UHF Senders

[Richard_FM]

I noticed that Dusty Gizmos has a UF-66 UHF Sender unit as their widget of the week.

http://www.dustygizmos.com/index.htm

I remember they were featured on Watchdog once in the late 1980s as being something you could be but not legally use, as the potential to interfere with your neighbours TVs, not to mention the possibility of being used for setting up pirate TV stations!

Later on legal ones appeared that broadcast around 2GHz, often with a remote control signal return for use with multiroom satellite & cable systems.

[dragonser]

Hi,
that reminds me of the time I got asked to look at someones TV and video in the 1980's.
they were complaining about the pictures not being clear. Turns out they had somehow swapped the leads to the aerial and tv receiver round on the video recorder, so they were feeding the uhf output from the video recorder into their communal aerial system...

[Dai Corner]

Friends and I may or may not have fed the output of a VCR via a UHF preamp to the rooftop aerial and played slightly dubious tapes.

[Restoration73]

Note that UHF indicates only a UK market. VHF types were widely used in the U.S.,
typically set to ch. A2. I have one for CCIR ch.12, so nominally 5.5MHz sound.
They can all be adjusted, of course.

[G6Tanuki]

Originally Posted by dragonser

Hi,
that reminds me of the time I got asked to look at someones TV and video in the 1980's.
they were complaining about the pictures not being clear. Turns out they had somehow swapped the leads to the aerial and tv receiver round on the video recorder, so they were feeding the uhf output from the video recorder into their communal aerial system...

There was at least one instance when back in the 1980s someone has used a then-high-tech camcorder to video themselves and their partner indulging in bedroom-antics, but misconnected the camcorder when they came to play it back so everyone in their tower-block got an unexpected 'pre-watershed' eyefull.


The "video senders" were actually a useful source of bits: again back in the 1980s I looked-after a number of undocumented self-help TV repeaters in Mid-Wales: these generally had a high-gain antenna pointed at the nearest 'big' transmitter [Blaenplwyf] on one side of a hill, a few hundred metres of coax running over the top of the hill and a 'launch amplifier' connected to several 'contract'-style Yagis that pointed down the valley to the people who were paying me to do this. The obstruction of the hill provided enough attenuation that there was no 'howl-round' even though something like 40dB of gain was involved in the cascaded-video-sender amplifiers.
Someone [not me] had to lug a tractor-battery up to the top of the hill every couple if weeks to power the amps.

[Nymrod121]

Got called out whilst on mobile maintenance duties at Holme Moss some time in the late '80s; a number of calls from viewers in the Shipley area complaining of severe patterning & distorted sound on their TV sets. One enterprising individual had connected their VCR to one of the afore-mentioned UHF 'senders' and thence to the roof-top antenna. It obliterated BBC2 for several streets around. Having DF'd it to within one street of several terraced properties, we handed it over to the DTI for them to resolve. Apparently the owner of the kit got slightly belligerent with the enforcement team. After a night in the local nick for a potential BotP charge, the numpty was sent home ... and a hefty fine was handed down by the courts some time later.

The Eleventh Commandment applies ... "Thou Shalt Not Get Found Out"

Guy

[simpsons]

My brother, who lives in Sherman, Connecticut, uses an IView3500STB11, linked to a 5Ghz HDMI transmitter, over 100 metres up a hill to receive off air transmission in place of cable TV.
He uses uses a 64 element Yagi, oriented via digital compass, to receive UHF and 6 element VHF both channelized for New York reception which is over 80 miles away. They are located on top of a neighbours property who also now receives free to air signals and where the 5Ghz transmitting aerial is placed.
As the signals are in digital format and the frequencies subject to attenuation if aerial cable or weather attenuation and tree masking are not taken into account, choices of line of sight for the 5Ghz transmission and location and orientation of the UHF Yagi took some working out. Sourcing the Yagi also presented a problem as grouped arrays are not normally available in the USA. The answer lay in finding a local transmitter in a southern state and having it shipped. Remote control of the IView is established via the 5gHz receiver.

[Graham G3ZVT]

Originally Posted by Richard_FM

I remember they were featured on Watchdog once in the late 1980s as being something you could be but not legally use, as the potential to interfere with your neighbours TVs, not to mention the possibility of being used for setting up pirate TV stations!

Yes, they were outlawed by specific legislation

http://www.legislation.gov.uk/uksi/1998/722/made

And note that it's not just the use you put them to - simply possessing one is illegal.

I have wondered though, what makes a device a "video sender" for the purposes of this legislation?

The definition in paragraph 3 could equally be applied to a video modulator, particularly the ones used in aerial head-ends with their powerful launch amplifiers.

Someone might have bought a so-called "video sender" as a cheap way of feeding an aerial distribution system with the output of a security camera etc.
I doubt that in law, something is defined solely on what the manufacturer decided to call it, but what do I know.

