RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
At 05:40 PM 03/13/09, you wrote: There seems to be lots of opinions , how about a simple find the problem fella's ? I recently was asked to find some noise on a similar situation . We fired up my promax 577 tuned around a little whilst climbing and found the problem making the fix asy ( some wire clamps on the supporting structure) replacing them with stainless instead of galv... B ( google the 577 as they are very useful) Yeah, I was going to suggest a simplified version of what you're talking about - climb the tower with a little AM transistor radio tuned to a weak station, key the transmitter on and off, and see if you can find a noise hot spot or anything that when moved or vibrated causes the noise level to increase. However, I haven't tried this using VHF excitation, but I've used the same technique to find all kinds of other broadband noise sources. The local power company uses an AM receiver operating in the VHF range (I think I was told it was around 110 MHz) to locate bad/arcing insulators, fuses, etc. on primary lines. --- Jeff WN3A Aircraft handhelds are AM in the 120MHz region. Some handheld scanners do aircraft AM just fine. I remember seeing a Bearcat handheld scanner many years ago that knew that 30-50 was NFM, 54-72 is Wide FM, 72-76 is NFM, 76-88 is WFM, 88-108 is WFM, 108-136 is AM, 136-174 is NFM, etc. The unit, however, would allow you to force the unit into any modulation method on any frequency. I used one of those to prove to the FM CE that his FM transmitter had a very weak spur on a 440 repeater input... dialed up the input, switched to WFM and voilla - you heard the BeeGees playing Staying Alive at the same time that the FM station was playing it... one minuscule tweak on the transmitter and it was gone. A unit like that would be very handy for having on your belt with an earpiece in your ear while you shake and hammer on the tower hardware. Then there are the aircraft band handhelds made for airport use, or for pilots as something to toss in the flight bag and use as last resort, my entire panel has failed radios. Some of those, like the early Icoms go out of band into the ham band quite nicely. I wish I had been at the local ham swap meet a few months ago - an acquaintance of mine picked up an Icom aircraft handheld in the IC-04AT package (don't remember the exact model number) for $10, but it was less the battery and labeled doesn't work. Once he was out of sight of the seller he slid the battery from his IC2AT onto it and it powered up just fine, but with no speaker audio. A few stalls down was a guy selling cheap earplugs, like what you would use on a 1960s transistor radio. We plugged in one of those and the Icom worked just fine... it needed a new speaker. So keep your eyes open. AM VHF radios are out there, and some will go out of the aircraft band and do ham 2m and make great units for having on your belt while you shake and hammer on the tower hardware. Mike WA6ILQ
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
Aircraft handhelds are AM in the 120MHz region. Some handheld scanners do aircraft AM just fine. Ah! Somehow that hadn't occurred to me. The president of our club is a pilot and has one. I guess there are no weak, constant signals in the aircraft band (?) but maybe it's not necessary. I will try climbing the tower with it and see if it does anything when I move or vibrate guy wires and other hardware with the repeater transmitter on of course. It's possible the aircraft handheld will just be desensed by 2 meter RF and unable to hear the noise (?) but it will be interesting to see what happens. Paul N1BUG
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
Paul, Actually, if you're near enough to the airport, you should be able to hear the ATIS (Automatic Termininal Information System) broadcast. It repeats airfield/weather information continously. That'd be a constant (although perhaps not weak) signal in the aircraft band. Mike WM4B Paul N1BUG paul_n1...@myfairpoint.net wrote: Aircraft handhelds are AM in the 120MHz region. Some handheld scanners do aircraft AM just fine. Ah! Somehow that hadn't occurred to me. The president of our club is a pilot and has one. I guess there are no weak, constant signals in the aircraft band (?) but maybe it's not necessary. I will try climbing the tower with it and see if it does anything when I move or vibrate guy wires and other hardware with the repeater transmitter on of course. It's possible the aircraft handheld will just be desensed by 2 meter RF and unable to hear the noise (?) but it will be interesting to see what happens. Paul N1BUG
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
And, if it will tune the 108 MHz to 118 MHz band, you could receive a nearby VOR. mwbese...@cox.net wrote: Paul, Actually, if you're near enough to the airport, you should be able to hear the ATIS (Automatic Termininal Information System) broadcast. It repeats airfield/weather information continously. That'd be a constant (although perhaps not weak) signal in the aircraft band. Mike WM4B
