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Author Topic: Rotating a 2M Yagi from H to V polz  (Read 912 times)
AE3T
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Posts: 7




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« on: June 23, 2019, 07:25:20 AM »

I am re installing my 12EL 2M yagi which is used for primary tropo and MS operation on CW, SSB, & digi. I would also like to use the same antenna for long distance FM operation by rotating the boom from H to V polz. I have a Yaesu G-550 elev rotor which when mounted on the boom in place of the regular boom to mast bracket will do this job.

My question is on the possible radiation pattern disturbance that would be caused by this larger metal object on the boom in the plane of the elements?

Any other ideas on alternative methods to do this?
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WB6BYU
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Posts: 18458




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« Reply #1 on: June 23, 2019, 07:41:47 AM »

I remember seeing a beam mounted on roller bearings with a lever arm sticking out a foot or so that
allowed one to pull on a rope to rotate it 90 degrees.  That may be more simplistic than you had in mind.
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K3GM
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Posts: 2549




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« Reply #2 on: June 23, 2019, 09:44:27 AM »

Unless your mast is non conductive, you will experience the same serious performance loss in the vertical plane with a metal mast passing through the elements.
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K7RJB
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Posts: 225




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« Reply #3 on: June 24, 2019, 08:05:41 PM »

Fiberglass mast Paint it with non-conductive paint for UV protection
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WB6BYU
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Posts: 18458




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« Reply #4 on: June 24, 2019, 09:15:56 PM »

You still can have issues with the coax passing down through the vertical elements:
it should run off the back of the antenna (behind the reflector) to stay out of the way
of the elements when the antenna is vertically polarized.
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KB1GMX
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Posts: 1800




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« Reply #5 on: June 25, 2019, 11:17:42 AM »

The other problem is that not all beams work at 144.2 and 146
well especially the longer ones.  There are exceptions I know
but they are exactly that, designed for both.

I solved the need for vertical on 2 using a end mounted smaller
beam designed for the repeater end of the band.  An Arrow
146-4SS (two 146-4 stacked) wold work dandy for that.

Allison
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AE3T
Member

Posts: 7




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« Reply #6 on: June 29, 2019, 09:29:59 AM »

I solved the application by building an offset bracket that mounts my yagi to the az/el rotor and allows me to rotate the pol between H and V keeping any mast out of the plane of the elements and it works great.
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KM3F
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Posts: 909




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« Reply #7 on: July 05, 2019, 02:07:52 PM »


Hello Howard,   I use to hear you working EME some years ago nites when the moon was coming up over the Blue Mountain.
Yes the noise level has increased substantially over the years.
Now the vegetation is allowed to grow right up in the high lines and causes a lot of leakage. With so many poles in that condition it's hard to track it down.
Been off 6 and 2 SSB for some time spending time on long distance 2m and 222 band FM with stacked short beams.
Tip, don't stack vertically polarized beams horizontally as the beam width becomes very narrow and pattern elevated unless you have a need for that kind of performance.
Stack all vertically. The pattern broadens and lowers.
My goal is to get a contact in Canada some time on 222 SSB.
I have stacked short beams on 222 for FM and will be putting up a 12 el 222 for that as soon as I get to it.
Good luck, you've had a good run.
Ken.
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