[Graham G3ZVT]

Originally Posted by simpsons

My brother, who lives in Sherman, Connecticut, uses an IView3500STB11, linked to a 5Ghz HDMI transmitter, over 100 metres up a hill to receive off air transmission in place of cable TV.
He uses uses a 64 element Yagi, oriented via digital compass, to receive UHF and 6 element VHF both channelized for New York reception which is over 80 miles away. They are located on top of a neighbours property who also now receives free to air signals and where the 5Ghz transmitting aerial is placed.
As the signals are in digital format and the frequencies subject to attenuation if aerial cable or weather attenuation and tree masking are not taken into account, choices of line of sight for the 5Ghz transmission and location and orientation of the UHF Yagi took some working out. Sourcing the Yagi also presented a problem as grouped arrays are not normally available in the USA. The answer lay in finding a local transmitter in a southern state and having it shipped. Remote control of the IView is established via the 5gHz receiver.

I suppose that shows we have an advantage that perhaps your brother doesn't have, viz almost everything available via terrestrial TV, is also available free to air via satellite, and conveniently all at the same orbital position.

[paulsherwin]

There was a panic about video senders when they started to arrive in quantity, and they were specifically outlawed. As far as I know they are the only item of transmission equipment where possession (as opposed to operation) is illegal.

[simpsons]

Receiving the signal was only one of the issues as US Stations often identify themselves by both their call sign, viz ABC and channel number. TV sets have the software to for example show ABC CH7 when in fact the set is tuned to CH 57 and so on. To keep the lady of the house happy, the setup had to maintain this for HD channels and equivalent SD to suit the bedroom and kitchen TV's.

In other words, after what was a lot of engineering, no one in the house thought anything had changed!! The other issue was that the internet service was also through the cable TV company whose bundle always included TV.

Not sure how this overcome but on his visit to London, he and his wife got us watching his UK selected programs they get via a server based in Reading. His complaint was that the BBC Iplayer was only 720p not full HD. His AM/FM transmitter broadcasts Radio 2 or the World Service but as his nearest neighbour is 100 metres away and unlikely to scan the airwaves, he's not too bothered.

The downside is that whilst the umpteen acres and lake are out of this world, TV and radio are his lifeline and given the UK is 5 hours behind us, I imagine it's a little like time travelling in "Back to the future".

Chris

[Heatercathodeshort]

For younger Forum members who have never seen a 'Video sender' I managed to dig out this photo of one I took many decades ago.

They were dreadful things. The picture was OK but the sound usually suffered with distortion and hum.

To be honest they did not give me any bother service call wise. I did not sell them and advised customers to hard wire a signal to the bedroom.

I think the scare police did a pretty good job.

This example was taken to the Atomic Research Establishment at Harwell to be deactivated. It was bombarded with electric rays like something out of a 1920's science fiction comic. Oh well, another bit of fun destroyed. I await the handcuffs. Regards, John.

[paulsherwin]

I suspect the draconian possession rules were intended to discourage market traders and car booters from trying to sell them. These were major distribution channels for dodgy non-approved electronics in the pre-eBay, pre-Amazon era. There was a fear that senders would sell in vast numbers and cause all sorts of TV reception problems.

[Gulliver]

I may or may not have started a pirate TV station at Aston University in the early 90s using a slightly modified video sender.....

[mark2collection]

I vaguely remember such a thing allowing you to send pictures & sound from your Skybox to an upstair TV, must have been mid-90's, so probably in the order of GHz. The name 'Power Mid' rings a bell.

I couldn't possibly comment on my early years in the trade, living at home with my parents, my new VCR (somehow ) connected between the TV aerial & the signal booster for the other TV's around the house including upstairs.

Whilst watching said VCR I could hear my father muttering in another room about the poor reception on Channel 5 ... only for him to re-adjust his set & was now watching the same content as myself!

Luckily, nothing too saucy ...

Mark

[julie_m]

Originally Posted by Gulliver

I may or may not have started a pirate TV station at Aston University in the early 90s using a slightly modified video sender.....

Out at Handsworth, by any chance? I had heard rumours of something similar going on there .....

[paulsherwin]

No discussion of illegal activity please, even if historical.

[G6Tanuki]

The really cheap market-stall sit-it-on-top-of-the-telly video-senders from a few decades back I remember because of the way the antenna looked rather like a skeletal fish! The 'tail' of the fish fitted into a ball-and-socket type thing on a turret on top of the sender, and this allowed you to swivel it round to point the 'body' of the fish so its head aimed in the desired direction.

(There were similar 'amplified aerials' available).

[electronicskip]

You still see these things kicking around , in fact I saw one for sale in a charity shop not a week ago, I'm doubting if they even knew what it was in all honesty ..
Price was £6

[Hybrid tellies]

I think we all need to be a bit cautious with using this type of video sender today thanks to the 700Mhz UHF TV band clearance.
This means that the a lot of the TV transmitters that presently use channels 's 49-60 have all will be moved to the previously clear channels 31-38.
Most of these video senders output is around ch36 which can only be varied by two or three channels either side, plus they are also double sideband so for example if they transmit on ch36 they will overlap into channels 35 and 37.