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
Some amateur rigs receive AM aircraft band. Most of mine do, HT's and mobiles. That's what I use for power line sniffing. Chuck WB2EDV - Original Message - From: Paul N1BUG paul_n1...@myfairpoint.net To: Repeater-Builder@yahoogroups.com Sent: Wednesday, March 18, 2009 8:05 AM Subject: Re: [Repeater-Builder] Re: Quieting duplex noise from a tower Aircraft handhelds are AM in the 120MHz region. Some handheld scanners do aircraft AM just fine. Ah! Somehow that hadn't occurred to me. The president of our club is a pilot and has one. I guess there are no weak, constant signals in the aircraft band (?) but maybe it's not necessary. I will try climbing the tower with it and see if it does anything when I move or vibrate guy wires and other hardware with the repeater transmitter on of course. It's possible the aircraft handheld will just be desensed by 2 meter RF and unable to hear the noise (?) but it will be interesting to see what happens. Paul N1BUG
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
Careful with that powerline sniffing, Chuck. Last time I did that, I burned all the hair out of my nose. Mike WM4B Chuck Kelsey wb2...@roadrunner.com wrote: Some amateur rigs receive AM aircraft band. Most of mine do, HT's and mobiles. That's what I use for power line sniffing. Chuck WB2EDV - Original Message - From: Paul N1BUG paul_n1...@myfairpoint.net To: Repeater-Builder@yahoogroups.com Sent: Wednesday, March 18, 2009 8:05 AM Subject: Re: [Repeater-Builder] Re: Quieting duplex noise from a tower Aircraft handhelds are AM in the 120MHz region. Some handheld scanners do aircraft AM just fine. Ah! Somehow that hadn't occurred to me. The president of our club is a pilot and has one. I guess there are no weak, constant signals in the aircraft band (?) but maybe it's not necessary. I will try climbing the tower with it and see if it does anything when I move or vibrate guy wires and other hardware with the repeater transmitter on of course. It's possible the aircraft handheld will just be desensed by 2 meter RF and unable to hear the noise (?) but it will be interesting to see what happens. Paul N1BUG
RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
ATIS , VORs transmit from 112 Mhz to 120 Mhz AM , continuous... Aircraft band goes from 112-138 Mhz AM Some aircraft band HTs will recieve VOR transmission and give you the bearing to/from the VOR.. To: Repeater-Builder@yahoogroups.com CC: paul_n1...@myfairpoint.net From: mwbese...@cox.net Date: Wed, 18 Mar 2009 08:10:29 -0400 Subject: Re: [Repeater-Builder] Re: Quieting duplex noise from a tower Paul, Actually, if you're near enough to the airport, you should be able to hear the ATIS (Automatic Termininal Information System) broadcast. It repeats airfield/weather information continously. That'd be a constant (although perhaps not weak) signal in the aircraft band. Mike WM4B Paul N1BUG paul_n1...@myfairpoint.net wrote: Aircraft handhelds are AM in the 120MHz region. Some handheld scanners do aircraft AM just fine. Ah! Somehow that hadn't occurred to me. The president of our club is a pilot and has one. I guess there are no weak, constant signals in the aircraft band (?) but maybe it's not necessary. I will try climbing the tower with it and see if it does anything when I move or vibrate guy wires and other hardware with the repeater transmitter on of course. It's possible the aircraft handheld will just be desensed by 2 meter RF and unable to hear the noise (?) but it will be interesting to see what happens. Paul N1BUG
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
I dont know anything about this particular Tower or how and when it was put up. if its a sleeved tower like a Rohn 25g or 45,55, Universal. I always apply Lithium Grease at the joints. This Helps putting up and taking apart towers in the Future. this also a creates an Electrical conductivity between sections to prevent noise. maybe you can still get some and pack it into the joints may help. Just a shot in the dark for Future tower erections. Neal --- On Fri, 3/13/09, Paul N1BUG paul_n1...@myfairpoint.net wrote: From: Paul N1BUG paul_n1...@myfairpoint.net Subject: Re: [Repeater-Builder] Re: Quieting duplex noise from a tower To: Repeater-Builder@yahoogroups.com Date: Friday, March 13, 2009, 9:22 PM Yeah, I was going to suggest a simplified version of what you're talking about - climb the tower with a little AM transistor radio tuned to a weak station, key the transmitter on and off, and see if you can find a noise hot spot or anything that when moved or vibrated causes the noise level to increase. However, I haven't tried this using VHF excitation, but I've used the same technique to find all kinds of other broadband noise sources. The local power company uses an AM receiver operating in the VHF range (I think I was told it was around 110 MHz) to locate bad/arcing insulators, fuses, etc. on primary lines. Thanks Jeff. I will try that, and also inducing vibration in the tower structure(s) by wrapping it with something as soon as I can. Maybe I will get lucky and find something. If I don't find any specific problem areas, I'm leaning strongly toward trying Phillystran guys when I can come up with the $$$ to do it. I appreciate the input from everyone on this problem. Paul N1BUG Yahoo! Groups Links
RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
There seems to be lots of opinions , how about a simple find the problem fella's ? I recently was asked to find some noise on a similar situation . We fired up my promax 577 tuned around a little whilst climbing and found the problem making the fix asy ( some wire clamps on the supporting structure) replacing them with stainless instead of galv... B ( google the 577 as they are very useful) To: Repeater-Builder@yahoogroups.com From: n3...@yahoo.com Date: Sat, 14 Mar 2009 00:04:14 + Subject: [Repeater-Builder] Re: Quieting duplex noise from a tower Replace all electrical fixtures, i had a site they was was using sub standard fixtures that was creating all sorts of havoc. and this solved all duplex issues. Ryan n3ssl _ Need a new place to rent, share or buy? Let ninemsn property help. http://a.ninemsn.com.au/b.aspx?URL=http%3A%2F%2Fninemsn%2Edomain%2Ecom%2Eau%2F%3Fs%5Fcid%3DFDMedia%3ANineMSN%5FHotmail%5FTagline_t=774152450_r=Domain_tagline_m=EXT
RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
There seems to be lots of opinions , how about a simple find the problem fella's ? I recently was asked to find some noise on a similar situation . We fired up my promax 577 tuned around a little whilst climbing and found the problem making the fix asy ( some wire clamps on the supporting structure) replacing them with stainless instead of galv... B ( google the 577 as they are very useful) Yeah, I was going to suggest a simplified version of what you're talking about - climb the tower with a little AM transistor radio tuned to a weak station, key the transmitter on and off, and see if you can find a noise hot spot or anything that when moved or vibrated causes the noise level to increase. However, I haven't tried this using VHF excitation, but I've used the same technique to find all kinds of other broadband noise sources. The local power company uses an AM receiver operating in the VHF range (I think I was told it was around 110 MHz) to locate bad/arcing insulators, fuses, etc. on primary lines. --- Jeff WN3A
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
Yeah, I was going to suggest a simplified version of what you're talking about - climb the tower with a little AM transistor radio tuned to a weak station, key the transmitter on and off, and see if you can find a noise hot spot or anything that when moved or vibrated causes the noise level to increase. However, I haven't tried this using VHF excitation, but I've used the same technique to find all kinds of other broadband noise sources. The local power company uses an AM receiver operating in the VHF range (I think I was told it was around 110 MHz) to locate bad/arcing insulators, fuses, etc. on primary lines. Thanks Jeff. I will try that, and also inducing vibration in the tower structure(s) by wrapping it with something as soon as I can. Maybe I will get lucky and find something. If I don't find any specific problem areas, I'm leaning strongly toward trying Phillystran guys when I can come up with the $$$ to do it. I appreciate the input from everyone on this problem. Paul N1BUG
RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
Should do the trick although it might take som more effort... maybe your neighbour works for a satellite or comms company , couple of beers ? To: Repeater-Builder@yahoogroups.com From: j...@broadsci.com Date: Fri, 13 Mar 2009 20:40:57 -0400 Subject: RE: [Repeater-Builder] Re: Quieting duplex noise from a tower There seems to be lots of opinions , how about a simple find the problem fella's ? I recently was asked to find some noise on a similar situation . We fired up my promax 577 tuned around a little whilst climbing and found the problem making the fix asy ( some wire clamps on the supporting structure) replacing them with stainless instead of galv... B ( google the 577 as they are very useful) Yeah, I was going to suggest a simplified version of what you're talking about - climb the tower with a little AM transistor radio tuned to a weak station, key the transmitter on and off, and see if you can find a noise hot spot or anything that when moved or vibrated causes the noise level to increase. However, I haven't tried this using VHF excitation, but I've used the same technique to find all kinds of other broadband noise sources. The local power company uses an AM receiver operating in the VHF range (I think I was told it was around 110 MHz) to locate bad/arcing insulators, fuses, etc. on primary lines. --- Jeff WN3A _ Looking for a place to manage all your online stuff? Explore the new Windows Live . http://www.microsoft.com/australia/windows/windowslive/
