Dielectric plate ?

[Vipersan]

Hi friends ..
Can anyone tell me where I might find a slab of dielectric material for use in my H/V switching lnbf ?
I did already mention in a previous thread that the plate wasn't supplied with the lnbf as standard issue ..
It was suggested that I try cutting a piece out of a trade paint tub ..but either its the wrong material or isn't thick enough ..
I do know that I've had some success with a slice of polythene kitchen chopping board ...and that the presence of the dielectric is essential for resolving the weaker signals.
..for example
ERTU on 1 west is non existant without the plate..
With a thin piece of paint tub I get about S=10 % and Q = 9%
with the slice of cutting board this rises to S=20% and Q = 17% ..
The signal level will rise to useful levels(short periods of useful clear pictures) on a cloudless sky day.

Just as an afterthought ...my lnbf is rated 17K ....but I have seen simillar construction13K lnbf's for sale in the US ...

Would it be wortwhile having one of these shipped to the UK ?
would the extra 4K give me any noticeable improvement ...or am I just expecting too much from my dish..?

rgds

 

[nelson_b]

hi - Vipersan -

the dielectric plate that i,m usng in my pauxis came from the U.S.A
it was part of a combined C/KU l.n.b. package -- the l.n.b. turned out to be not practical for me . and the pauxis performed better -- so i used the plate and the feed on the pauxis

more info about it in post 6 - in the thread link below --

http://www.satellites.co.uk/satelli...154855-offset-dish-recommendation-c-band.html

i,v not seen them for sale anywhere else -- not sure what the best material to make one is --
if you purchase any satellite things from america- expect it to take a month to arrive -- and have to pay import v.a.t. charges on top of your purchase price

cheers - nelson .b .

 

[BombedOne]

_ttp://www.shop.unitorg.com/index.php?cPath=1_2&language=en&osCsid=a3mi3gdupgf31l4r70jjde1i24

check these ones. click on each and it will say for what brand of LNB it is. Find your LNB, then hit back, and assuming width of your LNB throat, you can easilly make needed plate according to photos.

 

[Vipersan]

Hi friends ..
Still experimenting with this dielectric plate ..I was lying in bed last night when it occurred to me that I might be able to part polarize the circular 'signal cloud'/transmission _outside_ the lnbs thoat & just above the scalar rings..

This morning I cut a larger 'T' shaped piece of polythene cutting board ..
and placed this in the open throat of the pauxis..
To my amazement ...the signal/quality improved dramatically ..

ERTU 1 west now showing

Signal 31 %
Quality 45 %
All pictures are now pixel free and totally stable under a cloudy sky ..
Now to find a sheet of PTFE/TEFLON... ;)

rgds
VS

 

[BombedOne]

This may be happening due to fact that your LNB entrance is not in focus point of the dish.

 

[Vipersan]

This may be happening due to fact that your LNB entrance is not in focus point of the dish.

You may be right BombedOne ...
But I have done everything I could to get the lnbf at the focal point...
I calculated my FD ...and the distance returned from the dish centre was 81cm ..
I located the feed assembly at 81cm ..and moved it forward and back to find absolute peak ..
So ..Im sure to within a cm that Im at focus ..
..and at no point can I get signal levels approaching what I currently have with the T shaped dielectric..
It may well not be that Im getting more signal gain ..but possibly just better conversion of Circular to Linear ...and this is maximising the quality of the signal with respect to backround noise..
..Whatever the explanation ..it _definately works ..and in my case is giving me 'effectively' 30% more useful signal from the Pauxis..
rgds
VS

 

[nelson_b]

Hi friends ..
Still experimenting with this dielectric plate ..I was lying in bed last night when it occurred to me that I might be able to part polarize the circular 'signal cloud'/transmission _outside_ the lnbs thoat & just above the scalar rings..

This morning I cut a larger 'T' shaped piece of polythene cutting board ..
and placed this in the open throat of the pauxis..
To my amazement ...the signal/quality improved dramatically ..

ERTU 1 west now showing

Signal 31 %
Quality 45 %
All pictures are now pixel free and totally stable under a cloudy sky ..
Now to find a sheet of PTFE/TEFLON... ;)

rgds
VS

nice one --

thats an interesting thing - you have done there --

i notice also that you have a different feed/ scalar ring setup
than you had in the pics you posted last week --

regards c.c.

 

[Vipersan]

nice one --

thats an interesting thing - you have done there --

i notice also that you have a different feed/ scalar ring setup
than you had in the pics you posted last week --

regards c.c.

Well spotted Nelson ..
It is indeed a replacement scalar feed ..
I've recently been gifted a corotor assembly ...
Not much use with my setup as it requires a receiver capable of driving the motorised polariser ...but the feed horn/plate was removable ..and has found its way on to the pauxis..
Even with the addition of a decent feed ...I still could not get the kind of signal level and clarity I'm now getting with the T-dielectric plate..
I'll post up some images when I get a chance ...and re-visit some borderline threshold transponders on other 'birds'..
rgds
VS

 

[pgh13]

Hi friends ..



Now to find a sheet of PTFE/TEFLON... ;)

rgds
VS

sheet PTFE is commonly used in engineering to seal joints. A friend in the chemical industry may be able to help. I thought it would be very expensive but try here h__p://www.directplasticsonline.co.uk. 4mm is about 11ukp

 

[Vipersan]

Hi friends ...
Just found this on fleabay and put in an order ..
4 pieces left of the same size ..
If anyone is interested ..

rgds
VS
hxxp://cgi.ebay.co.uk/PTFE-SHEET-8MM-200mm-x-150mm_W0QQitemZ360131960124QQcmdZViewItemQQptZLH_DefaultDomain_3?hash=item53d9899d3c&_trksid=p3286.c0.m14

 

[Channel Hopper]

A bit of perspex would be cheaper.

 

[Vipersan]

A bit of perspex would be cheaper.

..Can't argue with your logic ...
..I did consider perspex ..but couldn't put my hands on anything close to 8mm thick.
..If I find some ..I will give it a try though.
cheers

 

[doktorofsat]

my dielectric plate, modified rusian

 

[Vipersan]

my dielectric plate, modified rusian

...Hmm .
Looks very interesting m8 ...but I can't quite figure out whats what from the picture.
Can you explain a little as to what material ,dimensions and modifications you have made
Its not immediately obvious from your photo ..
..what are the silver strips and how do they work ?
rgds
VS

 

[mannyanthony]

I try this on the caibbean with a 3 1/2 dish and a old C lnb on 45w and it jump from quality of 65 to 85.

 

[Vipersan]

I try this on the caibbean with a 3 1/2 dish and a old C lnb on 45w and it jump from quality of 65 to 85.

Hi Manny ...

What exactly did you try ?
Was it the extended 'T' plate ?
If it is my mod ..I'm most interested to note that you also have seen the benefit of fitting one..
rgds
VS

 

[okyop]

Try to cut a glass 3 or 4 mm thick to 6cm to 3.3 cm and I think you get the best signal or large like the original one but 3.3 cm.
ciao

 

[okyop]

my dielectric plate, modified rusian

Hi
any chance to know how is done? thanks

 

[doktorofsat]

hi vipersana and okyop

I have little time but noew I made da scheatics of the plate and I will upload soon at the memeber dish at DoktorOfSat SETUP.Stay tunned

http://www.satellites.co.uk/satellite/867911-post1.html

 

[pride21]

hi doktorofsat i would like to thank you for the dialectric plate idea i made one today for my small offset dish and i was amazed the quality of my channels went up ertu on 1w went up to 52% with no breakup,but what was amazing the sat at 24w is a no no but with your plate in i got was ortm.