[Repeater-Builder] Interference / Intermod ?
Hello, Looking for some help or advice on a problem. I started get a squealing sound on my VHF repeater a while back. It was not consistent so it was hard to try and track the source. Well I found out a few days ago what the problem was. First let me fill you in on the Repeater. Motorola MSF5000 VHF @ 200 watts (its a 425 watt repeater) TX/RX 4 can cavities (about 2 yrs old, bought tuned from TX/RX) Cellwave StationMaster VHF Antenna @ 380' Andrews 1-5/8 Hardline from the Duplexers to the Antenna Second Repeater (backup) Motorola MSR2000 VHF @ 107 watts Wacom BpBr 4 can cavities Here's the issue. There is a new repeater, that came on the air, at the same time the squeal/intermod came on my repeater. My repeater is on 147.285 with a tone of 118.8. His repeater is on 146.685 (600khz lower then mine) about 20 miles away. His TX antenna is up at 155' Every time his repeater keys up, and mine keys up, the intermod noise is there, until his repeater drops, then it goes away. At first I thought it was HIS repeater causing the issue, which in a way it is, but I figured out it is not entirely his fault. I tried the other repeater, with the TX/RX cavities, and it still did the same thing. I tried the WACOM cavities on both repeaters, and still, the same issue. Now I can go outside the repeater site, in my car, and key up on 146.685mhz, and produce the same issue. I tried turning the power back to 100watts on the MSF5000, but still have the same issue. The only other test I have done, is put the MSF5000 in Disable, and when his repeater keyed up, I forced the MSF5000 into transmit, and the issue was not there. I dont have access, to any high end test equipment anymore. This repeater worked flawlessly for many years, until this issue came up. My question is... has anyone else experienced a problem like this Does anyone have any ideas for me to try to solve this issue, shy of me changing the repeater frequency? I already talked with this gentleman, and he has no interest at all, and changing frequencies back to 146.985... where he was. Thanks in advance to any help. 73, Pete K4QHR
[Repeater-Builder] New Repeater Desense Problems
Greetings Group, I had hoped to be able to purchase off-the-shelf components for a 2 meter repeater for our local club to use. I purchased a Maggoire HiPro R1VHF35, 35 watt version, and with their recommendation a set of FiPlex DVN-1533L Duplexers (6 cans). These were installed with LMR-400 cabling and a 50 foot run to a Diamond X- 50 Dual Band vertical installed about 40 feet above ground. We have a good ground, and the equipment is mounted in an open rack. The controller is a CAT-250, currently with COR receive only, although the CTCSS module is installed but not turned on at this time. I have been told however that the PL is being transmitted on the transmit signal for decode. I also had the Narrow Band IF Filter installed. Ever since we first hooked everything up, we have had receive desense problems. The cans have been retuned 3 times by two different radio shops in the area, and the problem still exists. With the exception of the duplexer and repeater itself, every other component in the system has been swapped out at least once. One observation by the first radio tech (ham) that came out was the very sensitive receiver on the order of 0.10 uv, versus the 0.20 uv as advertised. On the third tune-up of the duplexers, they discovered that the loops were 180 degrees out of phase, and when they turned them, the duplexers came right in. However, the problem persists. Great for in town use, but that's about it. We have used varied lengths of cables between the repeater and the duplexers, without any significant change in results. Next weekend, I am planning on looking at the tuning myself with borrowed test equipment. I know what I'm looking for pretty much, and it's got to be close to correct to work as it does. Any thoughts ideas, etc., would be appreciated. Bill KJ4EX
[Repeater-Builder] Micor UHF PURC Stations Needed
I am looking for Micor PURC 225 or 250 Watt UHF stations. We had a fire at a repeater site and lost a large collection of Micor Stations and accessories. I had 1 PURC station on the air in the building and another one stored there. If anyone near the West Coast has any of these they are willing to part with, or know of any, please email me off list. Stations with 900 or 72 MHz receivers are OK also. Thanks, Joe - WA7JAW
Re: [Repeater-Builder] china made radios
What is worse is the frs gmrs. Businesses have stopped buying the $400-$600 2-way portables to use the $59 frs units. This has devistated my 2-way business. You cann't call the F.C.C. on your customers or the will never buy from you again. Yet the F.C.C. will not do anything about it. [EMAIL PROTECTED] wrote: Yes, as a ham you can USE those radios, however, they cannot be legally imported into the U.S. Period. The community forums at E-Bay are full of stories of people who have bought them, only to have them confiscated by Customs. And then they're S.O.L. E-Bay keeps pulling the ads, but they pop up again like weeds. George, KA3HSW / WQGJ413 - Original Message - From: Ron Wright [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Sunday, July 06, 2008 8:12 AM Subject: Re: [Repeater-Builder] china made radios [snip] As Hams we can operate these rigs. However, they are not type accepted for the US and think use in commercial can be a problem even GMRS or MURS. The largest market for these rigs are the mom and pop businesses needing some sort of HT comm. I am not sure what customs would do with these if they knew of the non-type acceptance. Might be a problem, but mine came thru with no problem. Takes about 10 days for coming from far east, think China or Tiwan. 73, ron, n9ee/r
[Repeater-Builder] Re:Motorola GM300 vs SM120??
