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Providing RF signals for Sinclair FTV 1

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sideband
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I bought one of these off eBay a couple of years ago and did a short write-up on the old VRAT forum.

It basically worked OK after a little setting up and just for a test used the RF output of a VCR to feed enough signal to the Sinclair aerial to get a viewable picture. Since then it's been in a box unused.

I have always meant to try and get a low power RF TV signal just for the purposes of being able demonstrate this little piece of TV history. It only has a telescopic aerial with no facility for connecting an RF signal. Last month I bought an RF modulator from eBay so that at last I could feed some UHF signals into the dual-standard sets. This evening, for want of something better to do I started to play around with the RF output of the modulator. As with the VCR, there was just enough RF to produce a watchable picture when connected directly to the Sinclair aerial rod. Last week during a clear up I found a set-back RF booster. I connected the input of this to the output of the modulator and the output of the booster to the UHF aerial.  I connected a DVD player to the modulator.

Initially the result were poor with barely enough signal for the Sinclair. However I found that by tuning the modulator to C50 and above, the results were very much improved and I could receive the VCR signal via the telescopic aerial in most places around the workshop (loft) area. Just for interest I checked in my son's bedroom which is immediately below the loft and was able to pick up a noisy but watchable signal although it was quite critical depending where I stood.

So for initial results I'm quite pleased. I think I'll try cascading another booster (maybe two) so that I can receive a watchable signal downstairs. I suppose the main problem is that UHF receiving aerials are directional. I wonder if I should point the aerial downwards.....?

js640_SAM_1378.jpg

Off-air pictures on C50 via the telescopic aerial

approximately 10 feet from the UHF aerial

 
Posted : 17/08/2017 11:57 pm
Katie Bush
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Ah, a home made video sender then?

I have one of the original "Video Sender" units that I bought via eBay a couple of years back. It needed a minor repair, and it works to some reasonable degree. I keep it as an historical artefact of the 1980's, but I'd hardly consider it as a seriously viable transmitter.

Now I remember these things being outlawed because people were said to be using them to broadcast things like SKY Sport and what-not to whole streets of houses. Mine's good for about 30~40 feet in free air. If you're getting through walls and floors with your 'jerry rigged' modulator I'd say you're doing pretty well!

I remember once connecting a length of insulated wire to the RF output of a SKY DigiBox. Moreover, about 20ft of coax with the single wire 'element' at the end. placed alongside the telescopic rod of one of those Casio pocket LCD TVs you could receive a decently watchable signal. The insulated wire was approximately the same length as the TVs aerial and about an inch away - more than that and signal was lost.

 
Posted : 18/08/2017 9:35 pm
sideband
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Actually I thought the legal video senders didn't actually transmit anywhere in the UHF band? I had the feeling it was a couple of Ghz? So the first or 'master' unit was connected to the video source which then up-converted the signal to several Ghz. This signal was then transmitted to the 2nd sender which then down-converted it back to UHF via the aerial cable for the TV in another room.

I vaguely remember Philips being involved with marketing a 3rd-party unit that was 'legal for use in UK' and operated at a couple of Ghz. The power level was also heavily restricted.

I somehow think that mine is not strictly legal! However I'm betting that no-one in the immediate vicinity has an analogue TV or that it will just happen to be tuned to C50 since that was never in our local group anyway. 

 
Posted : 19/08/2017 8:29 pm
Katie Bush
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Hi Rich,

The original "Video Sender" - sold under that name, broadcasts at, or around, UHF channel 35 (VCR territory). A small tin box with a telescopic aerial at the rear and inputs for CVBS and audio (mono). The original Video Sender came as a transmitter only - the TV received the UHF directly.

Later, there came the "Giga Sender" - sold under that name, which works between 2.4GHz and 5.8GHz, with both a transmitter and receiver paired and encrypted to prevent interference with neighbouring senders on the same frequency (moreover, to stop other receivers picking up the signal!). Versions are available with as many as three paired receivers.

As to which channels are occupied, I think it could be a bit of a grey area, what with our UHF airspace being sold off for other commercial uses. I have an older 'Ice Crypt' FreeView receiver which can scan every individual channel in bands I, III, IV/V. If it detects decodable digital TV signals, it lights up a green bar-graph type display to indicate strength and yellow for quality. By change or design, if it detects other signals, ones it cannot decode (T2 for example), it lights up in grey to indicate strength only. It's surprising just how many adjacent channels we seem to have with signals on them.

I'd guess that if you were miles, well, a good few yards, from your nearest neighbour, there would be no chance of interference to their viewing. One thing the Ice Crypt won't do - it won't output on the same RF channels that it is tuned to receive, obviously to prevent unwanted RF interference.

