Re: [Repeater-Builder] 2M Vertical Dipoles
I posted a note on this a while back, but will recap here. I mounted four dipoles from a DB-224 on one leg of two sections of Rhon 25 and mounted the tower on an antenna range turntable. The pattern was a perfect circle, using DB Power readings around the 360 degrees. I thought I remembered the offset being 3 dB, but I must have been mistaken since it was pointed out that could not be the gain off the back of the antenna mounted this way. All four dipoles were stacked vertically on one leg of the tower and oriented directly away from the tower. The gain was measured as 9 dBd in the favored direction, coming down to 6 dBd at 90/270 degrees, and I thought I remembered the gain as 3 dBd off the back side of the tower, but it must have been a lower number. In any case, looking at the plot it appeared to be a perfect circle with an offset center. The center offset must not have been 3 dB. I was surprised that the tower did not cause a null off the backside, just caused a reduction in gain in that direction. This plot was submitted to the FCC to get repeater license WR5ADU and WR5ADV back in the '70s when antenna patterns for a repeater had to be submitted. 73 - Jim W5ZIT --- On Sun, 8/9/09, MCH m...@nb.net wrote: From: MCH m...@nb.net Subject: Re: [Repeater-Builder] 2M Vertical Dipoles To: Repeater-Builder@yahoogroups.com Date: Sunday, August 9, 2009, 6:33 PM Lots of comments on the unidirectional pattern which I suggested might not work well. Any comments on having the elements on one side of the tower right on the leg? Joe M. n...@no6b.com wrote: At 8/9/2009 05:47, you wrote: As frequency decreases, so does the importance of keeping the dipoles exactly above one another. This is why you can get away with mounting the bays of a LB array around a smaller tower (like Rohn 25) and still have very good omni-directional performance. Positioning the bays around a central supporting mast of a UHF array creates considerable pattern distortion and gain is lost. I once modeled this arrangement in NEC-Win: the resulting pattern looked like a warped pancake. On-horizon gain was all over the place. Bob NO6B - - -- Yahoo! Groups Links
Re: [Repeater-Builder] 2M Vertical Dipoles
Jim Brown wrote: This plot was submitted to the FCC to get repeater license WR5ADU and WR5ADV back in the '70s when antenna patterns for a repeater had to be submitted. Wow Jim, your an old geezer! Me too. I remember plotting the antenna pattern for a ground plane back in the early 70's for a repeater application. Silly, but it had to be done to meet the requirements. We got the call WR1ABR. 73, Joe, K1ike
Re: [Repeater-Builder] 2M Vertical Dipoles
As frequency decreases, so does the importance of keeping the dipoles exactly above one another. This is why you can get away with mounting the bays of a LB array around a smaller tower (like Rohn 25) and still have very good omni-directional performance. Positioning the bays around a central supporting mast of a UHF array creates considerable pattern distortion and gain is lost. DB Products and others used a method of exciting two dipoles at the same elevation - the double dipole. This makes the radiation center of the array the mast pipe, and at higher frequencies there is a big advantage to this. Frank Rossi, N3FLR and I did testing at my Seven Springs site in the early 90's with a Cushcraft UHF exposed dipole array. (Yes the ones with the RG-58 harness, poor connectors, and all that) I had a UHF repeater hooked to it and it was side mounted on the tower with stand-off brackets to minimize the blocking effects of the tower. I started out with the dipoles arranged one directly above another. In Greensburg and Pittsburgh (about 30 and 45 miles from the site) the repeater was usually full scale on Frank's S meter and he was received very well even on 5 watts. My house in Friedens (about 20 miles away) was in the null and I received the repeater on average about S-7. Testing was done for several days to get a benchmark. I then tried the antenna in omni, positioning the bays around the mast as Cushcraft suggested. The result was an increase toward Friedens of two S units (from S-7 to S-9) and a drop towards Frank from usually full scale to S-5 to S-9 - a considerable loss. It was soon learned that on UHF with single dipole arrays that you need to keep them one above another unless you can stand the considerable reduction in gain when going omni. The antenna worked so much better in every other direction than the exact null, that I went back to the directional pattern and dealt with it. The Cushcraft antenna was relegated to remote base use, and still works some 15 years later. It was sealed as well as could be done. The repeater was connected to a top mounted Stationmaster