Advice Needed Receivers with the lowest Symbol Rate?

[Vipersan]

I think I may have found suitable ally tube on Amazon of all places..
Last one in stock apparently.
3 pieces 30cm length OD 23mm ID 20mm
got to be worth a punt at a tenner..

 

[Vipersan]

So ..that was quick delivery.
The 3 lengths of ally tube from Amazon just arrived.
In actual fact the internal dameter is closer to 19.7 mm than the claimed 20mm..
I'd call that a win.

 

[Vipersan]

Is this risky...
Of course.
The vibrations could theoretically damage the bullseye.
but using a small drill on slowest speed fitted with a sacrificial 22mm spade bit...I'm down about a mm into the lnb throat.
The objective to make stepped cut into the cast aluminium.
Took about an hour so far but that's because I'm doing this as slowly as I can.
certainly the spade bit will most likely never cut wood again
lol

 

[Vipersan]

Well for good or ill ...the sleeve is in and pretty permanent now
Forced in under pressure from the workmate.
If I haven't damaged the bullseye with vibration..it will work...how well is another matter.
I guess I need to at least test it on the dish before proceeding.

 

[Vipersan]

..The good news IS....pause for fanfare....
It still works..
Not centred ..not clamped no skew ajustment...just hung loosly at the focus with no feed attached..
a paltry 0.4db on the beacon...But it still Functioning.
I guess I can move on to epoxy infill tomorrow....the bullseye case reasembled....the feed fitted...and another test.

 

[Channel Hopper]

Is this risky...
Of course.
The vibrations could theoretically damage the bullseye.
but using a small drill on slowest speed fitted with a sacrificial 22mm spade bit...I'm down about a mm into the lnb throat.
The objective to make stepped cut into the cast aluminium.
Took about an hour so far but that's because I'm doing this as slowly as I can.
certainly the spade bit will most likely never cut wood again
lol

Since the Bullseye is a crystal tuned box, there are no pucks inside that could disintegrate with vibration.

 

[satesco]

..The good news IS....pause for fanfare....
It still works..
Not centred ..not clamped no skew ajustment...just hung loosly at the focus with no feed attached..
a paltry 0.4db on the beacon...But it still Functioning.
I guess I can move on to epoxy infill tomorrow....the bullseye case reasembled....the feed fitted...and another test.

Your interest in the 25.5E Qatar-OSCAR 100 (QO-100), Amateur radio station – which I’ve been visiting less often in recent years – is prompting me to test the location more frequently. Who knows what new developments we’ll discover.
So far, I haven’t noticed any changes to the signal or the parameters used.

I’m pleased, however, that you want to improve your reception and are going into technical detail about how to do it, which is brilliant because it might encourage other amateurs to get into reception at this position.

Here’s what I received yesterday evening at this frequency with my amateur equipment, in particular the IBU LNB, which, although it picks up the signal, isn’t stable at a symbol rate of 333 when you want to display images from these feeds.

 

[Channel Hopper]

Well for good or ill ...the sleeve is in and pretty permanent now
Forced in under pressure from the workmate.
If I haven't damaged the bullseye with vibration..it will work...how well is another matter.
I guess I need to at least test it on the dish before proceeding.

Definitely not what I envisaged.

Are you good enough on the ladder to add spacers once the PF feed is added to the mangle ?

(After moving the cat off the lower rungs, take an image or two from the boresight, and directly down the feed, transfer is key)

 

[Vipersan]

Too dark now to do any more outside ...so figured it would be nice to get an idea of what the bullseye will look like post modding.
Nothing has been bolted up as yet so just loosly together.
If for some reason I need to mount just behind the scalar feed (very likely I will have to) I would use a 40mm plastic conversion collar.
In which case I can move the tripod itself ...thus moving the whole assemby closer to or further from the base of the dish bowl..
On the Alcoa the distance from dish base to suspended feed is (optimal) at 31.5 inches
rgds

 

[Channel Hopper]

This is Christine we are talking about.

 

[Vipersan]

She's had 2 names during her long life with me...both female. PFs are always female in my head.
I always named my offsets with male names so yes Christine or Stella...take yer pick.
She was 2nd hand when I bought her.
Sad aint I

Christine is an old girl 6 petal 1.8mtr PF made in the 70s ...does that make her a boomer ?
ALCOA - made in the USA I believe. ALuminium COmpany of America
She got renamed to Stella after I made those petal extensions out of mesh embedded in fibre glass ...
Sadly they only lasted 10 years as they eventually cracked and water ingress did the rest.
but she was 2.2 mtr for a while.
Now she's back to being plain old Christine.
I do believe there was a proper aluminium powder coated petal extention kit that was available back in the day.....but I've never seen one in the flesh.
Only photograhs from some Austrian dish enthusiast.
Not sure any were ever needed or sold in the UK.
cest la vie

 

[Channel Hopper]

I did not recall the new name, nor know the extension parts had failed.


The pf feed you now have is designed for a relatively deep dish, it could over illuminate on the 1.8m and so the secondary clamping point might be worthwhile afterall.

 

[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.

 

[Flippi]

This topic needs some cleanup. Nevertheless very interesting, but nothing to do anymore with low symbol rate receivers...