Bruce
I do not have an answer to you problem, BUT I have trouble shot issues in
antenna systems as you described.
If it a break down under Power. You friend is a High powered dummy load.
start at one end ( makes no difference which) at trace my way back or out from
the FIRST connection. I have (4) Hy-Gain Hi Towers an a 4 sq on 75/80 mtrs.
Not sure of the DX engineering base plate But my Homebrew aluminum is where I
connect the coax to and feed the tower from that connection. How are you
feeding the center conductor to the tower base ? This is the FIRST place I
would look at. If it is breaking down you MY see carbon trace ! But this
connection to the HOT feed must be SOLID . I use 1/4" SS bolts with internal
toothed washers and the seal that area ( i use DUM DUM . comes off easy and
cleans up with Brake clean )and then attach the feed from the ground plate
connector with soldered eyelets and another set of washers nuts ,. I use
striped RG213 ( no ground /no shield ) as the jumper.
YMMV
Wayne W3EA
> Date: Thu, 6 Oct 2011 07:59:30 -0400
> From: n8de@thepoint.net
> To: brucebeard@gmail.com
> CC: towertalk@contesting.com
> Subject: Re: [TowerTalk] Strange HV-18T HyTower issue
>
> Sounds like a cold solder joint where the wire comes from the SO-239
> at the base of the HyTower and goes to the radiator. Make certain
> there is NO corrosion anywhere from that connector to the center
> 'pole' of the antenna.
> 73
> Don
> N8DE
>
> Quoting Bruce Beard <brucebeard@gmail.com>:
>
> > The Antenna
> > 3 year old Hy Gain Hy Tower. Optional MK-17, 17M stub installed,
> > MK160A,160M long wire installed .
> > DX Engineering radial plate.
> > Fed with Andrew Heliax hardline.
> > 4000+ feet of radials.
> >
> > The Installation:
> > Mounted in concrete. Located in heavily wooded area. lots of
> > leaves and debris, constantly cleaning stuff from base of antenna,
> > never seems to make any difference.
> >
> > The problem:
> > First noticed that while working on 75M and 160M, after
> > transmitting, the antenna would go quiet. It is as if the attenuator
> > is coming on or the antenna is being disconnected. If I put just a
> > small amount of RF into the antenna system it "wakes up". This
> > condition is more apparent on 160M than 75M.
> > SWR is fine under power; however, I have noticed that SWR
> > (indicated on my LP 100A) sometimes begins rising, in ssb while
> > keyed but without drive (i.e. keyed but not speaking). Speaking and
> > thus putting power into the system brings SWR back down.
> >
> > Now I believe I am getting a flashover somewhere. Plate voltage will
> > spike on the amp after transmitting with power thus shutting off
> > the amp. My OCF dipole is fine with the same radio/amp/tuner
> > combination. My Yagi is fine with no symptoms although I don't use
> > the tuner for the Yagi.
> >
> > Replaced coax last year with no apparent change. Dropped antenna
> > for visual inspection and saw nothing that looked unusual.
> >
> > I am at a bit of a loss here and I need suggestions as to where my
> > problem might be or how to diagnose this (these) issue (s).
> >
> > 73,
> > Bruce Beard
> > AB1KC
> > ab1kc@arrl.net
> >
> > _______________________________________________
> >
> >
> >
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> > TowerTalk@contesting.com
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> >
>
>
>
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