Restoring a working antique dish to full functionality..

[Vipersan]

Quite the balancing act to get a steady photo down the boresite...
told ya I aint steady when I cant use at least one hand to steady myself.
Still close enough I think.
lol
...and yes she is a deep dish by design...which is why I've always had issues with illumination particularly in ku
Cband was much more forgiving.

 

[Vipersan]

Another 30minutes with glasspaper on a slate bed..and I'm calling it close enough.
I lightly sprayed the feed rings with black paint so that the low points would be evident after sanding.
Only hints of black on the outer ring now so theoretically close enough and flat enough to mate with the feed.

also decided that using epoxy was no longer neccessary ..I have a small tube of RTV gasket maker on order.
This will be used to fill between rings 2 an 3 to form a waterproof gasket under compression.

 

[Vipersan]

More tests with just the feed bolted to the modded bullseye...
So far it dont look good.
Finding the max illumination point is not going to be easy ...if at all possible.
clamped at the point where the new assembly is furthest forward No beacon
clamped just behind the scalar rings...2.4db beacon
clamp removed so that the CH feed is as far back as possible 3db beacon..
Maybe time to start undoing the tripod clamps to get the assembly even further away from the dish is the answer ?
Or maybe the CH feed scalar rings just cannot correctly illuminate Christine (deep dish).
at this point chip in with suggestions as this modded assembly is underperforming the unmodded bullseye.
??? with which I can at least aquire a 6db signal from the beacon.

 

[Vipersan]

Still no lock but improving...scalar rings flat to the spider ...constructed a way to hold the lnb central (see pix) from foamboard ...then moved the assembly further from the dish base by adding half an inch length to each of the tripod legs...
further to go perhaps but am getting 4db from the beacon now.
I'll try an inch next.
If it is possible to fully illuminate the dish with this feed ..I will find the sweet spot.

 

[Vipersan]

Still no lock but improving...scalar rings flat to the spider ...constructed a way to hold the lnb central (see pix) from foamboard ...then moved the assembly further from the dish base by adding half an inch length to each of the tripod legs...
further to go perhaps but am getting 4db from the beacon now.
I'll try an inch next.
If it is possible to fully illuminate the dish with this feed ..I will find the sweet spot.

Now at 1 inch extra distance per tripod leg ...
the distance measured from dish base to CH feed is now 34 inches ..well beyond that optimal 31.5"
and beacon is 1.1 db
conclusion.... the sweet spot is now somewhere between 31.5" and 34"
but of course the CH feed may not be really suitable for a deep dish.

 

[Channel Hopper]

I dont have the Alcoa specifications here but I think you posted critical measurements when extending the diameter with those panels. It is not as deep a dish as the one the feed came off but I will measure this later in the week.

Use the clamping point on the feed I sent you and measure the distance from dish base to just inside the transparent cap

(Once you have moved the cat off the ladder)

 

[Channel Hopper]

Imagery of the dish detail.

Diameter - 0.91m
Depth - 0.19m

Focal point on the standard setting, between 0.26m and 0.28m (though there is adjustment to 0.05m either side.

I have used the same reflector and feed on a number of installations, mainly in the 90/00's (5W French analogue to digital transition), using a WR75 transfer and NJRC LNB. Peak signal received midway at 0.27m making the feed suitable for this and other 0.3 f/D reflectors.

 

[Vipersan]

Just in case anyone was wondering..
I haven't abandoned the project...but I an waiting to receive one of these..see picture.
Thinner lighter and made of plastic not metal.
I'm sure I can adapt this for my needs...
advantages ..less metal occluding the beam transit plus ajustable diameter at mount point from 65mm C band ..down to 23mm.
Thus a greater chance of easily hitting that sweet spot.
In the meantime I've switched my attention to fitting a growlight in my greenhouse....late in the season but I still have 10 galia melons to somehow ripen before winter arrives.

 

[scopus]

Just in case anyone was wondering..
I haven't abandoned the project...but I an waiting to receive one of these..see picture.
Thinner lighter and made of plastic not metal.
I'm sure I can adapt this for my needs...
advantages ..less metal occluding the beam transit plus ajustable diameter at mount point from 65mm C band ..down to 23mm.
Thus a greater chance of easily hitting that sweet spot.
In the meantime I've switched my attention to fitting a growlight in my greenhouse....late in the season but I still have 10 galia melons to somehow ripen before winter arrives.

You could have had one off me VS, I have about 4 of them spare..

 

[Vipersan]

appreciated mate....but it's on order now
I just hope it will be easily adaptable to Christine.

