[SignalOne] Tuning the Broadband

[jerry]

The challenges continue...

   Now that I have decent power on the lower bands ( still pretty much 
zilch on 10M ) I'd like to
tune up the broadbands.  The schematic makes it obvious that they're 
just preset tunings for the
PI-L network - a separate trimmer for each band.  So you reasonably tune 
them just like the big
TUNE and LOAD knobs.

   They're hard to get at.  Especially the plate TUNE trimmers.  And 
they're stiff.  I was trying
to tune 20M into submission - you can't get straight the tune with a 
screwdriver.  It's complicated
by trying to do it *fast* before the tube cooks.

    The hexes around the screws are 7/32.

   What do YOU use to tune these things?  I have an open end ignition 
wrench that will work.  I really
don't like poking around with conductive metal tools that can slip off 
while this thing is running.

   I'm thinking to take a 7/32 socket.  Turn it down on the lathe so it 
fits inside the trimmer mounting
screws.  Cut it down really short so it fits in the 20M trimmer.  Weld a 
handle to it.

   Replacing the screen current sensing resistor really helped the 
transmit.  It's still not quite right
though.  I have to turn the drive all the way up to get decent power.  
And still zilch on 10M.  Too me,
that says there's a bad stage somewhere.  On lower bands, the system has 
enough excess gain to compensate.

   Checked into a roundtable on 20M this morning.  Got good reports. Rig 
was making full power.

                   - Jerry, KF6VB