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@contesting.com
[mailto:towertalk-bounces@contesting.com]On Behalf Of SERGE BERTUZZO
Sent: Wednesday, November 19, 2008 7:52 AM
To: towertalk@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
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|