Form experience: commercial radios have a better receiver than a ham radio or scanner. When you are looking at the price of the radio the higher priced radio generally has a better built receiver. while there is not much difference between the GM300 and the SM120 there would be a great difference between a SM120 and a MTR2000. A MTR200 would work much better in a high RF area then a SM120. 73's de N5SLI
Re: [Repeater-Builder] New Repeater Desense Problems
Replace the lmr400 with heliax .we hjave had nothing but problems with it since changing it to heliax the problem has been cleared up Thank You, Ian Wells, Kerinvale Comaudio, 361 Camboon Road.Biloela.4715 Phone 0749922574 or 0409159932 www.kerinvalecomaudio.com.au ---Original Message--- From: Bill Wilson Date: 8/07/2008 10:08:00 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] New Repeater Desense Problems Greetings Group, I had hoped to be able to purchase off-the-shelf components for a 2 meter repeater for our local club to use. I purchased a Maggoire HiPro R1VHF35, 35 watt version, and with their recommendation a set of FiPlex DVN-1533L Duplexers (6 cans). These were installed with LMR-400 cabling and a 50 foot run to a Diamond X- 50 Dual Band vertical installed about 40 feet above ground. We have a good ground, and the equipment is mounted in an open rack. The controller is a CAT-250, currently with COR receive only, although the CTCSS module is installed but not turned on at this time. I have been told however that the PL is being transmitted on the transmit signal for decode. I also had the Narrow Band IF Filter installed. Ever since we first hooked everything up, we have had receive desense problems. The cans have been retuned 3 times by two different radio shops in the area, and the problem still exists. With the exception of the duplexer and repeater itself, every other component in the system has been swapped out at least once. One observation by the first radio tech (ham) that came out was the very sensitive receiver on the order of 0.10 uv, versus the 0.20 uv as advertised. On the third tune-up of the duplexers, they discovered that the loops were 180 degrees out of phase, and when they turned them, the duplexers came right in. However, the problem persists. Great for in town use, but that's about it. We have used varied lengths of cables between the repeater and the duplexers, without any significant change in results. Next weekend, I am planning on looking at the tuning myself with borrowed test equipment. I know what I'm looking for pretty much, and it's got to be close to correct to work as it does. Any thoughts ideas, etc., would be appreciated. Bill KJ4EX
Re: [Repeater-Builder] New Repeater Desense Problems
Bill, In finding desense first one must locate the problem. A given. I would start with putting GOOD dummy load on the duplexer output and do a desense test. This can be done with a local signal gen where you can vary the gen output and keying and unkey the transmitter. You should see no difference in the received signal with tx keyed or unkeyed. If you do then the desense is in the repeater. Next do the same test with the dummy load on the transmtter only. This will test for the desense being inside or outside the radio part of the repeater. I would look at your LMR400 and antenna. I think the LMR400 is a double shielded cable with different metals for the 2 shields. This is a no no in duplexed system. It generates noise. It has been discussed here on this board many many times and for good reason. If this is a problem replace with a good heliax. It is worth the cost. This is a start. 73, ron, n9ee/r From: Bill Wilson [EMAIL PROTECTED] Date: 2008/07/06 Sun PM 10:24:30 EDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] New Repeater Desense Problems Greetings Group, I had hoped to be able to purchase off-the-shelf components for a 2 meter repeater for our local club to use. I purchased a Maggoire HiPro R1VHF35, 35 watt version, and with their recommendation a set of FiPlex DVN-1533L Duplexers (6 cans). These were installed with LMR-400 cabling and a 50 foot run to a Diamond X- 50 Dual Band vertical installed about 40 feet above ground. We have a good ground, and the equipment is mounted in an open rack. The controller is a CAT-250, currently with COR receive only, although the CTCSS module is installed but not turned on at this time. I have been told however that the PL is being transmitted on the transmit signal for decode. I also had the Narrow Band IF Filter installed. Ever since we first hooked everything up, we have had receive desense problems. The cans have been retuned 3 times by two different radio shops in the area, and the problem still exists. With the exception of the duplexer and repeater itself, every other component in the system has been swapped out at least once. One observation by the first radio tech (ham) that came out was the very sensitive receiver on the order of 0.10 uv, versus the 0.20 uv as advertised. On the third tune-up of the duplexers, they discovered that the loops were 180 degrees out of phase, and when they turned them, the duplexers came right in. However, the problem persists. Great for in town use, but that's about it. We have used varied lengths of cables between the repeater and the duplexers, without any significant change in results. Next weekend, I am planning on looking at the tuning myself with borrowed test equipment. I know what I'm looking for pretty much, and it's got to be close to correct to work as it does. Any thoughts ideas, etc., would be appreciated. Bill KJ4EX Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: [Repeater-Builder] New Repeater Desense Problems
Don't leave out the isolated TEE between the duplexer and dummy load, Ron. Hi, Steve NU5D Ron Wright wrote: Bill, In finding desense first one must locate the problem. A given. I would start with putting GOOD dummy load on the duplexer output and do a desense test. This can be done with a local signal gen where you can vary the gen output and keying and unkey the transmitter. You should see no difference in the received signal with tx keyed or unkeyed. If you do then the desense is in the repeater. Next do the same test with the dummy load on the transmtter only. This will test for the desense being inside or outside the radio part of the repeater. I would look at your LMR400 and antenna. I think the LMR400 is a double shielded cable with different metals for the 2 shields. This is a no no in duplexed system. It generates noise. It has been discussed here on this board many many times and for good reason. If this is a problem replace with a good heliax. It is worth the cost. This is a start. 73, ron, n9ee/r
Re: [Repeater-Builder] Interference / Intermod ?
