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 Rotators ...
 M0SPN     Quote Post
Posted: Jul 12 2005, 07:39 AM Post #1527 
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Hi All,

My plans for world domination are a stage closer to implementation ... I'm now looking at a single mast/pole with a 2m 5 element ZL on the bottom, a 70cm 7 element above, and a triband colinear perched on top. The 2m beam being the largest (at roughly 1sq.metre) means this will hopefully not put too much strain on the mast / rotator.

I've seen several rotators advertised for 40 to 60. My desired antennas are reasonably lightweight, and should come in below the maximum weight stated on the rotator specs.

Question is - are these cheap rotators perfectly usable for VHF/UHF work, or are they more hassle than they're worth? Whilst I'm reluctant to spend 300+ on a yaesu rotator, I'm also reluctant to hire ladders / pay others to get on the roof and fix a cheapy everytime it strips a cog / jams / cracks. The roof is very awkward to get to - and involves standing on a neigbours roof - so I'd prefer to get his agreement for a one off 'installation', get the metal in the air and leave it for as long as possible smile.gif

Any experience / suggestions would be very welcome. It seems crazy spending 150 on antennas, and then *at least twice that* on a rotator. However ... if that's what's needed I'll have to budget for it.

Antenna installation has been put on hold as the XYL has decided she wants to change her car. So ... antenna plans will have to wait until next month now rolleyes.gif

Steve M0SPN
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 Brian G8ADD   Quote Post
Posted: Jul 12 2005, 08:45 AM Post #1528 
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Steve, I bought one of the cheap rotators (40) as has several other amateurs round here. In my case the problem is the controller: the indicator is coupled to a plastic disk which carries the on/off and direction switching. The plastic disks in mine and that belonging to a friend disintegrated, the plastic is weak and brittle. The nylon gears in the controller belonging to another friend warped (during a contest the motor in the controller can get VERY hot!). The stop in the rotator motor belonging to another friend snapped off and he had to get it down and have a piece of metal welded on. In my case when the disk disintegrated I replaced it with a tpdt toggle switch and lived without the indicator. Usually I don't miss it but if I want to make a big change of direction to check a beacon I have to count seconds! The beacons are handy for direction checks, anyway!

The rotator itself seems robust but obviously works much better with the alignment bearing, unfortunately that limits you to a 30mm dia stub mast.

Though many of these units seem OK, I would suggest that if you envisage heavy use it may be better to go to the next one up, costing about 80. This fits concentrically to the mast and doesn't seem to need an alignment bearing, it will take nearly twice the weight of antennas.

Incidentally, mine carries the dual band yagi I described in another post plus an HB9CV for 6 metres - which is very light and well outperforms my triband vertical which I have taken down for now. The friend who had to get a stop welded on has a 9el tonna for 2m, an HB9CV for 4m and the most enormous colinear for 2m that I ever saw, its at least 12 ft long, so the rotator is obviously quite strong!

Older hams will remember the days when we improvised rotators using exWD pitch prop motors (which one does see advertised occasionally by hams clearing shacks), these were a bit big being about the size of a 5 litre paint can, but they could turn a house! If you ever come across one of those, grab it!! (Or tell me!!)

73

Brian G8ADD
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 Riverside   Quote Post
Posted: Jul 12 2005, 10:24 PM Post #1530 
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Hi Steve,
For years I used a cheap off-set rotator, which was sold as being for FM/TV broadcast, a 9ele 2m Tonna just above the rotator, an 11 ele 70cm Tonna 1 m above that and a 2m Ringo on top. Guess it did 7 or 8 years service, it jammed up completely one winter, just needed wd40 and a re-grease. I sold it on! My only problem was it did sort of steer into the wind if very strong and persistant, it could be cured by it resetting itself if you turned it fully both ways a few times, stop to stop. It was made by Stolle, dont know if they're still going. Big plus, it had a metal gear train at the business end, but no brake as such.
Even a small rotator will turn a big beam, the problems arise when it is windy, and its blowing side on. The aerials want to do a weather cock impersonation! I dont know of a cheap un that has a brake. I used to turn the beams into the wind if stormy and just hope the wind didnt change direction, lol.
Cheers, Bill, G6BCC
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73 n gud dx
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 Andy   Quote Post
Posted: Jul 17 2005, 11:02 AM Post #1534 
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Steve - my first rotator was a cheapo 'Hirschman' type, similar to the one you are talking about. It worked well for about 5 years with just a single 19 ele 70cm Tonna on it, but it started jamming up one winter and never recovered. unsure.gif
One thing I quickly learned about these things is that there is no 'position' feedback from the rotator to the controller, so it all depends on them both turning at the same speed, and obviously it gets out of sync quite easily - especially if the outside bit is feeling it's age! Mine played the fool for quite a time before it finally juddered to a halt.
Since 1995 I've had an EMOTO medium-duty jobby at the top of the mast, carrying two 12-ele beams for 70cm and a single 23-ele for 23cm. In the past it has cheerfully turned these plus a 2ft solid dish and several weighty microwave devices - it doesn't seem to mind - and apart from a slipping drive-belt in the indicator recently it hasn't put a foot wrong in 10 years. It has proper feedback, so you always know what's happening up top.
I got mine from Lowe's (W&S now) for 200, a bargain even by 1995 prices. smile.gif
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Andy, G1HBE. www.freewebs.com/g1hbe
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 M0SPN   Quote Post
Posted: Jul 28 2005, 10:25 AM Post #1538 
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Thanks for the info. I was on holiday last week - hence my slow reply smile.gif

Having just accidentally bought a second-hand Icom 706MkIIG (these things happen...), my antenna plans will have to wait a while. Although, now I have a decent HF, 6, 2 & 70 radio, it means the antennas will be the next on the list.

Fun fun fun!!!


Steve M0SPN
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