Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-13 Thread neal Newman



 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?
 
 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 all new Db Antennas
 On the 100 foot 
  tower. New Feedline. still had the noise...new
 grounding system. all 
  sections bonded. still Noise.   changed the guy cables
 to Phillystrand. 
  Problem went away
 
 
  
 
 
 
 
 
 
 Yahoo! Groups Links
 
 
 

  


[Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Paul N1BUG
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 quality RF load placed on the antenna port 
of the duplexer. It will run clean all day with the same load placed 
at the antenna end of the feedline.

With the antenna connected it will SOMETIMES run clean. At other 
times we get the crackling and popping of duplex noise. And at 
times we get increased noise floor (I can see it on the receiver 
limiter current but it has no specific sound, it's just like the 
normal receiver noise floor came up 20 to 30 dB!) None of this 
happens when it is run into the RF load. It is only when running 
into the antenna, and then only sometimes. The steady high noise 
floor, when present, happens only when my transmitter is up. It 
happens even if no other transmitters on the hill are up. It will 
occasionally go for days or even weeks without a glitch, then be 
essentially unusable for hours or days.

The crackling does seem to be worse in windy weather. The steady 
noise does not seem to be better or worse in any kind of weather, 
but occurs completely at random as far as I can tell.

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.

The tower is 100 feet of Rohn 25G guyed with 3/16 EHS. I have tried 
more than once to bond the sections of tower with straps across 
the leg joints, and similarly where guys attach to the tower and/or 
turnbuckles etc. at ground level. These efforts did not help and 
seemed to actually make matters worse. By the way, the guy ends use 
Big Grips, not clamps. Was that a mistake for a repeater tower?

I am looking for advice. If anyone has solved noise problems in a 
similar tower, I would very much like to know specifically what 
materials you used and how you installed them that worked for you!

I do have another newly erected 100 foot tower close by. It could be 
part of the problem. However, I was having this problem long before 
that tower went up so I'm still pointing fingers at my own stuff.

A 440 repeater on the same tower does not have any problems. Neither 
repeater seems to be affected by the other's transmitter. It is only 
the 2 meter repeater killing itself.

Both my tower structure and the new adjacent tower structure are 
hot with RF from my 2 meter transmitter, as evidenced by horrible 
noise when something like a screwdriver shaft is lightly rubbed 
against the towers or guys. I do not find any other metal structures 
in the vicinity that react that way.

There is NO loose hardware in my system. I've been over it time and 
time again. There is NO visible rust anywhere.

Any suggestions before I pull the rest of my rapidly thinning hair out?

Here's one for ya... this problem first reared it ugly head right 
after I put up the tower. For years prior to that I had run the 
antenna on a rusty metal mast with loose fitting joints without ever 
a hint of trouble!!!

Paul N1BUG
147.105 and 444.950


Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Chuck Kelsey
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 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 quality RF load placed on the antenna port 
 of the duplexer. It will run clean all day with the same load placed 
 at the antenna end of the feedline.
 
 With the antenna connected it will SOMETIMES run clean. At other 
 times we get the crackling and popping of duplex noise. And at 
 times we get increased noise floor (I can see it on the receiver 
 limiter current but it has no specific sound, it's just like the 
 normal receiver noise floor came up 20 to 30 dB!) None of this 
 happens when it is run into the RF load. It is only when running 
 into the antenna, and then only sometimes. The steady high noise 
 floor, when present, happens only when my transmitter is up. It 
 happens even if no other transmitters on the hill are up. It will 
 occasionally go for days or even weeks without a glitch, then be 
 essentially unusable for hours or days.
 
 The crackling does seem to be worse in windy weather. The steady 
 noise does not seem to be better or worse in any kind of weather, 
 but occurs completely at random as far as I can tell.
 
 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.
 
