Old Precision C120 Ku Feed

[moonbase]

Hi,

I found an old Precision C120 Ku feed today that is a slightly different design to the later version. Would anyone know if there was a technical reason for the change of design, pictures attached?

The old design feed is the crusty red one and it has a longer collar on the dish facing side and the ring of the innermost scalar is recessed in the coller. The more recent design has the shorter collar on the dish facing side and the ring of the innermost scalar is protruding from the collar.

The actual length of the waveguide tube in both feeds is the same, it is the scalar positioning and collar that are different. Over to Channel Hopper/John/Trust1/Other Gurus..... ?


Rgds

 

[Trust]

seems to me for different F/d ratio

 

[moonbase]

seems to me for different F/d ratio

Yes, could be, I did not think of that, it came off an old Precision 1.2m dish. I have feeds from other Precision 1.2m dishes and they are all the more recent design. It may be that Precision changed the parabolic shape of the 1.2m dish at some point in their history of manufacture?

I still have the old Precision dish that the feed came off, I will measure the F/D if I setup the dish again.

Thx

 

[John]

... I'd go for the f/D at the moment.
Drop Julian @ Elite a message with the pics, you never know there might be someone who might identify it, perhaps some old Precision staff ?.

 

[blademedia]

I would go for a new design to help prevent water down the throat to lnb,

 

[John]

I would go for a new design to help prevent water down the throat to lnb,

... they come with a small domed cap usually, have you got one at hand MB to show ?.

 

[blademedia]

Yes small plastic cap John, but look at the design, the older first one is encouraging any water droplets straight to where you don't want it, with the newer type its diverting it.

Its certainly not FD I have three here from three different sized dishes and there all identical.

 

[John]

Yes small plastic cap John, but look at the design, the older first one is encouraging any water droplets straight to where you don't want it, with the newer type its diverting it.

Its certainly not FD I have three here from three different sized dishes and there all identical.
View attachment 103967 View attachment 103968

Yep that's them, just been having a ferret to find mine, going OT a bit but came across another old thing from the past ... the good old EBU Descrambler.

 

[RimaNTSS]

Similar feedhorns I found on old SMW LNBs

 

[blademedia]

just been having a ferret to find mine,

Good old stuff John, while I was looking ive found my de/polarizer, I will be needing this shortly.

 

[John]

Good old stuff John, while I was looking ive found my de/polarizer, I will be needing this shortly.
View attachment 103974

Brand new as well matey, they look lovely. Iv'e a couple that i kept for prosperity but mine are a bit more battered lol

 

[blademedia]

Brand new as well matey, they look lovely. Iv'e a couple that i kept for prosperity but mine are a bit more battered lol

I do have the battered type somewhere John, I don't like using the new stuff unless forced, I'm a bit of a magpie

 

[Channel Hopper]

Hi,

I found an old Precision C120 Ku feed today that is a slightly different design to the later version. Would anyone know if there was a technical reason for the change of design, pictures attached?

The old design feed is the crusty red one and it has a longer collar on the dish facing side and the ring of the innermost scalar is recessed in the coller. The more recent design has the shorter collar on the dish facing side and the ring of the innermost scalar is protruding from the collar.

The actual length of the waveguide tube in both feeds is the same, it is the scalar positioning and collar that are different. Over to Channel Hopper/John/Trust1/Other Gurus..... ?


Rgds

Gurus

Many Precision dishes were supplied for non-satellite reception, installed in radomes for point to point communication. My guess would be the red feed is designed to reject spurious scatter that enters the radome after being reflected from nearby objects. The signal source is going to be no more than 20 miles away and therefore diverging (slightly), plus it will be affected more by low altitude atmospherics along the entire transmission path.

I could be completely wrong though.

 

[scopus]

Yep that's them, just been having a ferret to find mine, going OT a bit but came across another old thing from the past ... the good old EBU Descrambler.

The Filmnet one was better.....

 

[blademedia]

Little Precision NPRM and fixed mount ?

Satellite dish patio or flat roof mount. | eBay

 

[Trust]

I would go for a new design to help prevent water down the throat to lnb,

Hardly possible wenn placed in a PF

 

[blademedia]

Hardly possible wenn placed in a PF

That eliminates my theory then

 

[moonbase]

The old red Precision feed with the recessed central scalar was used on a Precision dish for satellite reception. It was part of a setup that used a KHM-36RL motor and a Ku band LNB. The KHM-36RL motor had the strange declination adjustment that used a pipe fitted at a non vertical angle to a circular steel plate. Rotation of the plate adjusted the declination angle, pics attached.


Rgds

 

[blademedia]

That's a nice motor, I have the same one somewhere, also have this tracksat that's similar

 

[moonbase]

That's a nice motor, I have the same one somewhere, also have this tracksat that's similar
View attachment 103995

blademedia,

Yes, the tracsat looks a very similar motor.
What size aluminium centre focus dish do you think these motors would be OK with, they look to be well built, possibly more powerful than a standard Jaeger 1224? I have attached some pics of a new one that was sold on another forum for €350


Rgds