RE: [Repeater-Builder] Re: Low Power VHF Repeater - Solar
I would think a simple small solar array and maybe a modest wind genny would be more tha enough to supply a small 5 watt repeater , not being sure of the costs in your part of the world but here in Au a 500 watt genny is around a grand so a suitable unit will be very affordable along batteries and voltage controller it's not going to be bad at all To: Repeater-Builder@yahoogroups.com From: ki4...@yahoo.com Date: Thu, 27 Aug 2009 01:39:18 + Subject: [Repeater-Builder] Re: Low Power VHF Repeater - Solar Hello Tim, We completed a Solar UHF GMRS repeater site this past May. Its been a huge success. We used a Kenwood 40 watt TKR-850 repeater and 2 100 watt solar panels. We started with 4 GMS batteries and they seem to support the system with plenty of amp hours to spare. You can go to our web site and review the repeater site with pictures. Look for ATL-575 solar site. www.NorthGeorgiaGMRS.com Feel free to contact me with any questions. wqfu...@northgeorgiagmrs.com Gary M. Beckstedt Sr --- In Repeater-Builder@yahoogroups.com, tahrens301 tahr...@... wrote: A friend of mine who is the foreman for a large ranch asked me about providing radio coverage. As there are a couple of hills (2000' AGL) around the ranch, coverage in some places would be spotty, so a repeater on one of the hills would be the best solution. However, there is no power available, so a solar/wind power solution would be necessary. (we get a lot of sun here!) I've done a couple of solar projects, but this needs to be pretty much commercial quality, so I was wondering if there is a commercial repeater available that would be a good candidate for solar power. I figure the RF power out could be 5 watts or less and still give good coverage throughout the ranch. Thanks, Tim _ What goes online, stays online Check the daily blob for the latest on what's happening around the web http://windowslive.ninemsn.com.au/blog.aspx
[Repeater-Builder] Motorola Spectra 16 Mode Scan limit HACKED!!!
Yes it has been done! I have figured it out and could not believe how easy it was to do. It is quite easy to do and does NOT involve bit-banging! I just figured out how to do this a few minutes ago so excuse me if I am to vague on the subject, but here is my tutorial for now. At first, I got a glitch and was able to do this by accident on one zone. Since it happened, I looked into how the RSS handles the Scan number. Read this thread (http://batboard.batlabs.com/viewtopic.php?f=15t=86921) for more information on how I expected the RSS to work. Turns out I was right! Just a half hour ago, I thought about the memory and how the RSS uses it when running. I remembered a program I used to cheat money in a game, like Sim City, by editing the program memory. Read on! This is how to do it. Ok, first you must do this on a windows PC. The latest Spectra RSS runs on my 1.6GHz PC just fine for editing code plugs. On your DOS machine or whatever, just get the codeplug from the machine you usually edit your codeplug on, and get it on a windows PC to edit. Then you are going to have to install this program: (http://www.systemsoftlab.com/artmoney731eng.exe) This is the program that edits the memory. Now start up your RSS. Load your codeplug and go to a scan list (I only tried this with zone scan lists and not scan lists based on channels, but it should be similar). Notice the amount of channels selected to scan. I am going to assume you are on a scan list that you want to expand, so your scan amount at the top probably says 16 of 16. Now with the RSS running, open up art money, agree to the terms. Then under select process, select the SPECTRA program. Then click search. Make sure Exact value is selected, and integer (standard), and address range is ALL. Now type the value of the modes you have selected to scan for that list. In this example it is all 16, so type in 16 and click search. It will find quite a lot. Now deselect a mode from scanning, to make it 15 of 16. Now go back to art money and click filter The point of this is to see what address out of all the searched ones changed from 16 to 15. make sure that Exact Value and Integer (standard) is selected. Now type in the value of the modes selected NOW, in this case 15. Now it should only find two address. The reason I am having you search is that I am not sure if it is static or not. However, every time I start up the program, Mine are the same address in art money. Mine are 0006A494 and 0006A496. I am wondering what you guys get. Anyway for me, it didn't matter what one I switched. Now change it to a value of 17. Now go back into RSS and ADD another mode to that Scan list. In this example you should get 18 of 16, which is incorrect. However, if you exit zone scan list and go back into it, it will now read 17 of 16. Select