No Rust
--- On Thu, 3/12/09, Chuck Kelsey wb2...@roadrunner.com wrote:
From: Chuck Kelsey wb2...@roadrunner.com
Subject: Re: [Repeater-Builder] Quieting duplex noise from a tower
To: Repeater-Builder@yahoogroups.com
Date: Thursday, March 12, 2009, 5:00 PM
Were they starting to show rust
OK guys... I thought I could figure this out on my own, but I was
wrong. I could use some wisdom from the group! I have been chasing a
stubborn case of duplex noise for a long time without success.
The 2 meter repeater will run clean all day at 100 watts (or any
lower power level) into a
Suspect any other nearby fiberglass antenna in your search.
Chuck
WB2EDV
- Original Message -
From: Paul N1BUG paul_n1...@myfairpoint.net
To: Repeater-Builder@yahoogroups.com
Sent: Thursday, March 12, 2009 12:09 PM
Subject: [Repeater-Builder] Quieting duplex noise from a tower
OK
Thanks Chuck. What would you consider nearby? There is one
fiberglass antenna on a tower 60 feet away. It was new when it went
up 2 years ago, but my problem existed before that tower/antenna
went up.
Aside from that the nearest other fiberglass antenna (or antenna of
any kind) is 250 feet
Three different antennas (all DB or Sinclair, two of them NEW) have
been tried with no significant change. The feedline (Andrew
LDF5-50A) has been swapped out once with no change.
I think that leaves the tower or other nearby metal structures as
the prime suspects.
You didn't give a
Great questions, Jeff. Thanks! Answers below...
Have you looked at the
transmitter output with a spectrum analyzer during the occasions when you
have desense to see if it's getting sloppy?
No. I wanted to but I'm very isolated up here and do not have access
to one.
Have you tried other
What type of power supply is in your system? Do you have a back up
battery? If so what type of charger is on it? Any other repeater
systems in close proximity?
Are you using a preamp? If so, what do you have ahead of it
for filtering,
and/or have you tested without the preamp?
Yes I use a preamp.
DB4062 duplexer and two DB4002B 11 pass cavities, pass cavity loops
set for 1 dB insertion loss each cavity. I tried tightening it up to
3 dB per
-Builder@yahoogroups.com
Sent: Thursday, March 12, 2009 1:21 PM
Subject: Re: [Repeater-Builder] Quieting duplex noise from a tower
Thanks Chuck. What would you consider nearby? There is one
fiberglass antenna on a tower 60 feet away. It was new when it went
up 2 years ago, but my problem existed
Have you tried putting one or more pass cavities on the transmitter? It's
more of a longshot, but if there's something strong coming back down your
feedline it could be getting to your PA resulting in intermod. The problem
would come and go with the strong signal obviously, and only when
Also, I'll ask the dreaded question... You are not using any foil/braid coax
(LMR-400, 9913, etc.) for any jumpers are you?
Nope, won't allow the stuff near my repeaters! grin
LDF5-50A runs up the tower, RG-214 mil spec double silver shield for
all jumpers.
Paul
What type of power supply is in your system? Do you have a back up
battery? If so what type of charger is on it? Any other repeater
systems in close proximity?
There is a backup battery which is float charged from the 13.8V DC
power supply. Presently the supply on duty is a homebrew beast of
:
From: Chuck Kelsey wb2...@roadrunner.com
Subject: Re: [Repeater-Builder] Quieting duplex noise from a tower
To: Repeater-Builder@yahoogroups.com
Date: Thursday, March 12, 2009, 2:59 PM
Oh, it's difficult to say how close close
really is, but keep it in mind
if you run out of other fixes
Were they starting to show rust?
Chuck
WB2EDV
- Original Message -
From: neal Newman cozy...@yahoo.com
To: Repeater-Builder@yahoogroups.com
Sent: Thursday, March 12, 2009 4:55 PM
Subject: Re: [Repeater-Builder] Quieting duplex noise from a tower
Samething here in NJ. the Club put
--- On Thu, 3/12/09, neal Newman cozy...@yahoo.com wrote:
From: neal Newman cozy...@yahoo.com
Subject: Re: [Repeater-Builder] Quieting duplex noise from a tower
To: Repeater-Builder@yahoogroups.com
Date: Thursday, March 12, 2009, 4:55 PM
Samething here in NJ. the Club put all new Db
At 3/12/2009 13:19, you wrote:
When you changed out antennas and heliax, I presume you replaced any
topside
jumpers as well?
Topside jumper and the jumper between duplexer and feedline were
replaced.
What kind of jumpers?
Bob NO6B
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