RE: [Repeater-Builder] Interference on VHF repeater
Had basically the same problem with w GE MASTR II repeater on VHF HI. The issue was with the repeater transmitter. When the repeater sat quiet for a while then it was keyed up the transmitter would have many spurs that would slowly travel up the band. This affected other repeaters that were open squelch or had the same PL. On the GE MASTR II PA there is a circuit just after the filter that was the problem. The tech had put a filter on the transmitter side to help with desense. This caused the network to be unbalanced and was causing the transmitter to spur. Once the transmitter ran for a while it cleared. David From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of brett Sent: Saturday, September 04, 2010 6:27 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Interference on VHF repeater Hi all, I have come across an interesting problem which you may be able to shed some light on. I have an intermod issue where my TX sometimes opens up my RX. I have the distinctive hollow pipe sound. Both TX and RX have the same CTCSS tone. The intermod product is however not always present, and after looking at the RX output from the duplexer with a SA I see a comb of products that move slowly in time. When one of the products in the comb falls within the RX bandwidth the RX opens, until it moves on. This is not a busy site, and I have been able to power down everything on site except my repeater. Problem remains unchanged. I have also disconnected feeders from all other RF equipment on site - still no change. The fact that the IM product frequency changes with time (drift rate is roughly a few kHz's an hour) makes me think that there is either another unknown source of RF on site which has poor freq stability (pretty unlikley), or somehow my TX freq is involved in producing this freq. I have inserted a 6dB pad in the antenna port of the duplexer and found that the IM products drop 12dB, and also curiously, the frequency of the products change. Removing the pad reverses this effect. I have repeated this many times and the result was always the same. It appears that the frequency of the IM product is dependent on the strength of the radiated field from my antenna. This is my question: I have read that it is possible for a strong EM field to excite metal (eg tower member) such that re-radiation will occur at a frequency which is different from that which excited it. Can anyone confirm they have seen this, or can anyone point me to a reference that talks about this? I should also mention there are multiple solar panels and associated regulators on site. The regulators have been discounted as possible sources, but the panels (given they may have bypass/blocking diodes) may be a mixing location, however the source of the drifting tone is still unclear. Thanks, Brett VK2CBD.
Re: [Repeater-Builder] Interference on VHF repeater
Brett, How did you determine it's an IM product? What repeater/controller combination are you using? I'd try powering down the controller and manually keying the transmitter. If that solves it, it could be the controller's reference oscillator or divider outputs leaking onto the PTT line or elsewhere. Any compact fluorescent lights nearby? 73, Paul, AE4KR - Original Message - From: brett To: Repeater-Builder@yahoogroups.com Sent: Saturday, September 04, 2010 5:26 AM Subject: [Repeater-Builder] Interference on VHF repeater I have the distinctive hollow pipe sound. Both TX and RX have the same CTCSS tone. The intermod product is however not always present, and after looking at the RX output from the duplexer with a SA I see a comb of products that move slowly in time. When one of the products in the comb falls within the RX bandwidth the RX opens, until it moves on. This is not a busy site, and I have been able to power down everything on site except my repeater. Problem remains unchanged.
Re: [Repeater-Builder] Interference on VHF repeater
Bret, you might have your PA going in to oscillation creating the spurs due to a highly reactive duplexer. We had a similar problem here many years ago and fixed it with a simple tuner on the TX similar ot the GE Z matcher . The one that we used was Home Brew. When the tuner was adjusted for minimum VSWR, the spurs went away. 73 John VE3AMZ - Original Message - From: brett brett_daw...@yahoo.com To: Repeater-Builder@yahoogroups.com Sent: Saturday, September 04, 2010 7:26 AM Subject: [Repeater-Builder] Interference on VHF repeater Hi all, I have come across an interesting problem which you may be able to shed some light on. I have an intermod issue where my TX sometimes opens up my RX. I have the distinctive hollow pipe sound. Both TX and RX have the same CTCSS tone. The intermod product is however not always present, and after looking at the RX output from the duplexer with a SA I see a comb of products that move slowly in time. When one of the products in the comb falls within the RX bandwidth the RX opens, until it moves on. This is not a busy site, and I have been able to power down everything on site except my repeater. Problem remains unchanged. I have also disconnected feeders from all other RF equipment on site - still no change. The fact that the IM product frequency changes with time (drift rate is roughly a few kHz's an hour) makes me think that there is either another unknown source of RF on site which has poor freq stability (pretty unlikley), or somehow my TX freq is involved in producing this freq. I have inserted a 6dB pad in the antenna port of the duplexer and found that the IM products drop 12dB, and also curiously, the frequency of the products change. Removing the pad reverses this effect. I have repeated this many times and the result was always the same. It appears that the frequency of the IM product is dependent on the strength of the radiated field from my antenna. This is my question: I have read that it is possible for a strong EM field to excite metal (eg tower member) such that re-radiation will occur at a frequency which is different from that which excited it. Can anyone confirm they have seen this, or can anyone point me to a reference that talks about this? I should also mention there are multiple solar panels and associated regulators on site. The regulators have been discounted as possible sources, but the panels (given they may have bypass/blocking diodes) may be a mixing location, however the source of the drifting tone is still unclear. Thanks, Brett VK2CBD. Yahoo! Groups Links
RE: [Repeater-Builder] Interference on VHF repeater
Brett, Some additional information will be helpful. What makes/models of equipment are in your repeater? Are all jumper cables and the antenna feedline double-shielded? Are any of the connectors nickel-plated? Are there any barrels or adapters in your jumpers? Is there an isolator/circulator following the transmitter? What antenna are you using, and how far above the repeater equipment is it located? Try putting your attenuator right at the RX input connector, and repeat your IM test. Putting it at the antenna output is not a good idea, since the TX output power can cause it to overheat. Your description of the IM product suggests that it might be a spur generated within your PA, which could drift due to temperature changes. Have you verified that your TX carrier frequency is stable, and not drifting? 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of brett Sent: Saturday, September 04, 2010 4:27 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Interference on VHF repeater Hi all, I have come across an interesting problem which you may be able to shed some light on. I have an intermod issue where my TX sometimes opens up my RX. I have the distinctive hollow pipe sound. Both TX and RX have the same CTCSS tone. The intermod product is however not always present, and after looking at the RX output from the duplexer with a SA I see a comb of products that move slowly in time. When one of the products in the comb falls within the RX bandwidth the RX opens, until it moves on. This is not a busy site, and I have been able to power down everything on site except my repeater. Problem remains unchanged. I have also disconnected feeders from all other RF equipment on site - still no change. The fact that the IM product frequency changes with time (drift rate is roughly a few kHz's an hour) makes me think that there is either another unknown source of RF on site which has poor freq stability (pretty unlikley), or somehow my TX freq is involved in producing this freq. I have inserted a 6dB pad in the antenna port of the duplexer and found that the IM products drop 12dB, and also curiously, the frequency of the products change. Removing the pad reverses this effect. I have repeated this many times and the result was always the same. It appears that the frequency of the IM product is dependent on the strength of the radiated field from my antenna. This is my question: I have read that it is possible for a strong EM field to excite metal (eg tower member) such that re-radiation will occur at a frequency which is different from that which excited it. Can anyone confirm they have seen this, or can anyone point me to a reference that talks about this? I should also mention there are multiple solar panels and associated regulators on site. The regulators have been discounted as possible sources, but the panels (given they may have bypass/blocking diodes) may be a mixing location, however the source of the drifting tone is still unclear. Thanks, Brett VK2CBD.
Re: [Repeater-Builder] Interference from local 600 kHz radio station.
