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[TowerTalk] Homebrew Tuner Thoughts Needed

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Subject: [TowerTalk] Homebrew Tuner Thoughts Needed
From: (Leroy Buller)
Date: Wed Mar 19 23:24:12 2003
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 thinking 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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