[TowerTalk] Compensating cap value in AV640

K8RI on TT k8ri-on-towertalk at tm.net
Mon Aug 22 18:36:53 PDT 2011


Any one know the value of the compensating cap in the matching network 
on the Hy-Gain AV-640 vertical. It goes between the 4:1 balun and the 
feed point on the radiating elements.

I'm pretty sure it's blown (I replaced it a year or two back) but don't 
remember the value. I'll have the antenna down in a day or two, but 
knowing the value ahead of time would save some time.

I run the legal limit and think this thing may need to be beefed up a 
bit, particularly for digital modes.
The antenna has gained a number of resonant points, usually one above 
and one below the desired points.  Last time it blew the cap and shorted 
some turns in the protective choke.

I'm thinking of beefing up the whole matching network. Last time I noted 
the plastic end caps on the driven elements were all burnt so there must 
be a fair amount of corona on the thing when running the amp.

73

Roger (K8RI)



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