[TowerTalk] HyGain AV640 Toroid core mix, or Beefing up an AV640

[Art Trampler]

Roger,

I was having trouble with the choke overheating on 40 meters because it had
been wound with a lot of the windings at five o'clock instead of having the
evenly spaced.  Anyway, that is fixed now, but I considered as a work around
getting a higher power choke balun and 4:1 unun from Balun Designs.  Granted
it would have been pricey, but it would have done the job and might meet
your needs.

Art, KØRO

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Roger (K8RI)
Sent: Sunday, April 04, 2010 8:52 PM
To: TowerTalk
Subject: [TowerTalk] HyGain AV640 Toroid core mix, or Beefing up an AV640


Any one have any idea as to the core mix used in the AV640 baluns?  It 
has two in the matching network. One is a current balun and the other a 
4:1.  Then they use a series cap to tune out the reactance of the 
slightly long antenna.
The is designed for all ham bands from 40 through 6 meters. Power is 
limited to 1.5KW PEP 40 through 10 and only 200 or 300 watts on six.

I'm assuming that either the core material and/or the series cap is what 
limits the power on six.
As the power is also limited for RTTY/Digitl 40-10 I'd assume it needs 
some larger (or more cores) to handle the heat in the 4:1 balun and 
probably the current balun as well.

I'd like to beef this thing up so it'll take 1.5KW for any mode, 
although I don't know of any mix that will let me do it over the entire 
range of 40 through 6 meters. I'd also feel a bit more comfortable 
running it the legal limit contest style although it's a back-up antenna.

73

Roger (K8RI)

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