There was a 6 meter repeater here in Connecticut that was receiving interference from an AM station several states away that was broadcasting on 1000KHz. It only occurred in the nighttime. (The 6 meter repeater was on a 1MHz split). They narrowed it down to something on the 21+ towers that are on the site, but never found it to my knowledge. It could have been a piece of loose hardware, rusty joint, bad antenna, etc. If I remember correctly, rain made it go away. This can be a real bugger of a problem to find. I would look at guy wires or anything that is long enough to pick up enough signal from your 600KHz station. Does it happen when it rains? 73, Joe, K1ike On 4/25/2010 11:06 PM, lpcoates wrote: Hi We have a local AM radio station on 600 kHz. Their transmitter site is about 10 miles from the center of the city. From what I've found on the web, they run 25,000 watts during the day and 8,000 watts at night. On at least one of our repeaters we're finding that this is mixing with the output of repeater to create a phantom signal exactly on the input. We're not sure whether the mixing is happening inside the repeater or in something in the environment near the repeater. We've confirmed this is the source of the problem on one repeter and supect it on another. Has anyone had experince with a loacl AM station on 600 kHz? We're looking for way to combat the interference. Thanks Bruce - VE5BNC
Re: [Repeater-Builder] Interference from local 600 kHz radio station.
I snowed here yesterday, does that count? ;-) In all seriousness so far we only know that it comes and goes. We've yet to find a clear pattern of day/night, week day/weekend (it's on an office tower) , hot/cold, wet/dry, etc. yet. We hope to do a bit of a fox hunt at the sight later this spring. 73, Bruce - Original Message - From: Joe k1ike_m...@snet.net To: Repeater-Builder@yahoogroups.com Sent: Monday, April 26, 2010 8:16 PM Subject: Re: [Repeater-Builder] Interference from local 600 kHz radio station. There was a 6 meter repeater here in Connecticut that was receiving interference from an AM station several states away that was broadcasting on 1000KHz. It only occurred in the nighttime. (The 6 meter repeater was on a 1MHz split). They narrowed it down to something on the 21+ towers that are on the site, but never found it to my knowledge. It could have been a piece of loose hardware, rusty joint, bad antenna, etc. If I remember correctly, rain made it go away. This can be a real bugger of a problem to find. I would look at guy wires or anything that is long enough to pick up enough signal from your 600KHz station. Does it happen when it rains? 73, Joe, K1ike On 4/25/2010 11:06 PM, lpcoates wrote: Hi We have a local AM radio station on 600 kHz. Their transmitter site is about 10 miles from the center of the city. From what I've found on the web, they run 25,000 watts during the day and 8,000 watts at night. On at least one of our repeaters we're finding that this is mixing with the output of repeater to create a phantom signal exactly on the input. We're not sure whether the mixing is happening inside the repeater or in something in the environment near the repeater. We've confirmed this is the source of the problem on one repeter and supect it on another. Has anyone had experince with a loacl AM station on 600 kHz? We're looking for way to combat the interference. Thanks Bruce - VE5BNC Yahoo! Groups Links
RE: [Repeater-Builder] Interference from local 600 kHz radio station.
No words of wisdom, Bruce. but wanted to offer my condolences. The dang pager interference we've got is about to drive me to drink. which is probably the ONLY nice thing I can say about it. Hope you find your demon! 73, Mike WM4B _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Bruce Coates Sent: Monday, April 26, 2010 10:27 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Interference from local 600 kHz radio station. I snowed here yesterday, does that count? ;-) In all seriousness so far we only know that it comes and goes. We've yet to find a clear pattern of day/night, week day/weekend (it's on an office tower) , hot/cold, wet/dry, etc. yet. We hope to do a bit of a fox hunt at the sight later this spring. 73, Bruce - Original Message - From: Joe k1ike_m...@snet. mailto:k1ike_mail%40snet.net net To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Sent: Monday, April 26, 2010 8:16 PM Subject: Re: [Repeater-Builder] Interference from local 600 kHz radio station. There was a 6 meter repeater here in Connecticut that was receiving interference from an AM station several states away that was broadcasting on 1000KHz. It only occurred in the nighttime. (The 6 meter repeater was on a 1MHz split). They narrowed it down to something on the 21+ towers that are on the site, but never found it to my knowledge. It could have been a piece of loose hardware, rusty joint, bad antenna, etc. If I remember correctly, rain made it go away. This can be a real bugger of a problem to find. I would look at guy wires or anything that is long enough to pick up enough signal from your 600KHz station. Does it happen when it rains? 73, Joe, K1ike On 4/25/2010 11:06 PM, lpcoates wrote: Hi We have a local AM radio station on 600 kHz. Their transmitter site is about 10 miles from the center of the city. From what I've found on the web, they run 25,000 watts during the day and 8,000 watts at night. On at least one of our repeaters we're finding that this is mixing with the output of repeater to create a phantom signal exactly on the input. We're not sure whether the mixing is happening inside the repeater or in something in the environment near the repeater. We've confirmed this is the source of the problem on one repeter and supect it on another. Has anyone had experince with a loacl AM station on 600 kHz? We're looking for way to combat the interference. Thanks Bruce - VE5BNC Yahoo! Groups Links
Re: [Repeater-Builder] Interference from local 600 kHz radio station.
Change the split of the repeater to anything other than 600 kHz. On Sun, Apr 25, 2010 at 8:06 PM, lpcoates bruce.coa...@sasktel.net wrote: Hi We have a local AM radio station on 600 kHz. Their transmitter site is about 10 miles from the center of the city. From what I've found on the web, they run 25,000 watts during the day and 8,000 watts at night. On at least one of our repeaters we're finding that this is mixing with the output of repeater to create a phantom signal exactly on the input. We're not sure whether the mixing is happening inside the repeater or in something in the environment near the repeater. We've confirmed this is the source of the problem on one repeter and supect it on another. Has anyone had experince with a loacl AM station on 600 kHz? We're looking for way to combat the interference. Thanks Bruce - VE5BNC Yahoo! Groups Links
Re: [Repeater-Builder] Interference
On 3/4/2010 8:56 AM, Leroy A. M. Baptiste wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater's receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI Is there another FM station on either 95.1 or 93.9? Guess what-600 KHz! Natural intermod source!
Re: [Repeater-Builder] Interference
I have a 1KW 103.5 FM Station on the same tower as my 147.21 Repeater. I cleared most of my SAME problems up with a circulator on the 7.21 transmitter and Ferrite Snap On's on any exposed audio line to the repeater. NOW that being said, the FM Station is using large good quality hardline. They had a bad jumper from the Hardline to the Transmitter and when that was replaced the interference was reduced. Now I have installed a 440 Repeater and suddenly I am hearing the FM on the tail of UHF so again I will be trying the same things. Good Luck. 73 JIM Wellsville KA2AJH On Thu, Mar 4, 2010 at 8:56 AM, Leroy A. M. Baptiste leroybapti...@spiceisle.com wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater’s receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI -- Jim Cicirello 181 Stevens Street Wellsville, N.Y. 14895 (585)593-4655
RE: [Repeater-Builder] Interference
The only other station in the building is on 107.500MHz -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of wd8chl Sent: Thursday, March 04, 2010 10:21 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Interference On 3/4/2010 8:56 AM, Leroy A. M. Baptiste wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater's receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI Is there another FM station on either 95.1 or 93.9? Guess what-600 KHz! Natural intermod source!
Re: [Repeater-Builder] Interference
On 3/4/2010 9:40 AM, Leroy A. M. Baptiste wrote: The only other station in the building is on 107.500MHz Doesn't have to be that close. It could be 10-15 miles away or more, depending on power, etc. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of wd8chl Sent: Thursday, March 04, 2010 10:21 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Interference On 3/4/2010 8:56 AM, Leroy A. M. Baptiste wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater's receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI Is there another FM station on either 95.1 or 93.9? Guess what-600 KHz! Natural intermod source!
Re: [Repeater-Builder] Interference
On 3/4/2010 9:40 AM, Leroy A. M. Baptiste wrote: The only other station in the building is on 107.500MHz It could also be from an AM station on 600 KHZ +/-10 KHz. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of wd8chl Sent: Thursday, March 04, 2010 10:21 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Interference On 3/4/2010 8:56 AM, Leroy A. M. Baptiste wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater's receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI Is there another FM station on either 95.1 or 93.9? Guess what-600 KHz! Natural intermod source!