In the early '70s we had a repeater made up with GE Prog line strips running 60 watts installed on an old rusty sheriff tower with non-insulated guys. On a foggy morning we would always hear radio station audio when we keyed the repeater. We traced the station audio to a site over 75 miles from our repeater, but the station operated on 600 kHz. The rusty guy attachment to our tower gave a nice rectifier to produce the mix + and - our transmit frequency, and gave rise to the BC station audio on our transmitter. We were unable to get rid of this problem for as long as we used the site. Thankfully, a foggy morning was a rare occurance and we were able to live with it a few days a year. Sounds like you have the source of the 600 kHz signal located, but now you need to figure out the point of the mix. Your transmitter, his transmitter, or some rectifying joint on your tower or nearby. I recently decided not to place a repeater antenna on the side of a tower erected on top of a water tank in favor of a location lower but much further from the guys for the tower. I was afraid of the problem with the non-insulated guys in the near field of our antenna. 73 - Jim W5ZIT --- On Sun, 7/6/08, Pete [EMAIL PROTECTED] wrote: From: Pete [EMAIL PROTECTED] Subject: [Repeater-Builder] Interference / Intermod ? To: Repeater-Builder@yahoogroups.com Date: Sunday, July 6, 2008, 10:23 AM Hello, Looking for some help or advice on a problem. I started get a squealing sound on my VHF repeater a while back. It was not consistent so it was hard to try and track the source. Well I found out a few days ago what the problem was. First let me fill you in on the Repeater. Motorola MSF5000 VHF @ 200 watts (its a 425 watt repeater) TX/RX 4 can cavities (about 2 yrs old, bought tuned from TX/RX) Cellwave StationMaster VHF Antenna @ 380' Andrews 1-5/8 Hardline from the Duplexers to the Antenna Second Repeater (backup) Motorola MSR2000 VHF @ 107 watts Wacom BpBr 4 can cavities Here's the issue. There is a new repeater, that came on the air, at the same time the squeal/intermod came on my repeater. My repeater is on 147.285 with a tone of 118.8. His repeater is on 146.685 (600khz lower then mine) about 20 miles away. His TX antenna is up at 155' Every time his repeater keys up, and mine keys up, the intermod noise is there, until his repeater drops, then it goes away. At first I thought it was HIS repeater causing the issue, which in a way it is, but I figured out it is not entirely his fault. I tried the other repeater, with the TX/RX cavities, and it still did the same thing. I tried the WACOM cavities on both repeaters, and still, the same issue. Now I can go outside the repeater site, in my car, and key up on 146.685mhz, and produce the same issue. I tried turning the power back to 100watts on the MSF5000, but still have the same issue. The only other test I have done, is put the MSF5000 in Disable, and when his repeater keyed up, I forced the MSF5000 into transmit, and the issue was not there. I dont have access, to any high end test equipment anymore. This repeater worked flawlessly for many years, until this issue came up. My question is... has anyone else experienced a problem like this Does anyone have any ideas for me to try to solve this issue, shy of me changing the repeater frequency? I already talked with this gentleman, and he has no interest at all, and changing frequencies back to 146.985... where he was. Thanks in advance to any help. 73, Pete K4QHR _
Re: [Repeater-Builder] Re:Motorola GM300 vs SM120??
