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Author Topic: 2 meter or 6 meter band?  (Read 1782 times)
NZ5E
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« on: April 26, 2010, 10:17:35 AM »

I am going to put either a 2 meter or 6 meter horizontal yagi on a 180' Rohn 25 tower, one or the other to minimize windload.  Which band would you choose for SSB?  In general in the continental United States, which SSB portion has the most local ragchew type activity when the band is not open for other modes of propagation?
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WB2WIK
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« Reply #1 on: April 26, 2010, 11:42:05 AM »

They're both very similar when there's no ionospheric propagation, and I think activity levels for normal tropo work are similar as well.

Why not put a 2m beam on top of the tower and a 6m beam on the side with a bracket and rotator down a bit below the top?  That would allow the beam to rotate about 315 degrees if you space if just right so it doesn't tangle in guy wires.  Pick a "black out" direction where there is almost nobody so the 45 degrees or so that you lose won't matter much...
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K3GM
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« Reply #2 on: April 26, 2010, 04:56:08 PM »

I agree.  Even a 5 element 6m yagi, side mounted on the tower would still have enough beamwidth to cover most of that unaccessable 45 degrees.
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WB2WIK
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« Reply #3 on: April 26, 2010, 05:36:04 PM »

When I had a bigger tower than I do now (90' of Rohn 25G) I had "stacked" 6m beams with one rotating above the tower and three more down the side of the tower.  Only the upper one could fully rotate, the others were limited but I put the "blackout zone" to the south of me, where there isn't much except Clipperton and Antarctica.  It worked fabulously.
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NZ5E
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« Reply #4 on: April 27, 2010, 07:56:50 AM »

...Why not put a 2m beam on top of the tower and a 6m beam on the side with a bracket and rotator down a bit below the top?...

http://i581.photobucket.com/albums/ss252/N1048D/Tower_640x480.jpg

I let a local internet provider use the sides of the tower for relay purposes so I don't want to mount anything except maybe an inverted-v on the side of the tower.  I will be removing the business band VHF folded dipole array that is now on the top of the tower and running a coax jumper from the existing 7/8" Heliax that now feeds the VHF folded dipole array to the 2 or 6 meter yagi.

I am trying to decide if I want to chance mounting something at the neck of the tower as big as a Hy-Gain DB-1217 for HF or just a rotatable 17 meter dipole to reduce windload.  Since 6 meters is about 3/4 wavelength of 17 meters, I would mount the 6 meter yagi 10' above a DB-1217 whereas I would only mount a 2 meter yagi 6' above.  If I go with a simple 17 meter rotatable dipole, I could turn the boom of the 6 meter yagi parallel to the 17 meter dipole to reduce interaction.  With the reduced windload of the 17 meter dipole as opposed to the DB-1217 yagi, I would consider putting a relatively small 3-element 6 meter yagi 10' above and parallel to the dipole and a relatively small 8-element 2 meter yagi sandwiched between with 5' separation from each.  Any other suggestions considering this is only Rohn 25 tower?
« Last Edit: April 27, 2010, 08:02:23 AM by Terry L. Browning » Logged
WB2WIK
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« Reply #5 on: April 27, 2010, 09:05:09 AM »

The photo doesn't show the guys very clearly: Do you have insulators in the guy wires?
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NZ5E
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« Reply #6 on: April 27, 2010, 09:19:09 AM »

The photo doesn't show the guys very clearly: Do you have insulators in the guy wires?

No insulators.  I originally put the tower up for my business radio repeater and wasn't thinking "ham radio".  I purposely did not put insulators in the guy wires and installed 3 ground rods at each guy wire anchor location as part of the lightning protection setup.

What effect of the guy wires prompted you to ask the question about insulators?

I will also be asking the internet provider to lower two omni antennas down from the top about 5'.
« Last Edit: April 27, 2010, 09:37:21 AM by Terry L. Browning » Logged
NZ5E
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« Reply #7 on: April 27, 2010, 10:05:26 AM »

I fully realize that there are almost too many variables to answer this question, but "in general" is 6 meters more prone to cause RFI to TV's, telephones, etc., than 2 meters?  I realize a lot of things have changed since I was active in Amateur Radio, most have cable TV, cordless telephones, etc.  There are a few houses located about 500' in different directions from the tower is the reason I ask.
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WB2WIK
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« Reply #8 on: April 27, 2010, 10:46:08 AM »

Nah, I run a kilowatt on 6m to an antenna much closer to where people live (50' above their heads and only 75-100' to the side) and have absolutely zero problems with RFI of any sort.

I can get into telephones, surround sound systems and PC amplified speakers (including those of neighbors) sometimes on much lower frequencies, though, mostly 40m/80m/160m.  Nothing above that.

Regarding the guy wire insulators: I asked because you mentioned wire antennas (inverted vees or whatever) hanging from the tower, and guys that aren't broken up by insulators can interfere with the operation of such antennas.  It's common to use no insulators on towers only used for VHF-UHF-SHF-EHF antennas, but very uncommon to use no insulators on towers that might support antennas for lower HF bands.
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NZ5E
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« Reply #9 on: April 27, 2010, 12:04:09 PM »

Guy wires are one of the reasons I am going to use a Double Bazooka antenna for 40 or 60 meters at the 130' level since the Double Bazooka is less prone to detuning by its environment.  I do expect the radiation pattern to be effected though.
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