Australian Ham Radio Discussion Forum ( AHRDF )

I'm looking at getting some elevation to my 2m irlp antenna, and was seriously considering mount it up a tree and offset from the trunk by about 2,000mm

What I'm considering doing is strapping/bolting (loosely) a 4m long 50mm gal pipe as far up the tree as I can, then 2 thirds up it, run a pipe off horizontally to take it away from the tree trunk. At the end of it, a stubby pole going vertically to then attach something like my existing Diamond x-200 vertical off of it.



As you should guess, the taller tree is the one I mean.

In the past have used a large pine tree to support a 2M collinear although a pine tree is relatively easy to climb. Take care as you slither up that straight tree trunk.

Good luck with the project.

Thanks for that... I'm hoping to have a few radio club mates come out to give me a hand..... I'm not good at climbing trees.

I was hoping someone might have some better ideas of securing the base pole on the tree.

(30-05-2018, 06:00 PM)VK4BLP Wrote: [ -> ]Thanks for that... I'm hoping to have a few radio club mates come out to give me a hand..... I'm not good at climbing trees.  

I was hoping someone might have some better ideas of securing the base pole on the tree.

Brendan,
Another option would be to make up a collinear antenna out of coax, put it in a length of poly pipe or similar or just heat shrink the joins and hang it from the tree, looking at the tree you should be able to keep the antenna away from the trunk, just might not be totally vertical you could even run a line out from the tree top, out as far as possible and hang the collinear antenna along that line.

73 from Michael
VK6TU

Never thought about that Michael.

I was thinking about the way I had thought of doing it, of changing it to a folded dipole at a later date.

Never considered a colinear before.

Brendan

I might be able to help you with a homebrew 2M coax collinear. It is already made and in electrical conduit with a SO239 on the bottom. It originally had 3 or 4 x 500mm aluminium tube ground plane radials but not sure where they went - easily enough replaced though. Not easy to transport as it is about 5-6 metres in length (will need to measure it for an exact dimension, later this morning ???).

Being conduit, it doesn't have great vertical stability but hanging it from the top by a rope over a branch then a vertical stabilising rope at the bottom via a spring to a tent peg (or other) into the ground would work. 

I don't recall where it resonated in the 2M band, probably around 147MHz.
 
Needs a coat of paint to match the tree trunk to make it disappear 

Doug

Revised 10AM : 5.4M long, looking a bit tired but probably works. My recollection is that it was a virtual copy of the 6dBD Scalar G22 VHF base antenna but made with electrical conduit (part 32mm/ part 25mm/ part 20mm / part 16mm) in lieu of a fibreglass housing.   Needs 4off 10mm dia aluminium radials each about 500mm long.

Sounds good Doug !

I'll have to give you a call some time soon then.

Brendan

Checked it today to find it faulty, opened it up and re-soldered a broken joint, fixed the reason for the broken joint (coax connector in the base tube not mounted solidly), then tested it. 
 
The SWR was 1.6:1 at 144, 1.4:1 across 145 to 147, rising to around 1.6-1.7 just under 148 MHz - tested without any ground plane radials but clamped to the box trailer frame. By rights, it should still have those 4 radials fitted in the final installation and the SWR may be even better.

Looking good electrically for your IRLP node but needs to be hung from the tree branch to solve the electrical conduit 'wag' and bend.

Doug