This is pretty much personal preference I think, but I've used both of them (if I can count SM50s and SM120s together) and I think the GM300 is a little better for this application. Seems to sound a little bit better (less white noise in the recovered audio). The 1-10W GM300 makes a really good exciter when it's run low and connected to an external amp. In fact, if anyone wants to sell any low power VHF GM300s I'd like to talk to you off-list :) On Jul 7, 2008, at 3:02 PM, Pat Patterson wrote: Form experience: commercial radios have a better receiver than a ham radio or scanner. When you are looking at the price of the radio the higher priced radio generally has a better built receiver. while there is not much difference between the GM300 and the SM120 there would be a great difference between a SM120 and a MTR2000. A MTR200 would work much better in a high RF area then a SM120. 73's de N5SLI -- Cort Buffington H: +1-785-838-3034 M: +1-785-865-7206
Re: [Repeater-Builder] New Repeater Desense Problems
Have you run the repeater into a dummy load and check for desense? David = From: Bill Wilson [EMAIL PROTECTED] Date: 2008/07/07 Mon AM 02:24:30 WET To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] New Repeater Desense Problems Greetings Group, I had hoped to be able to purchase off-the-shelf components for a 2 meter repeater for our local club to use. I purchased a Maggoire HiPro R1VHF35, 35 watt version, and with their recommendation a set of FiPlex DVN-1533L Duplexers (6 cans). These were installed with LMR-400 cabling and a 50 foot run to a Diamond X- 50 Dual Band vertical installed about 40 feet above ground. We have a good ground, and the equipment is mounted in an open rack. The controller is a CAT-250, currently with COR receive only, although the CTCSS module is installed but not turned on at this time. I have been told however that the PL is being transmitted on the transmit signal for decode. I also had the Narrow Band IF Filter installed. Ever since we first hooked everything up, we have had receive desense problems. The cans have been retuned 3 times by two different radio shops in the area, and the problem still exists. With the exception of the duplexer and repeater itself, every other component in the system has been swapped out at least once. One observation by the first radio tech (ham) that came out was the very sensitive receiver on the order of 0.10 uv, versus the 0.20 uv as advertised. On the third tune-up of the duplexers, they discovered that the loops were 180 degrees out of phase, and when they turned them, the duplexers came right in. However, the problem persists. Great for in town use, but that's about it. We have used varied lengths of cables between the repeater and the duplexers, without any significant change in results. Next weekend, I am planning on looking at the tuning myself with borrowed test equipment. I know what I'm looking for pretty much, and it's got to be close to correct to work as it does. Any thoughts ideas, etc., would be appreciated. Bill KJ4EX
RE: [Repeater-Builder] New Repeater Desense Problems
Not to hijack the thread, but a dummy load is NOT always a perfect test to eliminate the equipment. I think it’s a good start though. I just solved a situation where I had 15 db desense into a 600ft feedline / antenna and ZERO desense into a dummy load. This was using a sample slug ( same function as iso tee)in my bird 43 where the feed line attached to the cabinet. My assumption that the complete repeater, duplexers, isolator and cables were fine into a dummy load led me to look at the hardline and antenna and prepare for paying for a climb. Before we could properly test the feedline and antenna, the mastr II PA failed. (VHF) after replacing the amp, the 15 db desense problem was gone. So the failing amp liked the dummy load better than 600ft of 50ohm feedline and antenna . Or some product from the amp excited the feedline /antenna to create something on our input. The low level products on our input creating the desense were not visible when I had looked at the spectral output of the amp before it failed. Nothing like moving a mobile amp into a continuous duty heat sink, on you tailgate, on the 4th of July! 73 Don Kirchner W5DK From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, July 08, 2008 9:39 AM To: Bill Wilson; Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] New Repeater Desense Problems Have you run the repeater into a dummy load and check for desense? David = From: Bill Wilson [EMAIL PROTECTED] mailto:kj4ex%40yahoo.com Date: 2008/07/07 Mon AM 02:24:30 WET To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] New Repeater Desense Problems Greetings Group, I had hoped to be able to purchase off-the-shelf components for a 2 meter repeater for our local club to use. I purchased a Maggoire HiPro R1VHF35, 35 watt version, and with their recommendation a set of FiPlex DVN-1533L Duplexers (6 cans). These were installed with LMR-400 cabling and a 50 foot run to a Diamond X- 50 Dual Band vertical installed about 40 feet above ground. We have a good ground, and the equipment is mounted in an open rack. The controller is a CAT-250, currently with COR receive only, although the CTCSS module is installed but not turned on at this time. I have been told however that the PL is being transmitted on the transmit signal for decode. I also had the Narrow Band IF Filter installed. Ever since we first hooked everything up, we have had receive desense problems. The cans have been retuned 3 times by two different radio shops in