Topband: 80m shunt feed -DESCRIPTION

[Pete Smith]

At 10:27 PM 8/1/02 -0500, Ford Peterson wrote:
>It would be nice for him to get a tool for measuring feedpoint and try two
>things.  1) measure what he has; 2) move the tap point further up the tower
>if R<50 ohms, down if >50 ohms; and 3) move the shunt closer to the tower.
>
>On 160, I had great success with a similar sized tower running 450 ohm
>feedpoint and having the shunt 1 meter away from the tower and tapped at
>68'.  For 80 meters, he may be close to where it should be but for an
>elevated feedpoint impedance.  It is very difficult to advise without
>knowing some real data other than SWR.  Knowing Z and SWR you can calculate
>R j to make more sense of the data.

On the other hand, if the SWR minimum is adequately low and the SWR 
bandwidth sufficiently broad, does it matter much?

I had endless frustration with my much different tower trying to do what 
Ford suggests, not least because a local BC station drove my MFJ 259B 
nuts.  Finally went with an omega match and tuned it up using a transmitter 
and SWR meter right at the base of the tower.  I have no real idea what the 
values of R and j are.


73, Pete N4ZR

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