Re: [Repeater-Builder] Interference
Interesting problem, can you describe the interference?? --- On Thu, 3/4/10, wd8chl wd8...@gmail.com wrote: From: wd8chl wd8...@gmail.com Subject: Re: [Repeater-Builder] Interference To: Repeater-Builder@yahoogroups.com Date: Thursday, March 4, 2010, 6:57 AM On 3/4/2010 9:40 AM, Leroy A. M. Baptiste wrote: The only other station in the building is on 107.500MHz It could also be from an AM station on 600 KHZ +/-10 KHz. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of wd8chl Sent: Thursday, March 04, 2010 10:21 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Interference On 3/4/2010 8:56 AM, Leroy A. M. Baptiste wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater's receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI Is there another FM station on either 95.1 or 93.9? Guess what-600 KHz! Natural intermod source! Yahoo! Groups Links
RE: [Repeater-Builder] Interference
When you key up the repeater, and you release, the repeater is held open (Sometimes), and you can hear the interference coming in. If I disconnect the FM Station, the repeater is as clean as a whistle. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chris Quirk Sent: Thursday, March 04, 2010 11:34 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Interference Interesting problem, can you describe the interference?? --- On Thu, 3/4/10, wd8chl wd8...@gmail.com wrote: From: wd8chl wd8...@gmail.com Subject: Re: [Repeater-Builder] Interference To: Repeater-Builder@yahoogroups.com Date: Thursday, March 4, 2010, 6:57 AM On 3/4/2010 9:40 AM, Leroy A. M. Baptiste wrote: The only other station in the building is on 107.500MHz It could also be from an AM station on 600 KHZ +/-10 KHz. -Original Message- From: Repeater-Builder@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-buil...@yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-buil...@yahoogroups.com ] On Behalf Of wd8chl Sent: Thursday, March 04, 2010 10:21 PM To: Repeater-Builder@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-buil...@yahoogroups.com Subject: Re: [Repeater-Builder] Interference On 3/4/2010 8:56 AM, Leroy A. M. Baptiste wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater's receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI Is there another FM station on either 95.1 or 93.9? Guess what-600 KHz! Natural intermod source! Yahoo! Groups Links http://groups.yahoo.com/group/Repeater-Builder/ http://groups.yahoo.com/group/Repeater-Builder/ http://groups.yahoo.com/group/Repeater-Builder/joi n http://groups.yahoo.com/group/Repeater-Builder/jo in (Yahoo! ID required) repeater-builder-dig...@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-builder-fullfeatu...@yahoogroups.com repeater-builder-unsubscr...@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-builder-unsubscr...@yahoogroups.com http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Interference
my 2 penny worth, what happens with the rptr aerial disconnected if it is the clean the signal is coming down the aerial, try using a piece of coax cut as a 1/4 wave stubb on the rptr rx input, this is of course cut to the offending freq Steve, M1SWB - Original Message - From: Leroy A. M. Baptiste leroybapti...@spiceisle.com To: Repeater-Builder@yahoogroups.com Sent: Thursday, March 04, 2010 3:53 PM Subject: RE: [Repeater-Builder] Interference When you key up the repeater, and you release, the repeater is held open (Sometimes), and you can hear the interference coming in. If I disconnect the FM Station, the repeater is as clean as a whistle. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chris Quirk Sent: Thursday, March 04, 2010 11:34 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Interference Interesting problem, can you describe the interference?? --- On Thu, 3/4/10, wd8chl wd8...@gmail.com wrote: From: wd8chl wd8...@gmail.com Subject: Re: [Repeater-Builder] Interference To: Repeater-Builder@yahoogroups.com Date: Thursday, March 4, 2010, 6:57 AM On 3/4/2010 9:40 AM, Leroy A. M. Baptiste wrote: The only other station in the building is on 107.500MHz It could also be from an AM station on 600 KHZ +/-10 KHz. -Original Message- From: Repeater-Builder@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-buil...@yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-buil...@yahoogroups.com ] On Behalf Of wd8chl Sent: Thursday, March 04, 2010 10:21 PM To: Repeater-Builder@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-buil...@yahoogroups.com Subject: Re: [Repeater-Builder] Interference On 3/4/2010 8:56 AM, Leroy A. M. Baptiste wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater's receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI Is there another FM station on either 95.1 or 93.9? Guess what-600 KHz! Natural intermod source! Yahoo! Groups Links http://groups.yahoo.com/group/Repeater-Builder/ http://groups.yahoo.com/group/Repeater-Builder/ http://groups.yahoo.com/group/Repeater-Builder/joi n http://groups.yahoo.com/group/Repeater-Builder/jo in (Yahoo! ID required) repeater-builder-dig...@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-builder-fullfeatu...@yahoogroups.com repeater-builder-unsubscr...@yahoogroups.com http://us.mc456.mail.yahoo.com/mc/compose?to=Repe ater-builder-unsubscr...@yahoogroups.com http://docs.yahoo.com/info/terms/ Yahoo! Groups Links
Re: [Repeater-Builder] Interference
Are you hearing the audio from the FM station clearly through the 2 meter repeater? If so, the problem may not be coming from the antenna system. It may be coming in on the AC power line or the FM station ground system. You may try putting a dummy load on the farthest point that is possible, such as the jumper that connects to the hard line. You might also try powering the repeater off a battery and unplug/disconnect the AC power supply. In either case, you should not hear the interference. I had a similar problem from an FM broadcast station that had it's transmitter on the second floor of a wood building. The building was on top of a hill that was all rock. It turned out that the radiation was coming from the long ground wire that went to an old, ineffective ground system. The system that was hearing the interference was ~10 miles away. 73, Joe, K1ike Leroy A. M. Baptiste wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater’s receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI 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: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Interference
The 2m repeater and FM transmitter are at the same site? lh On Thu, Mar 4, 2010 at 8:56 AM, Leroy A. M. Baptiste leroybapti...@spiceisle.com wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater’s receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI
RE: [Repeater-Builder] Interference
Yes, they are. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Larry Horlick Sent: Friday, March 05, 2010 1:36 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Interference The 2m repeater and FM transmitter are at the same site? lh On Thu, Mar 4, 2010 at 8:56 AM, Leroy A. M. Baptiste leroybapti...@spiceisle.com mailto:leroybapti...@spiceisle.com wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater's receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI
Re: [Repeater-Builder] Interference
Is it IMD, though? Could it be in the audio chain? Leroy, did you troubleshoot from this angle? On Thu, Mar 4, 2010 at 12:53 PM, Leroy A. M. Baptiste leroybapti...@spiceisle.com wrote: Yes, they are. -Original Message- From: Repeater-Builder@yahoogroups.comRepeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.comRepeater-Builder%40yahoogroups.com] On Behalf Of Larry Horlick Sent: Friday, March 05, 2010 1:36 AM To: Repeater-Builder@yahoogroups.com Repeater-Builder%40yahoogroups.com Subject: Re: [Repeater-Builder] Interference The 2m repeater and FM transmitter are at the same site? lh On Thu, Mar 4, 2010 at 8:56 AM, Leroy A. M. Baptiste leroybapti...@spiceisle.com leroybaptiste%40spiceisle.com mailto:leroybapti...@spiceisle.com leroybaptiste%40spiceisle.com wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater's receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI
Re: [Repeater-Builder] Interference
Pardon me for butting in again. Start with the simple things like taking the aerial off the rptr rx and see if that cures it. How far apart are the FM and rptr aerials, as it sounds like pure rf getting into the rx. Is the duplexer tuned right to give around 80db isolation as it maybe the rptrs own tx causing probs allthough he did say taking the FM,s aerial off cured it. Still recon my idea of a coax notch filter in the rx input will cure it. Steve - Original Message - From: Larry Horlick To: Repeater-Builder@yahoogroups.com Sent: Thursday, March 04, 2010 11:33 PM Subject: Re: [Repeater-Builder] Interference Is it IMD, though? Could it be in the audio chain? Leroy, did you troubleshoot from this angle? On Thu, Mar 4, 2010 at 12:53 PM, Leroy A. M. Baptiste leroybapti...@spiceisle.com wrote: Yes, they are. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Larry Horlick Sent: Friday, March 05, 2010 1:36 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Interference The 2m repeater and FM transmitter are at the same site? lh On Thu, Mar 4, 2010 at 8:56 AM, Leroy A. M. Baptiste leroybapti...@spiceisle.com mailto:leroybapti...@spiceisle.com wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater's receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI
