Prodelin 0179-189 dish cleaning & conversion to polar mount

[beavs2112]

Hi folks . I rescued a Prodelin dish from the garbage a little while ago. In those pics the dish doesn't look so bad. However the feedhorn support arms were severely rusted & the dish has a severe case of mold growing on it. So I cleaned the dish & arms with a soapy water/bleach solution using a scouring pad. The results are good now. I am going to paint the arms & dish mount with cold galvaninizing compound aerosol spray paint http://www.rustoleum.com/product-ca...2100-system-galvanizing-compound-spray-paint/ I've semi completed the conversion from a fixed az/el mount to a polar mount. Credit for this design goes to members here ------ pendragon,stogie5150. here's stogies 1.8m dish modifications. So I'm going to copy most of that but put the threaded rods further apart and larger angle iron for more stability. Another part of the process is what to use for the feedhorn & lnb. These were transmit & receive setups originally but us FTA hobbyists can only legally receive signals not transmit. So I wanted to use the original feedhorn. more to come

 

[beavs2112]

I used the polar mount from my made in Yugoslavia MZT model STA 300/04 3 meter prime focus dish to convert. It is heavy duty enough to handle the weight of the prodelin back frame,dish & lnb supports. But I didn't like some things on this polar mount so I had to fix them first. The back frame pivot shafts were at an angle which put unnecessary stresses on the pivot bearings & shaft. Before at an angle So I took things apart and welded on some steel to put the frame pivot axis parallel to the back of the frame. The frame pivots on bearings in a steel block. Well the bearings they used had paper covers over the ball bearings and cage and these had rotted away. Water quickly seized the bearings and cage solid so the back frame couldn't pivot from left to right to track the satellite arc. Also water had corroded away a spacer bushing on the upper pivot shaft. So I cut apart the old useless bearing and used the hardened steel inner ring as the replacement spacer bushing. Then I painstakingly found replacement bearings that had a better cage & ball bearing cover. Now things pivot quite effortlessly and should stand up to the elements better. Then I welded on some steel to the MZT frame to fix the prodelin backframe onto the MZT frame. Buying a cobalt drill bit in one inch diameter size was expensive but worth it to drill into the hard steel frame metal. I have one of these http://www.milwaukeetool.com/power-tools/corded/1250-1 for drilling (kinda a poor mans drill press) but it has a lot of torque. now onto the Prodelin lnb & feed modifications.

 

[beavs2112]

So I want to use all of the signal coming from the 1.8m of the dish and that involves using the correct feedhorn and feed assembly. Well the dish was a transmit & receive version that the feed assembly didn't easily convert to receive only.
Credit for these most of these pics goes to b1llyboy here. Some are mine though. Also in the first pics you can see the rust on the feed support arms. So the combination transmit/receive unit comes apart.
Since the transmit portion interface doesn't allow a standard WR75 flange LNB to just bolt on I decided to remove it. Since I wanted to use this feedhorn and lnb support assembly I had to cut off the transmit portion interface with the angle grinder. The whole combination transmit/receive unit is made from aluminum so its easily drilled & cut. This will allow me to convert the transmit section to another receive section. Another obstacle was the adapter unit between the feedhorn and the transmit section had a 17.5 mm diameter. The diameter of the circular rf waveguide portion of the Prodelin feedhorn is 19mm. The diameter of the circular rf waveguide portion of the Skyware / Channel Master dual polarity ku feed assembly I want to bolt onto the prodelin feed assembly is 19mm also. So I wanted to bore out the diameter of the adapter unit hole to 19mm. This allows for a smooth transition of the rf signal from the feedhorn to the receive lnbs. So now I removed the transmit portion electronics to allow room for the Skyware/CM dual polarity ku feed assembly. Next page ....

 

[beavs2112]

I wanted to use this feedhorn and lnb support assembly for 3 reasons. It's important to use the feedhorn that is matched precisely to the dish. Also you want the feedhorn in the same precise location where the manufacturer placed it to point at the correct spot on the dish face. And this transmit/ receive unit is skewable so I can use it on a fixed az/el mount or a polar mount. Once the skew is set there is a screw that tightens a plastic ring around the transmit/receive metal box to hold it secure. So now I removed the transmit portion electronics to allow room for the Skyware/CM dual polarity ku feed assembly. I gave the unit & feedhorn back 2 coats of flat white rust paint to match the lnbs. Also I had to remove a portion of the tx/rx unit to allow the two norsat lnbs to fit inside the case. Here's the feedhorn & adapter & skyware omt portion bolted together with 2 Norsat LNBs attached. The lnbs don't fit inside the unit with the cover on so the original rx port has to come off (no need for it since the skyware omt has 2 receive ports. The original rx port is cut off and the hole filled with silicone caulking to prevent water getting in. Now I can turn the unit upside down if necessary to keep rain or sun off the lnbs. Now its ready to be bolted on and tested.

 

[primestar31]

Did you know that every photo thumbnail you posted points to satellites.co.uk/forums, and wants you to log into that forum in order to see the full size photo when you click on it?

You can't do that if you don't have an account with that other forum...

 

[beavs2112]

No I didn't ... sorry. embarrassed. I just did a copy & paste from there cause I didn't want to re-type everything. Darn! Ok I'll repost the pics again since they really help tell the story.

 

[beavs2112]

ok here's the pics from post #1 in order

 

[fred555]

Do you have a part number, link or something for this skyware feedhorn you speak of?

 

[beavs2112]

here's the pics from post 2 in order.

 

[beavs2112]

here's the pics from post 3 in order

 

[beavs2112]

Do you have a part number, link or something for this skyware feedhorn you speak of?

sure do fred ... the feedhorn is part of a kit that includes the feedhorn, dual polarity ku band omt ,feedhorn cover,junction block to bolt the feed to the support arms & hardware. Its part # 611606207 for the whole feed kit. Its a wideband ku dual polarity (H&V) feed. Here's the kit here's the feedhorn part Heres the feedhorn & OMT from another angle showing where the lnbs bolt on, And here's a fun comparison of the size deifferential between the 1.2m Skyware dish feedhorn & the 1.8M Prodelin dish feedhorn.
Skyware apparently uses the same 1.2m feedhorn on their 1.8m dish also. Attached is a pdf of their RX only feedhorn kits. Skyware recently changed their website so I'm not sure where everything is located anymore.
Our FTA parts are normally under the VSAT section.

 

[beavs2112]

heres the before & after the cleaning of the dish & feed arm.
the mold really seems to have eaten into the back of the dish so I should spray on some kind of sealer (clear lacquer maybe) to it before I paint it.

 

[fred555]

Darn, this place I buy from occasionally had them for cheap a while back:
http://multicomstore.com/products/reception/satellite.html

I did not know what they were for exactly. Usually If I see something from them
that I may remotely think I may ever need in the future, I buy it.
Like Norsat 8515s shipped for $75 I still need to jump on.

There is what I think is a 1.2 locally I need task about. New company took over a building with the dish left by other company. Its pole mounted on the ground so an easy removal.

 

[beavs2112]

I ordered my Channel Master/Skyware global feedhorn kit from here due to being able to order by cc. http://www.satcomresources.com/Skyw...rthogonal-Feed-Assembly?sc=28&category=249273
Price was US$ 103.00. I wanted it fast so shipping FedEx Priority International was US$ 54.00. I had it in 3 days which was great for cross-border.
sometimes they show up on e-bay.

 

[RimaNTSS]

beavs2112 I do not want to disappoint you, but it might happen that using simple LNB like Inverto Black Ultra instead of original feedhorn will bring you not worse results. But, great project!