I stand corrected...looked closely at the photos and on each side of the
ladderline I have a pair of 3 meg resistors in series (6 meg total per leg
to ground). The selection was made arbitrarily, I don't think it really
makes that much difference as long as the RF on each leg of the ladderline
has a nice low-Z path to the antenna and ligh-Z path to ground.
Oh...another thing...if you use spark plugs as a surge suppressor, open the
gap wide enough so when you run QRO (or QRO +++) the spark plug doesn't
fire. I also put a rubber boot over the sparkplug gap so it doesn't drip
when it rains nor ice over when the rain turns to ice. This is
trial-and-error....set up your plugs, then run max power in various modes &
freqs, watch for any sudden errors from your amp (for example smoke, flames,
and burning smell), odd SWR spikes, etc. I don't put a lot of faith in the
sparkplug as a surge suppressor, but it's better than nothing and I have the
gap at somewhere between 1/16"-1/8". The plugs don't fire when I run full
legal limit....I have never been there to witness what happens during a
thunderstorm!
73
de
k0dan
-----Original Message-----
From: K0DAN
Sent: December 10, 2013 13:42
To: Edward McCann ; towertalk@contesting.com
Subject: Re: K0DAN de AG6CX
Hi Ed...
The resistors need to be carbon composition and at least a couple megohms
each. IIRC mine are around 3 meg per leg (not sure....maybe their value
shows up in the attached photos), maybe 1/2 watt resistors?. I ran each leg
of the feedline to ground via a 1+ meg resistor (nothing across the
ladderline). This will be hi-Z for RF and will be invisible to your antenna
network, but if there is static DC voltage on the antenna or feedline, it'll
bleed it to ground. Values are probably not critical (higher wattage &
resistance is better), you just want to have something of high resistance to
bleed off charge. If the antenna gets hit by lighting, everything is
vaporized and hopefully the spark plug gaps and bleeders will spare your
equipment. Or not.
Attached photos tell the story better than I can. If you need more info, let
me know!
GL es 73
Dan
K0DAN
-----Original Message-----
From: Edward McCann
Sent: December 10, 2013 10:57
To: k0dan@comcast.net
Subject: K0DAN de AG6CX
Good Morning Dan:
Re your comment on static bleeder resistors and ladder line, could you
clarify if you connect the resistors across the ladder line (wire to wire )
or you are connecting each of the wires in the ladder line to ground through
the resistor?
Also, do you have a suggestion on adequate power rating of the resistors?
Thanks,
Ed McCann
AG6CX
Sent from my iPhone=
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