[Moon] Under what angle is a feed in a offset dish ??

Anders anders at la8lf.com
Sun May 7 22:08:36 CEST 2017


John

Try a more practical way. Put 4 ore more small mirrors around the rim 
fixed to dish surface by double sided tape.
Point dish at sun untill smallest burning  (hottest spot) is seen on an 
aluminium plate painted black. That is your focal
point. Now you can put the mouth of your feed at this point and tilt the 
feed untill maximum sun noise. Then you can
  play around carefully  moving feed up and down and sideways and 
slightly in/out all very carefully while monitoring sun noise.
  Finally check feed tilt for maximum sun noise.... This will probably 
take most of a full working day, but fun! Now
you should see some 1.6-1.8 dB moon noise on 3CM with flux of 70-75. 
Yesterday it was 72.
Your dish is most probably 0.60 f/D like mine. A scaled N2UO (W2IMU with 
OM6AA 5 step septum) fits well this f/D.
Good luck.
73 Anders LA8LF


Den 07.05.2017 17.36, skrev John Lambo:
> Hello all,
> If my dish is water level my feed looks 25 degree up to the dish .
> Maybe who can calculate beter then me can tell me is this is oke or 
> not ??
> Again any info is welcome .
> I hope to solve this problem at the end and put maybe a beter signal 
> from the moon HI  ....
>
>
> 73  John  PA7JB
>
>
>
> Op 7-5-2017 om 17:08 schreef John Lambo:
>> Bonjour Dom,
>> Yes i did mean under what angle me feed have to look to my dish ??
>> I know that the offset to look to the sky is 22 degree
>> I will go outside and measure under what angle my feed looks to the 
>> dish if it is water level .
>> Maybe now i also understand is why other amateurs see more moon and 
>> sunnoise.
>> I think i have made the wrong feed??
>> But as Sergei RW3BP use for his dish i think i do the same.....
>>
>> 73  John  PA7JB
>>
>>
>> Op 7-5-2017 om 16:15 schreef Dominique Dehays:
>>> oooops , my reply was wrong , U meant offset angle , not 
>>> illumination angle
>>>
>>> 73
>>>
>>> Dom
>>>
>>>
>>> Le 07/05/2017 à 14:48, Anders a écrit :
>>>> Hi John,
>>>>
>>>> My 3.8M offset dish is a Prodelin similar to your 2.4M.
>>>> The f/D is 0.6. The 3.8 meter offset reflector has a 22.62-degree 
>>>> elevation offset look angle. Therefore, when the reflector aperture 
>>>> is perpendicular to the ground, the antenna look-angle is 22.62 
>>>> degrees in elevation.
>>>> Your dish uses the same original off-set feeds (C-band) as my 3.8M 
>>>> dish. See www.LA8LF.com. I have sent you separately a pdf document 
>>>> on how to install the feeds on your 2.4M offset dish.
>>>>
>>>> 73, Anders LA8LF
>>>> **
>>>>
>>>>
>>>> ****
>>>>
>>>> *
>>>> *
>>>>
>>>> **
>>>>
>>>>
>>>> Den 07.05.2017 08.54, skrev John Lambo:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Hello Lunatics,
>>>>>
>>>>> I use a 2,4 meter Prodeline  1270 offset dish for EME now for 7 
>>>>> years.
>>>>> The support for the feed is changed to a other support.
>>>>> This beacuse the feed for 23cm is so big that the old support was 
>>>>> to high.
>>>>> You can look on the home page off OK1KIR how this feed is in my dish.
>>>>>
>>>>> http://www.ok1kir.cz/index.php?name=1296 
>>>>> MHz&page=gals&gallery=15&galpart=3&list=1&start=100
>>>>>
>>>>> But now my problem..
>>>>> If i change the feed from 23cm to a other band say 9cm or 6cm i 
>>>>> see on
>>>>> sun and moonnoise a offset on my  OE5JFL readout.
>>>>> This can be in elevation 2 degree and in azimute 0,7 degree.
>>>>> I know it is not that much but what i think this must not be 
>>>>> possible??
>>>>> The feed i use for all my EME bands is a RA3AQ feed with a round 
>>>>> septum.
>>>>> I wonder under what angle must my feed look to the dish ?
>>>>> So if my dish is water level under what angle looks the feed to 
>>>>> the dish??
>>>>> I know that more amateurs use a offset dish on EME and wonder if 
>>>>> they see the same ??
>>>>>  Thank you for reply...
>>>>>
>>>>> 73  John  PA7JB
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Moon mailing list
>>>>> Moon at moonbounce.info
>>>>> http://lists.moonbounce.info/listinfo/moon
>>>>>
>>>>
>>>> _______________________________________________
>>>> Moon mailing list
>>>> Moon at moonbounce.info
>>>> http://lists.moonbounce.info/listinfo/moon
>>>>
>>>
>>> _______________________________________________
>>> Moon mailing list
>>> Moon at moonbounce.info
>>> http://lists.moonbounce.info/listinfo/moon
>>>
>>
>
> _______________________________________________
> Moon mailing list
> Moon at moonbounce.info
> http://lists.moonbounce.info/listinfo/moon
>



More information about the Moon mailing list