Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
FM Broadcast started out Horizontally polarized. Circular polarization was later authorized under 2 stipulations. The vertical plane power can not exceed the horizontal power ERP, and the horizontal plane ERP is used for the stations ERP. So a station with a horizontal antenna can effectively double the ERP by switching to a circular antenna, of course it takes 2 CP antennas to equal one horizontal antenna. On the receive side of things, Horizontal is usually used in homes and Vertical or CP on cars. CP also helps quite a bit with mobile flutter.
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
HI to all, I guess that I do not have much to contribute on this thread but to me it is very interesting reading. Gary has my sympathy, his problem is duplicated here. Much of my repeater work relates to a low power portable repeater on 141 MHz. We live near a medium sized mountain range which has plenty of deer and wild pigs. Hunters go looking for them and perhaps get lost, or fall and break a leg. Also, there are recreational trampers who just get lost . Several times a year we have to go find, and rescue them. The last time was two days ago at 6.30 am. For once, it was not raining! Our repeater runs 5 watts output, needs to run three or four days off a gelcell, and most importantly has to fit into a backpack to be carried to a convenient hilltop. Fortunately, the split is 3 MHz so that the duplexer is of a reasonable size. The problem is getting reasonable coverage. Sure the search areas are fairly small but usually encompass several ridges and deep valleys. We use vertical polarisation with a 5/8 whip on the repeater and the search teams have flexible dipoles that fit into their backpacks. Sharp ridges and steep slopes contribute to coverage problems. Would circular polarization help?? I think not. Gordon ZL1KL Tauranga N.Z.
RE: [Repeater-Builder] Circular polarization for VHF repeaters?
I can't see a problem in making a test unit doesn't look like rocket science http://www.hardhack.org.au/polarisation some copper and solder http://www.astronwireless.com/topic-archives-antennas-polarization.asp To: Repeater-Builder@yahoogroups.com From: k...@catonic.us Date: Thu, 2 Sep 2010 00:31:15 -0500 Subject: Re: [Repeater-Builder] Circular polarization for VHF repeaters? On Thu, 2 Sep 2010, Gary - K7EK wrote: In the 80's there was a amateur radio repeater book by a fellow, Pasternak I believe, that took two gamma match style Cuschcraft Four Pole antennas, combined them, and did some magic with phasing lines to end up with a four bay circularly polarized repeater antenna. Unfortunately the description leaves much to be desired, at least for me, so I never built one. If he would have included specifics on phasing line lengths, cable types, etc, the job would have been a whole lot easier. Has anyone actually gone circular with Cushcraft Four Poles, and if so, could you please share it with me and/or this group? I have done some inquiring to commercial companies about a custom built two meter four bay circularly polarized array, but that is entirely out of the question. They want thousands of dollars. There must be an easier (and cheaper) way. Similarly, is anyone in this group running circular polarization on your amateur repeater(s), and if so, could you please share the details in a manner that could be duplicated without a lot of guess work? I know that I could easily solve my multipath problem by installing one or more remote receivers, however I would like to keep that as a last resort and shoot for a circularly polarized antenna system at the main repeater site. I do understand that there is approximately 3 db of loss as a result of this, but that is quite acceptable. The dividends would greatly outweigh the down side. Thanks for any constructive ideas, suggestions, links, etc, that you might be willing to share concerning this situation. There's also a recent article in QST about a passive Lindenblad using an active dipole as a center section and four passive aluminum wires suspended from a plastic mechanism. I've looked at that and said... that wire/plastic assembly, and one of the old Motorola TAD series dipoles ... would make a DC-grounded circularly polarized antenna that should be good for a few hundred watts, and a minimally preferential (non-circular) pattern. You're in unexplored territory. The best way in is to locate a low-power FM station that upgraded to a higher-power transmitter, buy the antenna from them, and get Jampro to cut it down for your frequency. Of course, that's real dollars... anything else will be improvised. It would be a good idea to look at the terrain you're trying to cover and see what beamwidth fits it best. If you have the money to spec out an antenna with some null-fill and a lot of gain, like a customized DB-228, you'll find that coverage is second to none. Typically speaking, you don't need much antenna gain to cover close in to the tower because the distance losses are less. And you can always address that with a 1/4 wave dipole on the top of the building connected to a voter reciever. Theoretically speaking, circular polarization results when the vertical and horizontal components are 90-degrees seperate from each other. The Cycloid dipole accomplishes this simply, using a vector sum of the two to make circular polarization. It's synthesized -- 1/2 horizontal + 1/2 vertical = so many degrees hypotenuse. It gets complicated to start working up in those regions, almost to the point of designing panel antennas and putting one on each side of the tower to get a decent pattern. It's difficult to phase antennas and preserve some form of a pattern with them. -- Kris Kirby, KE4AHR Disinformation Analyst
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
