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Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions.

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Old 17th Feb 2021, 11:50 am   #1
G6ONEDave
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Default VHF Band 1 and Band 3 frequencies

I am currently experimenting with a Band 1 modulator for 405 line tv, which I hope to be able to sell on as a kit, although early days yet. However whilst looking into it I needed to know what the various transmit frequencies were and having had no luck with internet searches, I found them in a Bush TV99 service manual. Here is the list all in Mhz which may be of help to other forum members.

Band 1 BBC;
Channel 1 Sound 41.5, Vision 45.00
Channel 2 Sound 48.25, Vision 51.75
Channel 3 Sound 53.25, Vision 56.75
Channel 4 Sound 58.25, Vision 61.75
Channel 5 Sound 63.25, Vision 66.75

Band 3 ITA;
Channel 6 Sound 176.25, Vision 179.75
Channel 7 Sound 181.25, Vision 184.75
Channel 8 Sound 186.25, Vision 189.75
Channel 9 Sound 191.25, Vision 194.75
Channel 10 Sound 196.25, Vision 199.75
Channel 11 Sound 201.25, Vision 204.75
Channel 12 Sound 206.25, Vision 209.75
Channel 13 Sound 211.25, Vision 214.75

There is a 3.5Mhz difference between sound and vision carriers with sound being the lower frequency in each channel.
Hope this might be helpful to others.
Dave
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Old 18th Feb 2021, 10:37 pm   #2
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Default Re: VHF Band 1 and Band 3 frequencies

Also note the larger jump between Ch 1 & Ch 2 compared to the others, that was to accommodate the DSB vision from the the original Alexandra Palace transmitter.

"Band 3 ITA" was probably correct in 1959, but later on Band III was used by the BBC at a few sites.
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Old 19th Feb 2021, 12:16 am   #3
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Default Re: VHF Band 1 and Band 3 frequencies

https://www.oldtellys.co.uk/otfrequenc.html

Note that in practice various transmitters had their frequencies offset by a small amount
e.g. + or - xxx Hz , done to reduce co-channel vision/sound mutual interference which could occur, especially when tropospheric or sporadic E reception conditions were present.
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Old 19th Feb 2021, 11:07 am   #4
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Default Re: VHF Band 1 and Band 3 frequencies

Quote:
Originally Posted by rambo1152 View Post
Also note the larger jump between Ch 1 & Ch 2 compared to the others, that was to accommodate the DSB vision from the the original Alexandra Palace transmitter.

"Band 3 ITA" was probably correct in 1959, but later on Band III was used by the BBC at a few sites.
BBC on Band III...
(shudder!)
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Old 23rd Feb 2021, 1:03 pm   #5
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Default Re: VHF Band 1 and Band 3 frequencies

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Originally Posted by Brigham View Post

BBC on Band III...
(shudder!)
The shame of it all. Auntie Beeb mixing with the riff raff at ITA
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Old 23rd Feb 2021, 2:48 pm   #6
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Default Re: VHF Band 1 and Band 3 frequencies

Quote:
Auntie Beeb mixing with the riff raff at ITA
More of a takeover I think, I do remember the BBC having advice about "continental interference" and enjoying the European programmes in fleeting glimpses and sneaking down to the telly after the beeb had stopped to see what I could see. Dad caught me once and we had a jolly good time "surfing the channels"
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Old 23rd Feb 2021, 3:12 pm   #7
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Default Re: VHF Band 1 and Band 3 frequencies

Hi,
was there ever channel 14 ? though I seem to remember it was never used... ?
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Old 23rd Feb 2021, 6:15 pm   #8
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Default Re: VHF Band 1 and Band 3 frequencies

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Originally Posted by dragonser View Post
Hi,
was there ever channel 14 ? though I seem to remember it was never used... ?
See: https://www.radios-tv.co.uk/community/postid/97364/


Cheers,
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Old 23rd Feb 2021, 6:33 pm   #9
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Default Re: VHF Band 1 and Band 3 frequencies

Quote:
Originally Posted by Synchrodyne View Post
Quote:
Originally Posted by dragonser View Post
Hi,
was there ever channel 14 ? though I seem to remember it was never used... ?
See: https://www.radios-tv.co.uk/community/postid/97364/


Cheers,
Fascinating!

