what to expect from an old girl..?

[Vipersan]

Ok ..My TD110 only covers 30 East to 58 west ...but is my best ku performer..
I have the TD88 which covers 5 East to 66 East ...so full coverage of the arc with 2 dishes but of course the TD88 is smaller so reception is limited.
There has been much discussion about 36 East ...but the TD110 can't 'see' this location ...and the TD88 isn't big enough for good reception ..approx 8db from
11439 H
tp C11 RRsat Global Communications Network ...and of course nothing from the TD110..
Both are fitted with a black ultra at the focus..
Enter Christina which as you probably know ..I use exclusively for C band ..and performs exceptionally well.
She's never been particularly good in ku ...but IF I could get anything close to the TD110s capability at 36 East ..I'd be happy.
The first problem is that the focus is occupied with C-band ..so it has to be an offset ...thus I've obtained another long neck ku black ultra and mounted this approx 5 degrees off focus ...
Optimised as best I can atm ...but performing better than the TD88 ..
11439 H
tp C11 RRsat Global Communications Network is coming in at 9.8db ...remember the TD88 only manages 8db
(all db referenced to the F15)
..but I cannot of course compare to the TD110 which draws a blank due to the troublesome tree.
So ..to compare a common signal I used BBC world news at 0.8 west ku.
The TD110 pulls a mighty 16.7 db ...
Christina (pf) a respectable but insufficient 11.2 db.
So ..In conclusion thus far ..
Christina with a black ultra (wrong feed as its designed for an offset dish) is performing better than the TD88 ...but not as well as the TD110 ...but then the lnb is offset by 5 degrees...so what should I have expected ?...certainly not miracles.
My last hope is to cut the feed off the black ultra ..and graft an invacom adjustable pf feed onto it ..
This is the next experiment..
If I can get above 11.2 db at 0.8West ..ie ..anything close to a black ultra at the focus of the TD110 ...I'll be a happy bunny..
Not expecting 16.7 db ...but would be very happy with 14 > 15 db ..
Anyone think fitting the invacom feed will achieve this ?
11.2db to 14 db is quite a big ask ...and remember the lnb wont be at the focus ..but will have a pf feed instead of an offset feed ..

Answers should be texted to ******* ...to arrive no later than *****.
Late answers will not be counted but may still be charged for..

rgds
VS

 

[wod]

Maybe you need to work out some sort of motorised feed to switch between c and ku band.

Are you in need of another project ?

 

[Vipersan]

Maybe you need to work out some sort of motorised feed to switch between c and ku band.

Are you in need of another project ?

Sadly not possible Wod ...as the C band feed / support system are integral to the tripod structure...
its fixed and solid forming the structure at the apex..
rgds
VS

 

[nelson_b]

This is the next experiment..
If I can get above 11.2 db at 0.8West ..ie ..anything close to a black ultra at the focus of the TD110 ...I'll be a happy bunny..
Not expecting 16.7 db ...but would be very happy with 14 > 15 db ..
Anyone think fitting the invacom feed will achieve this ?
11.2db to 14 db is quite a big ask ...and remember the lnb wont be at the focus ..but will have a pf feed instead of an offset feed ..

Answers should be texted to ******* ...to arrive no later than *****.
Late answers will not be counted but may still be charged for..

rgds
VS

it is quite a big ask -- but you never know till you try ----

i use a modified invacom feed / with home made C120 on my alcoa and can pull in some turksat east
beams -- with almost as much strength as the 1.8 channel master --- i used the Alcoa,s original k/u/ feed tube so had to cut out the centre ring from the invacom feed to fit it on --

but just how good it will be off centre i,m not sure --
when i first rebuilt the Alcoa i did a few tests with the above arrangement as an offset but did not log the results
from memory i think the results were quite good though -- but in the end i decided to keep the Alcoa as K/U for now -- and build a combined setup on the Channel master ---
i look forward to your experiment/results

cheers nelson.b.

 

[sonnetpete]

Are you in need of another project ?

Clear the forum for another long thread......VS is bored....

 

[Vipersan]

Clear the forum for another long thread......VS is bored....

Not totally bored Pete...
Currently watching (sad really).... one of them gameshows where the punter phones in with little or no chance of winning the cash....with a Russian lass in charge ..
Usually gets interesting after the watershed ....as even if the punter gets it wrong ...she gets her kit off a bit a time ...
;)

 

[Vipersan]

it is quite a big ask -- but you never know till you try ----

i use a modified invacom feed / with home made C120 on my alcoa and can pull in some turksat east
beams -- with almost as much strength as the 1.8 channel master --- i used the Alcoa,s original k/u/ feed tube so had to cut out the centre ring from the invacom feed to fit it on --

but just how good it will be off centre i,m not sure --
when i first rebuilt the Alcoa i did a few tests with the above arrangement as an offset but did not log the results
from memory i think the results were quite good though -- but in the end i decided to keep the Alcoa as K/U for now -- and build a combined setup on the Channel master ---
i look forward to your experiment/results

cheers nelson.b.

Impressive spiders web on that first photo Nelson...
Is the owner still resident ??

 

[nelson_b]

Impressive spiders web on that first photo Nelson...
Is the owner still resident ??

its still around there i think .
but it has no chance of getting inside the feed tube -- l.o.l.

