Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff?
At 1/17/2005 10:10 AM, you wrote: At 12:59 PM 1/17/2005 -0500, you wrote: Derek, Give the LMR-400 to someone who is not running Duplex. ---I've had very good results using LMR-400 on a relatively low power ( 30) full-duplex UHF link. I just happen to have had a 100' roll of the stuff and figured I'd try it, even with all the caveats about doing so. This is one of those topics that seems to be a your mileage may vary, as I know people who have had all sorts of grief using LMR types in full -duplex service, while others (like myself) have done fine with it. Since you have it, try it! If it works out, you're all set. If not, you can always replace it! Ken There seems to be a lot of varied experience with this type of cable. I've tried 9913 on a duplexer UHF repeater before had the same noisy experience you had Derek. OTOH I have a 40' roll of LMR400 that I use on my 2 meter portapeater it works just fine. A lot may have to do with what connectors are used how they're installed. If the shield RF is kept on the inside of the foil, it will never get to the foil/braid interface, where the staticy desense is likely occurring. But this also means that the performance will be dependent upon how well the antenna at the end of the feedline is decoupled from the coax. If there is any RF current flow down the outside of the coax from the antenna, you're in trouble no matter what. Silver-plated braided coax hardline don't have these issues since the shield material is uniform. Bob NO6B -- President and CTO - Arcom Communications Makers of state-of-the-art repeater controllers and accessories. http://www.ah6le.net/arcom/index.html We now offer complete Kenwood TKR repeater packages! AH6LE/R - IRLP Node 3000 http://www.irlp.net Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff?
Derek, Give the LMR-400 to someone who is not running Duplex. Pick up some Andrews Heliax. John VE3AMZ - Original Message - From: derek_mcintyre [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Monday, January 17, 2005 12:40 PM Subject: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff? Hello Group, I have read the messages and heard the debates about using LMR-400 or 99/13 type cables with aluminum foil mixed with tinned copper braid, and the duplex noise it presents when used on the output of the duplexer to the antenna. I have tried to stay away from this since I got serious about higher powered ( 110 watt) transmitters used for duplex service. I recently ran across a pile of LMR-400 DB I believe it's called, it has a sticky substance throughout and is said to be water tight. I used a 90 foot piece of this cable on a VHF repeater running ~ 80 watts out of the duplexer and feeding a very reliable, duplex noise free antenna on the tower. I couldn't believe the duplex noise I get from somewhere, and I am thinking it's the cable itself. When injecting a signal through a directional coupler, I am receiving ~ 0.25 uV for 20 dB SINAD while running full power. But each time I even think about touching the feedline, a ton of noise occurs (better than 30 dB of duplex noise). I have tried both crimp on and compression N-type connectors but no difference. The duplexer is a new Wacom with 214 interconnect cables. Can this LMR-400 really be the cause of noise this bad? There are two pagers (152.480 and 158.700) about 1/2 mile from the site. No other transmitters besides a few UHF repeaters. Everything at the site has an isolator on the transmitter output, including my 2M repeater. Something is arc'ing somewhere. Any suggestions besides changing the entire feedline to something more reliable, such as 1/2 inch Heliax or hardline without braid? Thanks, KC4FWC Derek. Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff?
The short, terse answers to these types of questions should be ignored, and you should try it out yourself. If it works, great! If you have problems, get rid of it and try something else. This is what makes ham radio fun. Steve WA6ZFT From: John J. Riddell [EMAIL PROTECTED] Date: 2005/01/17 Mon PM 12:59:29 EST To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff? Derek, Give the LMR-400 to someone who is not running Duplex. Pick up some Andrews Heliax. John VE3AMZ - Original Message - From: derek_mcintyre [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Monday, January 17, 2005 12:40 PM Subject: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff? Hello Group, I have read the messages and heard the debates about using LMR-400 or 99/13 type cables with aluminum foil mixed with tinned copper braid, and the duplex noise it presents when used on the output of the duplexer to the antenna. I have tried to stay away from this since I got serious about higher powered ( 110 watt) transmitters used for duplex service. I recently ran across a pile of LMR-400 DB I believe it's called, it has a sticky substance throughout and is said to be water tight. I used a 90 foot piece of this cable on a VHF repeater running ~ 80 watts out of the duplexer and feeding a very reliable, duplex noise free antenna on the tower. I couldn't believe the duplex noise I get from somewhere, and I am thinking it's the cable itself. When injecting a signal through a directional coupler, I am receiving ~ 0.25 uV for 20 dB SINAD while running full power. But each time I even think about touching the feedline, a ton of noise occurs (better than 30 dB of duplex noise). I have tried both crimp on and compression N-type connectors but no difference. The duplexer is a new Wacom with 214 interconnect cables. Can this LMR-400 really be the cause of noise this bad? There are two pagers (152.480 and 158.700) about 1/2 mile from the site. No other transmitters besides a few UHF repeaters. Everything at the site has an isolator on the transmitter output, including my 2M repeater. Something is arc'ing somewhere. Any suggestions besides changing the entire feedline to something more reliable, such as 1/2 inch Heliax or hardline without braid? Thanks, KC4FWC Derek. Yahoo! Groups Links Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff?