all the modes you want to scan, and as long as you don't go to 16 or below, you will be fine. if you do, just repeat the process. To do this to other zones, go to that zone scan list and repeat the above, but you probably won't have to search the address again and they should be the same, and now all you have to do in art money is edit the value. There is one downside. This pretty much eliminates front panel programming of scan list, but ONLY for the zones you exceed this limit on. The radio recognized that you are over. If you go to edit, and try to add another mode, it will say scan list full. If you delete a mode to scan, even if still above 16, the radio will NOT let you add anymore like the RSS can (RSS is easier to trick! ). So if you want to be full proof so you don't accidentally do this, go to Zone options, and go to the zones that you exceed the 16 scan limit on, and set Non-priority lists and priority lists to Zone Slaved. This will disable front end programming of the scan list for that zone ONLY. You only need to do this to zones that you are expanding. Ok, ok I know the above is somewhat a mess, but i typed it real quick. Sorry! I will try and create a better tutorial in a PDF format with pictures or something so people that aren't as experienced with windows and memory editing can do this no problem. However, the above explanation can probably be done by most people. VERY IMPORTANT ADDITIONAL INFORMATION!!! I have programmed it without a problem. Here is the deal with front programming. If you have zone slaved for both priority and non priority scanning modes, you cannot edit the scan list at all. You can, however, review the scan list on each zone by holding the SCAN key down on the control head. However when trying to deselect or select a mode or change a priority by pressing SEL, you get an error tone. What I found out is to set the priority modes to Op Select, so they can be front programmed. For one of my zones, it scans just about my whole county (47 modes). All are non priority, except SEL MODE (which is the selected mode you have selected on the
[Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
I am looking at building a 2M four bay antenna, But, I have a question My question is the design and construction of folded dipole antennas used as individual elements in bay type antennas. In doing research into their construction I came upon a catch. All design info I found in books, ARRL Antenna Book, etc, says a two element folded dipole has a nominal input impedance of 300 ohms. But, all sources, DB Products, Benelec, etc, I see say the nominal input impedance for each folded dipole element is 50 ohms, 300. I reference WB2EDV's article on a 440 antenna he built. But, the bottom line is can anybody point me to where I can find the info on designing each element for 50 ohm impedance? Jeff wd4nmq
[Repeater-Builder] Alinco DR-235T MK III as link radio w/ RC210
Morning Folks, Well we used the last of our grant money on a Alinco DR-235T MK III for our link between the 2 local 440 repeaters. I can get everything working except the RX audio coming from the link radio. We're using the following pins; RC210Alinco PTT Pin 3Pin 7 TX Pin 4 Pin 9 RX Pin 6 Pin 4 Gnd Pin 5Pin 5 COS Pin 7Pin 1 No change with the moving the Disc.Port 2 up and down either. Ideas? Robert KD4YDC
Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
Depends on the antenna. My article for 440 - each element is 50-ohms. That is due to mast spacing and the different diameters on the element. However, a similar UHF element on a Decibel antenna is 100-ohms and the major determining factor is spacing to the mast. Others (Sinclair, Comprod, Telewave) use a longer spacing from the mast and have a matching transformer section inside of the element to get it to 50-ohms. A folded dipole, out in the open, with no matching, is a bit less than 300-ohms. I've done very little 2-meter antenna work since I have very little interest there. Chuck WB2EDV - Original Message - From: wd4nmq_1 wd4...@gmail.com To: Repeater-Builder@yahoogroups.com Sent: Wednesday, August 26, 2009 8:11 PM Subject: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed I am looking at building a 2M four bay antenna, But, I have a question My question is the design and construction of folded dipole antennas used as individual elements in bay type antennas. In doing research into their construction I came upon a catch. All design info I found in books, ARRL Antenna Book, etc, says a two element folded dipole has a nominal input impedance of 300 ohms. But, all sources, DB Products, Benelec, etc, I see say the nominal input impedance for each folded dipole element is 50 ohms, 300. I reference WB2EDV's article on a 440 antenna he built. But, the bottom line is can anybody point me to where I can find the info on designing each element for 50 ohm impedance? Jeff wd4nmq
Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
The technique to match the natural 300 ohm impedance of a folded dipole to 50 ohms simply uses matching section of an electrical 1/4 wavelength of 125 ohm coax (RG-63B). It is usually installing inside the dipole in order to be able to weatherproof the dipole easily at the feedpoint but I imagine it could be installed external as well. I have a page with a pictorial of the design I used some years ago. I made a number of arrays for VHF and 220 MHz using this design some time ago. http://www.gorum.ca/sinc_ant.html (ignore the links at the bottom - I didn't finish the web page set) RG-63B is very hard to find and it is not cheap ($3/ft) but I do have a quantity left over from when I was making the dipoles 15-20 years ago. Burt VE2BMQ wd4nmq_1 wrote: I am looking at building a 2M four bay antenna, But, I have a question My question is the design and construction of folded dipole antennas used as individual elements in bay type antennas. In doing research into their construction I came upon a catch. All design info I found in books, ARRL Antenna Book, etc, says a two element folded dipole has a nominal input impedance of 300 ohms. But, all sources, DB Products, Benelec, etc, I see say the nominal input impedance for each folded dipole element is 50 ohms, 300. I reference WB2EDV's article on a 440 antenna he built. But, the bottom line is can anybody point me to where I can find the info on designing each element for 50 ohm impedance? Jeff wd4nmq
Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
The only possible problem with this design is feeding a balanced antenna (the folded dipole) with unbalanced feed. This will lead to some amount of feedline radiation; yes, it is using coax which is shielded but the unwanted RF current in this situation flows on the _outside_ of the coax, on the shield. Yes, this is a commercially successful design, but I've got to wonder... I think a better way would be to use a half-wave section of 50 coax as a combination 4:1 impedance transformer _and_ balun. Details in almost any ARRL Antenna Handbook. The only catch to this approach is that the folded dipole element must be designed to yield 200 ohms rather than the more common 300 ohms impedance, so that the 4:1 transform yields 50 ohms. Again, older versions of the ARRL Ant. Hdbk have details on doing this; it has to do with the element diameter element spacing. However, mounting of the antenna on a tower leg or equiv. may reduce the impedance from 300 ohms enough all by itself. When scaling antennas to other frequencies, pay close attention to the physical scaling. On 1.2 GHz, RF things can get quirky. Do not cut specific-length lines (e.g. phasing lines) using a ruler the cable's alleged velocity factor, that can be quite a way off. I use a noise bridge instead or network analyzer. --John --- On Thu, 8/27/09, Burt Lang b...@gorum.ca wrote: From: Burt Lang b...@gorum.ca Subject: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed To: Repeater-Builder@yahoogroups.com Date: Thursday, August 27, 2009, 7:21 AM The technique to match the natural 300 ohm impedance of a folded dipole to 50 ohms simply uses matching section of an electrical 1/4 wavelength of 125 ohm coax (RG-63B). It is usually installing inside the dipole in order to be able to weatherproof the dipole easily at the feedpoint but I imagine it could be installed external as well. I have a page with a pictorial of the design I used some years ago. I made a number of arrays for VHF and 220 MHz using this design some time ago. http://www.gorum. ca/sinc_ant. html (ignore the links at the bottom - I didn't finish the web page set) RG-63B is very hard to find and it is not cheap ($3/ft) but I do have a quantity left over from when I was making the dipoles 15-20 years ago. Burt VE2BMQ wd4nmq_1 wrote: I am looking at building a 2M four bay antenna, But, I have a question My question is the design and construction of folded dipole antennas used as individual elements in bay type antennas. In doing research into their construction I came upon a catch. All design info I found in books, ARRL Antenna Book, etc, says a two element folded dipole has a nominal input impedance of 300 ohms. But, all sources, DB Products, Benelec, etc, I see say the nominal input impedance for each folded dipole element is 50 ohms, 300. I reference WB2EDV's article on a 440 antenna he built. But, the bottom line is can anybody point me to where I can find the info on designing each element for 50 ohm impedance? Jeff wd4nmq
Re: [Repeater-Builder] IMTS Channel Designators
