[SignalOne] Tuning the Broadband

[parinc1]

Hi Jerry,
I always like reading your posts. Doing a great job and you have found some difficult problems already.
Take a look at what  my 1296MHz EME buddy went through to straighten out  a CX-7 he inherited. What a butcher job had been done to it:
https://www.sm2cew.com/CX7A/CX7A.html

Dale W4OP


________________________________
From: signalone-bounces at mailman.qth.net <signalone-bounces at mailman.qth.net> on behalf of jerry <jerry at tr2.com>
Sent: Monday, November 18, 2024 4:30 PM
To: Signalone <signalone at mailman.qth.net>; Signal One <signal-one at groups.io>
Subject: [SignalOne] Tuning the Broadband



This list is for discussions regarding collecting, repair, use and sale of Signal/One radios and accessories.

Documentation on Signal/One radios can be found at http://www.hamanuals.com and several other sites on the Web.

.
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



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