[Repeater-Builder] Repeater Desense?
Just replaced a damaged mast for our VHF repeater. Went with a 4-bay dipole as a replacement, along with switching out the old coax with 1/2 hardline. Everything else stayed the same, VXR-7000 and internal duplexer. All worked well after a final check, until night came along, when it seems to possible to a casulty of desense? In base mode, tx and rx are wonderful, but when switched to repeater mode as soon as it rx's and attempts to transmit, it cut's itself out. About a one second in, out, back in, out, etc. Not sure what happened but around mid-day it started working fine again, then last night started acting up again. Any thoughts? suggestions? Did recheck all connections from antenna down and everything is tight.
Re: [Repeater-Builder] Repeater Desense?
waterproof connections? - Original Message - From: kfd29 To: Repeater-Builder@yahoogroups.com Sent: Friday, July 10, 2009 9:58 AM Subject: [Repeater-Builder] Repeater Desense? Just replaced a damaged mast for our VHF repeater. Went with a 4-bay dipole as a replacement, along with switching out the old coax with 1/2 hardline. Everything else stayed the same, VXR-7000 and internal duplexer. All worked well after a final check, until night came along, when it seems to possible to a casulty of desense? In base mode, tx and rx are wonderful, but when switched to repeater mode as soon as it rx's and attempts to transmit, it cut's itself out. About a one second in, out, back in, out, etc. Not sure what happened but around mid-day it started working fine again, then last night started acting up again. Any thoughts? suggestions? Did recheck all connections from antenna down and everything is tight.
Re: [Repeater-Builder] Repeater Desense?
Sounds like a temperature related issue. You might recheck the duplexers and even knock on their housing while testing. I am no expert but am only throwing out suggestions. Brian - Original Message - From: Maire-Radios To: Repeater-Builder@yahoogroups.com Sent: Friday, July 10, 2009 7:08 AM Subject: Re: [Repeater-Builder] Repeater Desense? waterproof connections? - Original Message - From: kfd29 To: Repeater-Builder@yahoogroups.com Sent: Friday, July 10, 2009 9:58 AM Subject: [Repeater-Builder] Repeater Desense? Just replaced a damaged mast for our VHF repeater. Went with a 4-bay dipole as a replacement, along with switching out the old coax with 1/2 hardline. Everything else stayed the same, VXR-7000 and internal duplexer. All worked well after a final check, until night came along, when it seems to possible to a casulty of desense? In base mode, tx and rx are wonderful, but when switched to repeater mode as soon as it rx's and attempts to transmit, it cut's itself out. About a one second in, out, back in, out, etc. Not sure what happened but around mid-day it started working fine again, then last night started acting up again. Any thoughts? suggestions? Did recheck all connections from antenna down and everything is tight.
Re: [Repeater-Builder] Repeater Desense?
I was wondering the same... are you thinking a bad duplexers? or maybe re-tuning? "K5IN" k...@comcast.net 7/10/2009 10:13 AM Sounds like a temperature related issue. You might recheck the duplexers and even knock on their housing while testing. I am no expert but am only throwing out suggestions. Brian - Original Message - From: Maire-Radios To: Repeater-Builder@yahoogroups.com Sent: Friday, July 10, 2009 7:08 AM Subject: Re: [Repeater-Builder] Repeater Desense? waterproof connections? - Original Message - From: kfd29 To: Repeater-Builder@yahoogroups.com Sent: Friday, July 10, 2009 9:58 AM Subject: [Repeater-Builder] Repeater Desense? Just replaced a damaged mast for our VHF repeater. Went with a 4-bay dipole as a replacement, along with switching out the old coax with 1/2" hardline. Everything else stayed the same, VXR-7000 and internal duplexer. All worked well after a final check, until night came along, when it seems to possible to a casulty of desense? In base mode, tx and rx are wonderful, but when switched to repeater mode as soon as it rx's and attempts to transmit, it cut's itself out. About a one second in, out, back in, out, etc. Not sure what happened but around mid-day it started working fine again, then last night started acting up again. Any thoughts? suggestions? Did recheck all connections from antenna down and everything is tight. image/gifimage/xxx
Re: [Repeater-Builder] Repeater Desense?