the area, and the problem still exists. With the exception of the duplexer and repeater itself, every other component in the system has been swapped out at least once. One observation by the first radio tech (ham) that came out was the very sensitive receiver on the order of 0.10 uv, versus the 0.20 uv as advertised. On the third tune-up of the duplexers, they discovered that the loops were 180 degrees out of phase, and when they turned them, the duplexers came right in. However, the problem persists. Great for in town use, but that's about it. We have used varied lengths of cables between the repeater and the duplexers, without any significant change in results. Next weekend, I am planning on looking at the tuning myself with borrowed test equipment. I know what I'm looking for pretty much, and it's got to be close to correct to work as it does. Any thoughts ideas, etc., would be appreciated. Bill – KJ4EX
Re: [Repeater-Builder] New Repeater Desense Problems
Just to echo previous comments, the LMR type cable (any cable with aluminum foil/braid combination) is suspect. This subject comes up here about every other week. Chuck WB2EDV - Original Message - From: Bill Wilson [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Sunday, July 06, 2008 10:24 PM Subject: [Repeater-Builder] New Repeater Desense Problems Greetings Group, I had hoped to be able to purchase off-the-shelf components for a 2 meter repeater for our local club to use. I purchased a Maggoire HiPro R1VHF35, 35 watt version, and with their recommendation a set of FiPlex DVN-1533L Duplexers (6 cans). These were installed with LMR-400 cabling and a 50 foot run to a Diamond X- 50 Dual Band vertical installed about 40 feet above ground. We have a good ground, and the equipment is mounted in an open rack. The controller is a CAT-250, currently with COR receive only, although the CTCSS module is installed but not turned on at this time. I have been told however that the PL is being transmitted on the transmit signal for decode. I also had the Narrow Band IF Filter installed. Ever since we first hooked everything up, we have had receive desense problems. The cans have been retuned 3 times by two different radio shops in the area, and the problem still exists. With the exception of the duplexer and repeater itself, every other component in the system has been swapped out at least once. One observation by the first radio tech (ham) that came out was the very sensitive receiver on the order of 0.10 uv, versus the 0.20 uv as advertised. On the third tune-up of the duplexers, they discovered that the loops were 180 degrees out of phase, and when they turned them, the duplexers came right in. However, the problem persists. Great for in town use, but that's about it. We have used varied lengths of cables between the repeater and the duplexers, without any significant change in results. Next weekend, I am planning on looking at the tuning myself with borrowed test equipment. I know what I'm looking for pretty much, and it's got to be close to correct to work as it does. Any thoughts ideas, etc., would be appreciated. Bill - KJ4EX Yahoo! Groups Links
Re: [Repeater-Builder] RCA TCXOs for sale
Hi Jams, I am interested if no one else wants. 73 tnx, Mike KB5FLX [EMAIL PROTECTED] - Original Message - From: n0qzv_jhorn To: Repeater-Builder@yahoogroups.com Sent: Monday, July 07, 2008 10:15 PM Subject: [Repeater-Builder] RCA TCXOs for sale I have a set of TCXOs for a RCA 500 series repeater. They are 442.4 TX and 447.4 RX and were reworked by ICM. Please contact me directly with an offer. thank you James
Re: [Repeater-Builder] New Repeater Desense Problems
de W5DK wrote: Not to hijack the thread, but a dummy load is NOT always a perfect test to eliminate the equipment. I think it’s a good start though. I just solved a situation where I had 15 db desense into a 600ft feedline / antenna and ZERO desense into a dummy load. This was using a sample slug ( same function as iso tee)in my bird 43 where the feed line attached to the cabinet. My assumption that the complete repeater, duplexers, isolator and cables were fine into a dummy load led me to look at the hardline and antenna and prepare for paying for a climb. Before we could properly test the feedline and antenna, the mastr II PA failed. (VHF) after replacing the amp, the 15 db desense problem was gone. So the failing amp liked the dummy load better than 600ft of 50ohm feedline and antenna . Or some product from the amp excited the feedline /antenna to create something on our input. The low level products on our input creating the desense were not visible when I had looked at the spectral output of the amp before it failed. It sounds to me like the PA wasn't aligned properly. Or the duplexer is not aligned properly. Most, but not all, MastrII PA's have an output filter section that is tricky to align correctly. There is lots of info on it on the repeater-builder web site. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * 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] New Repeater Desense Problems
