Thunderstorm = shorted semiconductor junction (sometimes). Might not be
completely shorted either. I'd start looking at the repeater control board.
hope you have an extender card.
Ran a bunch of MII repeaters years ago and we ended up with PolyPhaser
lightning protection devices on every I/O; RF, power, telephone,etc. Solved
lots of post T-storm calls.
As always- Best Regards and YMMV!
Eric Lowell
Eastern Maine Electronics Inc.
48 Loon Road
Wesley ME 04686
eme....@starband.net
www.satnetmaine.com
207-210-7469
--- On Thu, 6/25/09, r_s_s_i <r_s_...@yahoo.com> wrote:
From: r_s_s_i <r_s_...@yahoo.com>
Subject: [Repeater-Builder] MastrII Repeater Issue
To: Repeater-Builder@yahoogroups.com
Date: Thursday, June 25, 2009, 4:58 PM
Good day… Looking for some advice.
I am using a UHF MastrII repeater as an extra receive site that is outside
mounted in an outdoor GE cabinet. The receiver is 449.4500 and CG 114.8 on a
Stationmaster antenna at 215 feet, and transmit out is 420 at 10 watts into a
yagi at 50 feet. I am using ½" Andrew heliax for both antennas. The antennas
are on a FM digital broadcast tower on 106.3 MHz transmitting around 3kW of
power (if my memory is correct) antenna at 400 feet. This site has been in
service for a couple of months, and has worked flawlessly. After a thunderstorm
went through Friday night with some heavy rain the repeater started keying up
on its own as if it was being kerchunked. It acts like it is hearing an input
signal to repeat, but at times the transmit relay just clatters and never
actually drives the PA enough to reach to the main site. It almost acts like
the squelch setting is just a tad too low causing the clatter, however I have
found this is not the case. On a couple of
occasions the repeater just keys and stays keyed for a second or two. I
checked using an IFR monitor the input frequency to see if something was being
heard and nothing was found when this clattering occurs. I also removed the
receive antenna to see if something was being heard locally and the issue
occurred while the antenna was off. The kerchunking occurs even if the CG board
(factory dip switch style) is in or out.
This repeater is very basic; I am using the GE factory repeater control card,
repeater audio, and 10-volt regulator cards. Voltage was checked from the
factory power supply to have input of 121.8 VAC with output at 14.9 VDC, and
10.04 VDC from the 10-volt regulator card. At first I was suspecting a possible
problem with the delay timer on the repeater control card, however it is set to
drop as soon as carrier received signal drops.
I traced the RUS voltage at several different locations and it seems to be
acting, as it should like it is hearing a signal. I had some spare parts along
so I tried a couple of things with no change or correction to the problem. A
different CG board (dip switch style) was installed, no change, even tried a
different PL. A spare receiver was installed, no change. 10-volt regulator was
swapped out, no change. Tried adjusting power level on PA, no change.
We used a site master to check the feed lines, both antennas and everything
looks good. Everything in the cabinet is dry with no sign of water.
Has anyone encountered a similar problem? I don't see anything from the FM
station on Spectrum Analyzer, but could it be interference? Anyone have
experience with radio station sites? I am going to pull the unit and bring it
home for a few days to see what happens. Someone suggested as a wild guess, an
intermittent electrolytic capacitor.
Ideas?
