Base Gain Master on top of Gizmotchy?? Questions

[Rob Berger]

Currently I'm running a Sirio Gain master ground plane. I'm building a 40 foot crank up tilt tower mast for a set of 4 element Gizmotchys. My question is I'd also like to put the ground plane on the tower, but I'm not sure where or how it should be mounted in relation to the beams, if this is even possible without some RFI. My plan was mounting it about a foot or so above the beam, but will this affect the performance of the beam. And If I put it above the beam will the pole affect the beam in performance or swr? Any help or suggestions would be greatly appreciated. I posted this one already but had no response. I'll also post a couple pics of the tower so you will have a good idea of what I'm building. Just a couple pics I got offline that gave me the idea. Thanks

 

[sonoma]

from the pictures it looks like the beam will be mounted flat if I am seeing what you are doing right. if the beam is flat then put your ground plane about 3 foot above the beam and you should be good to go. my last tower I had a maco 103 mounted flat and had a V5/8 ground plane mounted 3 foot above it and did not have any swr problems. the v 5/8 has lower radials and it did not cause any problems. put the beam up flat and swr was 1.2 and later put a ground plane up due to some locals I could not hear good on the flat side. my v 5/8 had a 1.4 swr after putting it above the beam and then the locals came in very good with it. the beam still had a 1.2 with the ground plane above it. any thing is possible to effect the swr with a install. not all will turn out as we would like.

 

[Rob Berger]

The pictures were just something I found online that gave me the idea. My brother is the shop manager at a local machine shop. They are building it for me.. I like this over a conventional tower and it works better with limited space. I'll be using a set of 4 element gizmotchy beams.

 

[Needle Bender]

I believe you'd be better off with an Imax in place of the GainMaster when above, but so close to, the beam(s).

The only thing you might possibly get from the GM over the Imax is less RFI, but I expect the performance of the GM in that configuration will suck.

 

[camaro1]

I don't know how you would mount a vertical above a gizmotchy beam, the gizmotchy has vertical elements and the mast going up the center for the gainmaster would mess with the gizmotchy


2 element gizmotchy:




your post title states "Gainmaster on top of Gizmotchy beam" the pics you posted are not a gizmotchy beam, those are just horizontal yagi's and those you can mount a vertical above them with out issues

 

[hotrod]

id mount the gainmaster on a pushup pole. then mount the beam on a tower

 

[Grogan]

I have a flat side maco 4 element at 43 ft and was wanting to mount a vertical above it. was going to get a vertical with no ground plane radials. looking at the Imax or gainmaster figured they would be the best mounted about 5 to 6 ft above the Maco any thoughts.

 

[undertaker]

I had a maco 3 element with an a99 above it worked just fine..

 

[tba02]

There is anecdotal evidence that the Gainmaster likes to be in the clear - what that means however is not so clear. I have had great luck with my GM, and the way it is mounted it sits on a 10 foot pole above the roof, but off to the side of the roof peak, which puts it about 6 feet above everything. I don't know that a flat beam underneath would have any negative impact, especially since the design seems less prone to requiring any coax/second half of the antenna needs that the A99/IMAX/End Feds seem to warrant.

 

[Staybolt]

Itll screw up the pattern and lobes of the beam. Put it on a seperate mast at least 36' away or more.

 

[unit_399]

This question has been asked in a number of threads on this forum.
Here is one
http://www.worldwidedx.com/threads/distance-between-two-antennas.217191/

Here is the answer I posted in that thread:

I contacted Tom Charles at MACO Antennas about this and this was his reply:

"Customers usually start by mounting the V58 between 2-3 feet above the Maco 107. If the SWR is high on the V58 and good on the 107 you just keep raising the V58 up until the SWR is acceptable on both antennas.
Customers usually end up with a spacing anywhere from 2 to 7 feet above the beam."

- 399