Hi Anthony, Hygain offers two baluns for the TH7DXX:
A BN86, which is the older style bifilar wound over ferrite bar. This is
also known as a voltage balun and as such is subject to arc over if the vswr
is high, such as accidentally using it on 40m with a 20m antenna.
The other balun is called a BN4000 and is made of coax with ferrite beads
over the coax. This is known as a current balun and is more robust in case
of high vswr. It has a higher power rating as a result.
The TH7DXX vswr curves are dependant on using the supplied balun to driven
element jumpers. The reason for this is they constitute a short balanced
line of considerable impedance and are an integral part of the antenna
matching scheme.
Omitting these jumpers is the primary reason that coax baluns don't seem to
work well with many of the Hygain beam antennas.
73,
Gerald, K5GW
CEO, Texas Towers
In a message dated 7/21/2013 9:31:33 P.M. Central Daylight Time,
wa4jqs@mikrotec.com writes:
>What balun is being used with the TH7DXX. over the years i have
>owned a few hy gain ants and burnt up the Hy Gain BA baluns that
>were offered. so i went to wind your own coax baluns.. i was reading
>a few of the old articals on tower talk and saw where the TH7DXX
>would not work well with a coax balun.. my amps are Alpha 3 tubers
>and Henrys so dont want to have to replace their so called high power
BA-4000
someday in the dead of winter hi hi... what are most of you using .
thanks for the help
73 Tony
Anthony W. DePrato WA4JQS
Since Sept 9th 1962
ARRL CDXC WIA FISTS A1OP
CQ DX HALL OF FAME # 39
DXCC HONOR ROLL
FOUNDER SOUTH SANDWICH ISLAND DX GROUP 1988
CALLS HELD
VP8BZL VP8SSI 3Y0PI ZD8JQS V31SS WA4JQS/ZS1 WA4JQS/KC4 WA4JQS/4K1
ZUT DE WA4JQS
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