I was looking and the various combinations and mapping them.. JL = 55x YL = 95x JP = 57x YP = 97x YJ = 95x YK = 95x JS = 57x YS = 97x YR = 97x JK = 55x KR = 57x These NXX prefix's all map out to routing prefix's that have always been special like 555 for numbers in movies... because they were special routing if at all... in any case they all are on 3 buttons of the keypad... so the combinations were what you could do with those key codes... ( or dial codes back then :-) ) Doug KD8B At 10:29 PM 8/26/2009, you wrote: Well, there, that explains it as good as can be. I recall the days when our phone number started with PL3 (for 753 exchange) and the PL stood for PLeasant. Chuck WB2EDV - Original Message - From: William Becks mailto:wbecks%40centurytel.netwbe...@centurytel.net To: mailto:Repeater-Builder%40yahoogroups.comRepeater-Builder@yahoogroups.com Sent: Wednesday, August 26, 2009 10:09 PM Subject: Re: [Repeater-Builder] IMTS Channel Designators Folks, A reasonable explanation can be found at URL: http://www.privateline.com/TelephoneHistory3A/mobile.htmlhttp://www.privateline.com/TelephoneHistory3A/mobile.html on how the Bell System used the two-letter Channel Designators as a prefix to the original MTS 5-digit mobile phone numbers. Later, when IMTS replaced the MTS system, Bell went to a seven digit dialing plan with the first three digits being the NPA (Area Code) for the mobile telephone registry. Bill, WA8WG - Original Message - From: Eric Lemmon mailto:wb6fly%40verizon.netwb6...@verizon.net To: mailto:Repeater-Builder%40yahoogroups.comRepeater-Builder@yahoogroups.com Sent: Wednesday, August 26, 2009 8:31 PM Subject: RE: [Repeater-Builder] IMTS Channel Designators Jesse, Actually, those are MTS channel designations; the IMTS came several years after MTS was deployed. The eleven Y and J channels were in the 152-158 MHz VHF band, while there were also ten Z channels in the 35-43 MHz Low band, and six Q channels in the 454-459 MHz UHF band. The low-band channels had an 8 MHz split, VHF channels had a 5.26 MHz split, and UHF channels had a 5 MHz split. The oddball VHF channels were later used for taxicabs. I am currently using two of those VHF channels in commercial repeater service, taking advantage of the small additional separation. Back in 1968, I put a two-channel GE Pacer (gasp!) with a Secode mechanical selector attached, in MTS service back in Rantoul, Illinois. Not too many folks in that part of Illinois had mobile telephones back then, and even fewer had a kluge like a Pacer. Despite its appearance, it worked quite well, and I learned to anticipate when the phone would ring by counting the clicks as the Secode unit stepped. I, too, would like to know the origin of the two-letter channel designators. 73, Eric Lemmon WB6FLY -Original Message- From: mailto:Repeater-Builder%40yahoogroups.comRepeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Jesse Lloyd Sent: Wednesday, August 26, 2009 5:32 PM To: mailto:Repeater-Builder%40yahoogroups.comRepeater-Builder@yahoogroups.com Subject: [Repeater-Builder] IMTS Channel Designators Hey All, I was having a discussion with a fellow tech and the topic of IMTS came up. Does anyone here remember the reason for the strange channel designators? JL YL JP YP YJ YK JS YS YR JK KR ? Why YL... why not channel B or Ch 2, they must mean something... Jesse Yahoo! Groups Links Yahoo! Groups Links
Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
Yes, it does depend on the antenna, to wit, diameter of the elements spacing between the elements. Can be made lower or higher than 300 ohms. There's nothing sacred about 300 ohm Z. It was a match for 300 ohm TV twinlead in the older daze. --John --- On Thu, 8/27/09, Chuck Kelsey wb2...@roadrunner.com wrote: From: Chuck Kelsey wb2...@roadrunner.com Subject: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed To: Repeater-Builder@yahoogroups.com Date: Thursday, August 27, 2009, 6:51 AM Depends on the antenna. A folded dipole, out in the open, with no matching, is a bit less than 300-ohms. Chuck WB2EDV
[Repeater-Builder] What have I got?
Hi, I have inherited a tabletop Motorola that has ben modified into a repeater. It has worked for years but now has quit. It is a L43BBB3190DM. What is that? It will not transmit when the PTT on the rear terminal strip is grounded. Where can I find a schematic or any info like the GE LBIs? Thanks, John -- John Mc Hugh, K4AG Coordinator for Amateur Radio National Hurricane Center, WX4NHC Home page:- http://www.wx4nhc.org
[Repeater-Builder] TQ-2310
I have a working Panasonic RL-H1800 with the: Mini-printer RL-P1004 RS232 interface RL-P3001 Battery Back-up RL-P9003 I/O Adapter RL-P6001 I/O Cable RL-P6006 Acoustic modem RL-P4001 AC Adapter RD-9498 Snap modules (MS BASIC SnapBASIC) 2 Manuals All housed within the RD-9808 atache case. Is this the same as the TQ-2310 suitcase programmer? Am I missing anything? What radios can I program with this (MLS1, MLS2)? I'm a novice so any information would be greatly appreciated.