 

[Vipersan]

Another tool to add to my collection.
Not bad for £8
Ordered a
23mm tungsten carbide teeth, 3-cutter design, pilot drill included, storage case, for sheet plate pipe work

The pilot drill is removeable
I'm hoping this will clean up the crude attempt I made at boring out the cast aluminium throat of the lnb with a wood spade bit.
chances are I can find a way to do this by hand rather than with a drill now that most of the material was already removed.
What have I got to lose ?

​

 

[Channel Hopper]

Another tool to add to my collection.
Not bad for £8
Ordered a
23mm tungsten carbide teeth, 3-cutter design, pilot drill included, storage case, for sheet plate pipe work

The pilot drill is removeable
I'm hoping this will clean up the crude attempt I made at boring out the cast aluminium throat of the lnb with a wood spade bit.
chances are I can find a way to do this by hand rather than with a drill now that most of the material was already removed.
What have I got to lose ?

​

You may be thinking too hard. Get the boresight centred (does the Alcoa have the removeable centre plate ?)

If so take it out and drill a hole in the polarmount for camera picturs from behind the dish.

When did you last string the panels (look down the rim first , ooerrr)

PS. FAO Flippi, will try to move Evan's latest quest for low symbol rate stuff onto a new thread when I get time.

 

[Channel Hopper]

Evan, what is the manufacturers specification of Christine , f/D dation and gain at 11GHz ?

 

[Vipersan]

I'll have a read through the limited documentation I have and hope the FD is in there..
Not sure gain will be specified tho'...simply because of her age..
After all she was designed for C band so may never have published gain at 11ghz.

As to the centre panel ..yes it is removeable ..in fact only today I found it resprayed and re-fitted.
I did think about mounting a laser pen at the lnb mount point and producing a green dot on the dish..which is why I refitted the centre panel.
Problem is ..no idea how 'true' laser pointers are ?

The last time she was strung was when I took the whole thing down some years ago..
Resprayed and regreased the mount new 15cm thick pole set in the ground...
It was at least a 2 man job.
I had space to do it then after shifting all my furniture.
I was a lot younger ...and I remember her being heavy even then.
I could string her in situe...but no idea how efective that would be.

Nothing spec wise in the manual.
great assembly instructions for both dish and mount...but no real spec ...just a few diagrams such as this :-

 

[Channel Hopper]

OK, laser pen is secondary, but a look at the rim will provide a view from the ground and quick idea if anything has shifted.

Christine might have had gravity working against her all these years, she might just need a strip and good shake.

 

[Vipersan]

OK, laser pen is secondary, but a look at the rim will provide a view from the ground and quick idea if anything has shifted.

Christine might have had gravity working against her all these years, she might just need a strip and good shake.

I may well invest in a ball of string and string her in situe..
Should give a rough idea maybe ?
I dont know how rare my assembly instructions are but might scan them for upload later this year.
cheers buddy

..and yes I might well be overthinking or overcompensating....but my philosophy fwiw is ..you can never have too many tools.
lol

 

[Channel Hopper]

Post a few pictures of Christine side on first, no need to move the cat yet.

Having looked at your 'down the orifice' picture of earlier the feed could be a couple of degrees away from centre meaning the feed might be in a Ku quiet area.

 

[Vipersan]

what have I learned today...?
took posession of a universal high gain ku prime focus lnb (new old stock)
now I know this wont lock at low SR at low signal levels.
...but much easier to mount and slide in and out.
It has 4 scalar rings unlike the CH c120 feed which has 3
Took some measurements with a metal tape...and established I could get a lock on 11996 H (fta mux)
It would appear the sweet spot is around 83 cm (32.6 inches) to the front of the scalar rings
or 81cm to the tip of the waveguide (31.8 inches)
This tallies nicely with the dish manual fd (31.5 inches)
also this is not accounting for any skew ajustment.
this lnb does not perform as well as the bullseye ..easily 2db less gain and of course will not lock low SR
I do get about a cm of distance manoeuver around the 'sweet spot' where little is gained or lost.
I'll put this down to christines old age and gravity over time.
ie ..she aint perfect any longer....but still pretty good for her age.

 

[Vipersan]

Post a few pictures of Christine side on first, no need to move the cat yet.

Having looked at your 'down the orifice' picture of earlier the feed coulld be a couple of degrees away from centre meaning the feed might be is a Ku quiet area.

I suspect her alignment may indeed be little out Stephen but not by a massive amount.
Also I fully intend to knock up some sort of laser to mount at the spider ...but may wait until I have the new spider to try.

 

[Vipersan]

Ok some dish shots ..whilst the cat (peppa) is having her lunch.
Sadly I dont have 360 deg access ..so hopefully these will do CH.
There is a definate oddity bottom right petal.
even I can see it and my eyes a shyte these days.
maybe something fixable with a block of wood and a hammer as it only appears to be the lip ?