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G8MNY > TECH 01.06.20 09:25l 112 Lines 5351 Bytes #999 (0) @ WW
BID : 58219_GB7CIP
Read: GUEST
Subj: Growing Loft to
Path: IZ3LSV<IR2UBX<DB0RES<ON0AR<OZ5BBS<CX2SA<N9PMO<JE7YGF<GB7CIP
Sent: 200601/0813Z @:GB7CIP.#32.GBR.EURO #:58219 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
Roof Aerials
By G8MNY (New Nov 09)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
When I started AR in 1977 as a VHF & above ham, I used a loft aerial system
that grew & grew.
n
/ Þ \Roof I put a pole loft floor to roof
/ Þ \ & eventually I found I had enough
/ Þ \ space to fit a homebrew 6 el 2m quad.
/. [-[-[Þ[-[-[].\ The vertical pole with a rotator at
/ ú Þ ú \ the bottom meant lots of
/ '. Þ .' \ experimenting was possible.
/__________ú__±±_ú__________\
Loft floor Rot
n
For vertical polarisation / Þ \
& working satellites I / Þ \
put a horizontal broom / Þ \
handle on the pole & ganged /. [-]-Þ--X .\
the 2m quad with 70cm / ú Þ ú \
46 element multibeam. / '. Þ .' \
/__________ú__±±_ú__________\
There was quite a bit RF loss through the roof so I decided to grow the pole &
pushed it out through the roof.
2M Quad [-[-[-Ý]-]-] As you see I put the extension 16ft pole
nÝ alongside with large clamps. The roof
/ ÞÝ\ hole goes through a sheet of ally with an
/ ÞÝ \ oval hole in it, so the pole side forces
/ ÞÝ \ are not taken by the drilled tile hole.
/. ÞÝ .\ The coax down the roof tube is free to do
/ ú ÞÝ ú \ what to needs to rotate. The 2" offset
/ '. Þ .' \ eccentricity is irrelevant on the loft
/__________ú__±±_ú__________\ pole & rotator.
Roof Pole
³Þ³ Ridge
Funnel/³Þ³\ /~\
³Þ³-~ ~-_
For water proofing, Roof ³Þ³-~Ally
I put a large beer _-~³Þ³Plate
funnel on the pole _-~ -~³Þ³
above the hole & also ~ {³Þ³³ ³} Large
placed the rotator in ³Þ³³ ³ Clamps
a large drip tray to {³Þ³³ ³}
to catch the leaks. Þ ³ ³
Coax Ý ³ ³
Þ ~ ³
Ý ³ ~
Þ ³ ³
Ý ²²² Rotator
Drip ±±±±±
Tray³____±±±±±__³ Loft Floor
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
To my surprise I did not have any complaints from the neighbours or planners
with the outside aerial! (would not be true today!)
Later I lifted it as high as I dare (moving the funnel down), but I noticed
some swaying in windy Wx. So I then designed & added some guys on a top
bearing.
Pole Guy ú
³ ³ Cast Guy Wireú _-~
Guy_ÚÄÄÄ¿-plate ú _-~
Eyelet.øÝ Þø. Tube/_-~ Roof
ú ³ ³\__Cast clamp ‡Ú/~--------Gutter
.' ³ ³ & Nylon Washer '~³~~~~~~~~~~
úGuys ³ ³ ³
These plastic covered steel guy wires are anchored on the 4 corners of the
house with a 7mm dia plastic covered flexible thin ally low pressure tube. The
wire is threaded through the tube & the tube bent around the masonry to "grab
it", this stops any wire chaffing & the wire length can be adjusted a few
inches & the ends loosely twisted together to finish off.
_
Later I found that 4 guys ÚÄÄÄÄÄÄÄÄÁÄÁÄÄÄÄÄÄÄÄ¿
was not enough & the ³~-_ | _-~³
pole folded in a storm. ³ ~-_ | _-~ ³
ÚÁ¿ ~-_|_-~ ÚÁ¿
So I redesigned it to have ³ ³~~~~~~~-ø-~~~~~~~³ ³
8 guys (used chimneys too) ÀÂÙ _-~ | ~-_ ÀÂÙ
& put it up higher with ³ _-~ | ~-_ ³
more & larger aerials on it too. ÀÄÄÄÄÄÄÄÄ¿| -_³
ÀÄÄÄÄÄÄÄÄÄÄÙ
//////////////////////// I ended up with a 24el on
³ 23cm for ATV & 19el for 70cm
/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ & an 8el 2m homebrew dual
/ / / / / / / / /Ý/ / / / / / / / / / boom quad.
, , , , Ý , , , , The 23 & 70cm aerials on stub
/³ _/³____/³____/³_Ý _/³ _/³ _/³ _/³ masts are fed with the large
/~³~~~/º³~~~/~³~~~/~³±Ý~/~³~~~/~³~~~/~³~~~/ ³ LDF450 coax & that goes down
³ ³ ³ º³ ³ ³ ³ ³±Ý³ ³ ³ ³ ³ ³ ³ ³ the thin walled 2" 16ft roof
³ / ³_º/ ³_/ ³_/ ±Ý³_/ ³_/ ³_/ ³_/ pole & it does 2 large turns
³/~~~~³/~~~~³/~~~~³/~~±~³/~~~~³/~~~~³/~~~~³/ in the loft space so that the
' ' ' ' úß±ßú ' ' ' whole lot can easily rotate.
.' ± '.
Why don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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