 The tower is 100 feet of Rohn 25G guyed with 3/16 EHS. I have tried 
 more than once to bond the sections of tower with straps across 
 the leg joints, and similarly where guys attach to the tower and/or 
 turnbuckles etc. at ground level. These efforts did not help and 
 seemed to actually make matters worse. By the way, the guy ends use 
 Big Grips, not clamps. Was that a mistake for a repeater tower?
 
 I am looking for advice. If anyone has solved noise problems in a 
 similar tower, I would very much like to know specifically what 
 materials you used and how you installed them that worked for you!
 
 I do have another newly erected 100 foot tower close by. It could be 
 part of the problem. However, I was having this problem long before 
 that tower went up so I'm still pointing fingers at my own stuff.
 
 A 440 repeater on the same tower does not have any problems. Neither 
 repeater seems to be affected by the other's transmitter. It is only 
 the 2 meter repeater killing itself.
 
 Both my tower structure and the new adjacent tower structure are 
 hot with RF from my 2 meter transmitter, as evidenced by horrible 
 noise when something like a screwdriver shaft is lightly rubbed 
 against the towers or guys. I do not find any other metal structures 
 in the vicinity that react that way.
 
 There is NO loose hardware in my system. I've been over it time and 
 time again. There is NO visible rust anywhere.
 
 Any suggestions before I pull the rest of my rapidly thinning hair out?
 
 Here's one for ya... this problem first reared it ugly head right 
 after I put up the tower. For years prior to that I had run the 
 antenna on a rusty metal mast with loose fitting joints without ever 
 a hint of trouble!!!
 
 Paul N1BUG
 147.105 and 444.950



Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Paul N1BUG
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 away.

Paul

Chuck Kelsey wrote:
 Suspect any other nearby fiberglass antenna in your search.
 
 Chuck
 WB2EDV


RE: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Jeff DePolo
 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 rundown of the station equipment, so some this may or may
not be applicable.

When change from the dummy load, either at the near end of far end, to a
real antenna, you're changing the load impedance.  What you may be
experiencing is an increase in spurioius products from the transmitter which
will manifest as desense at the receiver.  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?  An isolator might be a viable
candidate as a band-aid, but the right fix is to cure the problem at the
source by repairing or replacing the unstable device...

Have you tried other transmitters and/or amplifiers?

Do you have Polyphasers or anything other than coax between the duplexer and
the antenna?  If so, consider it suspect until proven otherwise.

Have you tested with the transmitter off?  Wondering if there's a
possibility there is something else coming down the hose that is causing
recever degradation, such as a nearby transmitter that's noisy or spurious.

Are you using a preamp?  If so, what do you have ahead of it for filtering,
and/or have you tested without the preamp?

Have you tried an antenna installed at a different height on the tower than
the current antenna to see if anything changes?

Do you have ground kits on the feedline going up the tower, and if so, are
they properly attached/bonded, particularly avoiding any dissimilar metal
contact?

 The tower is 100 feet of Rohn 25G guyed with 3/16 EHS. I have tried 
 more than once to bond the sections of tower with straps across 
 the leg joints, and similarly where guys attach to the tower and/or 
 turnbuckles etc. at ground level. These efforts did not help and 
 seemed to actually make matters worse. By the way, the guy ends use 
 Big Grips, not clamps. Was that a mistake for a repeater tower?

Big Grips (usucally called preforms) are generally OK, many a tower much
bigger than a 25G uses them.  They need to be properly protected to avoid
coming un-twisted due to ice sliding down the guy wire.  Pull-out strength,
if installed properly, is as good as conventional mechanical clamps.

To help determine if you have a mechanical problem that is being manifested
as noise when excited by the high RF field of the transmitter, try rapping
on the tower at the base and at the guy anchors with something (like a
crescent wrench).  The goal isn't to shake the tower, but instead to
induce a significant mechanical vibration.  See if the noise increases
(either audibily or visibly on the spectrum analyzer) with the vibration,
and dampens out as the vibration decays.

 I do have another newly erected 100 foot tower close by. It could be 
 part of the problem. However, I was having this problem long before 
 that tower went up so I'm still pointing fingers at my own stuff.

