Just Sharing This Threshold Extension (by Steve Birkill)

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s-band

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Following on from this thread, I thought that this info warranted a thread of its own.
Steve Birkill has kept a website of his alive after the associated company closed. There's a very good summary of tuner specifications here:


If you're wallowing in nostalgia, have a look around the rest of that site.
 
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s-band said:
Following on from this thread, I thought that this info warranted a thread of its own.
Steve Birkill has kept a website of his alive after the associated company closed. There's a very good summary of tuner specifications here:


If you're wallowing in nostalgia, have a look around the rest of that site.
Click to expand...

Nice one, - i'm going to have a wallow right now.
 
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A Dexcel LNA is mentioned mid-way down this page Real-World Technology: History
It must have cost a fortune with an isolator at the front and chip & wire hybrids on ceramic substrates for the LNA. If anyone wants to create a full retro set-up, I have a couple new, old stock:oops: The one I tested still works fine.

dexcel_81a.jpg dexcel_82a.jpg dexcel_83a.jpg
 
John

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s-band said:
A Dexcel LNA is mentioned mid-way down this page Real-World Technology: History
It must have cost a fortune with an isolator at the front and chip & wire hybrids on ceramic substrates for the LNA. If anyone wants to create a full retro set-up, I have a couple new, old stock:oops: The one I tested still works fine.

View attachment 152417 View attachment 152416 View attachment 152415
Click to expand...

Send it up Graham :)... curiousity is telling me to chuck it on the 2.2 for evaluation, seriously... but i think you will have to educate me further as to how to implement it
 
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s-band said:
Following on from this thread, I thought that this info warranted a thread of its own.
Steve Birkill has kept a website of his alive after the associated company closed. There's a very good summary of tuner specifications here:


If you're wallowing in nostalgia, have a look around the rest of that site.
Click to expand...

Dont forget this gem from Steve Birkill

www.rwt.co.uk/download/SJB_Guidebook.pdf

My web browser gave me a warning but the file waa safe to download.
 
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s-band

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Various L, S, C, X & Ka bits. 1.2m S/X/Ku/Ka Prodelin on Az-El (being refurbished)
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John said:
Send it up Graham :)... curiousity is telling me to chuck it on the 2.2 for evaluation, seriously... but i think you will have to educate me further as to how to implement it
Click to expand...

Mail sent. You'll need a few extra bits as well as this BDC extracted from a Titanium LNB & modded for dual band.

Tit_BDC+filter.jpg
 
Channel Hopper

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John said:
Send it up Graham :)... curiousity is telling me to chuck it on the 2.2 for evaluation, seriously... but i think you will have to educate me further as to how to implement it
Click to expand...
John, it has a noise figure of 120K, you would need the filters to catch anything but sparklies.
 
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Channel Hopper said:
John, it has a noise figure of 120K, you would need the filters to catch anything but sparklies.
Click to expand...
But that's a real 120K (1.5dB NF) not a latter day, marketing based, 10K. I'll measure it before sending just to make sure it's worthwhile

The LNBs I checked a while back were in the region of 45-75K (0.6-1dB NF) irrespective of what was marked on them. They might have done better under perfect conditions with an ideal match though.

The best test is to use Sun noise as it checks the whole system.
 
Last edited:
John

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Channel Hopper said:
John, it has a noise figure of 120K, you would need the filters to catch anything but sparklies.
Click to expand...

Yep noticed that CH, thinking about doing some comparisons against more modern Norsat lnb stuff i have on other sats as well - the curiousity bug has taken hold again.
 
Channel Hopper

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John said:
Yep noticed that CH, thinking about doing some comparisons against more modern Norsat lnb stuff i have on other sats as well - the curiousity bug has taken hold again.
Click to expand...
Well, if you are into professional stuff, no made up numbers.
 

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Captain Jack

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s-band said:
Following on from this thread, I thought that this info warranted a thread of its own.
Steve Birkill has kept a website of his alive after the associated company closed. There's a very good summary of tuner specifications here:


If you're wallowing in nostalgia, have a look around the rest of that site.
Click to expand...
Still valid trying to catch 70W analogue! It's literally just noise, until low threshold extension is cranked up. Very interesting.
 
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