what does the watt meter show? normal? reflected? - Original Message - From: Ken Franks To: Repeater-Builder@yahoogroups.com Sent: Friday, July 10, 2009 10:16 AM Subject: Re: [Repeater-Builder] Repeater Desense? I was wondering the same... are you thinking a bad duplexers? or maybe re-tuning? K5IN k...@comcast.net 7/10/2009 10:13 AM Sounds like a temperature related issue. You might recheck the duplexers and even knock on their housing while testing. I am no expert but am only throwing out suggestions. Brian - Original Message - From: Maire-Radios To: Repeater-Builder@yahoogroups.com Sent: Friday, July 10, 2009 7:08 AM Subject: Re: [Repeater-Builder] Repeater Desense? waterproof connections? - Original Message - From: kfd29 To: Repeater-Builder@yahoogroups.com Sent: Friday, July 10, 2009 9:58 AM Subject: [Repeater-Builder] Repeater Desense? Just replaced a damaged mast for our VHF repeater. Went with a 4-bay dipole as a replacement, along with switching out the old coax with 1/2 hardline. Everything else stayed the same, VXR-7000 and internal duplexer. All worked well after a final check, until night came along, when it seems to possible to a casulty of desense? In base mode, tx and rx are wonderful, but when switched to repeater mode as soon as it rx's and attempts to transmit, it cut's itself out. About a one second in, out, back in, out, etc. Not sure what happened but around mid-day it started working fine again, then last night started acting up again. Any thoughts? suggestions? Did recheck all connections from antenna down and everything is tight.
RE: [Repeater-Builder] Repeater Desense?
If this is a 2m repeater, and the duplexer is mounted inside the VXR-7000 cabinet, it must be a mobile notch duplexer. I don't believe that such a duplexer can perform with a 600 kHz split. Please elaborate on the make and model of duplexer you have, and the RX and TX frequencies. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of kfd29 Sent: Friday, July 10, 2009 6:59 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Repeater Desense? Just replaced a damaged mast for our VHF repeater. Went with a 4-bay dipole as a replacement, along with switching out the old coax with 1/2 hardline. Everything else stayed the same, VXR-7000 and internal duplexer. All worked well after a final check, until night came along, when it seems to possible to a casulty of desense? In base mode, tx and rx are wonderful, but when switched to repeater mode as soon as it rx's and attempts to transmit, it cuts itself out. About a one second in, out, back in, out, etc. Not sure what happened but around mid-day it started working fine again, then last night started acting up again. Any thoughts? suggestions? Did recheck all connections from antenna down and everything is tight.
RE: [Repeater-Builder] Repeater Desense?
Okay, so you definitely have a mobile notch duplexer, which has practically no bandpass effect since it works entirely by notching out the opposite frequency in the split. Since the problem began when you changed the antenna, my suspicion is that the new antenna's pattern allows more TX signal to bathe the repeater than before. Some versions of Yaesu/Vertex VXR repeaters were supplied with single-shield jumpers inside the cabinet, and this allowed some random desense to occur. That happened in my own VXR-5000, and I completely cured it by replacing the factory jumpers with RG-400/U double-shielded coax. The original Vertex jumpers had gray jackets with no identification, so they were replaced with RG-400/U. If you do make new cables, make them with the correct connectors on each end, so that you do not have to use any adapters. I think you're pushing the notch duplexer to the limit of its capability, and you can test this by dropping the TX power to 15 or 20 watts, and checking again for desense. Also, you might try temporarily swapping it for a BpBr four cavity duplexer. 73, Eric Lemmon WB6FLY -Original Message- From: Ken Franks [mailto:fra...@godwinschools.org] Sent: Friday, July 10, 2009 8:04 AM To: Eric Lemmon Subject: RE: [Repeater-Builder] Repeater Desense? it is a commercial VHF (rx 152, tx 159). yes, the duplexer is mounted inside. I went to take a look at the make/model and it was not legible due to a faded sticker. It should be within operating spec's though since it was the one purchased with the unit and been in service for 3 years. Interestingly enough, one of our IT people went to look at it and found that the closer he held the PT to the duplexer, the dropping of rx when tx'ing resolved but was pretty fuzzy sounding yet. Then, when he held the PT even closer and transmitted, it began to operate properly again and no longer sounded fuzzy. Eric Lemmon wb6...@verizon.net 7/10/2009 10:32 AM If this is a 2m repeater, and the duplexer is mounted inside the VXR-7000 cabinet, it must be a mobile notch duplexer. I don't believe that such a duplexer can perform with a 600 kHz split. Please elaborate on the make and model of duplexer you have, and the RX and TX frequencies. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of kfd29 Sent: Friday, July 10, 2009 6:59 AM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] Repeater Desense? Just replaced a damaged mast for our VHF repeater. Went with a 4-bay dipole as a replacement, along with switching out the old coax with 1/2 hardline. Everything else stayed the same, VXR-7000 and internal duplexer. All worked well after a final check, until night came along, when it seems to possible to a casulty of desense? In base mode, tx and rx are wonderful, but when switched to repeater mode as soon as it rx's and attempts to transmit, it cuts itself out. About a one second in, out, back in, out, etc. Not sure what happened but around mid-day it started working fine again, then last night started acting up again. Any thoughts? suggestions? Did recheck all connections from antenna down and everything is tight.
