of the coil were wrong I thought it was about time
to check everything and I did and to try and distinguish between radius and
diameter...

Using the L/C meter I wound a proper coil, I checked the calibration of my
plate current meter, I did a more thorough check of the grid current (it is
between 1 and 2 mA) and so on and so forth.
And I did connect a dummy load (even though they don't respond or send out
QSL cards when you tranmit into them).

None of the thing did make any real difference and the dip, the elusive dip,
was in the order of magnitude of maybe 2 mA, nearly impossible to see on my
meter.

Then I changed the circuit around as you suggested, testing the RFC and I
got a dip the likes of which I had never seen. The meter went slowly from
about 30 mA to 50 mA and then dropped to about 25 mA, I couldn't miss it.

But what does it mean. I gather my RFC is not ok. What is wrong??

I used a Series 4590 high current filter inductor I had around, it has the
Digi Key number DN 4528.


Happy about the dip but still not clear on the deeper reasons...

73 Uwe



Here's something else to try:

Often trouble of this sort is due to the RF choke used. What RFCs are
you suing, particularly in the plate circuit? Although the LC meter
may say they are a certain L, in real life they may have all sorts of
unwanted resonances.

To test this idea out, do the following:

- Remove the plate RFC
- Connect the antenna end of the plate coil to the B+ where the RFC
used to be connected. This point should already be bypassed to ground
through a disk capacitor of about .01 uF
- Disconnect the "loading" capacitor
- Remove the plate coupling capacitor.

What you will then have is the 200 volts being fed to the plate
through the coil, with one end of the coil going to the plate supply
and the other end connected directly to the plate of the 6V6. The
plate tuning capacitor is connected between the plate of the 6V6 and
ground.

End result is no plate RFC and a parallel resonant circuit. There's no
connection for an antenna yet, but that's not important right now.

Test out the rig and look for the plate current dip. It should be very
obvious because there is no load connected.

This is just a temporary setup to see if the RFC is OK.

73 es GL de Jim, N2EY