On 18/07/2010 15:06, the_constructor wrote:
wrote in message
...
On 17/07/2010 22:45, the_constructor wrote:
Being a white stick radio operator, I have to find someone to put the
antenna up on the chimney stack for me, but before I do, I need some
advice
please.

Obviously, a small pole needs to be attached to the chimney stack so that
the antenna which is a glass fibre aerial weighing 0.9Kg can be fitted
just
above the stack itself. Neither I nor my neighbour have chimney pots.

I would estimate that the pole would be overall about 3 feet long and
then
the antenna fitted at the top of the pole to clear the stack.

At this point, I have to ask is the antenna for V/UHF, or HF use? If the
latter, I would advise a double lashing kit.

Should I use 1 or 2 lashing kits to hold the pole. The pole will be 2"
alli
scaffold, already obtained, curtousy of the housing refurbishment
contractors.

Have you gone for the thick walled stuff, or the zip up type?

Dave

Yes, I am a licensed radio ham. Jim G1SSO located in County Durham.

The bracketry I was thinking of is something like this:

http://www.aerialshack.com/inch-chim...ket-p-346.html

I am using the same thing for my tri bander on the corner of the house
and it has been up over ten years now without a problem at all.

Just popped up to the shack to check on a dual bander that must be very
similar to yours and that came with 4 foot 25 mm or one inch diam
aluminium pole about 4 foot long.

This is the spec of the antenna:

Compact white fibreglass dual-band base antenna for 2m and 70cm.

Frequency Bands 2m/70cm
Max Power 200W
Length 1.7m
Radials 3
Gain (2m) 4.5dB
Gain (70cm) 7.2dB
Weight 0.9kg
Type (2m) 3 x 1/4 wave
Type (70cm) 3 x 5/8 wave

Very similar to the one I have in storage.


The alli tube that I have is 2" dia and roughly 3/8" wall. As I say, I would
imagine all I need is about 3 feet.

Or just enough to get the radials above the chimney pot. But this is
where length matters ;-)

I was thinking of running a 10mm green earth cable from the mounting
brackets down to a ground spike, but someone commented that it may upset the
antenna.

It won't upset the aerial at VHF and above, but it won't do anything to
prevent lightening striking either. You will only need an earth for HF.
and that is only for ballancing the antenna system.

Also I want a termination box with an N socket attached, on the
wall in my shack and to run a similar cable to ground.

A good choice and make sure you un-plug when there is static (warm dry
weather and high winds.) or thunder in the area. I once lost the front
end of a UHF rig through that.

Dave g6khp