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[TowerTalk] Homebrew Tuner Thoughts Needed

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Subject: [TowerTalk] Homebrew Tuner Thoughts Needed
From: (realex)
Date: Thu Mar 20 06:19:42 2003
If the MFJ works, why bother with the other one?
Bob, W5AH

-----Original Message-----
[]On Behalf Of Leroy Buller
Sent: Wednesday, March 19, 2003 10:24 PM
Subject: [TowerTalk] Homebrew Tuner Thoughts Needed

Years ago, I made a Lew McCoy tuner (Ultimate Transmatch) using new EF
Johnson Air Variables and a nifty new 28 mh roller inductor.  I think one is
a split stator (250 pf each section) and the other is a 250 pf or 500 pf...I
can't remember.  I mounted these new components up in an SB200 linear
cabinet and it matched by Heath line very well.  Well, the Heath line is
looooong gone and I changed the tuner from Ultimate to SPC.  But, here is
the rub.  I am having a heck of a time finding a good setting on the tuner
14 Mhz and above.  I do have a small coil after the roller inductor of about
5 or 6 turns of #10 wire about an inch and a half  in diameter and spaceed
about a quarter of an inch.  That was suppose to help on the higher bands.
But, for some reason it is not working very well above 14 Mhz.  If I
remember right, I went to the SPC because ot was better on 160 meters and
did not have to have a door knob capacitor switched in to get enough
capacitance.  But, I remember th!
inking that the SPC design doesn't work well on the higher frequencies.
I've tried to research the issue on the web, but I get a lot of
gooble-de-gook, but not much hard substance.  Can anyone enlighten me as I
have not been able to come to a conclusion about this issue.  What confounds
me (and that is easily done these days) is that my cheap little MFJ tuner
will tune all my antennas down to nothing (my antennas are cut for CW and
need some tweeking on the SSB part of the band) and have no trouble on any
band.  So, I am looking for some ideas here....should I keep it SPC or go
back to the T?

Lee - K0WA


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