Re: [Repeater-Builder] Interference
I'm thinking the same thing, audio chain. I would be surprised if the 5KHz deviation receiver could recover much audio from a wide band FM broadcast station. If the FM station is audio on the 2 meter receiver is very clear, I would say audio chain like you are stating. Joe Larry Horlick wrote: Is it IMD, though? Could it be in the audio chain? Leroy, did you troubleshoot from this angle? 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: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] Interference
Hi Steve, thanks for taking time out to help me solve this problem. I will try taking the aerial of the repeater RX to see what happens. The distance between antennas is about 20 feet. The FM antenna is circularly polarised, and the @ Meter is a DB224E with all diploes in line. Taking the FM transmitter off the air solved the problem. Re the duplexers they were tuned with a spectrum analyzer, the repeater receives signals as far away as 100 odd miles. I think it has been conclusively proved that the interference is coming from the FM transmitter. But I will make some more checks and see what happens, I will post my results. Thanks again guys. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Steve Sent: Friday, March 05, 2010 8:14 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Interference Pardon me for butting in again. Start with the simple things like taking the aerial off the rptr rx and see if that cures it. How far apart are the FM and rptr aerials, as it sounds like pure rf getting into the rx. Is the duplexer tuned right to give around 80db isolation as it maybe the rptrs own tx causing probs allthough he did say taking the FM,s aerial off cured it. Still recon my idea of a coax notch filter in the rx input will cure it. Steve - Original Message - From: Larry Horlick mailto:llhorl...@gmail.com To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com Sent: Thursday, March 04, 2010 11:33 PM Subject: Re: [Repeater-Builder] Interference Is it IMD, though? Could it be in the audio chain? Leroy, did you troubleshoot from this angle? On Thu, Mar 4, 2010 at 12:53 PM, Leroy A. M. Baptiste leroybapti...@spiceisle.com mailto:leroybapti...@spiceisle.com wrote: Yes, they are. -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com ] On Behalf Of Larry Horlick Sent: Friday, March 05, 2010 1:36 AM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: Re: [Repeater-Builder] Interference The 2m repeater and FM transmitter are at the same site? lh On Thu, Mar 4, 2010 at 8:56 AM, Leroy A. M. Baptiste leroybapti...@spiceisle.com mailto:leroybaptiste%40spiceisle.com mailto:leroybapti...@spiceisle.com mailto:leroybaptiste%40spiceisle.com wrote: Hello all, I am having some interference problems, it is coming from an FM transmitter on 94.500MHz, and getting into the Amateur Radio repeater's receiver on 146.1600MHz. It is not there all the time, but when the repeater is keyed up, you can hear it getting in. The 2 Meter repeater is fed with heliax cable from the duplexer to the antenna, the transmission line on the FM station is ordinary coaxial cable, the power output is about 300 Watts, any ideas? Leroy. J39AI
Re: [Repeater-Builder] Interference or Intermod ( ? ) Help....here goes
Can you make out anything that they are saying? Is the volume of the modulation the same as users on the repeater? If you have a lot of transmitters in the area of your repeater site it may take a little detective work to find the interference. Or, it may just be in your equipment. Aren't repeaters fun? 73, Joe, K1ike Michael Ryan wrote: “Sounds like someone talking into a reverb chamber….” 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:repeater-builder-dig...@yahoogroups.com mailto:repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] Interference or Intermod ( ? ) Help....here goes
First I would completely remove the external amplifier and connect the repeater directly to the duplexer. Then turn the power up to where it belongs on the transmitter. Sounds like the transmitter is generating a spur. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Michael Ryan Sent: Thursday, February 26, 2009 12:51 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Interference or Intermod ( ? ) Helphere goes My recent efforts at putting a 220 repeater on the air here in western Florida have been mildly succesful. I am using a Neutec designed repeater. ( I know there are some uhf and vhf models around, this one is on 220, a RANGER brand ). The repeater is open access. And runs quiet all day or night, nothing cracking the squelch at all. But during times when there is a conversation going on after a few minutes a rather nasty signal captures the repeater sometimes in short bursts, sometimes much longer. Sounds like someone talking into a reverb chamber.. I had been using a Mirage brick amp in the rack, but suspected that this amp might be the problem, some oscillation or internal mixing of some sort. This turned out not to be the case, the amp though still in the circuit is OFF but we still get the garbage. When the amp would be ON, and I would sometimes hear this stuff start, and I could turn OFF the amp an it would stop. But shortly later even with the amp OFF, it is back.very odd that it would appear to me. Now, all cables in the rack are RG-400. Every one in the rack. Half inch hardline runs to the antenna, though there is a splice with a double male N connector as I recall. The Neutec unit does about 25 watts output but I have it cut back to about 10 watts thinking it will run cooler. Thus with the small brick amp it was doing about 65 watts output to the Telewave 4 cavity duplexer. While at the site tonight, I could hear something getting into the recvr. The repeater was UP, but no one talking at that moment. Again, nothing on it's own ever appears to break the squelch. The noise was heard through the repeater's on board speaker, meaning it was coming through the antenna / recvr and not something produced in the rack I would assume. There is a cel tower about 1,000ft away and another tower with ( who knows ) how many other users, another 500ft further away. Based on this little bit of info what would the masses suggest in first FINDING the offending source if is indeed intermod?Then, is there much than can be done short of moving my machine? Any ideas or suggestions? * Mike
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] Interference on a 6 meter repeater
Good Point. I may have inadvertently done this test while doing something else. One of the hams at the repeater site noticed that turning off the Yaesu telemetery transceiver did not make the problem go away. He used the ON/OFF switch on the front of the radio to turn it off. I believe that this did not remove the power to the PA in the radio, which is normally connected directly to the PA and not switched through the ON/OFF switch. I asked him to disconnect the DC cable to the radio and call me back if it is still happening. I never heard from him, so I assumed that removing the power from the radio made the interference go away. I will verify this the next time I am at the site. I never thought of rectification in the coax or the antenna causing the IM. Thanks, Joe, K1ike Mark Harrison wrote: Hi Joe, That's odd that the cavity in the telemetry radio feed didn't change things, but it goes away when the radio is disconnected from the antenna. A third condition to try would be with the cavity connected to antenna but leave radio disconnected. If the IM is still present then I'd be looking very carefully at the telemetry antenna, connectors, feedlines, lightning protection, etc. It could be that a parasitic diode junction is occurring somewhere in the antenna system, generating the IM, but only when the radio or cavity is just providing a DC path for the diode to self-bias (or perhaps the radio is even providing a small bias current up the antenna cable, as some radios do). When the telemetry transmitter comes on it probably swamps the parasitic diode so much it stops working as a diode for the duration. p.s. was it a bandpass or notch cavity? good luck, Mark vk3byy -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 Joe Sent: Monday, 11 February 2008 1:02 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] Interference on a 6 meter repeater I've been working on an interference problem on a 6 meter repeater and would like to pass it by the brain trust for some input. The repeater is on 53.85Mhz with the input on 52.85Mhz. When the repeater is keyed up, NOAA weather radio comes through the repeater output loud and clear. (Decode PL turned