The positioning of that invacom feed is very sensitive -- the slightest move in or out has a big effect on the signal strength/quaility ----

 

[Vipersan]

Beautiful clear day here today ...not sure tomorrow will be as good for Manchester ..but still
Had a non adjustable ku pf feed lying around but is fixed for a shallower and smaller dish ..only 2 valleys as opposed to the 3 on the invacom adjustable scalar..
But with a bit of judicious application of file and emery cloth I made it fit neatly inside the first tapered ring of a naked inverto black ultra ..
Friction being the only thing bonding the 2 halves together..
This was then lashed in roughly the right spot as the original offset black ultra ...as it will no longer mount in the cradle I made ..see pics..
So not even optimised ..just placed roughly and the elevation on Christina moved to accomodate the change in position ..
et voila ..
14.2 db on BBC News 0.8W as opposed to 11.2 with the unmodified black ultra..

Is 15 db doable ???
I'd say an emphatic yes ...but will have to wait for the arrival of my invacom feed ..
Hopefully Burnham Beech ..will get it in the post after the weekend..

Here are the pics..
Time for a nice cuppa now...
;)
rgds
VS

 

[BM300]

One of the best C/Ku feed-horns I have used is the Seavey C/Ku

I am sure that you have seen it but here it anyway:

View attachment 43679

Try it.

Model ESA-124D has a dual port, no motor.


​

 

[Vipersan]

One of the best C/Ku feed-horns I have used is the Seavey C/Ku

I am sure that you have seen it but here it anyway:

View attachment 43679

Try it.
​

The information is appreciated BM ....but since I have no possible way to drive a motorized polariser I'm afraid I shall be sticking with 13/18v switching..
Besides which I firmly believe with an open throat approach to C band ...the fringe stuff becomes more viable..
Servo controlled probes are good ...and they do have the advantage of skew control ...but most receivers these days don't provide the hardware for driving such devices...and I still believe any form of mechanical intervention on all but the biggest of dishes with extra dbs to spare introduce a noticeable insertion loss..
regards
VS

 

[Vipersan]

...Will this affect my guarantee d'ya think ???

 

[Vipersan]

...Just finished making and fitting a copper ferrule liner to complete the inside of the cut offset feed ...retaining enough of the original casting to make a solid attachment to the invacom feed when it arrives..
And the remaining valleys of the original feed left intact should make a nice gasket retainer...
The ferrule is made from a short lenght of 22mm copper pipe ..with a slight step cut on the furthest point inside the lnb to accomodate the slight step ridge in the original feeds moulded structure ..
Once inserted and tight ..the whole assembly was upturned and placed face down on emery cloth on a flat board ...
circular motions employed to grind the copper ferrule flush to the cut lnb outer surface..
here are the pics..
Obviously I cannot remove the ferrule from the modified black ultra now.. as its in too tight .
rgds
VS

 

[Vipersan]

Ok ..first may I thank Burnham Beech for his fast delivery of the Invacom feed..which arrived this morning ..
Once I had it I was able to guage the slots to cut in the retained flange of the black ultra..
This done ...I re-purposed a rubber tyre off an old VCR drive idler as a gasket ...
Some stainless steel nuts n bolts completed the ensemble...and some small cuts made inside the original black ultra casing to accomodate the extra thickness of the bolts used..
The whole lot assembled and the result is in the pictures ..
My Black Ultra with void guarantee Hybrid PF LNB

rgds
VS
..
Can't test it yet ..as I'm currently repacing approx 30 mtrs of old cable with CF100

 

[Vipersan]

..been up the ladders again to fit and try the black ultra hybrid ..
I would estimate the hybrid ..unoptimised has produced another 0.8db overall..
I still can't get results equivilant to a black ultra at the focus of a TD110 ...but for an offset untweaked ..I guess 14.4 db aint bad ..
(signals referenced to BBC world news 0.8W..
Some tweaking might squeeze a little more ..and I'll attempt this asap ..
But in the meantime ..here are some pics of the Hybrid mounted..
Its already outperforming ANY ku lnb I've ever had on Christina ..at the focus or otherwise..
Chances are ..placing it at the focus would up the signal again ...but No way I'm sacrificing my Cband reception..
rgds
VS

 

[Vipersan]

..Well ...did some more experimenting last night....and had a power cut for the entire area which didn't do my project or indeed ..my pcs nor my server any favours ..
All sorted now thank gawd..
This experiment involved hanging a 2nd C band lnb to the other side of the one at the focus ..
Roughly same distance from the dish centre ...pointing directly AT the centre ..and seperated again by roughly 5 degrees as is the ku..
After much tweaking and elevation adjusted ..and using 5W as the target...
Chosen because using circular polarisation removes any skew errors that might occur..
..only half the signal level I can obtain at the focus was possible ..
Yes it works ..but very inefficiently...
I can only conclude from this that PF dishes do not readily lend themselves to offset lnbs ...and certainly not C band..
This may go a long way to explain why the ku offset lnb ..though working cannot output greater signal levels on a 2m pf than at the focus of a TD110..
I guess it is too big an ask ..
What might be possible is to aim off centre with the ku at 2 or 3 petals of the dish ...
effectively using only part of the dish surface as an offset dish ..
..though this would require completely changing the look angle (declining the dish considerably ...to behave just like an offset...
I doubt its worth the difficulty in finding where to place the lnb ...or indeed creating a greater declination of the PF..
Certainly this would be pointless from a Cband perspective as 2 or 3 panels would barely bring in the stronger sats.
So ..I guess I'll just make do and accept the ku offset working below par much like the performance of a dish somewhere between a TD88 ..and a TD110..
One day I may just pop the Hybrid black Ultra at the focus ...just to see _what_ ku levels can be achieved.
rgds
VS