[TowerTalk] Polyphaser failure

["Richard L. King" <k5na@texas.net>]

I recently had a problem with an 80M sloping dipole. The problem was that 
at about 100 watts the antenna the SWR would jump up and the antenna would 
become quiet. If you let things sit for a while, the antenna would start 
working again after a little while.

I did the usual trouble-shooting of checking the coax, splices, and even 
lowering the antenna to check it out. I couldn't find anything wrong so I 
hooked everything back together again.

I returned to the shack to try the antenna again and as I slowly raised the 
power level, I heard a small, quiet snap sound from the direction of my 
antenna bulkhead entry plate. The antenna failed just as I heard this 
sound. The sound was so quiet, that I had never noticed it before.

I have a bulkhead full of Polyphaser devices and have never had one to fail 
before. But I determined by replacement that I had a bad polyphaser that 
was breaking down at about 100 watts. It is a IS-B50HU-C0 model for 
bulkhead mounting and is good for 3KW between 1.5 and 50MHz. As I mentioned 
before the Polyphaser was being used going to an 80M antenna and I didn't 
determine whether it was shorting or going open.

My questions are:

1. Has anyone else experienced this kind of failure before?

2. Do Polyphasers go bad on a regular basis? I have 16 of them installed 
and this is my first failure ever.

3. When they fail, are they repairable?

Just curious if I should just throw the bad one away.

73, Richard

k5na@texas.net 


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