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[CQ-Contest] Looking for input on balanced line feeder length

To: <cq-contest@contesting.com>
Subject: [CQ-Contest] Looking for input on balanced line feeder length
From: "Paul Mackanos - K2DB" <k2db@k2db.com>
Reply-to: k2db@k2db.com
Date: Sun, 11 Mar 2012 22:37:42 -0400
List-post: <cq-contest@contesting.com">mailto:cq-contest@contesting.com>
Forward from one of the guys in our club.

Paul K2DB


Hi all, 


    I am looking for any input anyone has in regard to balanced line feeder
length. I am sure most are familiar with my situation with my antenna tuner.


    I have a 135 foot dipole, fed with approximately 53 feet of 450 ohm
ladder line.


My original tuner was an MFJ-986 and it has worked without and problems with
the amp @ 1k.


    I wanted to changed to a true balanced line tuner, I did my research and
found the the Palstar BT1500A looked to be a good choice. In early January I
ordered a Palstar BT1500A. When I received the tuner and put it on-line I
experienced several problems, I had a tremendous amount of rf into the
shack, it actually took out the ptt circuit and the audio circuit of my
FT-897D. The only thing that was changed in the shack was the tuner, I
pulled the MFJ out and slid the Palstar in. In the third week of January the
Palstar was sent to the factory to have it looked at. The tuner was repaired
and returned to me, the packing slip listed a long list of parts that had to
be replaced in the tuner. 


   When I received the tuner back, I took the MFJ out of line, put the
Palstar on line, on low power ( 100 watts ) it was tuning, but didn't appear
to tune as well as it did when I first received it. I was still experiencing
rf into the shack, enough that I was tripping the power supply due to it. 


    My ground system consists of an 8 foot ground rod right outside the wall
of the shack, approximately 4 feet of #4 stranded wire running into the
shack going to a buss bar, and from the buss bar I have 1 inch braid going
to each piece of equipment individually, they are not daisy chained. All
equipment is grounded, power supply, tuner, amplifier, and the radio. When
attempting to tune up, we heard some arching and wasn't sure if it was the
amp, or the tuner. We opened the tuner, turned all the lights of and found
it was in fact the tuner. The coil on one of the relays was arcing to
ground. A video of the arcing was sent out on the reflector, that arcing
accrued at approximately 400-500 watts. 


   I once again contacted Palstar and informed Paul the owner of the
situation, and told him we had a video of the arcing, and he said I know
what an arc looks like I don't need a video to show him. He instructed me to
send the tuner back again and he would fix or replace it. After it being
gone the second time for about 2 weeks, I sent Palstar an e-mail and told
them, I didn't want the defective one repaired, I would like a new one or
what ever we had to do to get a refund. That brings me up to where I am
today, I am expecting the new tuner to arrive tomorrow ( Monday March 12th )
in UPS.


    I am extremely nervous to put the new tuner in-line and attempt to use
it, due to the fact if this one fails I can only assume that Palstar will
not stand behind it after being damaged twice already. I have had several
conversation with some club members already, but I wanted to reach out to
anyone and everyone that may have some input to my situation. 


    I have received varying opinions on what maybe happening in regards to
the length of my balanced line. Some are saying it shouldn't matter the feed
line length, and some are saying it most definitely has an effect with
certain lengths of feed line. I am truly confused to why the one tuner would
work with no issues, and the what I assumed to be a better tuner has several
issues on the same system. 


    My 135 foot dipole on one end is about 65 feet in the air, and other end
is about 35-40 feet in the air. The balanced line comes straight down and
turns into the wall of the shack. The balanced line is not in contact with
anything along its path. The only way I could shorten the feed line is to
possibly lower the one end and make it more of a slopper. If I were to add
more feed line to the length, it would have to lay on the ground, and I know
that is not a desired thing for balanced line. 


    I am looking for any information anyone has to offer in regards to
balanced line antennas. Whether it be personnel experience, book reference I
can go and read, or anything you may know of on the web? I admit I only know
very little when it comes to this topic, and it may very well be something I
am doing that maybe causing my own problem I am just not sure what it may
be. I anticipate that the tuner will arrive tomorrow, and for now it is just
going to go onto the shelf until I can make heads or tales of what is going
on here, as I said if the goes south again, I think Palstar will be telling
me I have a wonderful $700.00 paper weight and I don't want that to happen.


   Any and all input will be greatly appreciated, as I said I have varying
opinions already, nothing really leaning to one side, so if you have
anything thing you can and would be willing to share I would appreciate it.
If I have left anything out that would help in your response please feel
free to ask. 







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