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Re: [TowerTalk] rf burns

Subject: Re: [TowerTalk] rf burns
From: chris casey <>
Date: Fri, 10 Feb 2012 17:49:03 -0600
List-post: <">>
I undid the wrap on the splice and one just fell apart in my hand. I
got it all put back together and sealed up, noalox'd the outside plugs
and sealed those up with tape and silicone.

I still get some noise in my headphones when tuning up but not near as
much, and my key base no longer tries to kill me when I touch it.

Definite progress.

I didn't have time to add length to it and go around the tree rather
than through, but this gets me going again. Only to find noise and
fading signals at the moment, but a happily loaded antenna.

Thanks everyone.

On Tue, Feb 7, 2012 at 11:30 AM, K0DAN <> wrote:
> Make sure all the banana plugs are making good contact (remove + clean +
> squirt of Deoxit), and that your splices are clean and making good contact
> (I would recommend twisting them, then soldering them). Remove the feedline
> from the tuner and put an ohm meter across should measure a fairly
> low resistance.  If the loop or feedline has opened up, you no longer have a
> closed loop, and that could definitely bring high RF back into the shack.
> Bonding all your equipment to a single point ground is also important.
> GL es 73
> dan
> k0dan
> -----Original Message----- From: chris casey
> Sent: February 06, 2012 11:31 PM
> To:
> Subject: Re: [TowerTalk] rf burns
> Rig goes to tuner with a couple feet of flexible "big" coax of some
> sort, not the little rg-58 type, no reducer needed for the connector,
> but not sure what specific type of coax it is from my vantage point
> nowhere near my operating position at the moment...  to the tuner, a
> 1.5KW MFJ without the roller inductor, but it has served me well over
> the years. From the balanced binding posts goes 450ohm window line, a
> couple feet to threaded brass rod to pass through the back of the
> desk, and then a few feed with banana plugs to go through a pair of 6"
> double female so-239 headed through a blocked off window. Outside
> another set of banana plugs  which then run out and through a pine
> tree and to  a closed 80M-ish loop around the back yard.
> There is a splice as the length was pruned for one years sweeps
> operating position and extended for the next as I always ended up
> somewhere else, garage, laundry room, travel trailer, screen porch
> etc.
> My splice technique is to cut out a section of solid spreader, twist
> each conductor over the opposite to lay fairly flat, solder, well
> overlapped heat-shrink, then drill a couple holes on each side of the
> spreader i cut and small zip tie it at the splice joint which keeps it
> from twisting and collapsing in. It sure looks like it should work ok,
> you can't spot the splice at a glance from any distance. But it sure
> is a place to look for a failure, if it had a bad solder or something
> it would likely stay fairly solid with the twist and be flakey. Banana
> plugs are soldered on as well.
> I have tried to find what a western union splice is but I couldn't
> believe I couldn't find a good explanation. Just lots of references to
> it. But I havent tried for a few months, seems like it shouldn't be
> that hard.
> I know there are "bad" lengths of balanced line to avoid, but I have
> no idea how long my feed line is also as its been adjusted to fit
> spaces not to fit any measure.
> I didn't think one had common mode currents on balanced line like you
> would find on unbalanced coax.
> I'll re-work the splice and check the plugs, see what I can see.
> On Mon, Feb 6, 2012 at 9:17 PM, Robert Carroll <> wrote:
>> I don't know the exact design of your antenna.  But assuming it is a
>> continuous loop and not open anywhere except where the feed-line connects,
>> I'd ship an amp or so dc down the feedline (at relatively low voltage) and
>> watch the current flowing. It should be pretty constant.  If it drops
>> off--or if you don't have continuity to start with--you may have a bad
>> joint
>> somewhere or a broken conductor.  I ran into that once with a loop where I
>> had to solder several pieces of wire together.  One of the soldered joints
>> had become defective and the dc (as well as the rf) impedance was all over
>> the map.  I have had similar problems in 450 ohm line--and I have plenty
>> of
>> splices in all my 450 ohm line.  I recommend (if the line is solid) using
>> the Western Union splice, soldering, and coating with liquid tape.
>> Bob W2WG
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