[time-nuts] Choke Ring Pictures

Bob Camp lists at rtty.us
Sun Mar 14 20:02:29 UTC 2010


Hi

Machining a chunk of Plexiglas sounds like more trouble that I would want to go to for a cheap choke ring setup. 

Maybe a hemispherical Plexiglass serving bowl ....

Bob

On Mar 14, 2010, at 3:42 PM, bg at lysator.liu.se wrote:

> 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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> 
> 
> 
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