[TowerTalk] Proposed roof install of Force 12 on 9 ft Glen Martin Roof Tower

[Kurt]

Greetings Fellow Towertalkians,

I am slowly gathering parts and money for a tower project, that I hope 
to install in a year or two. In the meantime, I would like to upgrade my 
antennas as my budget allows. I got a pretty good deal on a 9 ft Glen 
Martin roof tower and a Force 12 C-4XL.

The house is 2500 Sq. Ft, 1973 two story. There is a 700 Sq. Ft attached 
garage too. Typical residential,  wood frame construction with roof 
rafters on 24” centers. All roofs have soffits of about 12” around the 
entire house.  I am reinforcing the rafters per the Glen Martin 
installation instructions.

I currently have a 3 different roof mounted antennas, a 10M vertical 
mounted on a 3 foot tripod, and a 2M/440 application mounted on a tripod 
with a vertical and a 2M 14El Yagi on the same mast. In order to make 
room for the Force 12’s 23.8 ft turning radius, the 2M/440 set up is 
being moved and upgraded to a 4 foot Glen Martin roof tower. As an 
aside, while I’m up there sometime this summer, I would like to 
reinstall my large, deep fringe area,  TV antenna and rotor. My plans 
are to install this on another Glen Martin 4 ft. tower, because I could 
also attach side arms to it for improving both my cell phone and 
internet coverage.

I am concerned about not having enough separation between antennas to 
prevent interaction and RF overloading. I thought I had read somewhere 
that I need ¼ wavelength separation vertically for antennas on the same 
mast. But how far away horizontally from the Force 12 would I need to 
mount another antenna(s)? Is there any way to install filters through a 
switching network? Not that I’m planning on running a multi operator, 2 
radio system, but how do the big contest stations handle this? What does 
one do if they don’t have acres of land so their receiving antennas are 
far away from the transmitting antennas?

Other questions I have are, what is the best way to route the coax runs 
across the roof? Has anyone fabricated or used coax standoff’s and roof 
mounted them to manage the coax runs? How did you make them? How did you 
attach them? How did you seal them to prevent leaks? Remember the 12” 
soffits I mentioned? I have never liked having to go over the 12” rafter 
tail of the roof. The run either rubs on a gutter or deflects the 
shingles that hang slightly over the drip edge. What is the best way to 
route my coax down from the roof? Has anyone used a roof vent to go into 
the house directly from the roof? Has anyone ever purchased and 
installed a separate electric utility service mast and weather head and 
used it as a way to get the coax runs through the roof and soffit and to 
the ground and shack? Also, can I route the 4 awg copper ground with the 
coax, or should I keep this separate?

Thanks. Kurt
KD8MGN