[MAMS] April 2011 Microwave Activity Day

Mon Apr 4 16:33:10 EDT 2011

In my case on Saturday, it was a hindrance to microwave antennas,
equipment and operating! I couldn't even keep the dish up long enough
to aim it at anything.
:-)

73, Zack W9SZ

On Mon, Apr 4, 2011 at 3:29 PM, Dr. Gerald N. Johnson
<geraldj at weather.net> wrote:
> Wind is often a significant hinderance to VHF and microwave propagation.
> Without wind and clouds, night radiant cooling of the earth's surface
> cools air near the surface causing a temperature inversion that enhances
> refraction. Evaporative cooling over water bodies gives much the same
> effect. In the prairie typically that morning inversion is about 1000
> feet above the ground. Often visible when flying up in a small airplane
> or observing a smoke or steam plume from a fire or power plant. Wind
> stirs the boundary layer and destroys the inversion by mixing. Gusts are
> better at mixing. Cloud cover over land holds in heat and so tends to
> prevent the little inversion forming.
>
> A high pressure dome has no wind under it and that inversion can build
> and isn't destroyed and can build up over days to cover a large area
> with propagation out to 1500 miles or better.
>
> We work beyond line of sight with normal conditions because of the
> atmosphere is less dense with altitude and that gradient of density
> causes some refraction, the 4/3 earth radius rule.
>
> 73, Jerry, K0CQ
>
> On 4/4/2011 10:31 AM, Zack Widup wrote:
>> Conditions on Saturday were evidently very poor. I cannot verify that
>> I was NOT putting out power on 902 MHz, so I am going to assume I
>> actually was when I tried to work Wally W9OBG. When I got everything
>> home and checked it out, it appeared the only damage to the IF rig
>> from a fall onto the ground was a damaged squelch control knob/shaft,
>> and everything else was working normally. I was getting 10 watts out
>> of the 902 MHz transverter as expected. Since Wally was running 200
>> watts or more and I was only getting him S9, and he couldn't hear my
>> 10 watts at all, I am now assuming conditions were that bad. Lloyd
>> NE8I has said that condx were really poor up in Michigan where he was.
>>
>> I can get to the hilltop in EN50rl just about any morning of the week
>> between maybe 6:30 and 8 AM CDT. as well as some hours during most
>> weekends. If the Hepburn forecast looks good and if anyone wants to
>> try to work me, let me know. I just hope it isn't a windy day!
>>
>> I haven't attempted an SDR radio for a microwave IF. It might be a
>> good idea as you could see a good chunk of the spectrum all at once,
>> and when you've identified a signal all you have to do is peak your
>> dish on it. But there is so little time and I'm spending a lot of time
>> trying to get my 24 GHz transverter going. I just made a few boards
>> that are basically the W1GHZ Miniverter-F but the helical filters for
>> 432 that I have are smaller than the ones he is using (hence I made my
>> own boards with my filter size specs rather than order some from him).
>> I want to use this as a 432 MHz IF for the 24 GHz SDH transceiver I
>> have. I'm also working on putting together the LO chain to give me 6
>> or 7 dBm at 11.800 GHz. I might get that done this week.
>>
>> Then I'll start thinking about 47 GHz.
>> :-]
>>
>> 73, Zack W9SZ
>>
>>
>> On Mon, Apr 4, 2011 at 9:56 AM, M Ragouzis<n0obi at yahoo.com>  wrote:
>>> Hi Dave
>>>
>>> Thanks for the note of the 11th.
>>>
>>> My brother  Bruce ,  may have a 6 foot fiberglass dish to give away , he spoke
>>> about it yesterday and he lives near you.
>>> I have a phone call in to his message center now just so he doesn't cut it up
>>> before some one has a chance at it.
>>>
>>> I hope things are going well for you , we should have a breakfast meeting some
>>> time , what do you think ? , I do not know anyone in the club by face ( how many
>>> are here in the st louis area ) .
>>>
>>> Is anyone working on SDR using the Apple i-phone or i-Pod products for  a 10
>>> ghzreceiver ?
>>>
>>> I'm still working on getting the SDR radio up and running , I found a 741 OP amp
>>> in the junk drawer last night , the RF front end will work through the computer
>>> sound card but not through Jim's i-phone or i-pod , so it looks like the i stuff
>>> needs more gain , Jim discovered ad added the 10M ohm resistor across the mic
>>> input to let the i-phone/pod know that it has and external mic.
>>>
>>> Plugging in the mic/sdrrffront end caused a spike to form on the display but
>>> nothing more than this , were getting closer.
>>> I don't know that the 741 will be quiet enough , but as things are right now
>>> something would be better than nothing.
>>>
>>> If we go through the 1/8 inch jack we only get one channel so it I or Q and we
>>> have just a one channel direct conversion radio ( ? ).
>>> But we will have the ability to use the software to narrow down the band width ,
>>> so this should be real good for 10 ghz.
>>>
>>> I have the 2 meter N-channel amp built , I just need to tune it up .as you know
>>> we were talking about dynamic range problem's , I hope this and sdr will make a
>>> running receiver.
>>>
>>> OH , I picked up a "Gunn Oscillator " that I tuned to 10.368 ghz , so it might
>>> be good for CW even though its a little wide  ( I have a filter ) .
>>>
>>> So much stuff to do so little time.
>>> Mike
>>> N0obi
>>> 73
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> ________________________________
>>> From: Dave Calvert<kb0pe at yahoo.com>
>>> To: Mid-America Microwave Society<mams at mailman.qth.net>
>>> Sent: Sat, April 2, 2011 9:28:53 PM
>>> Subject: [MAMS]  April 2011 Microwave Activity Day
>>>
>>> I went to EM49au ( AT&T microwave tower site ) and setup at 6am and was ready to
>>>
>>>
>>> go on 902, 3456 and 5760....  It was windy and the bands were dead!  I looked
>>> around
>>> for the beacon on 902 (K3SIW's) and nothing.  I did have some long q's on
>>> 144.200
>>> at around 11am with South St. Louis and that was it....
>>> 73,
>>> Dave -KB0PE
>>>
>>> Starting Monday April 11th, 7-11PM local. 2M Sprint.
>>> Tuesday April 19th - 222 Sprint.
>>> Wednesday April 27th - 432 Sprint.
>>>
>>>
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