[time-nuts] Choke Ring Pictures

[bg at lysator.liu.se]

Hi,

I have two AT575-90s - the Aeroantenna L1 chokering - resold by CMC, Leica
and others. They work really well as witnessed by others here. One nice
touch is that they  - at least the CMC badged - come with a
"marine"-thread to 5/8" survey-mount adapter.

However, this model is not present at

   http://www.ngs.noaa.gov/cgi-bin/query_cal_antennas.prl?Model=AER

so it does not count as a true geodetic antenna. ;-)

The cone cover is indeed good. Snow/ice-buildup would have been a
showstopper this year in Sweden. For real geodetic use "spike"-cones are
long out of fashion. From my understanding a thin plexiglas makes good
cone material. Combine a halfsphere (upper) with a suitable lenght "tube".
Make the center of the sphere as close to the phase center of the antenna
as possible.

Here is an illustration.

   http://swepos.lmv.lm.se/stationer/opp.htm

--

   Björn

> Hi
>
> All of these gizmos are going to work better outdoors than indoors. Coming
> up with a rainproof / bird proof / bug proof cover for the choke ring that
> also is rational at RF is one more "gotcha".  Both loss and dielectric
> distortion effects are worth worrying about.
>
> Bob
>
>
> On Mar 14, 2010, at 1:23 PM, GandalfG8 at aol.com wrote:
>
>> In a message dated 14/03/2010 15:46:55 GMT Standard Time,
>> cfharris at erols.com writes:
>>
>> I would  call those aluminum cake, not pie, pans.  It looks like you
>> bought
>> a  set for making wedding cakes.
>>
>> Is there a different definition of "pie"  in G8 land?
>> -----------------
>> Hi Chuck
>>
>> No other definition that I'm aware of, other than David's of course, but
>> I
>> was just replying to Brian, KD4FM, so I guess that makes it a US of A
>> definition:-)
>>
>> regards
>>
>> Nigel
>> GM8PZR
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>
>
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