off) I identified the problem as intermodulation in a Yaesu VX-2500V transceiver at the site used for telemetery on a simplex frequency of 173.3375Mhz. The mix is: 4(53.85)-162.55=52.85 (repeater input) The VHF transceiver frequency is not involved in the mix, but the PA stage of the Yaesu is where the mix is being created. I proved this by disconnecting the coax to the Yaesu and the IM goes away. Also, when the Yaesu keys up on 173.3375, the interference goes away on the repeater. The IM is only being caused when the Yaesu transceiver is in the receive mode. No cavity is on the Yaesu, it goes directly to the antenna. The site is on a water tank, so there is only about 10 feet of horizontal separation between the telemetry antenna and the 6 meter repeater antenna. The NOAA station is running 500 watts 1.6 mile away, line of site. I added a VHF cavity tuned to 173.3375 to the Yaesu telemetry radio, but it did not fix the problem. (The can had about 25dB rejection at 162.55Mhz and about 40dB rejection at 53.85Mhz.) Prior testing showed that reducing the 6 meter repeater output from 25 watts to 2 watts solved the problem. My next thought is to put a highpass filter and the VHF cavity in series with the telemetry radio antenna. I am thinking of using a 6/2 meter diplexer, terminate the 6 meter port with 50 ohms, and connect the telemetry radio to the 2 meter port. The diplexer should give good rejection to the 6 meter signal going into the telemetry radio (along with the additional isolation of the VHF cavity) and the VHF cavity would give rejection of the NOAA radio signal. If this works, I will contact TX/RX and see what they can provide to make the installation professional. We are guests at the site and need to provide something professional to the water company. Any ideas? We already thought of changing frequency on the 6 meter repeater, but that would be difficult to coordinate. 73, Joe, K1ike Yahoo! Groups Links
Re: [Repeater-Builder] Interference on a 6 meter repeater
Another point. The only change I saw when the cavity was inline is that it cleaned up reception for the telemetry system. This is going to be my selling point to allow us to keep the filter on the water company telemetry system. They had some minor adjacent channel interference 73, Joe, K1ike Mark Harrison wrote: Hi Joe, That's odd that the cavity in the telemetry radio feed didn't change things, but it goes away when the radio is disconnected from the antenna. A third condition to try would be with the cavity connected to antenna but leave radio disconnected. If the IM is still present then I'd be looking very carefully at the telemetry antenna, connectors, feedlines, lightning protection, etc. It could be that a parasitic diode junction is occurring somewhere in the antenna system, generating the IM, but only when the radio or cavity is just providing a DC path for the diode to self-bias (or perhaps the radio is even providing a small bias current up the antenna cable, as some radios do). When the telemetry transmitter comes on it probably swamps the parasitic diode so much it stops working as a diode for the duration. p.s. was it a bandpass or notch cavity? good luck, Mark vk3byy -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 Joe Sent: Monday, 11 February 2008 1:02 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] Interference on a 6 meter repeater I've been working on an interference problem on a 6 meter repeater and would like to pass it by the brain trust for some input. The repeater is on 53.85Mhz with the input on 52.85Mhz. When the repeater is keyed up, NOAA weather radio comes through the repeater output loud and clear. (Decode PL turned off) I identified the problem as intermodulation in a Yaesu VX-2500V transceiver at the site used for telemetery on a simplex frequency of 173.3375Mhz. The mix is: 4(53.85)-162.55=52.85 (repeater input) The VHF transceiver frequency is not involved in the mix, but the PA stage of the Yaesu is where the mix is being created. I proved this by disconnecting the coax to the Yaesu and the IM goes away. Also, when the Yaesu keys up on 173.3375, the interference goes away on the repeater. The IM is only being caused when the Yaesu transceiver is in the receive mode. No cavity is on the Yaesu, it goes directly to the antenna. The site is on a water tank, so there is only about 10 feet of horizontal separation between the telemetry antenna and the 6 meter repeater antenna. The NOAA station is running 500 watts 1.6 mile away, line of site. I added a VHF cavity tuned to 173.3375 to the Yaesu telemetry radio, but it did not fix the problem. (The can had about 25dB rejection at 162.55Mhz and about 40dB rejection at 53.85Mhz.) Prior testing showed that reducing the 6 meter repeater output from 25 watts to 2 watts solved the problem. My next thought is to put a highpass filter and the VHF cavity in series with the telemetry radio antenna. I am thinking of using a 6/2 meter diplexer, terminate the 6 meter port with 50 ohms, and connect the telemetry radio to the 2 meter port. The diplexer should give good rejection to the 6 meter signal going into the telemetry radio (along with the additional isolation of the VHF cavity) and the VHF cavity would give rejection of the NOAA radio signal. If this works, I will contact TX/RX and see what they can provide to make the installation professional. We are guests at the site and need to provide something professional to the water company. Any ideas? We already thought of changing frequency on the 6 meter repeater, but that would be difficult to coordinate. 73, Joe, K1ike Yahoo! Groups Links
RE: [Repeater-Builder] Interference on a 6 meter repeater
Hi Joe, That's odd that the cavity in the telemetry radio feed didn't change things, but it goes away when the radio is disconnected from the antenna. A third condition to try would be with the cavity connected to antenna but leave radio disconnected. If the IM is still present then I'd be looking very carefully at the telemetry antenna, connectors, feedlines, lightning protection, etc. It could be that a parasitic diode junction is occurring somewhere in the antenna system, generating the IM, but only when the radio or cavity is just providing a DC path for the diode to self-bias (or perhaps the radio is even providing a small bias current up the antenna cable, as some radios do). When the telemetry transmitter comes on it probably swamps the parasitic diode so much it stops working as a diode for the duration. p.s. was it a bandpass or notch cavity? good luck, Mark vk3byy -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Joe Sent: Monday, 11 February 2008 1:02 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Interference on a 6 meter repeater I've been working on an interference problem on a 6 meter repeater and would like to pass it by the brain trust for some input. The repeater is on 53.85Mhz with the input on 52.85Mhz. When the repeater is keyed up, NOAA weather radio comes through the repeater output loud and clear. (Decode PL turned off) I identified the problem as intermodulation in a Yaesu VX-2500V transceiver at the site used for telemetery on a simplex frequency of 173.3375Mhz. The mix is: 4(53.85)-162.55=52.85 (repeater input) The VHF transceiver frequency is not involved in the mix, but the PA stage of the Yaesu is where the mix is being created. I proved this by disconnecting the coax to the Yaesu and the IM goes away. Also, when the Yaesu keys up on 173.3375, the interference goes away on the repeater. The IM is only being caused when the Yaesu transceiver is in the receive mode. No cavity is on the Yaesu, it goes directly to the antenna. The site is on a water tank, so there is only about 10 feet of horizontal separation between the telemetry antenna and the 6 meter repeater antenna. The NOAA station is running 500 watts 1.6 mile away, line of site. I added a VHF cavity tuned to 173.3375 to the Yaesu telemetry radio, but it did not fix the problem. (The can had about 25dB rejection at 162.55Mhz and about 40dB rejection at 53.85Mhz.) Prior testing showed that reducing the 6 meter repeater output from 25 watts to 2 watts solved the problem. My next thought is to put a highpass filter and the VHF cavity in series with the telemetry radio antenna. I am thinking of using a 6/2 meter diplexer, terminate the 6 meter port with 50 ohms, and connect the telemetry radio to the 2 meter port. The diplexer should give good rejection to the 6 meter signal going into the telemetry radio (along with the additional isolation of the VHF cavity) and the VHF cavity would give rejection of the NOAA radio signal. If this works, I will contact TX/RX and see what they can provide to make the installation professional. We are guests at the site and need to provide something professional to the water company. Any ideas? We already thought of changing frequency on the 6 meter repeater, but that would be difficult to coordinate. 73, Joe, K1ike Yahoo! Groups Links
Re: [Repeater-Builder] Interference from Public-Safety Station (Was: Coax Length...)
