Bruce, what you describe sounds more like a cold solder joint, loose
connection, or relay contact problem. Typically a short due to a flashover
stays
shorted/does not heal itself.
You might try connecting the antenna coax directly to the radio antenna
connector to see how that works. If still bad, connect the antenna end of the
coax to a dummy load and retest. If still bad, the problem has to be in the
coax run.
Once you have a system that works properly, you can add other pieces of
equipment until the problem reappears.
Happy hunting!
73,
Gerald K5GW
In a message dated 10/6/2011 6:58:21 A.M. Central Daylight Time,
brucebeard@gmail.com writes:
I am trying to be "scientific" in my approach here. The only common relays
or switches in the system ate in the tuner as the amp is new and the
condition predated it. The tuner is an AT5K plus with vacuum relays and a
roller inductor. I have the issue even when I put the tuner into "bypass".
This leads me to believe that the issue isn't in the inductor. The second
antenna is also connected to the same tuner, I have no problems with this
antenna so perhaps I should switch antenna ports and see if the problem
follows the antenna....
I have switched coax from the back of the tuner to the antenna with no
change in behaviour, that leaves the connector at the DX Engineering plate.
Could this be my issue? Maybe the flashover is a result of a short here? Is
there any way to test it? Should I get another one and see what happens?
73,
Bruce Beard
AB1KC
brucebeard@gmail.com
---------- Forwarded message ----------
From: Pete Smith <n4zr@contesting.com>
Date: Thu, Oct 6, 2011 at 7:37 AM
Subject: Re: [TowerTalk] Strange HV-18T HyTower issue
To: Bruce Beard <brucebeard@gmail.com>
Definitely sounds to me like a relay or switch somewhere in the signal
path,
or (less likely) a connector. Many relays and switches can develop an
oxide
coating on the contacts sufficient to attenuate signals on receive, but
when
you pass just a bit of power through them the oxide temporarily burns off.
73, Pete N4ZR
The World Contest Station Database, updated daily at
www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at
reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000
On 10/6/2011 7:18 AM, Bruce Beard wrote:
> 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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