[Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
Actually... the 4 and 8 bay antennas, 2 dipoles side by side on one horizontal cross arm, mounted over the same assembly spaced vertically on the mast/pole. The 8 bay antenna has 4 cross arms (2 dipoles on a horizontal cross arm) per mast/pole. Didn't matter which way the dipoles bays were aligned. Normally two of the horizontal cross arms were parallel or perpendicular depending on the desired pattern. I should try one of the 2 dipole horizontal arms by itself to see if it just as easily makes a gremlin (IMD). I have a large number of the vertical in-line (single) sinclair antennas and they work very well. I also have some of the above multi bay antennas in the UHF Version without the grunge (gremlin) generator problem. A Sinclair Engineer (at IWCE) told me they reworked the VHF problem generator antenna models and the newer, current versions don't have that problem. I have yet to hear reports from persons using the current version. The dipole engineering is sound and I've used it (and their products) in many other locations and applications. There's just some quirk in that version of putting 2 or 4 VHF dual dipole assemblies over each other with the supplied coax harness that becomes an easy IMD/PIM (grunge) generator. cheers, s. Chuck Kelsey wb2...@... wrote: OK, those weren't a problem according to Skipp. The problem ones were those with two dipoles mounted at the same elevation on opposing sides of the mast. Chuck WB2EDV - Original Message - From: Nate Duehr n...@... To: Repeater-Builder@yahoogroups.com Sent: Monday, May 25, 2009 12:13 AM Subject: Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy) On May 22, 2009, at 6:08 AM, Chuck Kelsey wrote: Nate - Were these dual-dipole arrays - a total of 4 elements? Or were they two elements - one mounted over the top of the other? Chuck WB2EDV 2-elements only, vertically mounted one above the other. http://www.sinclairtechnologies.com/catalog/product.aspx?id=1682 -- Nate Duehr, WY0X n...@...
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
On Wed, 20 May 2009 17:29:21 -, skipp025 skipp...@yahoo.com said: Note the problematic Sinclair VHF dipole arrays are/were the models with two Dipoles per mast position, which means each location on the mast has a horizontal bar with a folded dipoles at each end of the mast (two parallel dipoles per horizontal mast). The traditional in-line folded dipole arrays work muy bueno... (very well). Just the dual side-by-side FD arrays are the train wreck (in what appear to be the 4 and 8 bay assemblies). I would also cautiously throw in here (knock on wood) that we've had EXCELLENT luck with the 2-bay vertical Sinclair folded-dipole antennas for situations where lower-gain or just less space/weight/height of the antenna was needed on VHF. They're significantly less expensive than the bigger antennas also, and would be a great starter antenna for a VHF group limited on funds, or just starting out. We replaced a ten year old antenna (you guys all know this drill) that had slowly degraded (but we didn't know it yet) when we had to move towers a few years ago at one of our sites, and decided that the appropriate sized antenna for that site was now going to be a 2-bay to fit the tower space. It wasn't what we wanted for gain to the horizon, but we knew we'd just have to live with it. Living with it has been EASY. The darn site covers 10-15 more miles on an HT than it did prior to the swap-out, and is heard in places on mobiles that it was never heard at all before. (Unfortunately the tower move shadowed it up a popular canyon/wilderness area BEHIND the mountain-top site, and that's brought a few (literally two or three) complaints...) One theory is that this is a LOW mountain-top site, and there's mountains BEHIND it that with higher take-off angles from the 2-bay, we're bouncing around more. Not multipath, mind you... just filling in better all over the place. Obviously the bad antenna wasn't helping things any, but the change is too dramatic to only be a function of that. So, for those looking at Sinclair antennas... I really can't say anything bad about the little 2-bay Sinclairs! There may be problems with those cross-arm folded dipole array things Skipp was giving a try... maybe it's just not a design Sinclair is any good at. But as for the vertical folded-dipole arrays, we're about to fire up another VHF machine on one of them... I'll share with the group how that one works out. Two clubs at the