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Author Topic: Height above hazer  (Read 1662 times)

Posts: 157

« on: December 25, 2013, 06:21:32 PM »

Seems like a dumb question, but have heard there is no dumb questions. Right after the holidays, my hazer system will be attached to my 40 foot tower. On that system will be a brand new TA 33 jr from Mosley with the WARC bands. The Mosley will be the only antenna up there. I have a 10 foot new mast. To take the stress off my 21 year old Yeasu G800 rotor, I am thinking of shortening that mast a little bit. I am 3 miles in from the Gulf of Mexico so everything is flat all the way around so height is not a problem. I have a Brand new Yeasu GS-065 thrust bearing installed on the hazer that should help the rotor. I talked to Mosley about spacing if there was another antenna up there and they suggested 8 to 12 feet. What about the top of the hazer. 6 feet, 7 feet. What is the suggestions, comments.

Posts: 18

« Reply #1 on: December 26, 2013, 05:01:51 PM »

no problem.

Used to have a TA-33 just clearing the tower above my Hazer  Had a 3 el 6m beam 4ft above it.  Now have a Tennadyne T6.  It is mounted same way and works fine
(guys mounted to tower, not bottom of Hazer, so hazer will not go all way to top of tower.  Takes a 6 foot mast to just clear top of tower.)

Interaction of vertical tower to horizontal Yagi not a problem, two Yagi's mounted close, maybe a problem.

Posts: 157

« Reply #2 on: December 27, 2013, 02:52:29 AM »

Ok.  Thanks,  I have had 2 mosleys before this.  a 33 jr and a 53-M.  Both were  about 9 feet above the top of the tower.  To take the stress off my OLD rotor, I was going to put it at about 5 feet above the hazer.  Main concern was it the interaction between the two. 

Posts: 1551


« Reply #3 on: December 27, 2013, 03:06:09 AM »

It's not clear to me that shortening the mast will take any significant stress off the rotor.  Shortening the mast will only reduce dead weight, and the thrust bearing should take care of that.  Torque due to long boom lengths and excessive wind load
are the things that kill rotors.  I would mount the 33jr just high enough to clear the top of the tower, and the WARC as far above it as you can.  That's the best you can do.

You posted that you are 3 miles from the Gulf with flat ground all around, so height is not an issue.  That applies more to point-to-point communications, and really doesn't have as much bearing with HF antennas (unless you were totally screened in one direction by very high terrain).  Height above local ground will definitely impact the pattern, and higher is better for low-angle DX contacts.  But again, the tower is what it is and it's the best you can do with what you have.

BTW, I also have a Hazer and I have no problem with guy wires preventing it from going all the way to the top.  If you have a flat-topped top section, you should have no problem there.  If you have a tapered top section the Hazer will only go up to the beginning of the taper, and you'll have to mount the 33jr up a little from the top of the Hazer to clear the tower.


Don, K2DC

Posts: 157

« Reply #4 on: December 28, 2013, 03:36:03 AM »

Thanks Don and K5ACO.  The tower is a flat top made by rohn.  I will take both of the suggestions to heart.  When I mounted the mast on the hazer, my first thought was "Man that's a long mast, better shorten it.  The boom length is just 12 feet.  It's 4 elements on 10,15, and 20 and the  WARC bands are rotatable on dipoles on 12 and 17 meters all in the same antenna.  No high buildings at all here.  The only obstruction is a stand of very large pine trees in the neighbors yard probably 35 feet away in the NNW area.  Anxious to get it in the air, but it's been too cold and wet to do much in the last 2 weeks. 
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