At 07:24 PM 07/06/08, you wrote: Greetings Group, I had hoped to be able to purchase off-the-shelf components for a 2 meter repeater for our local club to use. I purchased a Maggoire HiPro R1VHF35, 35 watt version, and with their recommendation a set of FiPlex DVN-1533L Duplexers (6 cans). These were installed with LMR-400 cabling and a 50 foot run to a Diamond X- 50 Dual Band vertical installed about 40 feet above ground. We have a good ground, and the equipment is mounted in an open rack. The controller is a CAT-250, currently with COR receive only, although the CTCSS module is installed but not turned on at this time. I have been told however that the PL is being transmitted on the transmit signal for decode. I also had the Narrow Band IF Filter installed. Ever since we first hooked everything up, we have had receive desense problems. The cans have been retuned 3 times by two different radio shops in the area, and the problem still exists. With the exception of the duplexer and repeater itself, every other component in the system has been swapped out at least once. One observation by the first radio tech (ham) that came out was the very sensitive receiver on the order of 0.10 uv, versus the 0.20 uv as advertised. On the third tune-up of the duplexers, they discovered that the loops were 180 degrees out of phase, and when they turned them, the duplexers came right in. However, the problem persists. Great for in town use, but that's about it. We have used varied lengths of cables between the repeater and the duplexers, without any significant change in results. Next weekend, I am planning on looking at the tuning myself with borrowed test equipment. I know what I'm looking for pretty much, and it's got to be close to correct to work as it does. Any thoughts ideas, etc., would be appreciated. Bill KJ4EX Who told you to use the LMR coax for duplex use? Doesn't anybody read the archives of this group? There has been at least a dozen instances over the last few years where people have popped up and been told that LMR CABLE IS JUNK WHEN USED IN DUPLEX SERVICE. Go to this page: http://www.repeater-builder.com/antenna/ant-sys-index.html Read the 4 paragraphs under System Engineering and also the second and third articles there. This is also of interest: http://www.repeater-builder.com/antenna/andrew-shielding-effectiveness.pdf As to what cable you should use... it all depends on how well you want to hear. Increasing the talk range is easy - how much amplifier and duplexer can you afford? The average amateur radio repeater is limited by the fact that every user wants to use a 2w or 4w handheld instead of a 30w of 50w mobile. If you can't hear them you can't repeat them, so a repeater that has a 1.5db of feedline loss (100 feet of LMR400 at 2m) from the antenna to the receiver is not going to hear as well as one that has 0.5db of loss (100 feet of 7/8 inch heliax at 2m). People never seem to think about feedline loss on received signals... Look at the bottom third of this page: http://www.repeater-builder.com/antenna/wa2ise-coaxial-cable.html and look at the loss per 100 feet. Always favor your receiver. Once you have lost received signal (i.e. it's down into the noise level) all the preamps do is bring up the noise. This is also of interest: http://www.coasteltools.com/tech_cable_db_loss.htm And some evening spend some time reading this: http://www.repeater-builder.com/db/db-about-rf-communications.pdf Yes, some of the info is 40 years old, but the physics of RF hasn't changed. Mike WA6ILQ
[Repeater-Builder] MSR 2000
Hello Gentlemen; I recently acquired a pair of MSR 2000 100 watt repeaters that are on 160 mhz. I am not very well acquainted with the Motorola gear although every one assures me they are far superior to the Mastr II gear I am presently using - My question is, can the 160 mhz units be moved to 146 with out a lot of trouble or at all? These are operational units, one is new and one used - If they cannot handily be moved to the amateur freq then are they of very much value or I guess I should ask, is there any demand for them? Thanks / NØATH Dave
[Repeater-Builder] Re: MSR 2000
MSR2000 far superior to the Mastr II ? Nah. I'm a Motorola kind of guy and I sure wouldn't make that statement. They are both capable of excellent performance so unless you need to replace your Mastr II gear because of equipment failures / problems you really wouldn't see any performance improvement. Value? Not much. MSR 2000 hasn't been made for many years. Now, on the other hand, if they were MTR2000 repeaters, that would be a much different situation. - --- In Repeater-Builder@yahoogroups.com, N0ATH [EMAIL PROTECTED] wrote: Hello Gentlemen; I recently acquired a pair of MSR 2000 100 watt repeaters that are on 160 mhz. I am not very well acquainted with the Motorola gear although every one assures me they are far superior to the Mastr II gear I am presently using - My question is, can the 160 mhz units be moved to 146 with out a lot of trouble or at all? These are operational units, one is new and one used - If they cannot handily be moved to the amateur freq then are they of very much value or I guess I should ask, is there any demand for them? Thanks / NØATH Dave
Re: [Repeater-Builder] Re: MSR 2000
Well I dug out my MSR2000 hiband service manual, and as I remembered, the PA is intermittent duty and not continuous duty. The manual does mention a temperature sensor that goes to a feed back loop and reduces output power for self preservation when things get hot. The radio is pretty much a Mitrek design with what looks pretty close to a Micor PA. I set up one hiband station with a dual receiver (some kind of telco simplex base / repeater operation and it seemed like out of the box I could not get full power out - I did not try and do any modes on a 2M ham freq. I also maintained an UHF MSR - Med Base / Rept - seems like 75 watt version and had a couple of collector burns in the PA - otherwise seemed to be OK stations. Steve NU5D nj902 wrote: MSR2000 far superior to the Mastr II ?