I guess that when TV was first started - pre-WWII - there were no 'standards' and you just asked the Postmaster General [or his local equivalent] to allocate you some bandwidth... up in those odd "VHF" frequencies where nothing-else is really happening anyway [sssh... don't mention RADAR!]

Historically, part of me wonders if early-TV could have been developed with vision on VHF but sound on MW: it would have made TV receivers cheaper if they didn't need to include a sound-strip, and could have also excited consumer-interest if people had been able to listen to the audio-channel of TV broadcasts on their existing MW/LW radios.
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Old 23rd Feb 2021, 6:45 pm   #10
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Default Re: VHF Band 1 and Band 3 frequencies

Quote:
Originally Posted by rambo1152 View Post
Also note the larger jump between Ch 1 & Ch 2 compared to the others, that was to accommodate the DSB vision from the the original Alexandra Palace transmitter.
For some weird reason NZ had a similar gap between our channels 1 and 2, although we were always system B and I'm pretty sure never had a DSB transmitter!

Channel 1 - 45.25 / 50.75
Channel 2 - 55.25 / 60.75
Channel 3 - 62.25 / 67.75

and then band III channels 4-11 were 175.25/180.75 and up at 7 MHz spacing. Channels 1, 3, 5, 7 and 11 were in use here in Invercargill until DSO in 2013.
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Old 23rd Feb 2021, 6:52 pm   #11
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Default Re: VHF Band 1 and Band 3 frequencies

Post war, UK had a 56 mc/s amateur band and when this was abandoned (for TV) a
narrow 70 mc/s band was provided. UK did not offer 50MHz to hams until 1984.
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Old 23rd Feb 2021, 7:41 pm   #12
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Default Re: VHF Band 1 and Band 3 frequencies

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Originally Posted by G6Tanuki View Post
...and could have also excited consumer-interest if people had been able to listen to the audio-channel of TV broadcasts on their existing MW/LW radios.
'Television Sound' had become available on several radios by about 1938. Still AM, though this was on the '7-metre band' of course.

Steve
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Old 23rd Feb 2021, 8:04 pm   #13
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Default Re: VHF Band 1 and Band 3 frequencies

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'Television Sound' had become available on several radios by about 1938. Still AM, though this was on the '7-metre band' of course.
If it had caught on, those awfully nice public servants in the ministry would have seen it necessary to create a new licence that listeners would need...

David
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Old 23rd Feb 2021, 10:48 pm   #14
emeritus
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Default Re: VHF Band 1 and Band 3 frequencies

An amendment to the WT act a few years ago means that you don't need a TV licence if you get your sound from a "set-top box". It has to be a STB: using a VCR with no TV attached will not do.
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Old 24th Feb 2021, 12:37 am   #15
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Default Re: VHF Band 1 and Band 3 frequencies

Quote:
Originally Posted by arjoll View Post
Quote:
Originally Posted by rambo1152 View Post
Also note the larger jump between Ch 1 & Ch 2 compared to the others, that was to accommodate the DSB vision from the the original Alexandra Palace transmitter.
For some weird reason NZ had a similar gap between our channels 1 and 2, although we were always system B and I'm pretty sure never had a DSB transmitter!

Channel 1 - 45.25 / 50.75
Channel 2 - 55.25 / 60.75
Channel 3 - 62.25 / 67.75

and then band III channels 4-11 were 175.25/180.75 and up at 7 MHz spacing. Channels 1, 3, 5, 7 and 11 were in use here in Invercargill until DSO in 2013.

Nothing too weird in fact.

For Region 3, into which NZ falls, the ITU 1947 Atlantic City meeting set Band I as covering 44 to 50 and 54 to 68 MHz. There were country-by-country exceptions added over time. In the NZ case, there was an exception to allow 50 to 51 MHz for TV broadcasting. This was recorded at the ITU 1959 Geneva meeting. I imagine that this exception was requested once it was decided to adopt the European 625/50 system with 7 MHz channel, later known as System B. This allowed channel NZ1 to span 44-51 MHz. Presumably doing it this way was a better overall fit with other spectrum user requirements than would have been assigning 47 to 54 MHz to NZ1, to make it contiguous with NZ2 and NZ3, and giving up 44 to 47 MHz.


Cheers.
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