Re: [Repeater-Builder] TQ-2310
There is also a ROM module that holds several sets of eproms for each different model of radio.. Some take one some take 2.. it holds 8 proms I think.. if I remember correctly.. At 11:19 AM 8/27/2009, you wrote: I have a working Panasonic RL-H1800 with the: Mini-printer RL-P1004 RS232 interface RL-P3001 Battery Back-up RL-P9003 I/O Adapter RL-P6001 I/O Cable RL-P6006 Acoustic modem RL-P4001 AC Adapter RD-9498 Snap modules (MS BASIC SnapBASIC) 2 Manuals All housed within the RD-9808 atache case. Is this the same as the TQ-2310 suitcase programmer? Am I missing anything? What radios can I program with this (MLS1, MLS2)? I'm a novice so any information would be greatly appreciated.
Re: [Repeater-Builder] Re: Diversity FM reception
I think the larger problem is a lack of standardization in receive antenna systems for broadcast FM. The late 60s/70s brought along ignorant antenna designs, like the windshield-integrated dipole and the 45-degree swept-back dipole. Now we've got even more ignorant designs like the 45 degree stubby on the roof of cars (06 or newer Hyundai Santa Fe is a good example of this mistake), or oddball angled foil designs in/on window glass (01-05 Hyundai Santa Fe is a good example of this). Absolutely worthless for any linear polarization. Amusingly, on the 01-05 Santa Fe, Hyundai decided to integrate a 10 db-ish RX amplifier in the back near the antenna. It also doesn't have any input filtering. Transmitting on VHF anywhere near the vehicle with any bit of power at all absolutely slaughters any FM RX you might have, even when listening to 50kW + LOS transmitter. AM Broadcast is the worst, where all you get to hear is fuel pumps, alternators and ignition... JS Al Wolfe wrote: Back in the late 60's or early 70's we tried this on one of the stations I was involved with. CP can work with separate antennas but only if the vertical and horizontal elements are in the same vertical axis and fed in quadrature or 90 degrees out of phase. And the SWR needed to be absolutely flat, as in 0 reactance or the circular polarization and its benefits were negated.. The results at the time showed some improvement in our mobile coverage but there was a three db hit in general using the same transmitter set up as before the CP experiment. The project was eventually abandoned. Later the roto-tillers, cycloid dipoles, and vees were developed where the circularity was supposedly inherent to the antenna design. I personally like the roto-tiller type as they seem to actually generate a circular pattern with the vertical and horizontal radiation and circularity being fairly predictable. A lot of broadcasters consider circular polarization as a legal back-door method of doubling your ERP. It's pretty much the standard for most FM broadcasters anymore. 73, Al, k9si, retired, mostly Years ago before CP antennas were commonly available, FM stations would feed two separate antennas on the tower. One was H, the other V. Was that then 45 degree polarization??
RE: [Repeater-Builder] Re: Diversity FM reception
The late 60s/70s brought along ignorant antenna designs, like the windshield-integrated dipole and the 45-degree swept-back dipole. Now we've got even more ignorant designs like the 45 degree stubby on the roof of cars (06 or newer Hyundai Santa Fe is a good example of this mistake), or oddball angled foil designs in/on window glass (01-05 Hyundai Santa Fe is a good example of this). Absolutely worthless for any linear polarization. Marketing always trumps engineering. Form wins out over function. You gotta be able to sell it. My memory is failing me, but I think it was Volvo that was putting two embedded-in-glass antennas with diversity-receive radios in their cars a few years ago (this was FM obviously). I heard that they worked extremely well. Can anyone confirm? --- Jeff
Re: [Repeater-Builder] Re: Diversity FM reception
Except engineering gets to screw up things under the hood - so the vehicle needs to be half torn apart to change a battery or the plugs ;-) Chuck - Original Message - From: Jeff DePolo j...@broadsci.com To: Repeater-Builder@yahoogroups.com Sent: Thursday, August 27, 2009 3:32 PM Subject: RE: [Repeater-Builder] Re: Diversity FM reception Marketing always trumps engineering. Form wins out over function. You gotta be able to sell it.
Re: [Repeater-Builder] What have I got?