What else is nearby?  Buildings, utility lines, etc.?
 
 Here's one for ya... this problem first reared it ugly head right 
 after I put up the tower. For years prior to that I had run the 
 antenna on a rusty metal mast with loose fitting joints without ever 
 a hint of trouble!!!

If the antenna was top-mounted on the rusty mast, but is now side-mounted on
the new tower, that could explain a lot of the difference.  The top-mounted
antenna will couple much less energy to the supporting structure than would
a side-mounted antenna.

--- Jeff WN3A




Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Paul N1BUG
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 transmitters and/or amplifiers?

Several PAs have been tried. Solid state and tube, GE and Motorola. 
No change with any of them. There is very little change in desense 
when I vary the power level unless I drop the power very low, like 
less than a watt. Then it goes away like somebody threw a switch.

The exciter has not been swapped out for a different type. However I 
have tried 4 of the same type exciter (PLL variety Mastr II), no change.

Another thing I tried was essentially a homebrew Z match between 
the PA and duplexer, no change.

 Do you have Polyphasers or anything other than coax between the duplexer and
 the antenna?

I know I should have them, but I don't.

 Have you tested with the transmitter off?

Yes, many, many times. It never happens with the transmitter off. 
I'm very confident about that.

 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 cavity, no help there.
The problem is still there without the preamp.

 Have you tried an antenna installed at a different height on the tower than
 the current antenna to see if anything changes?

Yes, and it does change but does not go away. If I take the antenna 
off the tower and put it 20 to 30 feet away from the tower, the 
problem is drastically reduced but not completely gone.

I can't quantify changes with absolute numbers... only 
generalizations... since the problem is intermittent and varies 
greatly even when I'm not changing anything.

 Do you have ground kits on the feedline going up the tower, and if so, are
 they properly attached/bonded, particularly avoiding any dissimilar metal
 contact?

Another thing I should have but don't.

 Big Grips (usucally called preforms) are generally OK, many a tower much
 bigger than a 25G uses them.  They need to be properly protected to avoid
 coming un-twisted due to ice sliding down the guy wire.  Pull-out strength,
 if installed properly, is as good as conventional mechanical clamps.

Preforms, right. I was wondering about the integrity of RF contact 
between the preform and the EHS wire since the preforms are coated 
with whatever that stuff is on the inside.

 To help determine if you have a mechanical problem that is being manifested
 as noise when excited by the high RF field of the transmitter, try rapping
 on the tower at the base and at the guy anchors with something (like a
 crescent wrench).  The goal isn't to shake the tower, but instead to
 induce a significant mechanical vibration.  See if the noise increases
 (either audibily or visibly on the spectrum analyzer) with the vibration,
 and dampens out as the vibration decays.

I missed that test! I have tried shaking the tower, which seems to 
have no consistent affect. I will try inducing vibration by rapping 
it with a wrench.

 What else is nearby?  Buildings, utility lines, etc.?

A couple small wood buildings, including my own. Mine was the only 
one there when this problem started. I have been over my internal 
wiring and every piece of metal under my control, no suspected items 
found. There is a 13.2 kV rural distribution power line and phone 
line running past the site about 70 feet from my tower, plus power 
drops to my building and another nearby. My antenna was closer to 
the utility lines when it was on the mast and was not having problems.

 If the antenna was top-mounted on the rusty mast, but is now side-mounted on
 the new tower, that could explain a lot of the difference.  The top-mounted
 antenna will couple much less energy to the supporting structure than would
 a side-mounted antenna.

Good point. I have tried top and side mounting on the tower. Top 
mounting helps, but not nearly enough.

Paul


Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread DCFluX
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?


RE: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Jeff DePolo
  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 cavity, no help there.
 The problem is still there without the preamp.

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 your Tx
was keyed.

 Preforms, right. I was wondering about the integrity of RF contact 
 between the preform and the EHS wire since the preforms are coated 
 with whatever that stuff is on the inside.