* Eric Lemmon [EMAIL PROTECTED] [2007 Jul 26 22:34 -0500]: Nate, Was the interference present before the duplexer was retuned? Honestly, I don't know. It was off the air for some time most likely due to the final transistor becoming unsoldered on one lead and the controller being out to lunch. Also, I didn't monitor it to speak of the past several years. So, this is almost like a new problem. If not, then I suspect that the tuning is not correct. Although I applaud your ingenuity in the duplexer tuning setup, a proper tuning of the notches on a BpBr duplexer really needs to be done on a spectrum analyzer or a network analyzer. The typical BpBr duplexer has a very broad peak that can be tuned precisely only with a network analyzer or a spectrum analyzer with a return-loss bridge. When tuned for return loss, the bandpass can be tuned with great precision. A network analyzer also has the advantage of presenting precise source and load impedances to the cavity being tuned, which makes it easy to tune them individually for cascade connection. Separate matching pads are not required with such an instrument; the match is built-in. I suppose that stuff could be rented. Goes through change in the couch. Nope no spectrum analyzer fund there! The other option is the send it to the factory at the mercy of UPS... Seriously, while doing it right is the best way, most of us don't have access to that sort of equipment. We have an ancient IFR-1200 at the shop that is too old to even put a tracking generator in (we've asked). And for the price of the equipment above I could buy many other things that would be far more satisfying including a down payment on a countryside QTH, if one ever comes available. So, we use the SINAD method. Honestly, I don't know what the big deal is as the loss figures matched the specs and we did nothing to disturb the coupling (I *won't* touch that!). We can discuss impedances, but in the real world, there will always be a difference between the test equipment and the devices that are connected together on site. A lot of good information has come from this thread as well as useful ideas. Thank you! But, shelling out 5 to 6 Grand for a couple of dB improvement is not in my budget. ;-) How many cans are in your Wacom duplexer, and what diameter are they? 4, 8 most likely. You might find it useful to employ the interference calculation procedures found in GE Datafile Bulletin 10002-2: www.repeater-builder.com/ge/datafile-bulletin/df-10002-02.pdf Also download the interference analysis worksheet here: www.repeater-builder.com/ge/datafile-bulletin/df-10002-03.pdf The above documents were only recently added to the GE Master Index, and have great potential value in this instance. As for your original question, I believe that cable length between the additional bandpass cavity and the duplexer output should not be critical if proper tuning procedures are followed to ensure 50-ohm source and load impedances. Thanks for the info Eric (and to everyone else as well). Honestly, I expected a reply or two, but it's been fun to see everyone run with this thing. :-) 73, de Nate -- Wireless | Amateur Radio Station N0NB | Successfully Microsoft Amateur radio exams; ham radio; Linux info @ | free since January 1998. http://www.qsl.net/n0nb/ | Debian, the choice of My Kawasaki KZ-650 SR @| a GNU generation! http://www.networksplus.net/n0nb/ | http://www.debian.org
Re: [Repeater-Builder] Interference and t-1504 questions- THE CONCLUSION!
If anyone is intrested... The noise came back again last night. One of our guys drove around and thought he may have a bead on it, so he gave me a locomotive number. Of course- I figured by this morning the noise would be gone, as usual... Not So! Well. I key'd up the system ant the noise was still there! Straight to the railyard I went, which is about a 45 minute drive for me. Let me interject a detail- the other day I met up with the radio guys at the yard, and the lead is a ham! He was sympathetic to the cause and offered to help in any way he could, if one of his radios was bad he didn't want to be a spectrum polluter either. He also clued me into what we were hearing. 452.9375 is the frequency the locomotive uses to talk back to the FRED (Flashing Rear End Device- the blinky box on the back of trains that replaced the caboose). The Fred talks back on 457.9375. That means the haystack is big- every locomotive in the yard has a transmitter on 452, which makes it very small needle! Back to today. Of course- I get there and- as usual- the noise had stopped.l went in and takled to the radioman just to fill him in. He was of course frustrated as well that it stopped. So we agreed to wait til next time. As I'm walking out of the building- Poof- like magic I hear it on the portable!. I went back in and grabbed him and we proceeded to go for a walk in the yard. As were walking it's getting stronger and stronger- except were constantly changing directions so it wasn't like we were getting closer. It kept getting stronger- the strongest I've ever heard yet. He noticed that the activity was pretty hot and heavy. He told me the locomotives only poll the fred every 30 seconds to a minute. This was constantly going. This gave him the clue we needed- there is a digipeater in the yard for that service. The digipeater would be the only thing talking that much. We went up to the control tower where the box is- unplugged it- and bang- no more interference! Within 1/2 hour he changed it to a backup box and so far so good! The litttle black box digipeater must have been getting squirly off and on the whole time. So let's hope that's it. It's nice to find the needle. Tom W9SRV TGundo 2003 [EMAIL PROTECTED] wrote: Summary so far- That extra can did nothing for solving the interference. It still came through later that day. Here are the facts: 1. I can hear the interference on the repeater reciever, an Icom 2710 dual bander, and a Motorola GP-300 portable- all while the repeater transmitter is not keyed up. 2. I ran all the possible frequencies in the area through the intermod calculator and came up with nothing. 3. I watched the carriers on the railroad freqs with a spectrum analyzer on site several times. There is quite a bit of activity going on all the time across all the frequencies I listed in a previous post. I'm assuming all the locomotives have these tx's in them, and the yard nearby is a locomotive repair shop next to the main yard. At any one time there's 20-30 locomotives sitting around that part of the yard. I didn't see anything at the time spuring on my input frequency. It might have been just hard to see- they are quick bursts of data packets and the spur may have been down too far for my analyzer to recieve (Sencore). What's intresting is that the interference disappeared all of the sudden that day. I went back over with the spectrum analyzer and basically saw the same pattern of activity, but no interference coming through on any recievers. It has been quiet ever since. Best guess I can come up with is that one of the locomotives has a bad radio and it has moved on down the line. It's hard to troubleshoot what's not there. So hopefully it's gone for good. If not, to be continued.. Tom W9SRV Nate Duehr [EMAIL PROTECTED] wrote: On May 24, 2007, at 8:40 AM, TGundo 2003 wrote: I tuned up the extra can I have as best I could with the probes I have, figuring something is better than nothing). I could get abour 30dB of isolation through it with about 1db of loss on my RX freq. I put it in-line after the rx cans on the duplexer and it seemed to have stopped the interference (at least fot the 15 minutes I listened afterwards). We'll see if this does the trick. I would like to install an Advanced Receiver Reasearch preamp I have sitting waiting for it, but I need to get this interference resolved first. Still quiet after a few days, Tom? Just curious how it worked out. -- Nate Duehr, WY0X Yahoo! Groups Links - Get the free Yahoo! toolbar and rest assured with the added security of spyware protection. - Building a website is a piece of cake. Yahoo! Small Business gives you all the tools to get online.
Re: [Repeater-Builder] Interference and t-1504 questions- THE CONCLUSION!
At 07:29 AM 06/08/07, you wrote: (big chunks cut out) He also clued me into what we were hearing. 452.9375 is the frequency the locomotive uses to talk back to the FRED (Flashing Rear End Device- the blinky box on the back of trains that replaced the caboose). The Fred talks back on 457.9375. That means the haystack is big- every locomotive in the yard has a transmitter on 452, which makes it very small needle! (cut) This gave him the clue we needed- there is a digipeater in the yard for that service. The digipeater would be the only thing talking that much. We went up to the control tower where the box is- unplugged it- and bang- no more interference! Within 1/2 hour he changed it to a backup box and so far so good! The litttle black box digipeater must have been getting squirly off and on the whole time. So let's hope that's it. It's nice to find the needle. It's even nicer to have a co-operative and helpful needle-finder... someone that knows where all the needles are, and has the keys to open the doors... (your railroad radio tech) Tom W9SRV Let's hope the problem doesn't come back. So was the digipeater an actual Moto product or something the railroad guys tossed together? If it was Moto, what was their name for it? Mike WA6ILQ
Re: [Repeater-Builder] Interference and t-1504 questions- THE CONCLUSION!
