[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: A dish and environment question




I think so, but you'll not be able to do super DX.  For example I've worked 
ZL stations from W0, but the elevation of the bird was only like 10 degres.

But Asia and western Europe for you should be okay.

Since you likely have 2m SSB receive capability, getting an inexpensive 
downconverter first is a good idea.  Make a W0LMD single band patch feed for 
your 1.8 m dish (which is good sized, it really is), get a downconverter and 
listen.
There is a guy in Calif that sells Cal Amp MMDS units for $30US, I don't 
know if he'd be willing to ship to Austrailia or not. The better Transystems 
3731's are
I think $70US from another ham in Texas.  Someone can correct me on this if 
I'm off a bit.

And you can make 10 or so contacts the first time you are on during good 
squint conditions, so your dollar per qso ratio whould be better if that is 
your main concern.

I doubt if the rotator will do it. OK it will in no winds.  It might survive 
winds if you point the dish straight up.  If you forget to do this in high 
winds, you'll probably strip out the rotator.  In any case the dish needs to 
be (very nearly) perfectly counterweighted and balanced.

I'd first try to armmstrong the dish.. near apogee I only had to nudge the 
4' dish (1.2 m) about every ten minutes or so, less if I swung past the 
peak.  TVRO acutators and gear motor drive systems are up to the task.. I've 
put together a set of sprockets, chain and a surplus gear motor for about 
$50 US so the Az can be done cheaply.  Brand new "superjacks" are less than 
$100US and can be used right as is for el.

I used a plastic chair for my dish mount.  A picture of this was published 
in the June 2002 QST. (also http://www.fredspinner.com/W0FMS/rubeao40.html)

I find building the system, aligning the dish, tweaking it up, etc. is the 
main sorce of joy I get out of AO-40 (and the hobby in general), so there 
was no doubt it was worth it for me.

Good Luck.

Fred W0FMS


>From: Phil <phil@spiderweb.com.au>
>To: amsat-bb@amsat.org
>Subject: [amsat-bb] A dish and environment question
>Date: Thu, 16 Jan 2003 09:15:21 +1000
>
>Hello All,
>
>I'd like to put some gear together for AO-40 but I'm not sure if the 
>results
>will be worth the cost. Each two-way contact on the LEO satellites has cost
>me about $300 each and listening to one's own voice is not a lot of fun. 
>I'm
>really concerned that the received signal will be just too weak to be 
>useful.
>
>I'm located in a valley with the closest wall being about 3 km away and the
>distance to the furthest wall of hills is probably 20 km. The more distant
>range is, no doubt, not a problem however to clear the range to my north, 
>the
>satellite would need an elevation of around 15 degrees to be visible.
>
>I'm also surrounded by tall spotted gum trees (native eucalypts) and this 
>is
>my real concern. To be clear of the trees the satellite would need to be
>elevated by around 45 degrees and up to 60 degrees in some directions.
>12 GHz satellite TV works well here despite the trees but that's probably 
>not
>a very good indicator.
>
>The dish that I've been offered is a 1.8 metre diameter prime focus petal 
>type
>(ex Sky TV, I think). I don't know if it's of solid or mesh construction. I
>wonder if my KR 400 rotator (no break) is up to the task, even if the dish 
>is
>a mesh type? I don't think that AO-40 is always available in the same 
>general
>direction, otherwise I could use a wife rotator to make small periodic
>adjustments.
>
>So, what's the verdict, is it all likely to be worth the effort despite the
>hills, trees and the light-weight rotator?
>
>--
>Regards,
>Phil
>phil@spiderweb.com.au
>
>----
>Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
>To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org


_________________________________________________________________
MSN 8 with e-mail virus protection service: 2 months FREE* 
http://join.msn.com/?page=features/virus

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home