RE: [Repeater-Builder] Repeater Desense?
It's difficult to answer that question without more information about your system. Please answer these questions: 1. What make and model antenna was used before you replaced it with the four-bay antenna? 2. What make and model antenna is now installed? 3. How long is the new 1/2 hardline, and is it Andrew LDF4-50 Heliax? 4. What is the present transmitter power output, measured at the TX output jack? 5. What is the receiver 12dB SINAD sensitivity, measured at the RX input jack? 6. What type of cable is used to connect the end of the hardline to the antenna jack on the duplexer? 7. Do you have the test equipment to verify the tuning of the duplexer? 8. Have you confirmed that the transmitter is not producing spurious signals at the RX frequency? If it turns out that the notch duplexer is not up to par, an economical solution might be to add a bandpass cavity between the existing notch duplexer's RX output jack and the repeater's RX input jack. However, my personal preference would be to replace the notch duplexer with a BpBr cavity duplexer, such as a Telewave TPRD-1584 shown here: www.telewave.com/pdf/TWDS-6039.pdf You're looking at an expenditure of $1,500 or so, not including double-shielded jumpers and high-quality connectors. If the cable in Item 6, above, is anything but RG-214/U, RG-400/U, or Heliflex, that may be the cause of your problem. Ideally, that particular jumper should always be made to order, with the correct connectors on each end- no barrels or adapters. RG-213/U, 9913, and LMR-400 are definitely a no-no! 73, Eric Lemmon WB6FLY -Original Message- From: Ken Franks [mailto:fra...@godwinschools.org] Sent: Friday, July 10, 2009 8:49 AM To: Eric Lemmon Subject: RE: [Repeater-Builder] Repeater Desense? Thanks! I'll check it out after lunch here. Our IT guy has a little knowledge since we used to run a TV broadcast out of the school here but it has been many, many years. Do you feel that purchasing a BpBr 4-cavity would be a wise investment for us, over the mobile notch? What are the benefits? This is a part of our District's school safety/security radio system so we'd like to make it as solid as possible. Thanks! Eric Lemmon wb6...@verizon.net 7/10/2009 11:30 AM Okay, so you definitely have a mobile notch duplexer, which has practically no bandpass effect since it works entirely by notching out the opposite frequency in the split. Since the problem began when you changed the antenna, my suspicion is that the new antenna's pattern allows more TX signal to bathe the repeater than before. Some versions of Yaesu/Vertex VXR repeaters were supplied with single-shield jumpers inside the cabinet, and this allowed some random desense to occur. That happened in my own VXR-5000, and I completely cured it by replacing the factory jumpers with RG-400/U double-shielded coax. The original Vertex jumpers had gray jackets with no identification, so they were replaced with RG-400/U. If you do make new cables, make them with the correct connectors on each end, so that you do not have to use any adapters. I think you're pushing the notch duplexer to the limit of its capability, and you can test this by dropping the TX power to 15 or 20 watts, and checking again for desense. Also, you might try temporarily swapping it for a BpBr four cavity duplexer. 73, Eric Lemmon WB6FLY -Original Message- From: Ken Franks [mailto:fra...@godwinschools.org mailto:Franks%40godwinschools.org ] Sent: Friday, July 10, 2009 8:04 AM To: Eric Lemmon Subject: RE: [Repeater-Builder] Repeater Desense? it is a commercial VHF (rx 152, tx 159). yes, the duplexer is mounted inside. I went to take a look at the make/model and it was not legible due to a faded sticker. It should be within operating spec's though since it was the one purchased with the unit and been in service for 3 years. Interestingly enough, one of our IT people went to look at it and found that the closer he held the PT to the duplexer, the dropping of rx when tx'ing resolved but was pretty fuzzy sounding yet. Then, when he held the PT even closer and transmitted, it began to operate properly again and no longer sounded fuzzy. Eric Lemmon wb6...@verizon.net mailto:wb6fly%40verizon.net 7/10/2009 10:32 AM If this is a 2m repeater, and the duplexer is mounted inside the VXR-7000 cabinet, it must be a mobile notch duplexer. I don't believe that such a duplexer can perform with a 600 kHz split. Please elaborate on the make and model of duplexer you have, and the RX and TX frequencies. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of kfd29 Sent: Friday, July 10, 2009 6:59 AM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com