Gordon, something worth trying might be low-band. About 20 years ago, I lived in an area where hams did course communications for rally events in very mountainous terrain. I remember experimenting one night about 2am with my partner at the other end of a heavily wooded course, about 12 miles end-to-end. 444 MHz simplex, 5 watts, colinear mobile whip - no copy. 146 MHz simplex, 5 watts, 5/8-wave mobile whip - no copy, but would barely break the carrier squelch. 29.6 MHz simplex, 4 watts, FM CB conversion, 1.3m helically-wound mobile whip - full quieting and S9+. Antennas might be a bit of a trick for portables on 10m, and a repeater might have to be crossband, but worth a shot. 73, Paul, AE4KR - Original Message - From: Gordon Cooper To: Repeater-Builder@yahoogroups.com Sent: Thursday, September 02, 2010 1:51 AM Subject: Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters? Our repeater runs 5 watts output, needs to run three or four days off a gelcell, and most importantly has to fit into a backpack to be carried to a convenient hilltop. Fortunately, the split is 3 MHz so that the duplexer is of a reasonable size. The problem is getting reasonable coverage. Sure the search areas are fairly small but usually encompass several ridges and deep valleys. We use vertical polarisation with a 5/8 whip on the repeater and the search teams have flexible dipoles that fit into their backpacks. Sharp ridges and steep slopes contribute to coverage problems. Would circular polarization help?? I think not.
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
I would agree that lower gain antennas can make a big difference in some instances. Higher gain mean more nulls. Chuck WB2EDV - Original Message - From: petedcur...@gmail.com To: Repeater-Builder Sent: Thursday, September 02, 2010 10:38 AM Subject: Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters? It looks like the FCC rules give you extra power when opting for dual polarization. Doesn't mean the circular antenna contributes to extra coverage, in fact it looks like the extra RF power allowed for the two polarities is giving you more coverage? The web article for which I gave a link was from Europe and involved IBC Israel BBC UK tests and their conclusion was similar on Vertical Polarization. Many lack of coverage issues I've seen with extremely high sites is due to the use of high gain antennas with little or no down tilt. I have seen issues like this resolved by simply using a lower gain, say going from 10db gain down to 7 dB gain and applying 4 - 6 degrees of down tilt. Lowering the gain widens the beam and addition of down tilt puts the major part of the RF signal closer in and that improves coverage but it still puts a signal out to the RF horizon. Peter On Thu, Sep 2, 2010 at 1:47 AM, JOHN MACKEY jmac...@usa.net wrote: FM broadcast is NOT changing to vertical polarity! Most stations today are going on the air with either circular polarity or cross polarity (consisting of signal in BOTH the vertical and horizontal poles) With FCC licensing today, a FM station licensed for 10KW can have 10 KW in the vertical plane and 10 kW in the horizontal plane. So there would be no reason to only have the power in one plane. In the last 3 years, I have built 2 FM stations. Both used circular or cross polarity. -- Original Message -- Received: Wed, 01 Sep 2010 10:32:51 PM PDT From: petedcur...@gmail.com To: Repeater-Builder Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters? Hi, I remembered circular polarization was used for FM broadcast due to FM car radios, but when I looked it up I found out some interesting facts, see the link below, https://www.digitaltraders.com/index.php/index.php/components/com_kunena/template/default_ex/templates/ja_edenite/index.php?option=com_contentview=articleid=57Itemid=134 https://www.digitaltraders.com/index.php/index.php/components/com_kunena/template/default_ex/templates/ja_edenite/index.php?option=com_contentview=articleid=57Itemid=134Interesting white paper on FM Broadcast and why they had historically had circular polarization and why they are now changing to vertical polarization. Peter On Thu, Sep 2, 2010 at 1:22 AM, burkleoj joeburk...@hotmail.com wrote: Gary, I am in Southern Oregon and I understand exactly what you are experiencing. We have very similar problems down here with our club's repeater. I have often talked about and even done some serious looking at remodeling a set of broadcast loops and harness for 2 Meters. I know there was a southern California repeater back in the 70's that used circular polarization with excellent results. They were able to provide much better coverage in their main service area, but did loose some long distance coverage outside their main coverage area. We have had the best success by using a lower gain antenna. We have been using the Telewave broadband two loop antennas with 2 - 4 degrees of downtilt, for both our 2 Meter and 440 MHz repeaters. I have found much better close in (0-30 Miles) coverage, less muti-path, and they cost quite a bit less than a Super Stationmaster. Good Luck and keep us posted with what you find for results. Joe - WA7JAW --- In Repeater-Builder@yahoogroups.comRepeater-Builder%40yahoogroups.com, Gary - K7EK gary.k...@... wrote: Greetings, I am in a particularly sticky situation with one of my two meter repeaters in Lakewood, WA (Tacoma). I have generally great coverage, however there is a very annoying problem with multipath and raspy signals in a large portion of my coverage area. Since the Puget Sound area of Western Washington is very hilly and mountainous, multipath is very damaging to all forms of VHF communication. -- No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.851 / Virus Database: 271.1.1/3108 - Release Date: 09/02/10 02:34:00
[Repeater-Builder] Motorola R2600 question
Wondering if anyone has found a source for the memory backup battery for the Motorola R2600 Service Monitor? Motorola says the part is obsolete and General Dynamics is doing some research, but it doesn't sound good. This one is so dead, that it doesn't show polarity, otherwise I could just replace it with some alkalines. Any ideas are welcome.