same site bought two of the 2-bays (one each) last fall, and tried to rush them to the hill for another tower move... unfortunately both antennas had a mishap on the way here (run over by a forklift) and by the time the replacements arrived, we were into snowy season. Now this spring, the 2-bays are up, one's in service, and ours goes in service in the next few weeks (hopefully... lots of work to do still), and so far the other group seems happy with the performance. I expect similar once I get the repeater moved and attached to ours. Of course, using brand new hardline and connectors, and rebuilding that entire site from the ground up in a new building isn't hurting anyone either...! But at the end of the summer, it'll be interesting to start seeing where people hear/use that machine. We're not going for massive coverage down there... the mountain already takes care of most of that... but what I really want to see is if the same bounce around effect helps this close-in, low-mountain machine as much as it did the other one. (Heck, if I knew the 2-bays worked THAT good from this type of site, I'd have put these things up sooner! S much easier to lift a 2-bay VHF than a 4 or 8 bay... no need for trucks or winches or big brute muscles... just a dude or two on the ground and a pulley... GRIN!) Nate WY0X -- Nate Duehr n...@natetech.com
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
Nate Duehr wrote: I would also cautiously throw in here (knock on wood) that we've had EXCELLENT luck with the 2-bay vertical Sinclair folded-dipole antennas (snip) (Heck, if I knew the 2-bays worked THAT good from this type of site, I'd have put these things up sooner! S much easier to lift a 2-bay VHF than a 4 or 8 bay... no need for trucks or winches or big brute muscles... just a dude or two on the ground and a pulley... GRIN!) Thanks for sharing your experience Nate. In the last week I have been consistently surprised by how well the single dipole I put up on the tower is working. Signals are down a bit from the 8 element array in what were its favored directions, but not by as much as I was expecting. Perhaps I should consider making a 2-bay out of parts from the beast and evaluate that for a while before deciding about going to a 4-bay. Assuming I don't run into noise problems again when I start combining these dipoles into arrays, I'll end up going to 4 eventually. I'm trying to cover an impossible area from the only site available. It's a good site but our terrain around here is NOT VHF friendly. Yep... that darn 8-bay was HEAVY. Ya don't even wanna know how that was installed! Er... or I'm afraid to tell anyone for fear they'd wanna have someone who shall remain nameless committed! ;-) Paul N1BUG
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
Nate - Were these dual-dipole arrays - a total of 4 elements? Or were they two elements - one mounted over the top of the other? Chuck WB2EDV - Original Message - I would also cautiously throw in here (knock on wood) that we've had EXCELLENT luck with the 2-bay vertical Sinclair folded-dipole antennas for situations where lower-gain or just less space/weight/height of the antenna was needed on VHF.
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
Skipp, Do you have any idea WHY the models with two dipoles side-by-side are problematic and the in-line models are not? Are there differences in the construction of the individual dipoles that cause problems? Differences in the phasing harness? I'm thinking about using these dipoles to build an in-line 4 bay array with my own harness, but if the dipoles themselves are prone to problems that would seem a waste of more time and money. I was considering doing that even before the array became a noise nightmare, since it would produce a pattern somewhat more to my liking and maybe (depending on how it was done) reduce weight and wind load. When (if?) I recover from blood loss to black flies at the repeater site today, I will report on my findings testing individual dipoles from the problematic array Paul N1BUG skipp025 wrote: Note the problematic Sinclair VHF dipole arrays are/were the models with two Dipoles per mast position, which means each location on the mast has a horizontal bar with a folded dipoles at each end of the mast (two parallel dipoles per horizontal mast). The traditional in-line folded dipole arrays work muy bueno... (very well). Just the dual side-by-side FD arrays are the train wreck (in what appear to be the 4 and 8 bay assemblies).
