Top band DX-ing is real ham radio challenge. 160m is also referred as the "Gentleman's band"...
160 meters - DX-ing on the Edge...

Telescoping Fiberglass Mast - part I.

11. prosince 2006 v 22:18 | Petr, OK1RP |  Antennas
Hi folks,
as most of TOP banders also I am looking long time for usable material to make some support for receiving nor even transmitting antennas on 160m. Well on the market is possible to buy lot of fishing poles where its possible to put it up to 12m but most of them has pretty low tickness of last few sections and also it has only few millimeters which makes big bending of that end.
Just a few days ago I started very interesting discussion on Top band mailing list by replying to Dave's, WX7G email as follows...
Dave,
as I am looking long time for usable mast for flag RX ant I am interested in that. BUT what about bending the smallest part ? Is it enough thickness over there?
Petr, OK1RP

> ------------ Původní zpráva ------------
> Od: <Telegrapher9@aol.com>
> Předmět: Re: Topband: Telescoping Fiberglass Mast
> Datum: 08.12.2006 12:21:01
> ----------------------------------------
> Mike,
> The Wireman stocks two lengths of the Spiderbeam fiberglass masts. 40' and 60' for $99 and $279. I recently bought the 40' version and I am very impressed with it. I plan to buy the 60' and give it a try. They can be extended to a shorter length of course.
> Dave WX7G
Dave, replied to me an interesting informations...
Petr,
the 12 meter mast is made up of 12 sections. The top section has a diameter of 8 mm. The bottom section diameter is 55 mm. The wall thickness of each section is 1.4 to 2.0 mm. There is no wind survival rating on this mast. And, the sections do not lock - they stay where they are by friction and it is reported that the sections will loosen in a wind. I bought it for something that can be pushed up and used on a few hours and then taken down. The mount the mast I use two 2" I.D. PVC couplers that are bolted to the fence. The mast simply slips through these and is secured. If a wind comes up and blows the thing over it will remain on my property and I don't expect that it will damage anything. So I put it up without guy wires and hope for the best. The 18 meter mast is made up of 12 sections, with the top section having a diameter of 3 mm. That is thin and even for a thin vertical wire I might not extend the upper section. To put the 12 meter mast on 160 meters I slipped a thin PVC T on top. I drilled holes 7.5 cm apart on the horizontal part of the T and ran two #26 AWG wires into the shack window. These terminate into a 75 uH inductor sitting on the desk and then into an MFJ tuner. The six 15 meter radials terminate into a 30 uH inductor sitting on the desk and then into an MFJ tuner having a ground tuning feature. Measurements show a radiation efficiency of 15%. Good enough for what it is. I have adjust one of the MFJ tuner knobs every 10 kHz.
73, Dave WX7G
Spiderbeam Fiberglass Mast
Well, if anybody would like to check this product then here is a link to the Spiderbeam page:
Spiderbeam HD 12m fiberglass pole
I can recommend the 12m version as it has still 8mm diameter/1.4mm thickness of the top section and the price is still resonable. More detailed parameters as follows:
High strength professional telescopic fiberglass pole
fully extracted length (height)
12m (40ft)
transportation length1.18m (3ft 10")
weight
3.3kg (7lbs)
bottom diameter55mm (2 1/6")
top diameter8mm (1/3")
wall thickness1.4mm - 2mm
(1/18" - 1/12")
number of segments12
pole materialblack fiberglass, UV protected
specially reinforced multilayer winding
The most interesting informations are that even the top segment is 8mm in diameter (and 1.4mm wall thickness), so the poles can be used to their full 12m length - unlike other poles where the top segment is very thin as a whip. During our tests we were able to put 80m inv vee dipoles (made from 1mm diameter enameled copper wire (AWG 18) and open wire feedline) right at the top of the 12m pole.. No way you can do this with a regular "fishing rod"! At 9-10m height, the poles can easily support small VHF / UHF yagis.
OK, its the Spiderbeam supplier but what about others?
Another possibility is the Kelemenantennen Fiberglas Mast supplier in Germany.
mast glass fiber 12 m
Item N°: GFK-MAST-12
Mast is made of glass fiber for light antennas
hight: 12 m
12 x 1,10 m segments
length for transport: 1,18 m
weight: approx. 3 kg
diameter at the top: 9 mm
diameter at the bottom: 53 mm
As You can see its the 12m Fiberglass mast also where few parameters are a bit different. Last top section has still 9mm (instead of 8mm in Spiderbeam mast) but no tickness info on web pages.
The concept of the mast and even the design seems to be the same. Also there the bending at the top part is expected. More informations You can find there:
http://www.kelemenantennen.de/Kelemen-Shop_eng/index.html
Third supplier of the Fiberglass Masts by DK9SQ.
image14.jpg (100573 Byte)
This version of the Telescoping Fiberglass mast has 10m. The same design and diameters of the top and bottom sections sounds like its made by one manufacturer only.
image27.jpg (100005 Byte)
I have purchased two masts few years ago and from my experience I can not recommend to use as support of an Inverted L or the vertical for permanent usage. The bending of the last few meters is so big that in the windy WX will be 40% of the mast bended down. Well maybe for short mast to support Flag in 5.2m height should be usable but I did not tried.
Price of the both preview masts is quite same for 12m version. In case of the DK9SQ the price is couple Euro higher but for 10m mast only.
Informations for that mast You can find (in German) there:
http://www.qsl.net/dk9sq/
OK, its all for part I. about the Fiberglass poles. I am promissing that it will continue in part II. with another suppliers. Finally we will find good pole for our receiving Flags or even for Inverted V nor verticals on 160m...
73, Petr OK1RP
 

Buď první, kdo ohodnotí tento článek.

Nový komentář

Vezměte na vědomí, že diskuse je moderována. Než se nový komentář začne zobrazovat, musí jej nejdříve schválit autor blogu.

Přihlásit se
  Ještě nemáte vlastní web? Můžete si jej zdarma založit na Blog.cz.
 

Aktuální články

Reklama