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eHam Forums => Misc => Topic started by: KA1MZY on September 26, 2007, 05:18:50 AM



Title: Antenna mount non-penetrating roof mount
Post by: KA1MZY on September 26, 2007, 05:18:50 AM
Thinking of using one of these vs a gable mount.  Anyone used one with any problems with SWR or other reflective issues?  The antenna will be a diamond x300 with a 5 or 10 foot pole.

A link to an image of the antenna mount here.  

http://www.lashen.com/vendors/vmp/images/FRM.jpg


Title: Antenna mount non-penetrating roof mount
Post by: W0FM on September 26, 2007, 10:21:38 AM
I assume you have a flat roof.  Not knowing the dimensions of the base of this mount, it's hard to say if it will support your mast and antenna in windy conditions.  That said, I often use bags of premix concrete on the base of tripods and flat roof mounts like this.  Sand bags and cinder blocks can also work.  I think I'd count on weighting this mount down for your application.

73,

Terry, WØFM


Title: Antenna mount non-penetrating roof mount
Post by: W0FM on September 26, 2007, 10:24:48 AM
and, there should be no impact on your SWR or antenna performance caused by this mount.  It's location, maybe, but not the mount.


Title: Antenna mount non-penetrating roof mount
Post by: W3LK on September 26, 2007, 08:59:40 PM
Having used some temporary mounts of that style, if the dimensions of the mount are less than 4'x4', I would put at least one 50 lb bag of cement, or the equivalent in cinder blocks on every side.

Actually, I'd put that much on each side no matter how big the base is.

73,

Lon - W3LK
Naugatuck, Connecticut


Title: Antenna mount non-penetrating roof mount
Post by: KA1MZY on September 27, 2007, 05:20:05 AM
Yes I have a rear porch which is flat.  I can't weight it down too much since the porch is as old as the house I'm guessing ( I haven't looked yet since it's covered with siding ).  With a house over 30 years old, I have to be careful.

This is the reason I'm looking at this mount.  My gable wood on the house is old and not sure the mount would hold.  I need to check the wood under my siding to find out if the gables are secured with more than just some old nails.

I would use a couple cinder blocks to hold it down and it should be ok.  The diamond antenna only weighs 3LB, and the base is some 30LB.


Title: Antenna mount non-penetrating roof mount
Post by: W3LK on September 27, 2007, 09:18:07 AM
It's not the weight of the antenna; it's the moment arm of a long antenna and mast v the footprint of the base.

If your deck can hold you without you falling through, it can hold a properly weighted portable base. :)

73,

Lon - W3LK
Naugatuck, Connecticut


Title: Antenna mount non-penetrating roof mount
Post by: W3LK on September 27, 2007, 09:21:17 AM
<< I can't weight it down too much since the porch is as old as the house I'm guessing ( I haven't looked yet since it's covered with siding ). With a house over 30 years old, I have to be careful.>.

You are mnaking invalid assumptions about the condition of the house. My house is 64 years old (built the year I was born) and it is very solid. My daughter's house was built in 1770 - it predates the Revolutionary War - and is very solid.

Investigate; DON'T make assumptions.

73,

Lon - W3LK
Naugatuck, Connecticut


Title: Antenna mount non-penetrating roof mount
Post by: W7IBI on September 27, 2007, 12:43:26 PM
I have used one of these mounts on a flat roof in the past with no problems. Mine was sized to hold 8x8x16 concrete blocks in the angle iron base.
 
If your roof won't hold this with several concrete blocks, stay off that porch!

If you can stand on the spot where you would like to have the antenna, you should be fine...


Title: Antenna mount non-penetrating roof mount
Post by: KA1MZY on September 28, 2007, 01:42:16 PM
Thanks for the suggestions guys.