look-alike home brew 23 half-waves in phase with 3 degrees of downtilt. This antenna buries the S-Meter in all directions. http://www.repeater-builder.com/antenna/wa6svt.html I know of one high profile VHF repeater in Pittsburgh that uses a dipole array with the dipoles faced into the tower. It has amazing omni-directional range. Kevin Custer MCH wrote: I'm sure someone on *this* list will be able to correct me if I'm wrong, but I think you can mount virtually any of the dipole type antennas on the tower leg as long as you're not looking for a 360 pattern. An offset or figure-8 pattern, though, no problem. In fact, I've done this for commercial users, and in some cases such as Low Band dipoles, that's the only way to can mount them. You might even be able to get away with it mounting one on each leg for a 360 pattern (with a little more gain in one direction for a 4-bay antenna), but your gain would be messed up since the signal would then be out of phase for each element in any given direction. Joe M. Doug Rehman wrote: I remember seeing a vertical dipole from one on the amateur antenna manufacturers that was designed to bolt onto your mast or tower leg. I think it might have come in a kit of 2 or 4. I thought it was Cushcraft, but I couldn't find it. Does anyone have any idea what antenna I thought I saw? Thanks, Doug K4AC Yahoo! Groups Links Internal Virus Database is out of date. Checked by AVG - www.avg.com Version: 8.5.387 / Virus Database: 270.13.38/2274 - Release Date: 07/31/09 05:58:00 Yahoo! Groups Links No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.392 / Virus Database: 270.13.48/2291 - Release Date: 08/08/09 18:17:00
Re: [Repeater-Builder] 2M Vertical Dipoles
At 8/9/2009 05:47, you wrote: As frequency decreases, so does the importance of keeping the dipoles exactly above one another. This is why you can get away with mounting the bays of a LB array around a smaller tower (like Rohn 25) and still have very good omni-directional performance. Positioning the bays around a central supporting mast of a UHF array creates considerable pattern distortion and gain is lost. I once modeled this arrangement in NEC-Win: the resulting pattern looked like a warped pancake. On-horizon gain was all over the place. Bob NO6B
RE: [Repeater-Builder] 2M Vertical Dipoles
It was indeed the Telewave ANT-150D that I had seen; I just found the ad in the August QST. Unfortunately, the Telewave is out of the budget for this project though. Is anyone familiar with the Antenex YDA1364? (4 dipole array) http://www.ameradio.com/product/9449/description.html Has anyone done business with ameradio.com? Their price is $217; Hutton's is $309. I only need 2 dipoles, but it looks like the harness could be easily split for two sets of 2 dipoles. (They offer a 2 dipole array for the higher frequency range, but not for the range covering 2 meters.) Since I need omni coverage on a rotating mast, maybe putting two elements back to back would work (like the UHF DB antennas use for each bay)? Doug K4AC From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Edmund F Leavitt Sent: Saturday, August 08, 2009 10:49 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] 2M Vertical Dipoles Do you recall if it was a dipole or folded dipole? Edmund Leavitt Ph: 253 582-5034 Ham / MARS / Federal K7EFL / AFA0AH / KPS654 Lakewood, WA USNG: 10TET36292223
Re: [Repeater-Builder] 2M Vertical Dipoles
Lots of comments on the unidirectional pattern which I suggested might not work well. Any comments on having the elements on one side of the tower right on the leg? Joe M. n...@no6b.com wrote: At 8/9/2009 05:47, you wrote: As frequency decreases, so does the importance of keeping the dipoles exactly above one another. This is why you can get away with mounting the bays of a LB array around a smaller tower (like Rohn 25) and still have very good omni-directional performance. Positioning the bays around a central supporting mast of a UHF array creates considerable pattern distortion and gain is lost. I once modeled this arrangement in NEC-Win: the resulting pattern looked like a warped pancake. On-horizon gain was all over the place. Bob NO6B Yahoo! Groups Links
Re: [Repeater-Builder] 2M Vertical Dipoles