Re: [Repeater-Builder] MSR 2000
Dave, The MSR2000 VHF was made for 2 freq bands, 132-150.8 and 146-174. So both segments can be used in the 146-148 2 meter band. However, the PAs were made for 3 bands, 132-150.8, 150.8-160 and 160-174. If your unit is on 160-174 the PA will probably not move down to 146. However, if repeater is in 150-160 range the PA should still work with degraded performance; 90%. The MSR2000 was a mix of the Micor and Mitrek (a smaller trunk mount radio). The exciter and receiver were seperated and the Micor PA painted a different color. All was given a new package. They do make an excellent repeater. They have very quite and clean transmitters. The GE Mastr line is also an excellent product and uses the same technology as the MSR2000. The MSR2000 that is new would mean it would have a longer life. However, most used I've seen are clean and have years left. This is a factor when putting on a repeater. The commercial guys don't like the older stuff due to this. The MSR2000 will perform about the same as the Mastr IIs, so if the GE is working don't fix it. However, it can be fun to work with finnneee gear as the MSR2000 is. 73, ron, n9ee/r From: N0ATH [EMAIL PROTECTED] Date: 2008/07/08 Tue PM 03:48:35 EDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] MSR 2000 Hello Gentlemen; I recently acquired a pair of MSR 2000 100 wattrepeaters that are on 160 mhz. I am not very well acquainted with the Motorola gear although everyone assures me they are far superior to the Mastr II gear I am presently using - My question is, can the 160 mhz units be moved to 146 with out a lot of trouble or at all? These are operational units, one isnew and one used - If they cannot handily be movedto the amateur freq then are they of very much valueor I guess I should ask, is there any demand for them?Thanks / NØATH Dave Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: [Repeater-Builder] MSR 2000
Dave, I have not had as satisfying an experience with MSR2000 machines as others here on the list... Mine was a 460 MHz unit tuned down to 444 MHz, and the receiver was nearly deaf - even after being tuned up several times by a Motorola service shop tech. (0.9 µv sensitivity) Another recurring problem I had was with the PA - it kept burning up the harmonic filter. And when the PA went out, it had to go back to Motorola for repair - mainly because the harmonic filter is constructed on a ceramic substrate and I (nor anyone else I could contact) had the proper tools to repair it without cracking and ruining the ceramic. I assume they used silver solder to make the connections but I can only wonder, given the same failure repeatedly. (Yep, I know all about assuming...) I ended up taking the MSR2000 out of service and replacing it with a Kenwood TKR-820 for the transmitter and Micor receivers/SpectraTAC voter network. That repeater works like a champ! Now on the other hand, I'm running an MSF5000 on 900 MHz and *it's* working like a trooper!! Mark - N9WYS -Original Message- From: N0ATH [EMAIL PROTECTED] Date: 2008/07/08 Tue PM 03:48:35 EDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] MSR 2000 Hello Gentlemen; I recently acquired a pair of MSR 2000 100 watt repeaters that are on 160 mhz. I am not very well acquainted with the Motorola gear although everyone assures me they are far superior to the Mastr II gear I am presently using - My question is, can the 160 mhz units be moved to 146 with out a lot of trouble or at all? These are operational units, one is new and one used - If they cannot handily be moved to the amateur freq then are they of very much value or I guess I should ask, is there any demand for them? Thanks / NØATH Dave
[Repeater-Builder] IFR 1900 Schematics
Does anyone know of a source for the IFR-1900 schematics? I have each of the Service, Calibration Operating manuals, however, schematics are not within them. I assume this is because Aeroflex still supports the units for a lucrative fee and doesn't want competition. Thanks, Eric
Re: [Repeater-Builder] IFR 1900 Schematics
I couldn't find any. The block diagram for the COM-120C is kinda close. If you transmitted into the Aux port, and the step attenuator was at a fairly high level of output, you will need to replace the MMICs in the generator module. http://blog.myspace.com/index.cfm?fuseaction=blog.viewfriendID=85474861blogID=394848267 On 7/8/08, w2zt [EMAIL PROTECTED] wrote: Does anyone know of a source for the IFR-1900 schematics? I have each of the Service, Calibration Operating manuals, however, schematics are not within them. I assume this is because Aeroflex still supports the units for a lucrative fee and doesn't want competition. Thanks, Eric Yahoo! Groups Links
[Repeater-Builder] Re: IFR 1900 Schematics
Eric - I too am looking for doc on this svc mon. I need the Service Calibration doc you have and hope you can help me out with some copies or steer me in the direction of your supplier. TIAdan n2aym NOTE: Please email me at my qrz listed email address. --- In Repeater-Builder@yahoogroups.com, w2zt [EMAIL PROTECTED] wrote: Does anyone know of a source for the IFR-1900 schematics? I have each of the Service, Calibration Operating manuals, however, schematics are not within them. I assume this is because Aeroflex still supports the units for a lucrative fee and doesn't want competition. Thanks, Eric
[Repeater-Builder] Re: New Repeater Desense Problems
--- In Repeater-Builder@yahoogroups.com, wd8chl [EMAIL PROTECTED] wrote: It sounds to me like the PA wasn't aligned properly. Or the duplexer is not aligned properly. Most, but not all, MastrII PA's have an output filter section that is tricky to align correctly. Are you referring to the Z matching adjustments on continuous-duty amps? Laryn K8TVZ
RE: [Repeater-Builder] IFR 1900 Schematics