Re: [Repeater-Builder] Repeater Desense
Eric Lemmon wrote: The most recent instance was with a Cushcraft ARX-270 2m/440 antenna. I tried one of these antennas first as a low profile repeater antenna, then as a remote base antenna. I was so disappointed with it that I took it down and threw it in the trash. Yes it was brand new. That antenna will never bother me or anyone else again. I'm not a big fan of Cushcraft antennas anyway, but whoever designed the ARX-270 didn't have a clue Repeater Builder is currently vending a dual band antenna that works well in duplex service. We'll have several at Dayton, with a special show price. Scott and I have installed several for non critical ham repeater duty and are very pleased with their performance so far. Kevin 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] Repeater Desense
Repeater Builder is currently vending a dual band antenna that works well in duplex service. We'll have several at Dayton, with a special show price. Scott and I have installed several for non critical ham repeater duty and are very pleased with their performance so far. I won't be able to attend, but I'm interested. Where do I find out more? 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] Repeater Desense
Yes. Many repeater receivers are simply not well enough shielded to keep the TX from leaking into the RX box. Even some commercial repeaters will suffer desense if 100% shielded feedline is not used. I have seen serious desense occur when a dual-band (2m/440) antenna is used on a repeater, due to the uneven gain versus frequency response of many such antennas. Invariably, the desense went away when a good broadband antenna was used. 73, Eric Lemmon WB6FLY DCFluX wrote: Has anyone had desense due to the fact that the repeater's antenna is too close to the repeater itself? Like 12 feet of vertical separation and 2 feet horizontal? 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] Repeater Desense
At 5/12/2005 12:37 PM, you wrote: Yes. Many repeater receivers are simply not well enough shielded to keep the TX from leaking into the RX box. Even some commercial repeaters will suffer desense if 100% shielded feedline is not used. I have seen serious desense occur when a dual-band (2m/440) antenna is used on a repeater, due to the uneven gain versus frequency response of many such antennas. A narrowband antenna by itself will not generate desense. Your problem was probably due to corrosion, dielectric breakdown, or some other cause related to poor construction/materials in the amateur grade antenna. I would like to know what model antenna this was though, since I have yet to see any desense problems with my Comet antennas. Bob NO6B 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] Repeater Desense
Bob, The most recent instance was with a Cushcraft ARX-270 2m/440 antenna. I watched this antenna being assembled, and I can state that there was no corrosion, maladjustment, or looseness involved. We used that antenna briefly for a 2m repeater simply because it was already in place, and we had a special event to cover. A Motorola RKR-1225 repeater was hooked to it using LDF2-50 Heliax feedline. When the Cushcraft antenna wouldn't work without major desense, I swapped it for a Sinclair SRL-222 dipole, which worked perfectly. 73, Eric Lemmon WB6FLY Bob Dengler wrote: At 5/12/2005 12:37 PM, you wrote: Yes. Many repeater receivers are simply not well enough shielded to keep the TX from leaking into the RX box. Even some commercial repeaters will suffer desense if 100% shielded feedline is not used. I have seen serious desense occur when a dual-band (2m/440) antenna is used on a repeater, due to the uneven gain versus frequency response of many such antennas. A narrowband antenna by itself will not generate desense. Your problem was probably due to corrosion, dielectric breakdown, or some other cause related to poor construction/materials in the amateur grade antenna. I would like to know what model antenna this was though, since I have yet to see any desense problems with my Comet antennas. Bob NO6B 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] Repeater Desense
