First thing to remember is a really radical thought: The power rating of a
voltage balun has to be decreased by the highest SWR factor existing on the
line. That is, a 2 kW rated (at 1:1) balun is only good for 1 kW at 2:1
VSWR or 200 watts if your wattmeter shows a 10:1 VSWR looking at the
antenna. The reason is that the current (heating) losses in the windings go
up as the square of the maximum current - remember hearing about "I squared
R". A 4:1 VSWR means the current max value is twice the minimum, therefore
you'll be heating up the core four times as much as if you had a 1:! VSWR on
the line. It doesn't matter whether the line is unbalanced coaxial or
balanced open wire.

In your case the ratio of rated power divided by working power is 1.25, so
the maximum VSWR tolerable before you exceed the dissipation rating of the
balun is only 1.25. Or working the other direction, to always stay cool you
need to find a balun rated for (1200) x (VSWRmax) watts.

The input reactance of the Windom changes as you change the driving
frequency (and band), therefore the VSWR on the feedline does also. The
balun may stay reasonably cool on a few frequencies, but will be flaming hot
on most others.

--
Karl Beckman, P.E.
WA8NVW - licensed since 1964



"Ralph Mowery" wrote in message
news
Does anyone make a 4:1 balun that I can use for an off center fed antenna
that will take the legal limit of power ?

I did find one that is around $ 80 to $ 100 that is suspose to handle it.
I hate to pay that much for a ring of 'iron' and a few feet of wire wound
on it and it will not work.

I have up a home made version of the Carolina Windom. Bought a balun
rated for 1.5 kw. I only run around 1200 watts out of a Drake L4B amp.
That balun will heat up and quit working ( swr goes way up from about
1.7:1 at the frequency I use most) if I run more than about 500 to 600
watts SSB to the antenna for any length of time. The antenna is fed with
a good grade of rg8 and about 20 feet from the antenna is a current balun
(the one with the beads over the coax). It will heat up some but when I
take it out of the line, the 4:1 balun still heats up . The 1:1 bead
choke does not heat up to any big ammount when I put it on a dummy load
and put 1200 watts to it.

I had a low power balun up with the same antenna and running 100 watts the
antenna seemed to work fine.

If it was not for the wide bandwidth and good results I have been getting
, I would just run an 80 meter dipole and no balun. Also want an antenna
for 40 meters.
Have the usaul triband for 10,15,20.