On Wed, 20 May 2009 17:29:21 -0000, "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! Soooo 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