The BBB is a unique situation. Moto used that suffix on three different radios. One was a all-tube base from the 50's/60s, The later was a 70s/80s design that was based on the Mocom-70 mobile radio. The third was a handheld marketed as the MT-500. Can you post an interior photo? A 2135 key will open either of the base stations. More details at http://www.repeater-builder.com/motorola/motorola-suffixes.html But all of the BBBs were crystal controlled. The tube base had plug-in crystals, the Mocom 70 based radio used channel elements (packaged oscillators with the crystals inside) as did the handheld. If you can't find someone with crystals or elements on your frequencies you are looking at having to order crystals. But to break it down, L43BBB3190DM L=tabletop base 4=RF power level, 30-40 watts 3=136-174 MHz, but in three bandsplits: 136-150, 150-162, 162-174. See below. BB = Model suffix. B=Base station 3=PL option 1=narrowband (5KHz) 90=4 frequency option D=hardware revision level M=shipping option As to what split, look for a TRD or TTD followed by 4 digits, or maybe four digits and one or two letters stamped on the chassis somewhere. Optionally follow the receive coax and if it plugs into a front end module look for a three-letter and 4-digit number with a letter or two at the end (like TLN4321A) but it may not be the specific letters TLN. Let us know what the TRD, TTD, or front end part number is. Mike WA6ILQ At 09:13 AM 08/27/09, you wrote: Hi, I have inherited a tabletop Motorola that has ben modified into a repeater. It has worked for years but now has quit. It is a L43BBB3190DM. What is that? It will not transmit when the PTT on the rear terminal strip is grounded. Where can I find a schematic or any info like the GE LBIs? Thanks, John -- John Mc Hugh, K4AG Coordinator for Amateur Radio National Hurricane Center, WX4NHC Home page:- http://www.wx4nhc.org Yahoo! Groups Links
[Repeater-Builder] Re: Diversity FM reception
My memory is failing me, but I think it was Volvo that was putting two embedded-in-glass antennas with diversity-receive radios in their cars a few years ago (this was FM obviously). I heard that they worked extremely well. Can anyone confirm? --- Jeff That is correct at least in the Volvo Wagons, our current '04 V70 wagon has such an antenna, and I beleive our old '96 of the same model had a one too. It is placed in the the rear side window, and looks simmilar to the defogging foil on the back windshield. As far as performance is concerned, it works on FM, not exceptionally well but I would not say I'm dissatisfied. Of course however, AM is limited to very local stations.
Re: Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
Actually 300 ohms is special. It is the impedance of a folded dipole with equal diameter elements, the end result of bending a single piece of tubing into a U. And the impedance is not affected by the spacing between the elements (according to the handbook theory). Burt VE2BMQ John Sehring wrote: Yes, it does depend on the antenna, to wit, diameter of the elements spacing between the elements. Can be made lower or higher than 300 ohms. There's nothing sacred about 300 ohm Z. It was a match for 300 ohm TV twinlead in the older daze. --John --- On *Thu, 8/27/09, Chuck Kelsey /wb2...@roadrunner.com/* wrote: From: Chuck Kelsey wb2...@roadrunner.com Subject: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed To: Repeater-Builder@yahoogroups.com Date: Thursday, August 27, 2009, 6:51 AM Depends on the antenna. A folded dipole, out in the open, with no matching, is a bit less than 300-ohms. Chuck WB2EDV start: -00-00 end: -00-00
Re: Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
Anyone built this non-folded dipole array project? It uses 3/4 copper pipe, PVC stand offs and 75 ohm coax for the phasing harness... http://forums.radioreference.com/attachments/antennas-coax-forum/16043d1213582941-4-bay-vhf-dipole-array-project-low-cost-high-performance-vhf-dipole-array.pdf http://forums.radioreference.com/antennas-coax-forum/109144-4-bay-vhf-dipole-array-project.html http://forums.radioreference.com/antennas-coax-forum/155082-hme-brewed-4-bay-uhf-dipole-array.html On Thu, Aug 27, 2009 at 3:19 PM, Burt Lang b...@gorum.ca wrote: Actually 300 ohms is special. It is the impedance of a folded dipole with equal diameter elements, the end result of bending a single piece of tubing into a U. And the impedance is not affected by the spacing between the elements (according to the handbook theory). Burt VE2BMQ John Sehring wrote: Yes, it does depend on the antenna, to wit, diameter of the elements spacing between the elements. Can be made lower or higher than 300 ohms. There's nothing sacred about 300 ohm Z. It was a match for 300 ohm TV twinlead in the older daze. --John --- On *Thu, 8/27/09, Chuck Kelsey /wb2...@roadrunner.comwb2edv%40roadrunner.com/* wrote: From: Chuck Kelsey wb2...@roadrunner.com wb2edv%40roadrunner.com Subject: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed To: Repeater-Builder@yahoogroups.comRepeater-Builder%40yahoogroups.com Date: Thursday, August 27, 2009, 6:51 AM Depends on the antenna. A folded dipole, out in the open, with no matching, is a bit less than 300-ohms. Chuck WB2EDV start: -00-00 end: -00-00