The box was not moto or anything normal- I believe the logo on the box was Railmaster or something like that. It was a wall mount box (That was sitting on a shelf) about 12 x 10 x 8 that was all black and had only a power cord coming out of it and a single N connector for the antenna. That's it, no other controls or anything that I saw. There were two of these sitting on the shelf next to each other, one for 452 and the other for 457, which is how they were labeled in black marker on the box. I saw two seperate antenna lines coming to them, so I assume there were two antennas up top- but I could not see them from where I was. Maybe there was a duplexer somewhere but I did not see one nearby. The tech actually came up on the repeater an hour later to check and make sure everything was ok. You're exactly right- It's good to have someone with a map and a magnet looking for the needle. Tom Mike Morris WA6ILQ [EMAIL PROTECTED] wrote: At 07:29 AM 06/08/07, you wrote: (big chunks cut out) He also clued me into what we were hearing. 452.9375 is the frequency the locomotive uses to talk back to the FRED (Flashing Rear End Device- the blinky box on the back of trains that replaced the caboose). The Fred talks back on 457.9375. That means the haystack is big- every locomotive in the yard has a transmitter on 452, which makes it very small needle! (cut) This gave him the clue we needed- there is a digipeater in the yard for that service. The digipeater would be the only thing talking that much. We went up to the control tower where the box is- unplugged it- and bang- no more interference! Within 1/2 hour he changed it to a backup box and so far so good! The litttle black box digipeater must have been getting squirly off and on the whole time. So let's hope that's it. It's nice to find the needle. It's even nicer to have a co-operative and helpful needle-finder... someone that knows where all the needles are, and has the keys to open the doors... (your railroad radio tech) Tom W9SRV Let's hope the problem doesn't come back. So was the digipeater an actual Moto product or something the railroad guys tossed together? If it was Moto, what was their name for it? Mike WA6ILQ Yahoo! Groups Links - Get the free Yahoo! toolbar and rest assured with the added security of spyware protection.
Re: [Repeater-Builder] Interference and t-1504 questions
Summary so far- That extra can did nothing for solving the interference. It still came through later that day. Here are the facts: 1. I can hear the interference on the repeater reciever, an Icom 2710 dual bander, and a Motorola GP-300 portable- all while the repeater transmitter is not keyed up. 2. I ran all the possible frequencies in the area through the intermod calculator and came up with nothing. 3. I watched the carriers on the railroad freqs with a spectrum analyzer on site several times. There is quite a bit of activity going on all the time across all the frequencies I listed in a previous post. I'm assuming all the locomotives have these tx's in them, and the yard nearby is a locomotive repair shop next to the main yard. At any one time there's 20-30 locomotives sitting around that part of the yard. I didn't see anything at the time spuring on my input frequency. It might have been just hard to see- they are quick bursts of data packets and the spur may have been down too far for my analyzer to recieve (Sencore). What's intresting is that the interference disappeared all of the sudden that day. I went back over with the spectrum analyzer and basically saw the same pattern of activity, but no interference coming through on any recievers. It has been quiet ever since. Best guess I can come up with is that one of the locomotives has a bad radio and it has moved on down the line. It's hard to troubleshoot what's not there. So hopefully it's gone for good. If not, to be continued.. Tom W9SRV Nate Duehr [EMAIL PROTECTED] wrote: On May 24, 2007, at 8:40 AM, TGundo 2003 wrote: I tuned up the extra can I have as best I could with the probes I have, figuring something is better than nothing). I could get abour 30dB of isolation through it with about 1db of loss on my RX freq. I put it in-line after the rx cans on the duplexer and it seemed to have stopped the interference (at least fot the 15 minutes I listened afterwards). We'll see if this does the trick. I would like to install an Advanced Receiver Reasearch preamp I have sitting waiting for it, but I need to get this interference resolved first. Still quiet after a few days, Tom? Just curious how it worked out. -- Nate Duehr, WY0X Yahoo! Groups Links - Get the free Yahoo! toolbar and rest assured with the added security of spyware protection.
Re: [Repeater-Builder] Interference and t-1504 questions
On May 24, 2007, at 8:40 AM, TGundo 2003 wrote: I tuned up the extra can I have as best I could with the probes I have, figuring something is better than nothing). I could get abour 30dB of isolation through it with about 1db of loss on my RX freq. I put it in-line after the rx cans on the duplexer and it seemed to have stopped the interference (at least fot the 15 minutes I listened afterwards). We'll see if this does the trick. I would like to install an Advanced Receiver Reasearch preamp I have sitting waiting for it, but I need to get this interference resolved first. Still quiet after a few days, Tom? Just curious how it worked out. -- Nate Duehr, WY0X
Re: [Repeater-Builder] Interference and t-1504 questions
On May 23, 2007, at 8:48 PM, tgundo2003 wrote: 2. Has anyone had any problems with interference from the Railroad Locomotive Remote control and telemetry systems? They are on 452. and 457.. I have a UHF repeater near a railyard and they are clobbering the input at times. When you say clobbering the input have you looked at this signal with a spectrum analyzer? I doubt they're really on your input. What is your receive frequency? You're more likely fighting a mix with something else or they have serious problems with that transmitter. If they're really on your input, which I assume is at least 3-5 MHz away... they gotta fix that if there's any reasonable amount of separation between you and them. Would be best to know before you bug 'em, but if they're friendly -- they'll likely have the right test gear to find out what their transmitter is doing... if anything. What kind of radio is your receiver, are there any other high-power transmitters in the area, and what frequency is your receiver on? If their transmitter is on full-time, and it only clobbers you part- time, it's a mix... with something else that's going on and off the air... you need to find that signal and then do the math to see if the mix makes sense... etc. -- Nate Duehr, WY0X
Re: [Repeater-Builder] Interference and t-1504 questions
My receiver is a Morotola Mitrek (Converted mobile). My input freq is 447.3750 We have heard the interference correlate with their freq 452.9375 (hear the signal coming through at the same time via a scanner on 452). This morning it was pretty bad again- I stopped by with a spectrum analyzer- the 452.9375 was definatly STRONG- but it looked clean. There were a few other carriers near it, but only half or less in amplitude. Other potential frequencies they may use (But we have not heard anything on a scanner, just on 452.9375) are: UHF Frequencies Frequencies on the same line can be paired for possible full duplex or repeater use. 452.9375 is a common EOT device frequency in Canada. 457.9375 is a common EOT device frequency in the USA. 452.3250 / 457.3250 452.3750 / 457.3750 452.4250 / 457.4250 452.4750 / 457.4750 452.7750 / 457.7750 452.8250 / 457.8250 452.8750 / 457.8750 452.9000 / 457.9000 452.9125 / 457.9125 Telemetry 452.9250 / 457.9250 Remote Control/Remote Indicator 452.9375 / 457.9375 Telemetry/Remote Control/Remote Indicator 452.9500 / 457.9500 Remote Control/Remote Indicator 452.9625 / 457.9625 Telemetry/Remote Control/Remote Indicator [edit] New UHF narrowband splinter frequencies 452.90625 457.90625 452.91875 457.91875 452.93125 457.93125 Remote Control/Remote Indicator 452.94375 457.94375 Remote Control/Remote Indicator 452.95625 457.95625 Remote Control/Remote Indicator 452.96875 457.96875 Remote Control/Remote Indicator I tuned up the extra can I have as best I could with the probes I have, figuring something is better than nothing). I could get abour 30dB of isolation through it with about 1db of loss on my RX freq. I put it in-line after the rx cans on the duplexer and it seemed to have stopped the interference (at least fot the 15 minutes I listened afterwards). We'll see if this does the trick. I would like to install an Advanced Receiver Reasearch preamp I have sitting waiting for it, but I need to get this interference resolved first. I would like to leave talking to the Railroad as a last resort. Thanks!! Tom W9SRV Nate Duehr [EMAIL PROTECTED] wrote: On May 23, 2007, at 8:48 PM, tgundo2003 wrote: 2. Has anyone had any problems with interference from the Railroad Locomotive Remote control and telemetry systems? They are on 452. and 457.. I have a UHF repeater near a railyard and they are clobbering the input at times. When you say clobbering the input have you looked at this signal with a spectrum analyzer? I doubt they're really on your input. What is your receive frequency? You're more likely fighting a mix with something else or they have serious problems with that transmitter. If they're really on your input, which I assume is at least 3-5 MHz away... they gotta fix that if there's any reasonable amount of separation between you and them. Would be best to know before you bug 'em, but if they're friendly -- they'll likely have the right test gear to find out what their transmitter is doing... if anything. What kind of radio is your receiver, are there any other high-power transmitters in the area, and what frequency is your receiver on? If their transmitter is on full-time, and it only clobbers you part- time, it's a mix... with something else that's going on and off the air... you need to find that signal and then do the math to see if the mix makes sense... etc. -- Nate Duehr, WY0X Yahoo! Groups Links - Park yourself in front of a world of choices in alternative vehicles. Visit the Yahoo! Auto Green Center.