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
Hi Randy, I remember working you on 2 meters. That is very interesting. I tried bonding all the joints. If anything it actually seemed to make things worse!? I have been seriously thinking about Phillystran. It's a big expense not knowing for sure where the problem lies, but the only way to find out may be to try it and see! Paul wb8art wrote: Hello Paul, Worked you a few times many moons ago. I would agree with Jeff with tapping and slightly causing movement with the repeater up with a weak signal. I have before experiened both an antenna (stationmaster) with internal broken joint which caused severe noise and desense but also dependent on movement in the structure. Also have seen with a 100ft. guyed 3/36 town like yours having the same issue. I tried grounding bonding all joints on guys to tower and between tower sections to no avail. Also tried isolating the preforms from tower and bottom supports with no change. I decided that the 3/16 stranded was the generation source. We changed the guys to Phillystran and never had another issue.
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
Im having the same issue with my repeater on a 100 ft tower guyed with 3/16 In a message dated 3/12/2009 3:39:30 P.M. Central Daylight Time, paul_n1...@myfairpoint.net writes: Hi Randy, I remember working you on 2 meters. That is very interesting. I tried bonding all the joints. If anything it actually seemed to make things worse!? I have been seriously thinking about Phillystran. It's a big expense not knowing for sure where the problem lies, but the only way to find out may be to try it and see! Paul wb8art wrote: Hello Paul, Worked you a few times many moons ago. I would agree with Jeff with tapping and slightly causing movement with the repeater up with a weak signal. I have before experiened both an antenna (stationmaster) with internal broken joint which caused severe noise and desense but also dependent on movement in the structure. Also have seen with a 100ft. guyed 3/36 town like yours having the same issue. I tried grounding bonding all joints on guys to tower and between tower sections to no avail. Also tried isolating the preforms from tower and bottom supports with no change. I decided that the 3/16 stranded was the generation source. We changed the guys to Phillystran and never had another issue. **Need a job? Find employment help in your area. (http://yellowpages.aol.com/search?query=employment_agenciesncid=emlcntusyelp0005)
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
Sorry, I have the same problem with my repeater on a 100 foot tower guyed with 3/16 cable. It seems when the temp drops below 60 F I get a squeal in the RX side of my repeater. I can shake the tower when its doing it and it will go away for a few minutes. We went up and grounded the antenna and bracket to the tower. I thought we were getting RX noise from a bad connection that would get worse when the temp dropped due to the metal shrinking. Still no luck fixing it. I'm not sure what to do now. 73, KD5UZA In a message dated 3/12/2009 3:39:30 P.M. Central Daylight Time, paul_n1...@myfairpoint.net writes: Hi Randy, I remember working you on 2 meters. That is very interesting. I tried bonding all the joints. If anything it actually seemed to make things worse!? I have been seriously thinking about Phillystran. It's a big expense not knowing for sure where the problem lies, but the only way to find out may be to try it and see! Paul wb8art wrote: Hello Paul, Worked you a few times many moons ago. I would agree with Jeff with tapping and slightly causing movement with the repeater up with a weak signal. I have before experiened both an antenna (stationmaster) with internal broken joint which caused severe noise and desense but also dependent on movement in the structure. Also have seen with a 100ft. guyed 3/36 town like yours having the same issue. I tried grounding bonding all joints on guys to tower and between tower sections to no avail. Also tried isolating the preforms from tower and bottom supports with no change. I decided that the 3/16 stranded was the generation source. We changed the guys to Phillystran and never had another issue. **Need a job? Find employment help in your area. (http://yellowpages.aol.com/search?query=employment_agenciesncid=emlcntusyelp0005)
RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