Re: [Repeater-Builder] Motorola R2600 question
Lets get some pictures johnny On Thu, Sep 2, 2010 at 10:25 AM, wa6epd lme...@cox.net wrote: Wondering if anyone has found a source for the memory backup battery for the Motorola R2600 Service Monitor? Motorola says the part is obsolete and General Dynamics is doing some research, but it doesn't sound good. This one is so dead, that it doesn't show polarity, otherwise I could just replace it with some alkalines. Any ideas are welcome. Yahoo! Groups Links
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
There is one local UHF group that has a back-to-back 6m repeater just for range extension. The Scom 7330 makes the parallel/separate link on/off mode real easy (and for up to 3 ports). At 02:10 AM 09/02/10, you wrote: Gordon, something worth trying might be low-band. About 20 years ago, I lived in an area where hams did course communications for rally events in very mountainous terrain. I remember experimenting one night about 2am with my partner at the other end of a heavily wooded course, about 12 miles end-to-end. 444 MHz simplex, 5 watts, colinear mobile whip - no copy. 146 MHz simplex, 5 watts, 5/8-wave mobile whip - no copy, but would barely break the carrier squelch. 29.6 MHz simplex, 4 watts, FM CB conversion, 1.3m helically-wound mobile whip - full quieting and S9+. Antennas might be a bit of a trick for portables on 10m, and a repeater might have to be crossband, but worth a shot. 73, Paul, AE4KR - Original Message - From: mailto:zl...@nzart.org.nzGordon Cooper To: mailto:Repeater-Builder@yahoogroups.comRepeater-Builder@yahoogroups.com Sent: Thursday, September 02, 2010 1:51 AM Subject: Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters? Our repeater runs 5 watts output, needs to run three or four days off a gelcell, and most importantly has to fit into a backpack to be carried to a convenient hilltop. Fortunately, the split is 3 MHz so that the duplexer is of a reasonable size. The problem is getting reasonable coverage. Sure the search areas are fairly small but usually encompass several ridges and deep valleys. We use vertical polarisation with a 5/8 whip on the repeater and the search teams have flexible dipoles that fit into their backpacks. Sharp ridges and steep slopes contribute to coverage problems. Would circular polarization help?? I think not. No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.851 / Virus Database: 271.1.1/3107 - Release Date: 09/01/10 11:34:00
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
On Thu, 2 Sep 2010, Gordon Cooper wrote: I guess that I do not have much to contribute on this thread but to me it is very interesting reading. Gary has my sympathy, his problem is duplicated here. Much of my repeater work relates to a low power portable repeater on 141 MHz. We live near a medium sized mountain range which has plenty of deer and wild pigs. Hunters go looking for them and perhaps get lost, or fall and break a leg. Also, there are recreational trampers who just get lost . Several times a year we have to go find, and rescue them. The last time was two days ago at 6.30 am. For once, it was not raining! Our repeater runs 5 watts output, needs to run three or four days off a gelcell, and most importantly has to fit into a backpack to be carried to a convenient hilltop. Fortunately, the split is 3 MHz so that the duplexer is of a reasonable size. You need lower power output and a further split and a big battery. Even running a repeater at five watts with commercial handhelds out in the field (each of which have a battery that will make it for eight hours), you're going to need somewhere around a 33Ah battery, which weighs 25 lbs. The problem is getting reasonable coverage. Sure the search areas are fairly small but usually encompass several ridges and deep valleys. We use vertical polarisation with a 5/8 whip on the repeater and the search teams have flexible dipoles that fit into their backpacks. Sharp ridges and steep slopes contribute to coverage problems. Would circular polarization help?? I think not. Remember, a quarter-wave has significant energy in the pattern from about five degrees to eighty-five degrees; if you're dealing with valleys, this may be a better choice for an antenna. -- Kris Kirby, KE4AHR Disinformation Analyst
