Sonny Hood wrote in
:

I have an efficiency question concerning feed lines. My present
system is RG-8X to my 75 meter inverted vee which is about 85 feet
away from the shack. I propose to replace some 88 feet of coax with
300 ohm window ladder line that is inserted into the coax run with 4:1
baluns to match the coax on each end. Also at the feed point of the
antenna switch from a voltage balun to a current balun (ferrite chock
type). By my calculations with a 98 watt generator I will increase
the power to the load by about 11-20 watts and with a 985 watt
generator, 117-210 more watts will reach the load. Figuring
theoretical total system (A) against total System (B) or by just the
difference in the 88 feet of ladder line versus coax. What do you
think the increase will be?

Sonny,

I have resisted the temptation to tell you that the question is wrong
rather than to answer the question... however...

You are trying to compare two configurations that are not optimal.

An optimal coax configuration would have a balun, usually at the antena
feed point so your coax loss budget is short changed a balun.

I assume from the fact that you have proposed coax that this is a one
band antenna. You haven't made it clear whether you can use an ATU to
transform the load to suit the tx, I will assume you can.

Why do you need two 4:1 baluns / transformers? The dipole is already an
approximately balanced load and loss on open wire line with a VSWR of 4:1
is still quite low. You could just attach the feedline directly to the
antenna, and use a 1:1 balun at the ATU. Alternatively, you could
lengthen the feedline a little so that it was an electrical half wave and
dispense with the ATU (still need the balun).

In the case of the latter (an electrical half wave of open wire line, 1:1
balun at the tx) you will achieve the lowest loss, but it is just a few
tenths of a db better than the balun/RG8X config if you work them
through.

The open wire line might not be as easy to route into and around the
shack, and depending on construction, more affected by water.

Owen