[Repeater-Builder] Re: Antenna separation question
Thansk for the input. That is almost exactly what I'm going to put on the air as far as cans go. I'll have a Hamtronics exciter and receiver amped up by a 110 Watt Micor base amplifier. Just about the same heights too. Antennas are both staion masters. but I like knowing that what I have been thinking about will actually work. One other question someone may know. Is it possible to run say a VHF and a UHF repeater off a dual band antenna with a diplexer or is there going to be issues. Thanks Wade KC0MLT --- In Repeater-Builder@yahoogroups.com, Ross Johnson kc7...@... wrote: That's exactly what I'm doing. VHF GE mastrII at 100 watts goes through 2 8 Sinclair pass cavities set at .5db gives 80 watts to the antenna. 4 bay exposed dipole at 75' The receiver and preamp goes through only one 8 Wacom also set at .5db then up to the collinear receive antenna at 100' Very very little desense almost undetectable. Also with the pass cavity on the receiver side preamps seem to be much more usable and effective in the real world. This machine hears very very well! More can be seen from my website. www.kc7rjk.net http://www.kc7rjk.net/ ~Ross -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of kc0mlt Sent: Tuesday, June 01, 2010 10:28 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Antenna separation question Ok just kicking this idea around the other day and the question came up about antenna separation. I know the basic 2 meter antenna separation is 50ft. (I am thinking 60ft to be safe) But is it possible to get them closer if I place some cavities on either the receive or transmit sides. Sounds dumb from some certian points of view, but I am waiting on the arrival of a decent duplexer (could be some time out though)so in the mean time I would like to get this up and going with a split antenna system for now. I was thinking maybe a 30ft separation... Would this idea work? If so does it need to be modified from what I was thinking?
[Repeater-Builder] Antenna separation question
Ok just kicking this idea around the other day and the question came up about antenna separation. I know the basic 2 meter antenna separation is 50ft. (I am thinking 60ft to be safe) But is it possible to get them closer if I place some cavities on either the receive or transmit sides. Sounds dumb from some certian points of view, but I am waiting on the arrival of a decent duplexer (could be some time out though)so in the mean time I would like to get this up and going with a split antenna system for now. I was thinking maybe a 30ft separation... Would this idea work? If so does it need to be modified from what I was thinking?
[Repeater-Builder] Re: Duplexer on the cheap worries
Thanks for the replies. I don't have the high end equipment to do some of the testing mentioned. I do have a service monitor and a dummy load, along with numerous receivers. The dummy load is kind of suspect (old and not really liking the strange signals I get from it at times) but it is all we can find around here right now. That is how I was setting it up first. I have tried the dummy load but me and friend were playing with the repeater with the load installed and got all sorts of noise and things. So we thought putting it on an antenna would be a better test. I did do some cable swapping and fed the signal from the TX to the service monitor (connected on the RX port of the Duplexer) with the antenna connected. The cables I had hooked to the Tee were the 1/2 wavelength rg-142. I replaced them, for testing purposes, with shorter runs of rg-213, approx. 1/4 wavelength. The signal on the service monitor, went away completely. No power or signal on the meter. With the longer cables I had no power but a jumping signal on the service monitor. I have some 214 I will be making the inter connect cables out of when I get things nailed down a bit more. Someone asked the freq. and spacing earlier, it is 145.340 TX and 144.74 RX (Typical 600KHz split). My friend had talked to some radio shop around here and they said RG-8 and LMR-400 were fine just keep them from moving around. I do plan on using 1/2 hardline and some superflex jumpers out at the site. Thanks for the help so far. Any other suggestions now? Wade KC0MLT --- In Repeater-Builder@yahoogroups.com, wd8chl wd8...@... wrote: On 5/21/2010 10:28 AM, kc0mlt wrote: Hello all. I am trying to figure out if the duplexer we have put together is up to the task or not. Here is the situation. We have four cavities 6.5 dia. one is a vari-notch the others are simple reject cans. Two rejects are on the TX side and one reject and the vari-notch are on the RX side. All set and tuned with rg-213 jumpers between cans and RG-142 from the cans to the Tee connector. We are doing some light testing with a cheap dual ban antenna on the garage. It is feed with RG-8 about 70 feet. We are having some issues with receive. It kind of sounds like desense but I think it is something wrong with the receiver. I was just wondering if the cobbeled together cans sound like thay are doing a good enough job as a duplexer or if we do have something to change on it. The repeater is only putting out 2 watts for testing. I would think I have enough separation for that power level. Any suggestions or thoughts woyuld be greatly appreciated. Thanks Wade KC0MLT Dump the RG-213 and RG-8 and use at least RG-214 between cavities, or 1/2 hardline on the run up to the antenna. RG-8 and -213 are single shielded and do not provide adequate isolation. You need 100% shielding. Also find a GOOD dummy load, and substitute that in place of the antenna. If you still have the problem, there is an antenna issue.