If you want to get better omni coverage, you'll need to attach the dipoles to a mast and use stand-off brackets to hold it away from the tower. The pattern will still be affected by the tower, but not as drastically. Chuck WB2EDV - Original Message - From: MCH m...@nb.net To: Repeater-Builder@yahoogroups.com Sent: Sunday, August 09, 2009 7:33 PM Subject: Re: [Repeater-Builder] 2M Vertical Dipoles Lots of comments on the unidirectional pattern which I suggested might not work well. Any comments on having the elements on one side of the tower right on the leg? Joe M. n...@no6b.com wrote: At 8/9/2009 05:47, you wrote: As frequency decreases, so does the importance of keeping the dipoles exactly above one another. This is why you can get away with mounting the bays of a LB array around a smaller tower (like Rohn 25) and still have very good omni-directional performance. Positioning the bays around a central supporting mast of a UHF array creates considerable pattern distortion and gain is lost. I once modeled this arrangement in NEC-Win: the resulting pattern looked like a warped pancake. On-horizon gain was all over the place. Bob NO6B Yahoo! Groups Links Yahoo! Groups Links
Re: [Repeater-Builder] 2M Vertical Dipoles
DOH! Let me rephrase that... Lots of comments on the omnidirectional pattern which I suggested might not work well. Any comments on having the elements on one side of the tower right on the leg? Joe M. MCH wrote: Lots of comments on the unidirectional pattern which I suggested might not work well. Any comments on having the elements on one side of the tower right on the leg? Joe M. n...@no6b.com wrote: At 8/9/2009 05:47, you wrote: As frequency decreases, so does the importance of keeping the dipoles exactly above one another. This is why you can get away with mounting the bays of a LB array around a smaller tower (like Rohn 25) and still have very good omni-directional performance. Positioning the bays around a central supporting mast of a UHF array creates considerable pattern distortion and gain is lost. I once modeled this arrangement in NEC-Win: the resulting pattern looked like a warped pancake. On-horizon gain was all over the place. Bob NO6B Yahoo! Groups Links Yahoo! Groups Links
Re: [Repeater-Builder] 2M Vertical Dipoles
That will work well to favor one area. Chuck WB2EDV - Original Message - From: MCH m...@nb.net To: Repeater-Builder@yahoogroups.com Sent: Sunday, August 09, 2009 7:40 PM Subject: Re: [Repeater-Builder] 2M Vertical Dipoles DOH! Let me rephrase that... Lots of comments on the omnidirectional pattern which I suggested might not work well. Any comments on having the elements on one side of the tower right on the leg? Joe M. MCH wrote: Lots of comments on the unidirectional pattern which I suggested might not work well. Any comments on having the elements on one side of the tower right on the leg? Joe M. n...@no6b.com wrote: At 8/9/2009 05:47, you wrote: As frequency decreases, so does the importance of keeping the dipoles exactly above one another. This is why you can get away with mounting the bays of a LB array around a smaller tower (like Rohn 25) and still have very good omni-directional performance. Positioning the bays around a central supporting mast of a UHF array creates considerable pattern distortion and gain is lost. I once modeled this arrangement in NEC-Win: the resulting pattern looked like a warped pancake. On-horizon gain was all over the place. Bob NO6B Yahoo! Groups Links Yahoo! Groups Links Yahoo! Groups Links
RE: [Repeater-Builder] 2M Vertical Dipoles
Chuck, Would that be with the dipoles all pointed in the same direction, of set up so they face different directions for Omni reception. I picked up an almost new DB224 but no mast so I am following this thread with interest. 73 JIM KA2AJH From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Sunday, August 09, 2009 7:43 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] 2M Vertical Dipoles That will work well to favor one area. Chuck WB2EDV - Original Message - From: MCH m...@nb.net mailto:mch%40nb.net To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Sent: Sunday, August 09, 2009 7:40 PM Subject: Re: [Repeater-Builder] 2M Vertical Dipoles DOH! Let me rephrase that... Lots of comments on the omnidirectional pattern which I suggested might not work well. Any comments on having the elements on one side of the tower right on the leg? Joe M. MCH wrote: Lots of comments on the unidirectional pattern which I suggested might not work well. Any comments on having the elements on one side of the tower right on the leg? Joe M. n...@no6b.com mailto:no6b%40no6b.com wrote: At 8/9/2009 05:47, you wrote: As frequency decreases, so does the importance of keeping the dipoles exactly above one another. This is why you can get away with mounting the bays of a LB array around a smaller tower (like Rohn 25) and still have very good omni-directional performance. Positioning the bays around a central supporting mast of a UHF array creates considerable pattern distortion and gain is lost. I once modeled this arrangement in NEC-Win: the resulting pattern looked like a warped pancake. On-horizon gain was all over the place. Bob NO6B Yahoo! Groups Links Yahoo! Groups Links Yahoo! Groups Links
Re: [Repeater-Builder] 2M Vertical Dipoles
