[Lowfer] Telescopic Mast Vertical - Question

[Stan, W1LE]

Hello Andy,

I am on a similar venture. Some ideas are already installed, but the 
final design is still in the thought stages.

1. Insulating the mast from ground: my vertical is about 30' from the 
house and guyed 3 ways. I chose to put the mast insulator at 27" above 
ground because of the possible snow fall/accumulation. I want the 
insulated mast to always be above the snow.

2. For your standoff bracket, 10' above ground, consider using small 
sections of PVC piping cut to fit around your masting. May be more 
solid/permanent.

My masting is older military type, using MS-44, for 60" stackable 
sections, with mil insulated base and mil nylon rope guys. Sections are 
1-5/8" OD and are aluminum with a swaged end to mate the next section. I 
guy every 3 sections. I have a 2' stub at the very top for the possible 
top hat (umbrella) loading capacitor, then the first(top) guy 2' below 
that. Right now I am at 52' of radiator and considering at least 2 more 
mast sections. Maybe after I consider everything and design the top hat 
the main mast might be shorter. I am also considering a center loaded 
inductor to improve performance.

I believe in one man installs/de-installs. I can put up this masting all 
by myself. To add more height, all I do is loosen the guy ropes, pull 
the bottom section up and away from the base insulator and add the new 
5' section. Then I plumb it up, tightening the guy ropes. I do use a 
surveying transit to be sure the masting is plumb/vertical. Right now I 
am plumb within a mast diameter from top to bottom. My guy anchors are 
at 80% of the height with elevated anchors on 4"x4"x10' pressure treated 
lumber, 3' in the ground. Plenty of room to walk around underneath the 
lowest guys.

I do use a heavily graphited "gas cock" grease between sections for 
enhanced conductivity long term.

The MS-44 is very old mil stock that I have collected over the past 25 
years and can no longer be found. But there is more modern mil masting 
available from Ebay with 44" stackable sections of aluminum. There is 
also thin wall fiberglass masting that is NOT sturdy. Thicker walled mil 
masting fiberglass can be found, but you really have to hunt for it.

My original thoughts for a top hat were to use telescoped aluminum 
tubing, about 20' diameter with interconnecting wires. 8 radial spokes 
from the top mast stub section.

I am begining to like the idea of using top loading wires, like you use. 
But I need to explore the mechanical loading.

My ground screen is sections of 3' galvi fencing, on the ground. If I 
bury it, it will corrode in a hurry and be useless. and the fencing 
wires are all electrically bonded together. Unlike chain link fence 
material that is loosely held together. Maybe chicken wire would be more 
cost effective.

GL in the project

Stan, W1LE    Cape Cod   FN41sr





ZZZZz




On 8/11/2018 2:19 PM, Andy - KU4XR via Lowfer wrote:
> Hi all:
>
> My recent antenna debacle is forcing me ( a good thing kinda ) to come up with a better and more permanent
> design.. After considering several types of setups, financial considerations, and one man maintenance has me
> settled on using a 40' Telescopic Mast as a Vertical radiator.. I have 2 questions :
>
> #1: I will insulate the mast from ground.. How high above ground should I try to get the mast ? minimum & optimum
>
> #2: I have no other place to mount the mast but to the side of my mobile home.. Lots of aluminum siding up
> 10 feet high, and , a metal roof .. I will use a stand off bracket to hold the mast at 10' AGL to the side of the
> mobile home.. it will be insulated ( mast wrapped with electrical tape ) - best I can do, and use dacron rope
> to guy the mast with porcelain insulators on the mast end .. Top Loading connected at the top section,
> and RF fed at the bottom of mast..
>
> I realize the coupling, and interaction effects of being beside the metal body of the mobile home, so , will that
> make Question #1 a moot point ?
>
> Thanks for any comments.. Hope to be back on the air soon:
>
> 73:
>
> Andy - KU4XR
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