[Repeater-Builder] Duplexer on the cheap worries
Hello all. I am trying to figure out if the duplexer we have put together is up to the task or not. Here is the situation. We have four cavities 6.5 dia. one is a vari-notch the others are simple reject cans. Two rejects are on the TX side and one reject and the vari-notch are on the RX side. All set and tuned with rg-213 jumpers between cans and RG-142 from the cans to the Tee connector. We are doing some light testing with a cheap dual ban antenna on the garage. It is feed with RG-8 about 70 feet. We are having some issues with receive. It kind of sounds like desense but I think it is something wrong with the receiver. I was just wondering if the cobbeled together cans sound like thay are doing a good enough job as a duplexer or if we do have something to change on it. The repeater is only putting out 2 watts for testing. I would think I have enough separation for that power level. Any suggestions or thoughts woyuld be greatly appreciated. Thanks Wade KC0MLT
[Repeater-Builder] Re: AC buzz on VHF
Ok a little update on the AC buzz. After some preliminary investigation we located two very noisy transformers on poles with in 1 1/2 miles of the site. The site was disconnected and a clamp on one of the wire was replaced and the wire attachments on our road side supply pole were check and ok'ed by the power company. We will be doing a little more searching with the HT in a tube method to hopefully get this taken care of. One interesting note, with an HT on an Air band frequency when held near the ground / power pole guy wires there is one heck of a buzz there! Even on some of the tower guy wires we get the harsh buzz, but not all...? In the mean time, is there any way we can eliminate / filter out the buzz? My thought was maybe coiling up the antenna to Hardline jumper out at the antenna end. Our jumper is will be made out of 9913 for now. Any other suggestions as to a filter? Thanks for all the input so far! Wade KC0MLT --- In Repeater-Builder@yahoogroups.com, Joe k1ike_m...@... wrote: I had a similar problem at my house and it was tearing up my packet digipeater. It turned out to be microspark interference. See this message: http://www.mail-archive.com/repeater-builder@yahoogroups.com/msg50828.html It turned out to be a tie-wire that is used to hold the wire into the insulator on the high voltage line in front of my house. The tie wire was just long enough to resonate in the 2 meter VHF band, but very little noise was being created on the AM broadcast band. Do the test that I described in the above message and see if it is AC power line interference. If it is, you should ride around the general area of the tower and listen on your car AM radio. When you get very close to it, you should hear the interference on both the VHF and Am radio. If you have a handheld scanner that receives AM it will be easier to find the interference. 73, Joe, K1ike On 4/26/2010 10:23 AM, kc0mlt wrote: Hello all, I am in the process of putting up a 2M repeater on what I would consider a pretty vacant site. There is only one other machine (70cm Repeater) currently out there. My concern is with an AC (60Hz) buzz that comes across on the VHF band. It doesn't have a signal to it that will key uip a radio, but when you receive an actuall signal you can here it. We have heard this on both handhelds and mobiles. This site is unique as it is a duel tower with old (unused)Microwave panels and drums on the bridge at the top of the two towers. The microwave equipment is no longer hooked up. We have had the power company totally unhook the power to the site and the buzz was still present. The nearest high voltage lines are about 1.5 to 2 miles away. You can not hear the buzz on any AM reciever. Does anybody have a clue as to what this could be and what we could to do prevent it? We have some thoughts on the grounding of the guy wire being a cause but we are unsure of that. Any ideas would be greatly appreciated! Thanks Wade KC0MLT Yahoo! Groups Links
[Repeater-Builder] Re: AC buzz on VHF
You say duplex noise. Meaning desense, or something else??? The 440 machine that is there is having issues with desense even after fine tuning the duplexer. Wade --- In Repeater-Builder@yahoogroups.com, Chuck Kelsey wb2...@... wrote: You want to get rid of any 9913 or LMR foil/shield cable in the system Can be a huge duplex noise generator. Chuck WB2EDV - Original Message - From: kc0mlt kc0...@... To: Repeater-Builder@yahoogroups.com Sent: Monday, May 03, 2010 10:15 AM Subject: [Repeater-Builder] Re: AC buzz on VHF Ok a little update on the AC buzz. After some preliminary investigation we located two very noisy transformers on poles with in 1 1/2 miles of the site. The site was disconnected and a clamp on one of the wire was replaced and the wire attachments on our road side supply pole were check and ok'ed by the power company. We will be doing a little more searching with the HT in a tube method to hopefully get this taken care of. One interesting note, with an HT on an Air band frequency when held near the ground / power pole guy wires there is one heck of a buzz there! Even on some of the tower guy wires we get the harsh buzz, but not all...? In the mean time, is there any