Yeah, they're coated with that semi-clear plasticy stuff usually.  I
wouldn't consider that to be a high risk factor, but hard to say.  How
close is the nearest guy wire attachment point on the tower to your antenna?

Is your antenna currently side-mounted or top-mounted?  If side-mounted, at
what height?

What kind of mounting brackets/clamps for the antenna?

What else is on the tower?

How are the feedlines attached to the tower?

Does the noise get any better or worse when it's raining out?

How are the guy wires attached to the tower (looped around a leg, with or
without thimbles, torque triangle/arms, etc.)?

I'm guessing not, but is the tower lit?

When you changed out antennas and heliax, I presume you replaced any topside
jumpers as well?

Where is your equipment with respect to the tower (i.e. how close to the
base)?  And how well-shielded is the equipment (enclosed metal cabinet
hopefully), and are you taking the usual precautions as far as cabling into,
and within, the cabinet to keep RF out?  

--- Jeff





Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Chuck Kelsey
Oh, it's difficult to say how close close really is, but keep it in mind 
if you run out of other fixes. The only test is to remove the suspect 
antenna from the site, and that may not be easy. Disconnecting it or 
grounding it will not help you diagnose.

Also, I'll ask the dreaded question... You are not using any foil/braid coax 
(LMR-400, 9913, etc.) for any jumpers are you?  If, so, replace it before 
you do anything else. Or is there some near your antenna for some other 
purpose?

Chuck
WB2EDV



- Original Message - 
From: Paul N1BUG paul_n1...@myfairpoint.net
To: Repeater-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 before that tower/antenna
 went up.

 Aside from that the nearest other fiberglass antenna (or antenna of
 any kind) is 250 feet away.

 Paul

 Chuck Kelsey wrote:
 Suspect any other nearby fiberglass antenna in your search.

 Chuck
 WB2EDV




Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Paul N1BUG
 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 your Tx
 was keyed.

I have tried putting one of the 11 pass cavities on the 
transmitter. No change. There is a fairly low traffic APRS 
digipeater (144.39) on a tower 250 feet away but my noise problem 
does not come in packet-length bursts. It was also down for a while 
and I still had the problem. The only other VHF transmitter is 158.x 
on the tower that is only 60 feet away. However I have never yet 
found that transmitter to be up when my problem was occurring. It 
sees VERY little use. The only other sources of RF are cell towers 
several hundred feet away.

 Yeah, they're coated with that semi-clear plasticy stuff usually.  I
 wouldn't consider that to be a high risk factor, but hard to say.  How
 close is the nearest guy wire attachment point on the tower to your antenna?

Close, just a couple feet below the antenna at the present time. In 
general, moving the antenna closer to a set of guys does seem to 
make the problem worse.

If I could somehow get to a point where I believe it's the guys, I 
would seriously consider replacing them with Phillystran, leaving a 
few feet of EHS at the anchor end.

 Is your antenna currently side-mounted or top-mounted?  If side-mounted, at
 what height?

Half and half at the moment, actually... the 20 foot stick is 
mounted on side arms at the 90 foot level of a 100 foot tower. 
Moving it to top mount does seem to decrease the desense by some 5 
to 10 dB (hard to quantify due to variability) but I still have 20 
to 30+ dB desense at times.

When side mounted, spacing from the tower also makes some difference 
(wider spacing = less desense) but again not enough to be truly helpful.

 What kind of mounting brackets/clamps for the antenna?

Sinclair heavy galvanized mounting clamps on the antenna, side 
support arms are heavy galvanized angle stock. Galvanized U bolts to 
tower legs. Other mounting arrangements have been tried, including 
the use of insulating material for side arms. Some change (less 
desense with the insulated mount) but still not enough to be really 
helpful.

 What else is on the tower?

The only things on the tower are my 147.105 and 444.950 antennas. I 
tried completely removing the 440 antenna and feedline from the 
tower, but nothing changed.

