[TowerTalk] Help - Stacking various antennas

[Steve Katz]

Serge, I have the same G-M roof tower and have used a 13' HD mast that extends about 8-1/2 feet outside (above) the tower, with HF beams on it, just fine.

As you know, the tower's strong and can be climbed.  I'm using the thrust bearing mounted at the top plate, as I assume you are, also.

Spacing should be 1/2 WL for the highest frequency antenna, ideally: This would be over nine feet at 50 MHz.  However I've placed 6m beam only 5' away from my HF yagis and didn't really notice any interaction.  I currently have an M2 6M7 yagi (much larger than the 3L CC) about 5' above my 8L HF LPDA (different tower) and the 6m antenna pattern is very clean.  If there's any interaction, it appears to be minimal.

WB2WIK/6

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com]On Behalf Of SERGE BERTUZZO
Sent: Wednesday, November 19, 2008 7:52 AM
To: towertalk at contesting.com
Subject: [TowerTalk] Help - Stacking various antennas


Hello everyone! I am seeking some advice on my antenna installation. 

I presently have a Glen Martin 9' tower mounted on the roof of my house. I am using a 8 foot aluminum mast (.25" wall). The mast currently extends approximately 5 feet above the top of the tower. I have a TA33JR beam mounted about 1 foot above the top of the tower and 4 feet above that I have a cushcraft DS3W (30/17/12M)  rotatable dipole. I am interested in getting involved in 6 meter activity and ideally would like to use a Cushcraft A503S 3 element 6 meter yagi. My first question is, how much separation should I have between the TA33JR and the 6 M antenna as well as the from the rotatable dipole to the 6 M yagi? As a follow up question, I would appreciate views as to how high I can safely go beyond the top of the 9' tower with my mast (again say a .025" wall aluminium). For your info, there should be no wind loading issues as the three antennas combined would be less than half of the tower wind loading rating at 100 mph. 

Thank you in advance for your advice and assistance.

Regards

Serge
VA3SB
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