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
The db/Andrew/Comscope folded dipoles do not have this problem? Why not? What is the difference? 73 de N5NPO Norm Knapp - Original Message - From: Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com To: Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com Sent: Wed May 20 11:11:06 2009 Subject: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy) Should be in the group archives a few years back. Sinclair renamed/changed the names/model numbers for pretty much the exact same vhf antennas I have had all the hell with... but they are pretty much the same design as the current models with reported changes in the coax harness/feed system to address the IMD/PIM problem. I've spoken to former Sinclair Engineers in person more than once... got a lot of smoke blown up my back side but no resolution/solution to the antenna models I still have in storage. I know of one state agency still using the problematic VHF dipole assemblies and still experiencing grief they don't acknowledge or seem to want to properly deal with. Go figure... The IMD/PIM generation happens/happened in that series 4 and 8 bay (two horizontal spaced dipoles per mast position) folded dipole antenna models. A Sinclair Engineer in a face to face conversation suggested I re-install my 4 bay antennas using the information from their current (same) product (with a different model number). No cigar... No fun... lots of money and time wasted. s. Chuck Kelsey wb2...@... wrote: Boy, for some reason, there's a discussion I don't recall. Oh well. The only array from Sinclair I was aware of as being trouble was their SRL222/SD222 series. Chuck WB2EDV - Original Message - From: skipp025 skipp...@... To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Sent: Tuesday, May 19, 2009 7:01 PM Subject: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy) There are known problems with this series of antennas... see my previous posts bad-mouthing Sinclair regarding this same situation.
[Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
Note the problematic Sinclair VHF dipole arrays are/were the models with two Dipoles per mast position, which means each location on the mast has a horizontal bar with a folded dipoles at each end of the mast (two parallel dipoles per horizontal mast). The traditional in-line folded dipole arrays work muy bueno... (very well). Just the dual side-by-side FD arrays are the train wreck (in what appear to be the 4 and 8 bay assemblies). s. NORM KNAPP nkn...@... wrote: The db/Andrew/Comscope folded dipoles do not have this problem? Why not? What is the difference? 73 de N5NPO Norm Knapp
[Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
Should be in the group archives a few years back. Sinclair renamed/changed the names/model numbers for pretty much the exact same vhf antennas I have had all the hell with... but they are pretty much the same design as the current models with reported changes in the coax harness/feed system to address the IMD/PIM problem. I've spoken to former Sinclair Engineers in person more than once... got a lot of smoke blown up my back side but no resolution/solution to the antenna models I still have in storage. I know of one state agency still using the problematic VHF dipole assemblies and still experiencing grief they don't acknowledge or seem to want to properly deal with. Go figure... The IMD/PIM generation happens/happened in that series 4 and 8 bay (two horizontal spaced dipoles per mast position) folded dipole antenna models. A Sinclair Engineer in a face to face conversation suggested I re-install my 4 bay antennas using the information from their current (same) product (with a different model number). No cigar... No fun... lots of money and time wasted. s. Chuck Kelsey wb2...@... wrote: Boy, for some reason, there's a discussion I don't recall. Oh well. The only array from Sinclair I was aware of as being trouble was their SRL222/SD222 series. Chuck WB2EDV - Original Message - From: skipp025 skipp...@... To: Repeater-Builder@yahoogroups.com Sent: Tuesday, May 19, 2009 7:01 PM Subject: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy) There are known problems with this series of antennas... see my previous posts bad-mouthing Sinclair regarding this same situation.
