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Re: [TowerTalk] Changing Air Variables in an Antenna Tuner?

To: K8RI <>
Subject: Re: [TowerTalk] Changing Air Variables in an Antenna Tuner?
From: kd4e <>
Date: Sun, 18 Mar 2007 21:25:02 -0400
List-post: <>
Great helpful ideas!

I checked out the ebay posting and saved the relevant
pics for future reference.

Will have to dig into the tuner to see where best to locate
the switched caps.


> As an added note, the Henry HF amps use a series of plastic cams on a 
> shaft geared to the band switch.
> There is a 2KD classic on e-bay that has several photos that show the 
> cams. Today is 18th and it should be there of a bit over 5 days.   Watch 
> for line wrap on the link.
>> There's also a cam on a shaft tied to a knob, or push-pull switch, 
>> disk of
>> plesiglass with arm mounted on one side.  In the case of the old B&W tank
>> coils/band switch we tied the caps to the 80 meter position. Let your
>> imigination be your guide.
>> You are certain to give away some high-end tuning capability because
>> the minimum capacitance of a big air variable will probably still
>> present a fairly low reactance on upper HF.
 >>> Why not add some 250 or 500pF doorknob caps that can be switched in
 >>> in parallel with the current capacitors?
 >>>> I'd like to improve performance on 80 & 160M
 >>>> QRO and read of one Ham changing the C1 240pf
 >>>> input series cap to 750pf and C2 114pf to 675pf.


Thanks! & 73, doc, KD4E

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