I have far less experience with this sort of thing than most anyone here but IMHO towers that are guyed SHOULD have insulators breaking up the guy wires, as close to the tower as possible, and at least one per guy wire. The guy wires that were installed on the tower where my repeater is installed MOVE ever so slightly on windy days. When the wires move you get static from the metal on metal surfaces. We broke the wires with JUST ONE insulator per leg and the noise we were getting on windy days disappeared. -MIke From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of hankjr...@aol.com Sent: Thursday, March 12, 2009 4:59 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Quieting duplex noise from a tower Sorry, I have the same problem with my repeater on a 100 foot tower guyed with 3/16 cable. It seems when the temp drops below 60 F I get a squeal in the RX side of my repeater. I can shake the tower when its doing it and it will go away for a few minutes. We went up and grounded the antenna and bracket to the tower. I thought we were getting RX noise from a bad connection that would get worse when the temp dropped due to the metal shrinking. Still no luck fixing it. I'm not sure what to do now. 73, KD5UZA In a message dated 3/12/2009 3:39:30 P.M. Central Daylight Time, paul_n1...@myfairpoint.net writes: Hi Randy, I remember working you on 2 meters. That is very interesting. I tried bonding all the joints. If anything it actually seemed to make things worse!? I have been seriously thinking about Phillystran. It's a big expense not knowing for sure where the problem lies, but the only way to find out may be to try it and see! Paul wb8art wrote: Hello Paul, Worked you a few times many moons ago. I would agree with Jeff with tapping and slightly causing movement with the repeater up with a weak signal. I have before experiened both an antenna (stationmaster) with internal broken joint which caused severe noise and desense but also dependent on movement in the structure. Also have seen with a 100ft. guyed 3/36 town like yours having the same issue. I tried grounding bonding all joints on guys to tower and between tower sections to no avail. Also tried isolating the preforms from tower and bottom supports with no change. I decided that the 3/16 stranded was the generation source. We changed the guys to Phillystran and never had another issue. _ Need a job? Find http://yellowpages.aol.com/search?query=employment_agenciesncid=emlcntusye lp0005 employment help in your area. __ NOD32 3931 (20090312) Information __ This message was checked by NOD32 antivirus system. http://www.eset.com
RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
We went the other way and earthed all guy wires with short wires connected back to the tower and have had no problems with static in windy weather Thank You, Ian Wells, Kerinvale Comaudio, 361 Camboon Road.Biloela.4715 Phone 0749922574 or 0409159932 www.kerinvalecomaudio.com.au ---Original Message--- From: Michael Ryan Date: 03/13/09 08:13:06 To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Quieting duplex noise from a tower I have far less experience with this sort of thing than most anyone here but IMHO towers that are guyed SHOULD have insulators breaking up the guy wires, as close to the tower as possible, and at least one per guy wire. The guy wires that were installed on the tower where my repeater is installed MOVE ever so slightly on windy days. When the wires move you get static from the metal on metal surfaces. We broke the wires with JUST ONE insulator per leg and the noise we were getting on windy days disappeared. -MIke From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups com] On Behalf Of hankjr...@aol.com Sent: Thursday, March 12, 2009 4:59 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Quieting duplex noise from a tower Sorry, I have the same problem with my repeater on a 100 foot tower guyed with 3/16 cable. It seems when the temp drops below 60 F I get a squeal in the RX side of my repeater. I can shake the tower when its doing it and it will go away for a few minutes. We went up and grounded the antenna and bracket to the tower. I thought we were getting RX noise from a bad connection that would get worse when the temp dropped due to the metal shrinking. Still no luck fixing it. I'm not sure what to do now. 73, KD5UZA In a message dated 3/12/2009 3:39:30 P.M. Central Daylight Time, paul_n1...@myfairpoint.net writes: Hi Randy, I remember working you on 2 meters. That is very interesting. I tried bonding all the joints. If anything it actually seemed to make things worse!? I have been seriously thinking about Phillystran. It's a big expense not knowing for sure where the problem lies, but the only way to find out may be to try it and see! Paul wb8art wrote: Hello Paul, Worked you a few times many moons ago. I would agree with Jeff with tapping and slightly causing movement with the repeater up with a weak signal. I have before experiened both an antenna (stationmaster) with internal broken joint which caused severe noise and desense but also dependent on movement in the structure. Also have seen with a 100ft. guyed 3/36 town like yours having the same issue. I tried grounding bonding all joints on guys to tower and between tower sections to no avail. Also tried isolating the preforms from tower and bottom supports with no change. I decided that the 3/16 stranded was the generation source. We changed the guys to Phillystran and never had another issue. Need a job? Find employment help in your area. __ NOD32 3931 (20090312) Information __ This message was checked by NOD32 antivirus system. http://www.eset.com
RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
This fixes the RF problem, but creates a new one. the guy anchors can now explode in a direct lightning strike if your shorting wires don't give up first. if the lightning thinks the path down the guy wire looks better than others. Nate WY0X From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of kerinvale Sent: Thursday, March 12, 2009 4:28 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
I've been looking at phillystran for many years now, but never implemented it. I've used 3/16 EHS with associated hardware. I too, have issues with noise. Any others out there who have, and can give any ideas on how to use it for guying a tower? Hardware used, hints and kinks? Or are there docs or web sites that can be referred to? TIA, Don, KD9PT - Original Message - From: Nate Duehr To: Repeater-Builder@yahoogroups.com Sent: Thursday, March 12, 2009 7:18 PM Subject: RE: [Repeater-Builder] Re: Quieting duplex noise from a tower This fixes the RF problem, but creates a new one. the guy anchors can now explode in a direct lightning strike if your shorting wires don't give up first. if the lightning thinks the path down the guy wire looks better than others. Nate WY0X From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of kerinvale Sent: Thursday, March 12, 2009 4:28 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
The tower is all steel so why wont the lightning hit the entire tower and guy ropes .Wether they are shorted to the tower or not a lightning hit will run through all the setup.I have had a VHF antenna hit with lightning and the tower was a1 ok and the antenna was blowen to pieces .All commercial communication towers here in aus are done with big earthing straps into the ground especially the anchors that are in concrete. Thank You, Ian Wells, Kerinvale Comaudio, 361 Camboon Road.Biloela.4715 Phone 0749922574 or 0409159932 www.kerinvalecomaudio.com.au ---Original Message--- From: Nate Duehr Date: 13/03/2009 10:18:50 To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Quieting duplex noise from a tower This fixes the RF problem, but creates a new one the guy anchors can now explode in a direct lightning strike if your shorting wires dont give up first if the lightning thinks the path down the guy wire looks better than others Nate WY0X From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups com] On Behalf Of kerinvale Sent: Thursday, March 12, 2009 4:28 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Quieting duplex noise from a tower
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
Hell, if half the MOTOROLA-INSTALLED towers around here were built to their own specs, I'd be impressed. Most of them are using screw in guy anchors with no dead-mans, and are a good dust-up of wind away from falling over. Haven't seen a Moto-tower yet that met R-56 around here! You gotta love Moto... great engineering, poor implementation. :-) Towers are kinda like civil engineering for bridges... everyone knows how to build them properly NOW, but no one went back and rebuilt the old ones... I didn't mean to make it sound like I knew everything there is to know about towers. I don't. I was just pointing out that PERHAPS adding grounds where they weren't before... to fix an *RF* problem... can lead to other problems that might have to be addressed... Like screwing up your carefully (or not so carefully) engineered lightning protection. Okey dokey? Everybody happy now? LOL! Y'all be careful out there and have fun... Nate WY0X On Mar 12, 2009, at 8:25 PM, Glenn Little WB4UIV wrote: If the tower and guys are installed properly, the guy points will not explode. The base of the tower is to be grounded via copper plated ground rods spaced at twice the length of the rods and bonded via exothermic welds 18 inches below grade. The tower base is bonded to this ground ring via exothermic welds. The guy points are grounded via galvanized ground rods. The ground wire is exothermic welded to the rod and grounded to the guy wires via guy clamps. The galvanized rods present a higher resistance ground than the base of the tower reducing the fault current through the guy wires. Reference Motorola R-56 and MIL-HDBK-419. 73 Glenn WB4UIV
