Duplexer generated possibly...
Reads like arc type pitting inside the duplexer. Take a
slow speed drill and run the duplexer tune shafts up and
down through their range a number of times. Hopefully
the plunger finger stock will knock off or polish off/down
the pit/arc spot enough. Don't know if Wacom uses
threaded tune shafts like Telewave and others... but
you get the idea.
After you've "used the plunger finger stock as a cleaner",
retune and try the duplexer and see if the problem goes
away... been there done that...
Two or three things cause it... one is no lightning or
disharge protection on the antenna. The most common problem
is often traced back to extended cavitiy plunger movement
(tune up and mechanical vibration) at high power into non
perfect conditions... but not exclusive to...
good luck,
skipp
www.radiowrench.com/sonic
> "kc4fwc" <[EMAIL PROTECTED]> wrote:
> I've wondered if induced signals into the tower may be causing a
> problem with the 2M repeater I have been working with lately. I've
> not seen a spark from induced signals yet, but suspect something is
> resonant and being re-radiated causing a problem.
>
> The 2M repeater was running on a brand new Celwave PD-340-3. I've
> tried several other antennass and have the same problem. The
> repeater is a pair of GM-300's back to back, running around 35 W
out
> of XMIT, going into 8 inch 4 cav duplexer by Wacom. Into the dummy
> load, no desense, no duplex noise (I use superflex for all jumpers
> and Heliax to the antenna). The antenna was top mounted at 150
feet
> of Rohn 25G.
>
> Normally, the repeater would work fine. No problems until early
> morning or at night. Mainly in early morning hours, the repeater
> would desense itself up to 20 dB, make all kinds of garbage noises
> like popping and crackling, it almost sounded like someone was on
the
> tower taking two screwdrivers and rubbing them together next to the
> antenna! Yet nothing on the tower is loose, and shaking the guy
> wires when the repeater is actually acting normal doesn't cause
> noise. I have even heard video buzz coming out of the receiver.
> When I kill the transmitter, all noise goes away and the receive
> signal is quiet.
>
> There is a Ch 6 TV tower about 15 miles from me. There are two
> pagers 152.480 and 158.700 about 1 mile from me. Other than that,
> the tower is in a remote area far away from saturated RF
generators.
> Like I said, the repeater works fine duplexed to the same antenna
> most of the time, just under certain conditions (like enhanced
tropo)
> does it mess up. I can't find out what's doing it.
>
> I finally wound up using dual antennas, dropping the TX antenna
down
> 30 feet from the RX, and it works like a charm. Could the tower
have
> induced currents and signals coming in and energizing something
> causing a mix? The separation is 600 KHz and I don't know of any
> strong AM stations on that frequency except for a 640 KHz station
> 50000 watts and 30 miles away. Guess I'll have to keep running
dual
> antennas until I figure out what's wrong?
>
> 73, KC4FWC
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