 How are the feedlines attached to the tower?

They are both LDF5-50A up the inside of the tower (that was fun), 
attached by many heavy duty nylon cable ties.

 Does the noise get any better or worse when it's raining out?

There *seems* to be some tendency toward the noise being worse 
during the first hour or so of a rain or snow event. But it is not 
always so. The noise is sometimes there when it is raining, but not 
always. It sometimes there when it is dry, but not always.

 How are the guy wires attached to the tower (looped around a leg, with or
 without thimbles, torque triangle/arms, etc.)?

The preforms are looped around a leg and through the Z braces of the 
tower. No thimbles at that end, there are some where the guys attach 
to the turnbuckles.

 I'm guessing not, but is the tower lit?

It is not.

 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.

 Where is your equipment with respect to the tower (i.e. how close to the
 base)?

About 30 feet away.

 And how well-shielded is the equipment (enclosed metal cabinet
 hopefully), and are you taking the usual precautions as far as cabling into,
 and within, the cabinet to keep RF out?  

Hmm. The cabinet (rack) is not completely enclosed. Each piece of 
equipment is in a shielded enclosure. There are feedthrough 
capacitors and chokes/beads on every non-RF lead entry point to a 
piece of equipment. However, the 13.6V interconnecting cables and 
117VAC power cords are not shielded. They do have the filtering 
wherever they enter equipment.

Paul



Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Paul N1BUG
 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


Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Paul N1BUG
 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 a 
linear supply (no switchers). I have tried Astron supplies in place 
of that, no changes noted.

There is one public safety repeater, transmit 158.x on a tower 60 
feet away. It was not there when my problem started, nor have I ever 
found their repeater to be in use when my problem is occurring. 
Actually I'm hard pressed to find that repeater in use, period.

Paul


Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread neal Newman

Samething here in NJ. the Club put all new Db Antennas On the 100 foot tower. 
New Feedline. still had the noise...new grounding system. all sections bonded. 
still Noise.   changed the guy cables to Phillystrand. Problem went away


--- 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, 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. The only test is to remove
 the suspect 
 antenna from the site, and that may not be easy.
 Disconnecting it or 
 grounding it will not help you diagnose.
 
 Also, I'll ask the dreaded question... You are not
 using any foil/braid coax 
 (LMR-400, 9913, etc.) for any jumpers are you?  If, so,
 replace it before 
 you do anything else. Or is there some near your antenna
 for some other 
 purpose?
 
 Chuck
 WB2EDV
 
 
 
 - Original Message - 
 From: Paul N1BUG
 paul_n1...@myfairpoint.net
 To: Repeater-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 before that
 tower/antenna
  went up.
 
  Aside from that the nearest other fiberglass antenna
 (or antenna of
  any kind) is 250 feet away.
 
  Paul
 
  Chuck Kelsey wrote:
  Suspect any other nearby fiberglass antenna in
 your search.
 
  Chuck
  WB2EDV
 
 
 
 
 
 
 
 
 Yahoo! Groups Links
 
 
 

  


Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Chuck Kelsey
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 all new Db Antennas On the 100 foot 
 tower. New Feedline. still had the noise...new grounding system. all 
 sections bonded. still Noise.   changed the guy cables to Phillystrand. 
 Problem went away


 


Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread Ralph Mowery




--- 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 Antennas On
 the 100 foot tower. New Feedline. still had the noise...new
 grounding system. all sections bonded. still Noise.  
 changed the guy cables to Phillystrand. Problem went away
 
 

I have a repeater on a 100 ft tower with guys.  Found the ends near the ground 
were wrapped through the anchor holes and had about 2 feet of free ends after 
the clamping bolts.  When the wind would blow the free ends against the guy 
wires all kind of noise would be generated.  Cut the wires so they could not 
rub against each other and the noise quit.



  


Re: [Repeater-Builder] Quieting duplex noise from a tower

2009-03-12 Thread no6b
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