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G8MNY > TECH 07.10.26 10:33l 111 Lines 5349 Bytes #1 (0) @ WW
BID : 7252_GB7CIP
Read: GAST
Subj: Growing Loft to Roof Aerials
Path: DB0FFL<DB0FHN<DB0RKB<DK0WUE<HB9ON<IK7NXU<IK6IHL<IZ3LSV<ED1ZAC<GB7CIP
Sent: 261007/0809Z @:GB7CIP.#32.GBR.EURO #:7252 [Caterham Surrey GBR] $:7252_GB
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
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 \ and 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 \
and working satellites I / Þ \
put a horizontal broom / Þ \
handle on the pole and 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 and 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 and the tube bent around the masonry to "grab
it", this stops any wire chaffing and 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 and 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
and put it up higher with ³ _-~ | ~-_ ³
more and larger aerials on it too. ÀÄÄÄÄÄÄÄÄ¿| -_³
ÀÄÄÄÄÄÄÄÄÄÄÙ
//////////////////////// I ended up with a 24el on
³ 23cm for ATV & 19el for 70cm
/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ and 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 and 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 and 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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