Help needed on Channel Master 1.2 dish

Burnham Beech

I'm installing a Channel Master 1.2m offset dish + Polar Mount in a new location. Looking for the following information.

1/ I found an old Channel Master document on the web which implies the offset is 22.6° - can anyone confirm this figure?

2/ I found a help sheet on setting the declination - see attachment. But the instuctions look wrong. If you look at the attachment it says the example shown is set for 32° latitude based on the position of the back edge of the top plate.

But based on my own measurements it appears the example is set for about 48° latitude - seems the setting should be based on the lipped edge of the top plate.

Anyone has any views of which is correct?

Attached Images

CM Declination.jpg (30.9 KB, 70 views)

timbo86

My measurement is taken from the top lip off the plate.These mounts are quite tricky to set up on the arc!

Burnham Beech

Thanks for your reply, you seem to confirm my own calculations.

I wonder why the Channel Master installation manual shows the wrong information. It looks an official document, although I don't have all the pages to confirm its source.

Does anyone on the forum with a 1.2m Channel Master dish supplied from new have the official documentation supplied with the dish?

Likvid

Yes i do have the information.

Burnham Beech

I would be very grateful if you upload your information in this thread if you have copies in jpeg format (or any other format that can be uploaded to this forum).

Channel Hopper

There are various CM dishes of 1.2m, but the offset angle is uaually calculated from the latitude of the installation, plus the offset of the main reflector.

Do you have the model number from the main dish reflector ? ( it will be embossed on the rear next to the CM markings )


If you are using the Gregorian antenna then there could well be a different setup to observe, but the manual diagram seems to show a standard receive only antenna plate.

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Likvid

I only have the PDF document, you can download it from my server here

_http://pal.pp.se/~kalle/CM1_2.pdf

Burnham Beech

Likvid

Thanks for that. I got that document before when I trawled the net but it's for the fixed AZ/EL mount, not the motorised polar mount. It is however the only document I've found that mentions the 22.6° (on page 8). But it is only a passing reference and it's only a guess on my part that this is the correct offset.


Channel Hopper

It says Part No. 3040646 & Mold No. 1.2M-1 on the rear if the dish. I am looking for the the offset of the main reflector. It is a standard offset dish, not a Gregorian (the dish looks like that shown in Likvid's PDF document).


Also, thanks to another offer of help to which I've replied by PM.

Likvid

The offset is 22.6 degrees.

I have installed this dish in France for a client this summer from Andrew, it's the same dish but Andrew bought Channel Master, Channel Master doesn't exist anymore.

It's Andrew these days.

And yes, the offset angle is 22.6 and it is correct as i have worked with this dish myself.