At 5/12/2005 01:41 PM, you wrote: Bob, The most recent instance was with a Cushcraft ARX-270 2m/440 antenna. Yup, heard similar stories about unexplained desense with that particular antenna. Possibly a bad capacitor. At any rate, unusable for duplex service. Definitely not representative of typical dual-band antenna duplex performance, though. Bob NO6B 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] Repeater Desense
I had an arx270 to slowly burn the cap out @ the feed point of the antenna. They will not handle 100 watts @ feed point on continuous duty. I contacted Cushcraft and they sent me a new cap at no charge. I use it home now, no repeater use. Bruce, KD4BOH. - Original Message - From: Eric Lemmon [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, May 12, 2005 3:41 PM Subject: Re: [Repeater-Builder] Repeater Desense Bob, The most recent instance was with a Cushcraft ARX-270 2m/440 antenna. I watched this antenna being assembled, and I can state that there was no corrosion, maladjustment, or looseness involved. We used that antenna briefly for a 2m repeater simply because it was already in place, and we had a special event to cover. A Motorola RKR-1225 repeater was hooked to it using LDF2-50 Heliax feedline. When the Cushcraft antenna wouldn't work without major desense, I swapped it for a Sinclair SRL-222 dipole, which worked perfectly. 73, Eric Lemmon WB6FLY Bob Dengler wrote: At 5/12/2005 12:37 PM, you wrote: Yes. Many repeater receivers are simply not well enough shielded to keep the TX from leaking into the RX box. Even some commercial repeaters will suffer desense if 100% shielded feedline is not used. I have seen serious desense occur when a dual-band (2m/440) antenna is used on a repeater, due to the uneven gain versus frequency response of many such antennas. A narrowband antenna by itself will not generate desense. Your problem was probably due to corrosion, dielectric breakdown, or some other cause related to poor construction/materials in the amateur grade antenna. I would like to know what model antenna this was though, since I have yet to see any desense problems with my Comet antennas. Bob NO6B 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/
[Repeater-Builder] Repeater desense Wacom WP-639
How can I test receive side of duplexer. It receives very Strong signals only. Tim 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] Repeater desense Wacom WP-639
Tim, One very basic test is to use a service monitor to first determine the sensitivity of your repeater's receiver at 12 dB SINAD. Let's say you measure its sensitivity as -117 dBm. Now disable the repeater function and, with the duplexer hooked up to both the transmitter and the receiver, repeat the measurement with the signal injected at the antenna connector of the duplexer. Most duplexers have an insertion loss around 1.5 to 2.2 dB, so the second measurement should be around -115 dBm. If that test passes, reconnect the antenna and have someone transmit on a handheld radio from a distance while you listen at the repeater. First listen with the repeat function disabled, and then enable the transmitter. If the weak signal goes away only when the transmitter is on, you definitely have desense. Check for the obvious, such as loose connectors, rodent-chewed cables, or missing shields. Are all of the jumpers double-shielded? Did this desense problem just suddenly happen, or has the repeater been this way from the beginning? Use an antenna analyzer to verify the antenna and feedline are okay. It may be a good idea to have the duplexer tuning checked on a network analyzer, just to see whether someone has tried to improve the reception by tinkering with the knobs. It is also possible that a lightning strike might have damaged the duplexer and/or the antenna. 73, Eric Lemmon WB6FLY wa3qcvr wrote: How can I test receive side of duplexer. It receives very Strong signals only. Tim 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/
