Don, this is a natural response, or lack thereof. If you ask, "will I have this
problem," and nobody else has had it, that doesn't mean they can guarantee YOU
won't have it, so they refrain from commenting.
I learned a lot from my experience with one outdoor, rooftop repeater I built.
I was expecting condensation in places where I could find no evidence of it
actually occurring. It finally dawned on me that even if the ambient humidity
is 100%, and condensation is collecting on the outside of the cabinet, the
equipment inside is safe as long as the temp there remains even slightly above
the outside.
If you have to mount the duplexers away from the transmitter and power supply,
condensation may be more difficult to control. Whenever possible, I will always
try to keep the cans (and all the equipment) slightly warmer than outside
ambient. I believe that in most installations, even in non-climate-controlled
buildings, this is likely to happen by default, especially if you are co-sited
with lots of other people's stuff.
On my rooftop repeater, I ended up using a completely sealed, gasketed steel
cabinet, painted a light color, with no vents to the outside whatsoever, and
relied on plain old heat loss through the cabinet walls for dissipation. When I
changed out my 2-watt, solar-powered, Repco UHF repeater for a 35-watt,
converted GE Mastr II powered from the AC mains, I expected problems, so I put
a 119ºF attic fan switch on the transmitter's heatsink, wired to a logic input
on the controller. It never triggered, even in the summer, and this was in
orlando, FL.
The commercial stuff is based on components which were designed to stay happy
for years locked in a car trunk. It may be possible to overdo ventilation. I
think I'd rather err on the side of staying a little warm in a repeater shack,
within reason.
73,
Paul, AE4KR
----- Original Message -----
From: ka9qjg
To: Repeater-Builder@yahoogroups.com
Sent: Tuesday, August 31, 2010 11:42 AM
Subject: RE: [Repeater-Builder] Duplexers
Wow this must of Really been a Dumb question , No one answered it
>> Will the Duplexer have any problems inside with Condensation from Heating
up in use and Cooling down