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
On Thu, 2 Sep 2010, Paul Plack wrote: Gordon, something worth trying might be low-band. About 20 years ago, I lived in an area where hams did course communications for rally events in very mountainous terrain. I remember experimenting one night about 2am with my partner at the other end of a heavily wooded course, about 12 miles end-to-end. 444 MHz simplex, 5 watts, colinear mobile whip - no copy. 146 MHz simplex, 5 watts, 5/8-wave mobile whip - no copy, but would barely break the carrier squelch. 29.6 MHz simplex, 4 watts, FM CB conversion, 1.3m helically-wound mobile whip - full quieting and S9+. Motorola Syntor Xs are relatively easy to locate, and can be programmed for 10m to 6m without any retuning. They were designed for 30-50MHz. -- Kris Kirby, KE4AHR Disinformation Analyst
[Repeater-Builder] Ctcss- internal or external
Hello all- I have put together a small repeater with 2 Maxon UHF radios. Here is the question. Is it better to use the internal ctcss decoder with a line to the controller or to use an external decoder such as the ts-64? Would there be an advantage of using one over the other? Thanks for the help. Craig
[Repeater-Builder] IC-RX7
Anyone here have an ICOM IC-RX7 receiver and would not mind contacting me off-list? I want to figure out what is the best way to organize the memories. The thing has a weird structure. k4fh at k4fh dot com 73, Chris k4fh
[Repeater-Builder] Looking For: LB (6m) Micor Repeater PA (continuous duty)
Hi Folks, I'm getting pretty close to putting up the machine, and I am looking for a 'real' PA for it. High split low band Micor PA so I can move it to 6 meters. Continuous duty. Already have the rest of the Micor components (RX, cards, exciter, etc). Please respond off-line. thanks! tim W5FN
[Repeater-Builder] Re: Motorola R2600 question - Answered
Thanks to all who responded. With their help, I was able to locate a replacement. It seems they have upgraded the battery from a NiCad type to a nickel-metal hydride type. See link below for source. http://www.energexbatteries.com/products.php?product=PMB-3.6BHV-replaces-PMB-3.6b Thanks again, -Lou-
RE: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
I completely agree! Back in the late 60's, I was Chief Engineer at WLRW- the first FM station in the state of Illinois to broadcast in stereo- and this was in Champaign-Urbana, not Chicago! The transmitter was an RCA BTF-10D which fed five Andrew Vee antennas and five Gates Rings, giving us about 25 kW vertical and 25 kW horizontal. The majority of FM stations then used horizontal polarization, for reaching FM table radios that had line-cord antennas and component stereo systems. AM/FM car radios became an option around 1967, and WLRW was ready with a vertical component to better reach car radios. I acknowledge that dual polarization is not the same as circular polarization, but it does accomplish what the station owner wanted back then: Full coverage of home and car/portable radios. I look forward to hearing about the changes that circular polarization can make to VHF repeater coverage. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of sbjohns...@aol.com Sent: Thursday, September 02, 2010 6:48 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Circular polarization for VHF repeaters? FM broadcasting in the US is not changing to vertical polarization. There may be some old stations still running horizontal, and vertical is used in some situations (such as stations low in the band needing to be cross-polarized from a nearby channel 6 TV signal) but circular polarization is by far the preferred method. I've had FM stations running both, and have a firm impression that circular is indeed better for mobile reception. I may get the chance to convert some stations from vertical to c-pol when the rules are changed now that the conversion to HDTV has been made. I may have access to some papers on the subject - I'll check. I believe c-pol could be better for amateur VHF repeater-mobile operations in high-multipath areas. Steve
[Repeater-Builder] A DB224E antenna...