way we can eliminate / filter out the buzz? My thought was maybe coiling up the antenna to Hardline jumper out at the antenna end. Our jumper is will be made out of 9913 for now. Any other suggestions as to a filter? Thanks for all the input so far! Wade KC0MLT --- In Repeater-Builder@yahoogroups.com, Joe k1ike_mail@ wrote: I had a similar problem at my house and it was tearing up my packet digipeater. It turned out to be microspark interference. See this message: http://www.mail-archive.com/repeater-builder@yahoogroups.com/msg50828.html It turned out to be a tie-wire that is used to hold the wire into the insulator on the high voltage line in front of my house. The tie wire was just long enough to resonate in the 2 meter VHF band, but very little noise was being created on the AM broadcast band. Do the test that I described in the above message and see if it is AC power line interference. If it is, you should ride around the general area of the tower and listen on your car AM radio. When you get very close to it, you should hear the interference on both the VHF and Am radio. If you have a handheld scanner that receives AM it will be easier to find the interference. 73, Joe, K1ike On 4/26/2010 10:23 AM, kc0mlt wrote: Hello all, I am in the process of putting up a 2M repeater on what I would consider a pretty vacant site. There is only one other machine (70cm Repeater) currently out there. My concern is with an AC (60Hz) buzz that comes across on the VHF band. It doesn't have a signal to it that will key uip a radio, but when you receive an actuall signal you can here it. We have heard this on both handhelds and mobiles. This site is unique as it is a duel tower with old (unused)Microwave panels and drums on the bridge at the top of the two towers. The microwave equipment is no longer hooked up. We have had the power company totally unhook the power to the site and the buzz was still present. The nearest high voltage lines are about 1.5 to 2 miles away. You can not hear the buzz on any AM reciever. Does anybody have a clue as to what this could be and what we could to do prevent it? We have some thoughts on the grounding of the guy wire being a cause but we are unsure of that. Any ideas would be greatly appreciated! Thanks Wade KC0MLT Yahoo! Groups Links Yahoo! Groups Links No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.814 / Virus Database: 271.1.1/2851 - Release Date: 05/03/10 02:27:00
[Repeater-Builder] AC buzz on VHF
Hello all, I am in the process of putting up a 2M repeater on what I would consider a pretty vacant site. There is only one other machine (70cm Repeater) currently out there. My concern is with an AC (60Hz) buzz that comes across on the VHF band. It doesn't have a signal to it that will key uip a radio, but when you receive an actuall signal you can here it. We have heard this on both handhelds and mobiles. This site is unique as it is a duel tower with old (unused)Microwave panels and drums on the bridge at the top of the two towers. The microwave equipment is no longer hooked up. We have had the power company totally unhook the power to the site and the buzz was still present. The nearest high voltage lines are about 1.5 to 2 miles away. You can not hear the buzz on any AM reciever. Does anybody have a clue as to what this could be and what we could to do prevent it? We have some thoughts on the grounding of the guy wire being a cause but we are unsure of that. Any ideas would be greatly appreciated! Thanks Wade KC0MLT
[Repeater-Builder] Re: AC buzz on VHF
Yes, it does go away when it rains. I can't believe I forgot that detail in the original post. I do thibnk the Air band AM reciever trick will be used by us to locate this. One other thing I just remembered. There is another site abuot 30 miles away. (The site that this tower orginally transmitted to.) that has the same problem. Wade --- In Repeater-Builder@yahoogroups.com, Eric Lemmon wb6...@... wrote: Remote hilltop sites are very often fed with a lateral power line that taps off from a major distribution line that could be miles away. If nothing but the hilltop site is on that lateral, and with the site owner's permission, the power utility can pull the cutout fuses to kill the lateral circuit. If the AC buzz goes away, the utility crews must find and correct the problem. As Kim points out, there are many possible causes of noise problems. Question: Does the noise change or go away when it rains? 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of whensle...@... Sent: Monday, April 26, 2010 7:59 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] AC buzz on VHF Distribution voltages begin at 2,400 and go to 34,500 volts. Transmission voltages begin at ... depends upon the utility. Could be 46,000, 69,000 or 115,000. Anyway... it's not the voltage. It's simply there is a device issue somewhere on a power line. Could be a bad connector. A bad transformer. A bad lightning arrester. A bad switch. A bad insulator. Bottom line, something is breaking down and creating this buzz. Begin by driving around the area and narrowing the area down. Then with a small yagi try to pin point things down to a few poles, or THE pole. Some electric companies have staff that can assist with RFI, and some do not. Don't assume they do. If you have questions, drop me a line. 73, Kim - WG8S
