Just Sharing This Coming to a forum near you soon - mobile dish test rig

[John]

It was time to scrap the Heath Robinson 1.2 Mtr test rig set-up and construct something a bit more functional for either C-band / Ku / Ka test use.... and possible inspire others. This is also a way of getting around Local Planning Permission as the structure is classed as 'Not Fixed/Permanent'.
Inspired by recent picture from forum member Nelson, who also has a 1.8 CM mobile version & others, to dig out my spare 1.8 CM that was sat doing nothing, and have decided to construct something mobile as well using spare bits and bobs of left over metal off-cuts etc and a pair of discarded Industrial catering trolleys that were found 'skipped' a few years ago. Basic idea is to wheel the mobile assembly out from the garage and onto the driveway next to the 2.2 mtr C-band set-up and manually move it East to West on the large castors with brakes. Elevation control is done with a spare 36" Qual actuator.
Sample pic shown

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[Channel Hopper]

How obediant is your assistant ?

(taught 'fetch/kill' commands on visiting council operatives ?)

Looking at the door diagonals, you could get something somewhat larger in/out of the garage, if you really wanted to.

 

[John]

How obediant is your assistant ?

(taught 'fetch/kill' commands on visiting council operatives ?)

Looking at the door diagonals, you could get something somewhat larger in/out of the garage, if you really wanted to.

Re: the assistant - she's docile, she will fetch but hasn't got a clue how to kill lol.
I managed to see the Council mob off by myself - because the 2.2 mtr dish structure is on a pivot point and tilted down to what you see in the pic it's classed as not permanent - so off they trotted tails between their legs. They sent me paperwork afterwards saying the structure could stay where it is.
I'm knocking this up as cheap and as simple as possible CH, the structure is well under way now and yeah i recon i could get a 2mtr through the doors .... but i 'aint. I will have to tilt the 1.8 CM backwards into a semi birdbath position so the the top of the dish can 'limbo' under the cross beam but i'll get the Quarl actuator to do all that.
I'll put a couple more pics up.

 

[John]

Showing the base sections of the two ex catering trolleys bolted together to form the 'T' shape. The castor wheels cross members were off something else but can't remember what. The wheel footprint as is now is 49" square - i will be casting some concrete ballast blocks to fit either side of the central dolly wheel to keep the thing grounded a bit better. I will fit extra wide outrigger arms if needed later.
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[Channel Hopper]

Out of interest, (based on a ruler up against the ipod 6 screen) , with the side door open the diagonal is close to 3.45m.

Of course with one of those offest dish shapes and the minimum diameter you could squeeze a lot more through the gap......

 

[John]

Out of interest, (based on a ruler up against the ipod 6 screen) , with the side door open the diagonal is close to 3.45m.

I will measure it in the morn

 

[John]

I will measure it in the morn

2.95 mtrs maximum - allowing for dish edge profiles

 

[Channel Hopper]

And if you include the side door ?

 

[John]

And if you include the side door ?

... Canna do - Permanent 4" vertical steel box section providing fixture for three hinges for garage door

 

[Channel Hopper]

A quality angle grinder and a precision hand will soon sort that out

 

[Captain Jack]

I have a couple of 1.8m dishes doing nothing.... But then my actual installed 1.8m is doing very little...

 

[John]

Done a bit more to this over the last week or so to keep me occupied - -
The 'Semi Bird Bath' laid back dish idea to enable the mobile test rig to slip under the available height of the garage door entrance didn't work - had to go the opposite direction and tilt forward. 36" Quarl jack fitted, limits set and tested & working fine no problem.
Fitted original CM feed and feed-arms today and landing point on dish face is as can be seen in the picture. I will get Rimants ref document out later and compare some measurements.
I was going to fit out-riggers and concrete ballast blocks to the base but the structure is so heavy it is just 'planted' to the ground ok.
Just need to cut off the redundant bits indicated to tidy up the structure and then that will be just about it.
Here's some pics ....
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[John]

Time to convert a modern cheap 'Blazer' PLL Ku lnbf into a C120 flange to go onto the CM feed.
These micro small lnbf's are decent performers for their price - around £7 or so.
The donor for this is the C120 coupling off a duff Inverto / Invacom (cant remember) C120 lnbf. The coupling is quite easy to remove just by careful tapping, saw the off-set scalar ring off the 'Blazer' lnbf and then epoxy the donor flange to the new PLL lnbf - cut the existing 'Blazer' plastic outer cover to suit the new front end shape of it and job done.
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[RimaNTSS]

I Was making same flanges yesterday (2 for Prodelin feedhorn and rest for CM). One chap asked to adopt IBU single and IBU twin to those flanges.

 

[John]

I Was making same flanges yesterday (2 for Prodelin feedhorn and rest for CM). One chap asked to adopt IBU single and IBU twin to those flanges.

... very nice indeed

 

[John]

.. Spotted some aircraft 'Experimental' stickers a few weeks ago from a site in the US , cheap as chips for a pair of them so grabbed some to titivate the test rig up
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[RimaNTSS]

Nice sticker @John . I see that you've set aiming point of the feed little bit too high (red dot). It should be ~10cm lower (green dot) IMHO.

 

[John]

Nice sticker @John . I see that you've set aiming point of the feed little bit too high (red dot). It should be ~10cm lower (green dot) IMHO.

The aiming point wasn't set by me Rima, the CM is using the stock arms and bottom arm bracket at the bottom of the dish and has the original lnb holder. I accurately 'sighted' through the original CM feed to see where it landed on the dish face and then marked it on the dish face. It would not be possible to bore sight it through to land on the lower spot using the original equipment. I think i mentioned a few posts back that i needed to look at your reference diagram showing all the relevant measurements for the 1.8 because it looked a bit different to your diagrams, but not got around to it yet

 

[John]

Nice sticker @John . I see that you've set aiming point of the feed little bit too high (red dot). It should be ~10cm lower (green dot) IMHO.

Re: the aiming point Rima, i'll ask Nelson if he would just slip the lnb off his 1.8 CM test rig and sight through the CM feed and mark the landing spot on his dish

 

[nelson_b]

Re: the aiming point Rima, i'll ask Nelson if he would just slip the lnb off his 1.8 CM test rig and sight through the CM feed and mark the landing spot on his dish

Sorry John .. my test rig -1.8 setup is dismantled currently ... if i get time i will lean the dish against the garage wall and put the arms and holder back on ... i,m looking at a holiday in NW Scotland next week if the weather comes good - and have a lot to do before leaving though ...