Greetings. I'm the trustee of our local club's 2m repeater. It's NE of the big town of Joplin, MO. (147.210) What I want to find out, I'm going to ask our club to buy a new 224e antenna (assuming that this is the correct version needed for T147.210 R147.810), and arrange the elements on the north edge of the tower we're on so that 3 elements point to the SW, to favor our town so that HTs can work it, and one element to the ENE to point some energy to Springfield for working severe weather. Altho I'm thinking about trying to link the repeater with either EchoLink or some other repeater to Springfield and just point all 4 elements to the SW. :-) But it's on the north leg (that leg points to the north), so if pointing them to the SW gets the highest gain, that sounds great to me. :-) The point is that there's a DB224 there now, not sure if it's an E version or not, but I think it has some issues right now, so I'd rather just get a new one up and bring the old one down and go thru it at our leisure, plus reorienting it so that we can actually USE it. :-) Anyways, I wanted to know if anyone had one here that was in either new- in-box or barely used condition, how much $$ they go for nowadays, and how hard is it to reorient the elements if it was originally designed / set for omni (3, 6, 9, 12 o'clock). Thanks! Ray, KB0STN Trustee, W0IN
[Repeater-Builder] 2011 Las Vegas VoIP event
Sent bcc We will do the annual VoIP event Saturday April 9, 2011 at Circus-Circus. Yes, a party Friday night same as last year. This is the weekend before the NAB Conference. See you there!!
[Repeater-Builder] Re: Motorola R2600 question
--- In Repeater-Builder@yahoogroups.com, wa6epd lme...@... wrote: Wondering if anyone has found a source for the memory backup battery for the Motorola R2600 Service Monitor? Motorola says the part is obsolete and General Dynamics is doing some research, but it doesn't sound good. This one is so dead, that it doesn't show polarity, otherwise I could just replace it with some alkalines. --- I wouldn't suggest replacing a rechargable battery with alkalines. The battery in the R2600 is labled: Plainview Batteries PMB 3.6 B A google search will find several sellers that have a replacement which differs in appearance but will fit in the same holes.
[Repeater-Builder] Re: Circular polarization for VHF repeaters?
Thanks to all that replied. I appreciate your input. I'm still looking for answers, but may be onto something. I have emailed Bill Pasternak, the author of that Cushcraft 4-pole conversion article. I re-read his original article and may have figured out what I must do. That, plus any additional input from Bill, should hopefully help me to complete the project. I will post again later if I have any success. Best regards, Gary, K7EK Personal Web Page: www.k7ek.net --- In Repeater-Builder@yahoogroups.com, Gary - K7EK gary.k...@... wrote: Greetings, I am in a particularly sticky situation with one of my two meter repeaters in Lakewood, WA (Tacoma). I have generally great coverage, however there is a very annoying problem with multipath and raspy signals in a large portion of my coverage area. Since the Puget Sound area of Western Washington is very hilly and mountainous, multipath is very damaging to all forms of VHF communication. Over the years I have read about folks employing circular polarization to overcome fading, nulls, multipath, etc. There is so very little written about this topic in amateur circles so I thought I'd bring it up here and see what I could come up with. In the 80's there was a amateur radio repeater book by a fellow, Pasternak I believe, that took two gamma match style Cuschcraft Four Pole antennas, combined them, and did some magic with phasing lines to end up with a four bay circularly polarized repeater antenna. Unfortunately the description leaves much to be desired, at least for me, so I never built one. If he would have included specifics on phasing line lengths, cable types, etc, the job would have been a whole lot easier. Has anyone actually gone circular with Cushcraft Four Poles, and if so, could you please share it with me and/or this group? I have done some inquiring to commercial companies about a custom built two meter four bay circularly polarized array, but that is entirely out of the question. They want thousands of dollars. There must be an easier (and cheaper) way. Similarly, is anyone in this group running circular polarization on your amateur repeater(s), and if so, could you please share the details in a manner that could be duplicated without a lot of guess work? I know that I could easily solve my multipath problem by installing one or more remote receivers, however I would like to keep that as a last resort and shoot for a circularly polarized antenna system at the main repeater site. I do understand that there is approximately 3 db of loss as a result of this, but that is quite acceptable. The dividends would greatly outweigh the down side. Thanks for any constructive ideas, suggestions, links, etc, that you might be willing to share concerning this situation. Best regards, Gary, K7EK
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
On Fri, 3 Sep 2010, Gary - K7EK wrote: Thanks to all that replied. I appreciate your input. I'm still looking for answers, but may be onto something. I have emailed Bill Pasternak, the author of that Cushcraft 4-pole conversion article. I re-read his original article and may have figured out what I must do. That, plus any additional input from Bill, should hopefully help me to complete the project. I will post again later if I have any success. Best regards, Gary, K7EK Personal Web Page: www.k7ek.net If you find a copy out on the 'net, please forward me a copy of the link. -- Kris Kirby, KE4AHR Disinformation Analyst
