[MAMS] April 2011 Microwave Activity Day

[Zack Widup]

On 4/5/11, Dr. Gerald N. Johnson <geraldj at weather.net> wrote:
>
>
> On 4/4/2011 4:39 PM, Zack Widup wrote:
>> Surprisingly, my dish wasn't damaged, even after it literally flew
>> over my car WITH the tripod at one point. I did get a scratch in the
>> car.
>
> At CSVHF last summer Bill Clark didn't seem to think that the stock
> Direct TV dish was made very well anyway, that its precision was poor.

I wasn't using a DirectTV dish. I was using a two-foot diameter
prime-focus dish that is very thick. It's been beaten around a lot and
hardly shows any signs of wear at all. I had it at CSVHF in the Dish
Row last year.

>>
>> My IF rig was damaged when the table blew over. I don't think a radome
>> would've kept either the radio or the dish from blowing over.
>
> Actually I was thinking of a RADOME big enough to hold dish, gear, and
> operator. It would practically have to be mounted on a truck with
> stabilizing jacks like a crane or bucket truck and heavy enough to hold
> it down in the anticipated wind.

That would probably do it if I had anything like that. I figured a
couple sandbags, one to hold down the dish tripod and one to hold down
the table, probably would've done the job. I don't know how to keep
the 902 looper from spinning. I had the bolts on the mast clamped as
tight as I could get them and it still spun around.

There are a lot of trees and big limbs down around here after the wind
we had over the last few days.

>>
>> Next time I won't bother to try to set up if the wind is that
>> ferocious. I suppose I could've carried some sand bags for weight but
>> there's only so much you can fit into a Toyota Corolla!
>
> We probably need to do some checks of path losses vs wind speeds for
> various times of the year. I suspect that under the wind conditions you
> had, signals are down seriously, like 20 to 40 dB on a 40 mile path,
> making outings and exercise in futility. I've seen more variation than
> that to Des Moines repeaters and packet nodes over the years, but I've
> not bothered to compare to wind speeds. The 4th edition of Kraus
> published for Asian consumption has many chapters on propagation and
> includes computations for refraction and obstacle gains at microwave.
> I've not read it all yet, but it may supply some research references if
> not some insight to these wind effects.
>> :-)

It would be interesting to note that. My path to Wally is about 100
miles. We've tried several times on 3456 and haven't made it yet but
we've worked before on 902. If I'd gotten started earlier I'd have
taken 144 MHz with me too, but given the wind problems I'm glad I
didn't. It would've been another antenna to blow over and patch up
later!

73, Zack