I was speaking of pointing all the elements in the same direction - away from the tower, all mounted on the same leg. You should see good gain for about 180 degrees in the direction the elements are pointed. Hard to say whet you'll get off the back of the tower, but it might not be as bad as you think. Sometime you just have to try it. Chuck WB2EDV - Original Message - From: Jim Cicirello To: Repeater-Builder@yahoogroups.com Sent: Sunday, August 09, 2009 7:51 PM Subject: RE: [Repeater-Builder] 2M Vertical Dipoles Chuck, Would that be with the dipoles all pointed in the same direction, of set up so they face different directions for Omni reception. I picked up an almost new DB224 but no mast so I am following this thread with interest. 73 JIM KA2AJH From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Sunday, August 09, 2009 7:43 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] 2M Vertical Dipoles That will work well to favor one area. Chuck WB2EDV
Re: [Repeater-Builder] 2M Vertical Dipoles
Anyone have any info on a Regency Micro-Comm U10R ? Especially the pinout of the 15-pin Molex plug? I have one here and was wondering if it was worth resurrecting. Mike WA6ILQ
[Repeater-Builder] 2M Vertical Dipoles
I remember seeing a vertical dipole from one on the amateur antenna manufacturers that was designed to bolt onto your mast or tower leg. I think it might have come in a kit of 2 or 4. I thought it was Cushcraft, but I couldn't find it. Does anyone have any idea what antenna I thought I saw? Thanks, Doug K4AC
Re: [Repeater-Builder] 2M Vertical Dipoles
Cushcraft used to have that antenna. Since discontinued. Regards de W1EL Eric Lowell Eastern Maine Electronics Inc. 48 Loon Road Wesley ME 04686 eme@starband.net www.satnetmaine.com --- On Sat, 8/8/09, Doug Rehman d...@k4ac.com wrote: From: Doug Rehman d...@k4ac.com Subject: [Repeater-Builder] 2M Vertical Dipoles To: Repeater-Builder@yahoogroups.com Date: Saturday, August 8, 2009, 10:11 PM I remember seeing a vertical dipole from one on the amateur antenna manufacturers that was designed to bolt onto your mast or tower leg. I think it might have come in a kit of 2 or 4. I thought it was Cushcraft, but I couldn't find it. Does anyone have any idea what antenna I thought I saw? Thanks, Doug K4AC
Re: [Repeater-Builder] 2M Vertical Dipoles
Cushcraft made a 4-pole array for 2-meters and for 440. Neither were particularly good antennas. They were gamma-fed dipoles with a connector that was nearly impossible to weatherproof. Lots better antennas out there. Chuck WB2EDV - Original Message - From: Doug Rehman d...@k4ac.com To: Repeater-Builder@yahoogroups.com Sent: Saturday, August 08, 2009 10:11 PM Subject: [Repeater-Builder] 2M Vertical Dipoles I remember seeing a vertical dipole from one on the amateur antenna manufacturers that was designed to bolt onto your mast or tower leg. I think it might have come in a kit of 2 or 4. I thought it was Cushcraft, but I couldn't find it. Does anyone have any idea what antenna I thought I saw? Thanks, Doug K4AC Yahoo! Groups Links
RE: [Repeater-Builder] 2M Vertical Dipoles
Thanks for the info on Cushcraft, although I thought I'd run across the antenna I'm remembering within the last couple of months (current production). I'm looking for something that I can mount on the mast of my home tower, interwoven between other antennas on the mast. (Obviously with appropriate spacing from anything that would seriously interact. Not looking to spend either copious amounts of money buying a commercial antenna or copious amounts of time building something from scratch.) Doug K4AC
RE: [Repeater-Builder] 2M Vertical Dipoles
I recently installed a Telewave ANT-150-D single dipole on a side mast for a link radio. It works perfectly. This is a commercial-quality, heavy-duty antenna that covers 138-174 MHz. Info here: www.telewave.com/pdf/TWDS-7045.pdf Disclaimer: Although I frequently mention Telewave as a source for RF products, I do so only as a satisfied customer. I have no financial connection to the company. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Saturday, August 08, 2009 7:19 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] 2M Vertical Dipoles Cushcraft made a 4-pole array for 2-meters and for 440. Neither were particularly good antennas. They were gamma-fed dipoles with a connector that was nearly impossible to weatherproof. Lots better antennas out there. Chuck WB2EDV - Original Message - From: Doug Rehman d...@k4ac.com mailto:doug%40k4ac.com To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Sent: Saturday, August 08, 2009 10:11 PM Subject: [Repeater-Builder] 2M Vertical Dipoles I remember seeing a vertical dipole from one on the amateur antenna manufacturers that was designed to bolt onto your mast or tower leg. I think it might have come in a kit of 2 or 4. I thought it was Cushcraft, but I couldn't find it. Does anyone have any idea what antenna I thought I saw? Thanks, Doug K4AC Yahoo! Groups Links
