[amsat-bb] Re: Station not coming together - the full post (sorry for repost, reply to this)
broberts at mta.ca
Wed Mar 7 15:33:48 PST 2007
Quoting Jonny 290 <jonny290 at gmail.com>:
> Lying in bed last night, I realized my solution to the 'noisy rotator'
> that's stopping me from putting up yagis.
> Ground mounted rotator!
> Pound a 1.25" steel pipe in the ground, bolt the rotator to that at
> level, run the mast up.
> Here's my thinking - 15 feet of PVC with a short yagi on top, mounted at
> degrees elevation, give or take. At the 10 foot 'eave' level, I create
> sort of crude bearing using PVC that allows the pipe to spin, but not
> wobble. Bolt that to the eaves and use it as the anchor point up top.
> pipe could down to just above ground level, where it's connected to the
> rotator output.
> I'm in a valley so winds never get higher than 40 mph gusts, and the
> should have plenty of 'give' to not mess up during a wind gust. I've
> stuff right nowon a 12 foot PVC mast that isn't even cemented together,
> it's tough.
> This would allow me a steerable antenna without bothering my roommate.
> rotator noise should be almost inaudible when it's mounted down so low
> (there won't be a window in the path to easily conduct noise) and if
> still an issue, it'd only take an hour to build an MDF box with a hole
> the top to cover, insulate and protect the rotator.
> Think it'll work? :D
Sounds like a good idea. I was going to write to say that I have a similar
set-up, with a Orbit 360 TV-type rotor only about 5 feet outside the window
of the room I use as a shack. When it rotates, it is quite audible, and if
I were trying to do work here I would find it distracting. If you undertake
the above contraption, I would recommend putting the bushing on the side of
the house first, before pounding the pipe in the ground :-)
A gain antenna really does make for a more forgiving setup. Be careful not
to make the beams too long: you'll lose the high elevation and you'll go
crazy tweaking your rotor. My 8 element 70cm does nicely with fixed
elevation. I also recommend foregoing circular polarization in these
antennas. See my discussion at:
(I can't seem to find a permanent link for archived messages.)
You were thinking of buying a downconverter for your HF rig. One further
option for exploring satellite communications is the FT-817. These can be
found second-hand quite cheaply on Ebay and other sources. I used a pair of
them for some time on LEOs, and though a bit low on power, they allow you
to walk outside and test your antennas in a handheld, short cable arrangement.
And for a satellite you might be able to work right now, check out AO-7 in
mode A, every other day right now. (Consult
to see what mode is up today.) My 10m vertical fed by 30m of RG-8x can hear
its telemetry, CW and some SSB. A loop around my shack might do even
better. Last year, my HF antenna was a horizontal long wire, and I never
did hear AO-7 because of the fragmented azimuthal pattern on 10m.
Since you seem to be interested in doing things yourself, you really would
enjoy the Davidoff book I recommended earlier, not to mention the AMSAT
Journal, whose quality is remarkably high and which is a perk of membership
73, Bruce VE9QRP
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