[TowerTalk] 75 Mtr. Yagi SWR

[Gary Dixon]

Hello Antenna Guru's,

I have a Create 75 Meter two element yagi ( AFA-75) that has recently
developed a funny SWR problem.
When working correctly the SWR was basically flat at 3790 and had about 100
KC +/- for the 2:1 points.

It is now 3:1 at 3790 and flat at 3990.  It jumped up the band 200 KC and I
also discovered it appears flat at 3450 KC as well.   Several years ago I
discovered that the SWR was also great on 30 meters. It was always about
1.5:1 on 30 meters and is still about the same there today even though it is
bad on 75 meters.

In an attempt to isolate a simple problem before having to lower the beam, I
did jumper around the W0MLY remote switch box to see it the box was causing
the problem. No change, still high SWR.

Several years ago I did have to replace the original Create Balun because I
attempted to use the beam on CW to work ZA when it first came on.  Bad move,
the high SWR caused the balun to smoke, short out and other #@^&%$% things.
Hi Hi

 I replaced the balun with a highly respected USA manufactured current balun
(1:1) with the beeds. It has worked great now for several years until a few
weeks ago when the SWR went high.

This time after I discovered the high SWR problem I had remembered possibly
transmitting on the 75 Mtr yagi very briefly instead of the 12 meter beam.
If this did indeed happen, would such an incident cause the SWR to just
shift up the band as I described if the balun were smoked??

If the balun is the problem would a RG-8 coax balun like Cushcraft uses on
the 40-2CD work just as well ?? 
It is made up of twelve turns of coax that is six inches in diameter and
probably is not as sensitive to operator errors. Hi Hi

Any thoughts would be appreciated.  

Thanks, Gary, K4MQG in South Carolina


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