Re: [Repeater-Builder] 2M Vertical Dipoles
FYI, MFJ just purchased the Cushcraft antenna line. Chuck WB2EDV - Original Message - From: Doug Rehman d...@k4ac.com To: Repeater-Builder@yahoogroups.com Sent: Saturday, August 08, 2009 10:31 PM Subject: RE: [Repeater-Builder] 2M Vertical Dipoles Thanks for the info on Cushcraft, although I thought I'd run across the antenna I'm remembering within the last couple of months (current production). I'm looking for something that I can mount on the mast of my home tower, interwoven between other antennas on the mast. (Obviously with appropriate spacing from anything that would seriously interact. Not looking to spend either copious amounts of money buying a commercial antenna or copious amounts of time building something from scratch.) Doug K4AC Yahoo! Groups Links
Re: [Repeater-Builder] 2M Vertical Dipoles
I've got experience with both their single ANT450D (single) and ANT450D6-9 (quad) UHF dipoles. I absolutely love them. I also frequently promote Telewave and have zero pecuniary interest in the company. In my experience their products are just awesome and the support is almost unbelievably good. I only believe it because I pinched myself and was awake during those conversations with folks at Telewave :) On Aug 8, 2009, at 9:34 PM, Eric Lemmon wrote: I recently installed a Telewave ANT-150-D single dipole on a side mast for a link radio. It works perfectly. This is a commercial-quality, heavy- duty antenna that covers 138-174 MHz. Info here: www.telewave.com/pdf/TWDS-7045.pdf Disclaimer: Although I frequently mention Telewave as a source for RF products, I do so only as a satisfied customer. I have no financial connection to the company. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Saturday, August 08, 2009 7:19 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] 2M Vertical Dipoles Cushcraft made a 4-pole array for 2-meters and for 440. Neither were particularly good antennas. They were gamma-fed dipoles with a connector that was nearly impossible to weatherproof. Lots better antennas out there. Chuck WB2EDV - Original Message - From: Doug Rehman d...@k4ac.com mailto:doug%40k4ac.com To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Sent: Saturday, August 08, 2009 10:11 PM Subject: [Repeater-Builder] 2M Vertical Dipoles I remember seeing a vertical dipole from one on the amateur antenna manufacturers that was designed to bolt onto your mast or tower leg. I think it might have come in a kit of 2 or 4. I thought it was Cushcraft, but I couldn't find it. Does anyone have any idea what antenna I thought I saw? Thanks, Doug K4AC Yahoo! Groups Links
Re: [Repeater-Builder] 2M Vertical Dipoles
Do you recall if it was a dipole or folded dipole? Edmund Leavitt Ph:253 582-5034 Ham / MARS / Federal K7EFL / AFA0AH / KPS654 Lakewood, WA USNG: 10TET36292223 On Sat, 8 Aug 2009 22:11:52 -0400 Doug Rehman d...@k4ac.com writes: I remember seeing a vertical dipole from one on the amateur antenna manufacturers that was designed to bolt onto your mast or tower leg. I think it might have come in a kit of 2 or 4. I thought it was Cushcraft, but I couldn't find it. Does anyone have any idea what antenna I thought I saw? Thanks, Doug K4AC You have a right to seek justice! Click here to find experienced lawyers across the USA. http://thirdpartyoffers.juno.com/TGL2141/fc/BLSrjpTOhjXagBI3wM1CfEenB4r9FkfTVzx0f1z5NEPhxxFnIBYiZWd5jck/
Re: [Repeater-Builder] 2M Vertical Dipoles
I'm sure someone on *this* list will be able to correct me if I'm wrong, but I think you can mount virtually any of the dipole type antennas on the tower leg as long as you're not looking for a 360 pattern. An offset or figure-8 pattern, though, no problem. In fact, I've done this for commercial users, and in some cases such as Low Band dipoles, that's the only way to can mount them. You might even be able to get away with it mounting one on each leg for a 360 pattern (with a little more gain in one direction for a 4-bay antenna), but your gain would be messed up since the signal would then be out of phase for each element in any given direction. Joe M. Doug Rehman wrote: I remember seeing a vertical dipole from one on the amateur antenna manufacturers that was designed to bolt onto your mast or tower leg. I think it might have come in a kit of 2 or 4. I thought it was Cushcraft, but I couldn't find it. Does anyone have any idea what antenna I thought I saw? Thanks, Doug K4AC Yahoo! Groups Links Internal Virus Database is out of date. Checked by AVG - www.avg.com Version: 8.5.387 / Virus Database: 270.13.38/2274 - Release Date: 07/31/09 05:58:00