Marion

 
Posted : 20/08/2017 7:03 pm
Katie Bush
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ADDENDUM....

Hi Rich,

This is the original Video Sender.

http://www.ebay.co.uk/itm/Video-Sender-Model-WV-050-/112516256431

That's not mine, but is identical to it.

 
Posted : 20/08/2017 7:08 pm
sideband
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Hi Marion

 

I've not seen those early ones but I suspect they are not strictly legal in UK. I know that Philips were paranoid about these early ones and even with the ones they eventually marketed, they got the boffins to check them to back-up certificates from the manufacturers to make sure they were legal.

 
Posted : 20/08/2017 10:28 pm
sideband
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Well I've now very roughly cascaded three boosters together and I have a useable signal around most of the house. It just about reaches the back downstairs room where the PC is so estimate around 50ft. There is nothing or at least very little outside the house so I'm not worried about any unwanted interest from outside.

 

At the moment the three boosters are strung together with whatever cables I had so next job will be to mount them onto a wooden board and then make some leads up using double-screened co-ax as short as possible.

 

At least it means that the little Sinclair can be demonstrated.

It's difficult to get good pictures of the miniscule screen. It does actually look quite good in real life

js640_SAM_1379.jpg

js640_SAM_1394.jpg

It starts getting a bit grainy if you blow it up too much. Any ideas about the film being shown? 

 
Posted : 23/08/2017 10:11 pm
Focus Diode
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Yes! "A Kind of Loving" from 1962. First picture shows Alan Bates and James Bolam, the second June Ritchie and Thora Hird. I have this on VHS myself from a Channel 4 transmission in the '80s.

Excellent result!

cheers

 

Brian

 
Posted : 24/08/2017 9:57 am
Nuvistor
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If you enjoyed the film "Kind of Loving", try the book, it's the first of a trilogy by Stan Barstow, the others in order, " The Watchers on the Shore" and " The Right True End"

I can only speak for myself but the trilogy was a really excellent read.

We sold a couple of those Sinclair TV's, never saw them again, a nice example you have there.

Frank

 
Posted : 24/08/2017 11:00 am
sideband
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I always liked these 'period' films...very typical of the time. This has always been one of my favourites and I managed to find it on DVD. Alan Bates and Thora Hird  are particularly good. I'm always on the lookout for more of this type of film for showing on the 405 sets.

 
Posted : 24/08/2017 1:30 pm
Marc
 Marc
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Yes, superb film. Try searching for "Woodfall films" and you'll find lots more movies of this type.

Marc.

Marc
BVWS member
RSGB call sign 2E0VTN

 
Posted : 24/08/2017 2:12 pm
Focus Diode
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nuvistor said
If you enjoyed the film "Kind of Loving", try the book, it's the first of a trilogy by Stan Barstow, the others in order, " The Watchers on the Shore" and " The Right True End"

I can only speak for myself but the trilogy was a really excellent read.

We sold a couple of those Sinclair TV's, never saw them again, a nice example you have there.  

Thanks Frank. The 1982 Granada adaptation covered the trilogy which was excellent too.

My favourite film of all time has to be "Payroll" (1961). A film I could watch time and time again without tiring from it.

Set in Newcastle upon Tyne and surrounding areas too, although no Geordies in the cast.

Back on topic: Is the Sinclair one of those sets with the "sideways" CRT? Perhaps Clive Sinclair invented the flat TV without realising it!

Cheers

 

Brian

 
Posted : 24/08/2017 2:49 pm
Nuvistor
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I think it was flat, had not thought about but perhaps that's the F in FTV.

https://en.m.wikipedia.org/wiki/TV80

Frank

 
Posted : 24/08/2017 2:54 pm
sideband
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Yes it's flat but viewed through a fresnel lens which also corrects the aspect ratio. The CRT is flat with a side gun assembly and is a work of art. If you look at the original VRAT thread here there is a picture or two of the CRT.

 
Posted : 24/08/2017 6:41 pm
ntscuser
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I first saw A Kind of Loving when staying with a family in director John Schlesinger's home town of Bolton in 1967, probably the first time it was shown on TV. I assume the TV was rented from Granada as the pushbutton label(s) for ITV had been replaced with the word 'Granada' which I found very odd. Don't remember much else about the set other than it was all pushbutton and I think dual-standard, although the family told me they didn't bother with BBC2 as they didn't have an aerial for it.

Classic TV Theme Tunes

 
Posted : 25/08/2017 12:11 am
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