Hi Folks!
Here are the responses that I received from WA1ZMS, KC2HIZ and N1SZ with
respect to what the W2SZ/1, Mt. Greylock Expeditionary Force uses on 903 MHz
and 1296 MHz based on my questions after looking at their "very cool" web
site.
Many thanks to each of you for your thoughtful responses!
I have a 45 ft Rohn 25 tower with the standard double bracket installation
to the wall of my house and am now considering putting the dish up on the
tower!
The one consideration is wind loading, so this leaves me with a couple of
alternatives:
1. Use a tubular grid dish. I would need to measure the gap between the
tubular elements of the reflector to see if makes sense at 1296 MHz.
2. Use the tubular dish and use chicken wire or hardware cloth to close
it up. This would add wind loading and if iced, would become solid with
respect to the wind.
3. Use a solid dish because I don't need to worry about wind loading.
Somehow I have my doubts about this option!
4. Use the solid dish but use a screw drive to elevate it to a "bird
bath" safe position. This option has other implications which are tempting!
5. Scrap the whole thing and use a pair of LONG 903 and 1296 MHz loop
yagis instead of the dish.
We'll folks! What do you think?
Thanks & 73,
Gordon Beattie, W2TTT
201.314.6964
Gordon,
Let me see if I can help get you the info on the feeds. You are correct
they are on Rohn 25 (temporary tower for the weekend). I believe it is on a
2" OD steel mast, but I'll double check. I've put it up a few times....
you'd think I'd know a bit more after being with the group 18 years.
Believe it or not, I think it is a HAM IV (or similar) we've got it on. I
do know there is a 3 degree offset between the two feeds, so when we go from
903 to 1296 we have to adjust the heading by 3.
73,
Jim, N1SZ
222 Band Manager W2SZ/1
Hi Gordon,
I'm often the 10GHz operator for W2SZ/1 and I help put up (and take
down) that 1296 dish. The folks with the technical details are at Dayton
but I think I can help a little.
It's a solid Andrew aluminum dish, I think on a 2 inch stainless mast.
There are 2 feeds (902 and 1296); both home brew; I think they are splash
feeds but I am not 100% on that. The rotator is a ProSisTel Big Boy, but
I'll be darned if I can recall which one. It sits at the top of 35 feet of
Rohn 25 guyed in 3 places (but with the winds up there we really should use
4 guys).
I operate 1296 in a pinch, and I can tell you that the pointing is pretty
sharp. Weak signals need to be pointed within about 5 degrees.
Up on Mt Greylock, one of the most important attributes of the rotator is
that is have really good brakes. The wind can torque a solid 6 ft dish like
*that*.
Sorry I don't have any technical details; I didn't build the station.
I'm just part of the labour to push it up and pull it down :-).
73 de KC2HIZ, Buck
Gordon-
I've been the 903/1296 operator at W2SZ/1 for the past 20+ years,
so I guess I'm the best person to try and answer your questions.
While we do not not have an ideal antenna situation at 'SZ
on 903/1296 what we have has worked well enough thus far
so that only in the past year or two have I/we talked about
a better dish & feed situation.
The dish is a 6ft solid Andrew with an f/d of 0.38. For each
band (903 & 1296) we use a simple dipole feed with a round
splash-plate reflector. The mast is 1.9" OD iron pipe and the
tower is 40ft of Rohn 25. For many years we used a Ham IV
rotor but about 6 years ago I switched to a Pro-Sys-Tel rotor.
While not a fan of the rotor control box (maybe a Green Heron
would be better), the rotor itself has been very nice and
turns the dish in all kinds of winds without trouble.
I hope I answered your questions. If you have any more please
ask and I'll do what I can to answer them.
Of course, if you ask too many questions you'll have to come
and join us on Greylock in June or Sept and try operating with
us! We can always use more help! hi....hi...
73,
-Brian, WA1ZMS
@ Dayton this weekend.
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