Re: [Repeater-Builder] Interference Found!
Adam, Any emission by a commercial/industrial system that causes significant interference to a licensed user in an adjacent band is a violation of FCC rules, period. You don't need to spend any more time trying to contact Verizon to resolve this issue. Write the FCC's Enforcement Bureau, and let Riley Hollingsworth take it from there. Believe me, once an FCC Nastygram gets Verizon's attention, they'll be all over that site, looking for the cause. If the problem is not corrected in a timely manner, a whopping fine will be assessed for every day it continues. Rest assured, every cent of the cost of correcting this interference problem will be paid by Verizon, not you. It will greatly help your case if you can show that the offending carrier is at 147.457 MHz, and is not the result of an image response in your receiver or of IM occurring in a poorly-designed receiver's front end. It will also add credence to your complaint if you can use repeatable T-Hunt tactics to pinpoint the source of the carrier to a specific antenna or cabinet. Take note as to whether or not the carrier is modulated and/or identified in any way, and whether it is continuous 24/7 or intermittent. Turn off all of your equipment before making these searches, just to be absolutely certain that the carrier is not generated within your own repeater. Many receivers, and a surprising number of controllers or IDers, generate birdies that render certain frequencies unusable. Be certain your own equipment is innocent before filing a complaint. Of course, you had better be certain that Verizon is, in fact, the offender before pointing a finger at them! If your repeater is officially coordinated, your case is even stronger. A 1 MHz split, in New York? Hmmm... 73, Eric Lemmon WB6FLY Adam C. Feuer wrote: Hello All, Back in September, I sent out a message asking if anyone had any interference experience with the 2 meter pair 146.460 / 147.460 as I have a constant carrier on my input. I didn't really receive any substantial replies and have been looking for the source ever since. Yesterday it was found! My input (147.460) is being crushed by a Verizon Light Span which is mounted in an outdoor enclosure at the site. It is emitting a strong carrier on 147.457... Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Interference Found!
Hi Eric, Thanks so much for the reply and the information. We are certain (100%) that the interference is coming from the Light Span. We DF'ed it right to the box and then used the spectrum analyzer to give us the exact frequency. Also, being the only box mounted out there in the woods wasn't too hard to figure out. Then, we proved are findings and witnessed how good our receiver could be without the interference but I won't go into those details here. Anyway, I think I'll start by giving them the benefit of the doubt and see if I might be able to find the right person to talk to at Verizon before I get the FCC involved. I know this will be a long process but I've lived with the interference for this long, another month or two won't kill me. However, if time goes by and I get no results I will resort to your suggestion. The 1meg split repeater was coordinated for about 20 years under TSARC and has now been grandfathered by UNYREPCO who does our coordination now. Thanks for the info Adam N2ACF - Original Message - From: Eric Lemmon [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Saturday, November 29, 2003 2:10 PM Subject: Re: [Repeater-Builder] Interference Found! Adam, Any emission by a commercial/industrial system that causes significant interference to a licensed user in an adjacent band is a violation of FCC rules, period. You don't need to spend any more time trying to contact Verizon to resolve this issue. Write the FCC's Enforcement Bureau, and let Riley Hollingsworth take it from there. Believe me, once an FCC Nastygram gets Verizon's attention, they'll be all over that site, looking for the cause. If the problem is not corrected in a timely manner, a whopping fine will be assessed for every day it continues. Rest assured, every cent of the cost of correcting this interference problem will be paid by Verizon, not you. It will greatly help your case if you can show that the offending carrier is at 147.457 MHz, and is not the result of an image response in your receiver or of IM occurring in a poorly-designed receiver's front end. It will also add credence to your complaint if you can use repeatable T-Hunt tactics to pinpoint the source of the carrier to a specific antenna or cabinet. Take note as to whether or not the carrier is modulated and/or identified in any way, and whether it is continuous 24/7 or intermittent. Turn off all of your equipment before making these searches, just to be absolutely certain that the carrier is not generated within your own repeater. Many receivers, and a surprising number of controllers or IDers, generate birdies that render certain frequencies unusable. Be certain your own equipment is innocent before filing a complaint. Of course, you had better be certain that Verizon is, in fact, the offender before pointing a finger at them! If your repeater is officially coordinated, your case is even stronger. A 1 MHz split, in New York? Hmmm... 73, Eric Lemmon WB6FLY Adam C. Feuer wrote: Hello All, Back in September, I sent out a message asking if anyone had any interference experience with the 2 meter pair 146.460 / 147.460 as I have a constant carrier on my input. I didn't really receive any substantial replies and have been looking for the source ever since. Yesterday it was found! My input (147.460) is being crushed by a Verizon Light Span which is mounted in an outdoor enclosure at the site. It is emitting a strong carrier on 147.457... Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Interference Found!
Adam, you have the right idea. IF you call the FCC, and they contact Verizon, and Verizon says you never contacted them directly, that will not look good in the FCC's eyes. The FCC Will consider hams to be a bunch of whiners who can't do anything for themselves. Now, if you do contact verizon and they don't want to do anything about it, that will look very nice in your favor if/when you *have* to contact the FCC about the problem. Too many people are too quick to look to the government to solve their problems. Who loses? We all do. Keep up the good work. I also do NOT agree that it matters if you repeater is coordinated or not, as this is not a ham-to-ham interference case. Your repeater is licensed - that's all that matters. And 1-meg split in NY? I think that's in the NY bandplan - at least in some parts of the state. It's common in the NE US for outputs from 146.415 - 146.505 MHz. Joe M. [EMAIL PROTECTED] wrote: Eric, I know it is a violation... However, don't we owe them the benefit of a chance to clean up their act.. If you had a repeater on the air that starting emitting spurs, wouldn't you want someone to let you know before they went to the commission.. Chances are, that they do not even know they have a problem. My .02. Regards, Rich On Sat, 29 Nov 2003 11:10:01 -0800 Eric Lemmon [EMAIL PROTECTED] writes: Adam, Any emission by a commercial/industrial system that causes significant interference to a licensed user in an adjacent band is a violation of FCC rules, period. You don't need to spend any more time trying to contact Verizon to resolve this issue. Write the FCC's Enforcement Bureau, and let Riley Hollingsworth take it from there. Believe me, once an FCC Nastygram gets Verizon's attention, they'll be all over that site, looking for the cause. If the problem is not corrected in a timely manner, a whopping fine will be assessed for every day it continues. Rest assured, every cent of the cost of correcting this interference problem will be paid by Verizon, not you. It will greatly help your case if you can show that the offending carrier is at 147.457 MHz, and is not the result of an image response in your receiver or of IM occurring in a poorly-designed receiver's front end. It will also add credence to your complaint if you can use repeatable T-Hunt tactics to pinpoint the source of the carrier to a specific antenna or cabinet. Take note as to whether or not the carrier is modulated and/or identified in any way, and whether it is continuous 24/7 or intermittent. Turn off all of your equipment before making these searches, just to be absolutely certain that the carrier is not generated within your own repeater. Many receivers, and a surprising number of controllers or IDers, generate birdies that render certain frequencies unusable. Be certain your own equipment is innocent before filing a complaint. Of course, you had better be certain that Verizon is, in fact, the offender before pointing a finger at them! If your repeater is officially coordinated, your case is even stronger. A 1 MHz split, in New York? Hmmm... 73, Eric Lemmon WB6FLY Adam C. Feuer wrote: Hello All, Back in September, I sent out a message asking if anyone had any interference experience with the 2 meter pair 146.460 / 147.460 as I have a constant carrier on my input. I didn't really receive any substantial replies and have been looking for the source ever since. Yesterday it was found! My input (147.460) is being crushed by a Verizon Light Span which is mounted in an outdoor enclosure at the site. It is emitting a strong carrier on 147.457... Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ The best thing to hit the internet in years - Juno SpeedBand! Surf the web up to FIVE TIMES FASTER! Only $14.95/ month - visit www.juno.com to sign up today! Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