[Repeater-Builder] Re: Maratrac as a repeater transmitter -connections
Thanks. I did get this thing going this last weekend(testing right now, no actual controler yet)with the help of your info from the first post. I checked the programming and it had 16 ch. reprogramed for one channel and still nothing. My bad for not checking the head type first. It was an advanced head. Why thy only had 16 channels in it is beyond me. After I got that resolved it took right off! The only thing id I cant get the power turned down below 70 watts. I tried turning it down in the programming that worked. but when we unhooked the computer and tried it we were over 150 watts. I got in the radio and turn the amp and the driver down all the way and it bottomed out at 70 watts. Is there something else I should have , or should be doing to get it down lower? OR do some of these not like to go down that far (60 watts). Thatnks for your help so far, it has been a great help! I think I will write and artical on this after I am done, as I couldn't find anything like that when I was looking. Wade KC0MLT --- In Repeater-Builder@yahoogroups.com, Brian Poellnitz n4bwp...@... wrote: Hi Wade, You're correct. Ground the PTT pin to TX. Mic audio would go to the TX audio output on the controller, or else this is gonna be a rally quiet repeater. ;) Brian N4BWP kc0mlt wrote: Am I correct in thinking to ground the PTT connection to get it to key up? Just looking at the diagrams I have, and seeing a voltage on the pin I would think so. Also Mic audio to ground or is it some other pin? Thanks for the reply! Wade KC0MLT
[Repeater-Builder] Re: Maratrac as a repeater transmitter -connections
Am I correct in thinking to ground the PTT connection to get it to key up? Just looking at the diagrams I have, and seeing a voltage on the pin I would think so. Also Mic audio to ground or is it some other pin? Thanks for the reply! Wade KC0MLT --- In Repeater-Builder@yahoogroups.com, Brian Poellnitz n4bwp...@... wrote: kc0mlt wrote: Hello all, I am looking for some information on getting the maratrac to key up and the audio connections into the radio wjen using it as a repeater transmiter. I am powering it with a partial control cable and no control head. I would like to be able to use the partial contorl cable for all of the needed connections but I am willing to use the RJ45 programming port inside the radio if need be. Any help with the connections would be very appreciated! (what pin /wires, how to actually get the radio to transmit -gnd the PTT???) things like that. I use a Maratrac as my UHF repeater TX. Interfacing is easy, with a couple of gotchas. First, the audio and PTT connections are easy. The RJ45 programming connector at the front edge of the radio uses the same pinout as most Radius mobiles. Pinout is here : http://www.batlabs.com/images/maxrad.gif Second, programming tips. The best way I have found is to program your unit for clamshell control head, and delete all modes (channels) except Mode 1, which is programmed to your TX frequency in both TX and RX. The gotcha is this: If you have an A7 (advanced) control head, DO NOT hook it up after you program the unit for clamshell. You will BRICK your radio, and I'm not sure if Motorola depot repair will take these radios any more. Instructions on powering the radio without a control head are here: http://www.batlabs.com/maratrac.html about a third of the way down the page. Basically, pins 17 and 13 to negative, and pins 19 and 4 to +12V. Make sure your power supply can handle the current draw at your power level. Speaking of power levels... TURN THE UNIT DOWN to about 60 watts (assuming you have a 100w drawer) and put a fan on it. This radio is not designed for continuous duty. Give it all the help you can. Don't go below 60w, as the radio will overheat due to inefficiencies in the PA. I've found that dialing back the power and using fans works well in a light-to-medium traffic machine. Oh, one more thing. The Maratrac uses a mechanical relay for TX/RX switching. The relay will last for a while, but it will eventually fail. I solved this by removing the T/R relay and running coax directly from the PA output out thru the hole left by the SO-239 connector, terminated in an inline SO-239. Of course, the antenna will no longer be connected to the RX, but hey... we're using this as a dedicated TX anyway, right? :) There you go. That should get you on the way to using your Maratrac as a dedicated TX. I hope anyone with additional info will chime in as well. 73's and good luck, Brian, N4BWP
[Repeater-Builder] Maratrac as a repeater transmitter -connections
Hello all, I am looking for some information on getting the maratrac to key up and the audio connections into the radio wjen using it as a repeater transmiter. I am powering it with a partial control cable and no control head. I would like to be able to use the partial contorl cable for all of the needed connections but I am willing to use the RJ45 programming port inside the radio if need be. Any help with the connections would be very appreciated! (what pin /wires, how to actually get the radio to transmit -gnd the PTT???) things like that.