I'd be willing to bet your noise problem is site related and has nothing to do with the feedline. Rusty wires and rusty metal can cause micro-arcing just like the shield/braid problem in the LMR400 cable, especially in windy conditions. The problem is your options are limited in trying to find and fix these noise sources. With the system being noisy and you physical present at the site, cap off the feed line at the antenna with a dummy load and check for noise. If there's still noise, It could be the feedline, duplexer or a repeater TX problem. If the dummy load trick eliminates the noise, Try using a separate antenna for RX and TX, and run them into the cans without the T connector. If you can get some decent vertical separation (40ft.) , this might be worth a try. This will provide more isolation from locally generated noise. Steve WA6ZFT From: derek_mcintyre [EMAIL PROTECTED] Date: 2005/01/17 Mon PM 12:40:14 EST To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff? Hello Group, I have read the messages and heard the debates about using LMR-400 or 99/13 type cables with aluminum foil mixed with tinned copper braid, and the duplex noise it presents when used on the output of the duplexer to the antenna. I have tried to stay away from this since I got serious about higher powered ( 110 watt) transmitters used for duplex service. I recently ran across a pile of LMR-400 DB I believe it's called, it has a sticky substance throughout and is said to be water tight. I used a 90 foot piece of this cable on a VHF repeater running ~ 80 watts out of the duplexer and feeding a very reliable, duplex noise free antenna on the tower. I couldn't believe the duplex noise I get from somewhere, and I am thinking it's the cable itself. When injecting a signal through a directional coupler, I am receiving ~ 0.25 uV for 20 dB SINAD while running full power. But each time I even think about touching the feedline, a ton of noise occurs (better than 30 dB of duplex noise). I have tried both crimp on and compression N-type connectors but no difference. The duplexer is a new Wacom with 214 interconnect cables. Can this LMR-400 really be the cause of noise this bad? There are two pagers (152.480 and 158.700) about 1/2 mile from the site. No other transmitters besides a few UHF repeaters. Everything at the site has an isolator on the transmitter output, including my 2M repeater. Something is arc'ing somewhere. Any suggestions besides changing the entire feedline to something more reliable, such as 1/2 inch Heliax or hardline without braid? Thanks, KC4FWC Derek. Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff?
I didn't think that the answer was short and terse. If one has the coax already and is going to try it on a low profile site, that's one thing. However, I hate to see someone go out and buy new LMR-XXX cable only to discover that they should have spent their money on something a bit better for not that much more money. Can you get away running LMR or 9913 type cable on a repeater? Maybe. Just don't be too disappointed if you find it doesn't work well. Chuck WB2EDV - Original Message - From: [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Monday, January 17, 2005 1:05 PM Subject: Re: Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff? The short, terse answers to these types of questions should be ignored, and you should try it out yourself. If it works, great! If you have problems, get rid of it and try something else. This is what makes ham radio fun. Steve WA6ZFT From: John J. Riddell [EMAIL PROTECTED] Date: 2005/01/17 Mon PM 12:59:29 EST To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff? Derek, Give the LMR-400 to someone who is not running Duplex. Pick up some Andrews Heliax. John VE3AMZ Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff?
Hello Group, I have read the messages and heard the debates about using LMR-400 or 99/13 type cables with aluminum foil mixed with tinned copper braid, and the duplex noise it presents when used on the output of the duplexer to the antenna. I have tried to stay away from this since I got serious about higher powered ( 110 watt) transmitters used for duplex service. I recently ran across a pile of LMR-400 DB I believe it's called, it has a sticky substance throughout and is said to be water tight. I used a 90 foot piece of this cable on a VHF repeater running ~ 80 watts out of the duplexer and feeding a very reliable, duplex noise free antenna on the tower. I couldn't believe the duplex noise I get from somewhere, and I am thinking it's the cable itself. When injecting a signal through a directional coupler, I am receiving ~ 0.25 uV for 20 dB SINAD while running full power. But each time I even think about touching the feedline, a ton of noise occurs (better than 30 dB of duplex noise). I have tried both crimp on and compression N-type connectors but no difference. The duplexer is a new Wacom with 214 interconnect cables. Can this LMR-400 really be the cause of noise this bad? There are two pagers (152.480 and 158.700) about 1/2 mile from the site. No other transmitters besides a few UHF repeaters. Everything at the site has an isolator on the transmitter output, including my 2M repeater. Something is arc'ing somewhere. Any suggestions besides changing the entire feedline to something more reliable, such as 1/2 inch Heliax or hardline without braid? Thanks, KC4FWC Derek. The fact that it comes up or changes when you touch the feedline answers that the problem is the feedline, or a connector. You will almost assuredly have to replace the feedline. And btw, there's no such thing as hardline *with* braid, as what makes it hardline is that it has a solid metal outer sheild, so a braid would have no effect. -- Jim Barbour WD8CHL Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff?
No offense intended. The guy had the cable so he had nothing to lose other than his time to try it out. Steve WA6ZFT From: Chuck Kelsey [EMAIL PROTECTED] Date: 2005/01/17 Mon PM 03:02:45 EST To: Repeater-Builder@yahoogroups.com Subject: Re: Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff? I didn't think that the answer was short and terse. If one has the coax already and is going to try it on a low profile site, that's one thing. However, I hate to see someone go out and buy new LMR-XXX cable only to discover that they should have spent their money on something a bit better for not that much more money. Can you get away running LMR or 9913 type cable on a repeater? Maybe. Just don't be too disappointed if you find it doesn't work well. Chuck WB2EDV - Original Message - From: [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Monday, January 17, 2005 1:05 PM Subject: Re: Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff? The short, terse answers to these types of questions should be ignored, and you should try it out yourself. If it works, great! If you have problems, get rid of it and try something else. This is what makes ham radio fun. Steve WA6ZFT From: John J. Riddell [EMAIL PROTECTED] Date: 2005/01/17 Mon PM 12:59:29 EST To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Duplex noise/LMR-400 w/sticky stuff? Derek, Give the LMR-400 to someone who is not running Duplex. Pick up some Andrews Heliax. John VE3AMZ Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