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
NORM KNAPP wrote: The db/Andrew/Comscope folded dipoles do not have this problem? Why not? What is the difference? 73 de N5NPO Norm Knapp - Original Message - From: Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com To: Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com Sent: Wed May 20 11:11:06 2009 Subject: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy) Should be in the group archives a few years back. Sinclair renamed/changed the names/model numbers for pretty much the exact same vhf antennas I have had all the hell with... but they are pretty much the same design as the current models with reported changes in the coax harness/feed system to address the IMD/PIM problem. I've spoken to former Sinclair Engineers in person more than once... got a lot of smoke blown up my back side but no resolution/solution to the antenna models I still have in storage. I know of one state agency still using the problematic VHF dipole assemblies and still experiencing grief they don't acknowledge or seem to want to properly deal with. Go figure... The IMD/PIM generation happens/happened in that series 4 and 8 bay (two horizontal spaced dipoles per mast position) folded dipole antenna models. A Sinclair Engineer in a face to face conversation suggested I re-install my 4 bay antennas using the information from their current (same) product (with a different model number). No cigar... No fun... lots of money and time wasted. s. Chuck Kelsey wb2...@... wrote: Boy, for some reason, there's a discussion I don't recall. Oh well. The only array from Sinclair I was aware of as being trouble was their SRL222/SD222 series. Chuck WB2EDV - Original Message - From: skipp025 skipp...@... To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Sent: Tuesday, May 19, 2009 7:01 PM Subject: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy) There are known problems with this series of antennas... see my previous posts bad-mouthing Sinclair regarding this same situation. Yahoo! Groups Links We have had several failures with 2 Siclair 219 C4-2 antennas and 1 Sinclair 229 (which was replaced by Sinclair after warantee). Symtoms were very bad dioding and reduced receiver sensitivity. As these antennas are $1200 and $1800 for 1/2 wave spaced 4 pole up here. We did not want a repeat of the problems. Our solution was to use Comprod antennas which have performed flawlessly. Roger VA7RS
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
O I C. I guess I have never seen dipole arrays in a horixontal array before. I didn't know that would work. - Original Message - From: Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com To: Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com Sent: Wed May 20 12:29:21 2009 Subject: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy) Note the problematic Sinclair VHF dipole arrays are/were the models with two Dipoles per mast position, which means each location on the mast has a horizontal bar with a folded dipoles at each end of the mast (two parallel dipoles per horizontal mast). The traditional in-line folded dipole arrays work muy bueno... (very well). Just the dual side-by-side FD arrays are the train wreck (in what appear to be the 4 and 8 bay assemblies). s. NORM KNAPP nkn...@... wrote: The db/Andrew/Comscope folded dipoles do not have this problem? Why not? What is the difference? 73 de N5NPO Norm Knapp
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
Very common for UHF. Not seen as often on VHF. Google some of the antenna manufacturers or Tessco and look around. Chuck WB2EDV - Original Message - From: NORM KNAPP nkn...@twowayradio.net To: Repeater-Builder@yahoogroups.com Sent: Wednesday, May 20, 2009 8:50 PM Subject: Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy) O I C. I guess I have never seen dipole arrays in a horixontal array before. I didn't know that would work.
[Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
--- In Repeater-Builder@yahoogroups.com, NORM KNAPP nkn...@... wrote: O I C. I guess I have never seen dipole arrays in a horixontal array before. I didn't know that would work. You've seen them. A DB420 (one example) has 8 positions vertically, each position has a pair of dipoles next to each other. Laryn K8TVZ
[Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
There are known problems with this series of antennas... see my previous posts bad-mouthing Sinclair regarding this same situation. I was only told that Sinclair has reworked the model and the update reportedly fixed the problem. I never received a return phone call or Email regarding my same type of problem with a lot of similar type/model Sinclair antennas I purchased. So I bad mouth that antenna model/series all I can and give Sinclair grief about their customer service and engineering at the IWCE Convention. So far they haven't cared to resolve my, nor 3 known similar customer/owner problems. When you start to stack more than one of that series/type folded dipoles into an array... they start to glitch themselves up pretty bad with IMD/PIM Issues. You will find the same type/series of antenna under a few different labels/model numbers. But it/they are still a very bad design. Search back through the group archives for more details regarding my previous posts. It's not a happy story... cheers, skipp skipp025 at yahoo.com Paul Kelley N1BUG paul.kelley.n1...@... wrote: Several weeks ago I posted about my ongoing battle with duplex noise on a 2 meter repeater. I have now found a big piece of the problem (maybe all of it) but I'm a little surprised. I am wondering if others have had similar experiences. Two years ago I put up a new (well... NOS, actually) Sinclair SD2352 antenna (8 dipoles, bidirectional pattern). I had no noise for several months after that, but then it started coming back. By this Spring the repeater had become all but unusable. Recently I took down the Sinclair and installed a temporary antenna. Noise gone! Huh? I subsequently disassembled the Sinclair to check for problems. Every piece of hardware was tight. I found no evidence of water in any of the N connectors on the harness, which I had wrapped with Scotch 23 rubber tape followed by Super 88 vinyl tape. The impedance of the complete array and of each individual dipole was still nominal, as it had been prior to being installed. I have now put one dipole from the array on the tower and it is running absolutely noise free. Moving it around on the tower doesn't have any affect... it is noise free wherever I put it. Lacking any other explanation it would seem something in the array became noisy after a short time. I don't know if it is a problem with one or more of the dipoles or perhaps something in the factory assembled portion of the harness. I have not yet attempted to do a post mortem on the factory harness assemblies. I am wondering if this is a unique experience or if this is a common failure mode in exposed dipole arrays? I don't recall hearing much about such arrays becoming noisy, at least in such a short time. Since these dipoles are 50 ohms, I think it would be easy enough to build two 4-dipole cardioid arrays from it, *if* the problem lies in the harness and not in one or more of the dipoles. I wonder if anyone knows what (if any) gimmick Sinclair used to get such broad SWR bandwidth on these dipoles? The exposed portion of the coax on each dipole is RG-213, 50 ohms... but I'm wondering if they may use some quarter wavelength (or ???) of some other impedance on the part hidden inside the dipole, especially since these things exhibit a clear double dip SWR curve (one dip near the low end of the design range, 138 MHz, and another dip near the upper end, 174 MHz, with a somewhat reactive bump in between). 73, Paul N1BUG
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
Boy, for some reason, there's a discussion I don't recall. Oh well. The only array from Sinclair I was aware of as being trouble was their SRL222/SD222 series. Chuck WB2EDV - Original Message - From: skipp025 skipp...@yahoo.com To: Repeater-Builder@yahoogroups.com Sent: Tuesday, May 19, 2009 7:01 PM Subject: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy) There are known problems with this series of antennas... see my previous posts bad-mouthing Sinclair regarding this same situation.
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
That's interesting Skipp. I'm searching. I did find a couple references to PIM/IMD problems and one about poor signal with this type antenna. The latter caught my eye as I've been sitting here half thinking coverage with this single dipole I tossed up there *seems* to be as good as with the whole array. I can't be sure since I haven't been out there to really see for myself what it is doing. At this point it's just a funny feeling I keep getting. Might be nothing to it... I'd have to go drive around for half a day to be sure. I will keep digging for old posts on the subject... Paul N1BUG skipp025 wrote: There are known problems with this series of antennas... see my previous posts bad-mouthing Sinclair regarding this same situation. I was only told that Sinclair has reworked the model and the update reportedly fixed the problem. I never received a return phone call or Email regarding my same type of problem with a lot of similar type/model Sinclair antennas I purchased. So I bad mouth that antenna model/series all I can and give Sinclair grief about their customer service and engineering at the IWCE Convention. So far they haven't cared to resolve my, nor 3 known similar customer/owner problems. When you start to stack more than one of that series/type folded dipoles into an array... they start to glitch themselves up pretty bad with IMD/PIM Issues. You will find the same type/series of antenna under a few different labels/model numbers. But it/they are still a very bad design. Search back through the group archives for more details regarding my previous posts. It's not a happy story... cheers, skipp