Yes, I have two 1900's at the moment and had to replace the final output MMIC in both of them. The original is an SHF-0186 made by Sirenza. As it's no longer manufactured and Aeroflex wants almost $90 for this $3 part, I replaced them with a Mini-Circuits ERA-6+. Since the ERA-6+ is a 5 volt unit as opposed to the 8 volt original, I had to change a couple of dropping resistors also. After this along with a couple of other repairs and a complete calibration they both work well and pass all of their self tests. I just know that sooner or later I'll experience a failure on the one I keep that will require a schematic to diagnose. Maybe by then Aeroflex will be less possessive of the schematics. Thanks, Eric _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of DCFluX Sent: Tuesday, July 08, 2008 4:29 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] IFR 1900 Schematics I couldn't find any. The block diagram for the COM-120C is kinda close. If you transmitted into the Aux port, and the step attenuator was at a fairly high level of output, you will need to replace the MMICs in the generator module. http://blog. http://blog.myspace.com/index.cfm?fuseaction=blog.viewfriendID=85474861bl ogID=394848267 myspace.com/index.cfm?fuseaction=blog.viewfriendID=85474861blogID=39484826 7 On 7/8/08, w2zt [EMAIL PROTECTED] mailto:w2zt%40comcast.net net wrote: Does anyone know of a source for the IFR-1900 schematics? I have each of the Service, Calibration Operating manuals, however, schematics are not within them. I assume this is because Aeroflex still supports the units for a lucrative fee and doesn't want competition. Thanks, Eric _,_._,___
Re: [Repeater-Builder] New Repeater Desense Problems
At 7/8/2008 11:37, you wrote: If you can't hear them you can't repeat them, so a repeater that has a 1.5db of feedline loss (100 feet of LMR400 at 2m) from the antenna to the receiver is not going to hear as well as one that has 0.5db of loss (100 feet of 7/8 inch heliax at 2m). ...except if your repeater is in SoCal, where the antenna noise temperature on 2 meters is about 10 dB above kTB, so throwing away a couple of dB between the antenna RX isn't going to hurt you. Bob NO6B
RE: [Repeater-Builder] Re: New Repeater Desense Problems
I think he was Laryn. I could see an argument that it may not have been aligned and caused the situation. But,, In this case the matching circuit was installed and set properly, also the duplexers and all were perfect. The system was stable for years then boom, desense. All I was saying was that this station worked Perfect into a dummy load (zero desense and all to spec) but did not into feedline(+15db) . So we cringed and focused there. We were getting ready to replace the antenna at 580 ft and spend some money after the dummy load test. Luckily the amp finished failing. What I relayed locally after this experience was that a complete system that works flawlessly into a dummy load may not be flawless. I do think the majority of desense problems can be diagnosed with a dummy load and a sampler slug / iso tee. I just wanted to throw a recent experience / monkey wrench into the thread hi. 73 Don W5DK m: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Laryn Lohman Sent: Tuesday, July 08, 2008 8:50 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: New Repeater Desense Problems --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , wd8chl [EMAIL PROTECTED] wrote: It sounds to me like the PA wasn't aligned properly. Or the duplexer is not aligned properly. Most, but not all, MastrII PA's have an output filter section that is tricky to align correctly. Are you referring to the Z matching adjustments on continuous-duty amps? Laryn K8TVZ
[Repeater-Builder] WANTED: GE MASTR II #PL19D43027262 Power Supply 12VDC VHF 110W RPT AMP
Hello all: I am looking to buy or trade for (see end of this message) a working GE MASTR II 12VDC power supply ( #PL19D43027262) and a GE MASTR II 110W output REPEATER DUTY vhf RF Amplifier. I have one complete MOTOROLA RT upright 6' 400w VHF Hi-Band repeater system and another complete MOTOROLA RT 400w VHF Hi-Band station LESS 6' rack that has the TX RX units converted to 146Mhz. (10w another complete 110w exciter) for sale or trade for the GE PS Repeater Duty amp. I perfer to deal with someone locally (Tampabay, FL area) but will consider any offers/deals. Please supply details to me OFF LIST at [EMAIL PROTECTED] mailto:[EMAIL PROTECTED] . I can be reached usually between 12noon - 9PM daily at (727)863-0102 or leave message if you get answering machine (I am medically and physically disabiled and have many Doctor apts in the early AM). Thanks 73.
Re: [Repeater-Builder] Re: New Repeater Desense Problems
On Jul 8, 2008, at 9:47 PM, de W5DK wrote: We were getting ready to replace the antenna at 580 ft and spend some money after the dummy load test. Luckily the amp finished failing. What I relayed locally after this experience was that a complete system that works flawlessly into a dummy load may not be flawless. Don, I think you said you looked at the PA output with a spectrum analyzer prior to its failure -- did you see anything? Was your MASTR II VHF, or UHF? Just curious. I've been fighting VHF MASTR II PA's for years here... I've got (literally) a pile of the continuous-duty PA's that need some sort of repair or another. UHF on the other hand, just work forever. It's a heartbreaker to have watched a friend meticulously rebuild a MASTR II VHF PA including following all the manufacturer specified torques for every single screw, including replacing all the thermal grease correctly with new after cleaning the thing up, using the right solder and heat to put everything back together with the newest mobile components we could find, hooking it to a WELL tested (we were already well into the troubleshooting stage/question of Why do these things blow up, damn-it!?) commercial antenna fed with good hardline, an isolator, swept with a Sitemaster... yadda, yadda, yadda Only to see that one die in 6 months time. Enough to REALLY piss you off -- when your mentors tell you that there must still be something wrong with the antenna system. Yeah, whatever... at 125 miles round trip to that site, I'm not sure I care anymore at today's gas prices. Tired of replacing the dang things. I think SOME of these in this pile are just old and were abused (overheated) in their lifetimes, but others... like this complete rebuild, were flawless. Then *pop*. Dead. Gr. -- Nate Duehr, WY0X [EMAIL PROTECTED]