Re: Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
John Sehring wrote: The only possible problem with this design is feeding a balanced antenna (the folded dipole) with unbalanced feed. This will lead to some amount of feedline radiation; yes, it is using coax which is shielded but the unwanted RF current in this situation flows on the _outside_ of the coax, on the shield. Yes, this is a commercially successful design, but I've got to wonder... Don't knock success. There are thousands of such antennas in operation and nobody complains about RF currant on the outside of the coax. I think a better way would be to use a half-wave section of 50 coax as a combination 4:1 impedance transformer _and_ balun. Details in almost any ARRL Antenna Handbook. But can you weatherproof it for commercial usage? The only catch to this approach is that the folded dipole element must be designed to yield 200 ohms rather than the more common 300 ohms impedance, so that the 4:1 transform yields 50 ohms. Again, older versions of the ARRL Ant. Hdbk have details on doing this; it has to do with the element diameter element spacing. However, mounting of the antenna on a tower leg or equiv. may reduce the impedance from 300 ohms enough all by itself. From my experience, the folded dipole impedance only starts to drop when you get closer than 1/4 wavelength from the mounting mast. 1/4 or 1/2 wave makes no significant difference on the impedance. Sinclair's 110C1 low band antenna is however mounted about 1/8 wave from the support and has a different matching coax internally (less than 100ohm I think). When scaling antennas to other frequencies, pay close attention to the physical scaling. On 1.2 GHz, RF things can get quirky. Do not cut specific-length lines (e.g. phasing lines) using a ruler the cable's alleged velocity factor, that can be quite a way off. I use a noise bridge instead or network analyzer. The design that I showed on the web page was for 2m and 220. I tried making a UHF array with the same 3/4 in diameter tubing and it was really flakey. I found it easier to work with 3/8in tubing at UHF. I did think about making 900 or higher dipoles with copper tubing type hardline like 0.141 in stuff used for microwave lines. I could not figure out how to change the impedance with the normally available 50 ohm stuff. It never got beyond the thinking stage. Burt VE2BMQ --- On *Thu, 8/27/09, Burt Lang /b...@gorum.ca/* wrote: From: Burt Lang b...@gorum.ca Subject: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed To: Repeater-Builder@yahoogroups.com Date: Thursday, August 27, 2009, 7:21 AM The technique to match the natural 300 ohm impedance of a folded dipole to 50 ohms simply uses matching section of an electrical 1/4 wavelength of 125 ohm coax (RG-63B). It is usually installing inside the dipole in order to be able to weatherproof the dipole easily at the feedpoint but I imagine it could be installed external as well. I have a page with a pictorial of the design I used some years ago. I made a number of arrays for VHF and 220 MHz using this design some time ago. http://www.gorum. ca/sinc_ant. html http://www.gorum.ca/sinc_ant.html (ignore the links at the bottom - I didn't finish the web page set) RG-63B is very hard to find and it is not cheap ($3/ft) but I do have a quantity left over from when I was making the dipoles 15-20 years ago. Burt VE2BMQ wd4nmq_1 wrote: I am looking at building a 2M four bay antenna, But, I have a question My question is the design and construction of folded dipole antennas used as individual elements in bay type antennas. In doing research into their construction I came upon a catch. All design info I found in books, ARRL Antenna Book, etc, says a two element folded dipole has a nominal input impedance of 300 ohms. But, all sources, DB Products, Benelec, etc, I see say the nominal input impedance for each folded dipole element is 50 ohms, 300. I reference WB2EDV's article on a 440 antenna he built. But, the bottom line is can anybody point me to where I can find the info on designing each element for 50 ohm impedance? Jeff wd4nmq
RE: [Repeater-Builder] Spectra power up 900mhz
Mac, Check to see if your radio is configured to require ignition sense. What is the complete model number of your radio? 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Mac McCullough Sent: Wednesday, August 26, 2009 10:19 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Spectra power up 900mhz I have a 900 mhz Spectra that will not power up .. i do have it hooked up like i have others, so i believe it is wired correctly.. am i missing a reset or master switch, or am i likey looking at ONE more doorstop here in the shack of plenty already .. mac/mc w5mc
Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
Hi AJ, I am thinking of building one element for a go kit antenna for temporary deployment on a existing mast or a piece of conduit. AJ aj.grant...@... wrote: Anyone built this non-folded dipole array project? It uses 3/4 copper pipe, PVC stand offs and 75 ohm coax for the phasing harness... http://forums.radioreference.com/attachments/antennas-coax-forum/16043d1213582941-4-bay-vhf-dipole-array-project-low-cost-high-performance-vhf-dipole-array.pdf
Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
One comment if I may, I noticed the UHF version shown had the dipoles spaced around the mast instead of directly one above the other. Spacing around the mast like that at this frequency gives very bad vertical and horizontal patterns and much reduced gain. That's because the horizontal displacement between dipoles is a large fraction of a wavelength. Laryn K8TVZ
Re: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
Correct. Don't do that with UHF. Can't imagine that the TV splitters held up too long under any real power ;-) Chuck WB2EDV - Original Message - From: larynl2 lar...@hotmail.com To: Repeater-Builder@yahoogroups.com Sent: Thursday, August 27, 2009 10:12 PM Subject: Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed One comment if I may, I noticed the UHF version shown had the dipoles spaced around the mast instead of directly one above the other. Spacing around the mast like that at this frequency gives very bad vertical and horizontal patterns and much reduced gain. That's because the horizontal displacement between dipoles is a large fraction of a wavelength. Laryn K8TVZ
RE: [Repeater-Builder] Spectra power up 900mhz
Try 12v in the pin next to ign sense I believe it is labled switched v+. If that powers the radio on then ther is a problem in the power switching circuit. Had one like that. When you sent power to the switched v+ line the front panel power switch would no longer turn the radio off, but who needs to turn a radio off anyway:) Sent by Good Messaging (www.good.com) -Original Message- From: Eric Lemmon [mailto:wb6...@verizon.net] Sent: Thursday, August 27, 2009 08:54 PM Eastern Standard Time To: Repeater-Builder@yahoogroups.com Subject:RE: [Repeater-Builder] Spectra power up 900mhz Mac, Check to see if your radio is configured to require ignition sense. What is the complete model number of your radio? 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Mac McCullough Sent: Wednesday, August 26, 2009 10:19 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Spectra power up 900mhz I have a 900 mhz Spectra that will not power up .. i do have it hooked up like i have others, so i believe it is wired correctly.. am i missing a reset or master switch, or am i likey looking at ONE more doorstop here in the shack of plenty already .. mac/mc w5mc Since 1974, the award-winning Alpert JFCS has helped families of all faiths throughout most of Palm Beach County, FL, via counseling, seniors services, residences for the disabled, mentoring children, support groups and a lot more. SOLUTIONS FOR LIVING www.JFCSonline.com Please take note of our new website and E-Mail Addresses. Please update your contacts ASAP. NOTICE: This e-mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged and confidential information. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, copying, or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately by replying to this message and please delete it from your computer.
Re: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
We strongly encouraged the gent to NOT use the TV splitters lol... The dipole spacing from the mast and the configuration of the dipoles around the mast was also in question... I guess the biggest upside to this project antenna is that all of the parts are readily available at Home Depot or Lowes, with the exception of the type F female Tee adapters which run a few bucks each online from L-com or Pasternack... The ones on eBay are just too short to fit a rubber weather bushing on to and expect it not to crush under the thread clearance - just a bit too short of threads for my liking. On Thu, Aug 27, 2009 at 8:42 PM, Chuck Kelsey wb2...@roadrunner.com wrote: Correct. Don't do that with UHF. Can't imagine that the TV splitters held up too long under any real power ;-) Chuck WB2EDV - Original Message - From: larynl2 lar...@hotmail.com larynl%40hotmail.com To: Repeater-Builder@yahoogroups.com Repeater-Builder%40yahoogroups.com Sent: Thursday, August 27, 2009 10:12 PM Subject: Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed One comment if I may, I noticed the UHF version shown had the dipoles spaced around the mast instead of directly one above the other. Spacing around the mast like that at this frequency gives very bad vertical and horizontal patterns and much reduced gain. That's because the horizontal displacement between dipoles is a large fraction of a wavelength. Laryn K8TVZ
