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When designing a coder it's best to start with 4xfsc as suggested by Dave Boynes. Then you can get the quadrature subcarriers directly in digits, rather than having to align an analogue phase shift network. I've learned since 1986Smile

If you want to encode an existing RGB output from a computer etc then you either have to lock the source to your coder or vice versa. When I used one of my coders with the COW at Dulwich I made the coder master. I took mixed sync from the coder to lock the COW. Subcarrier was free running wrt H whihc isn't ideal but is simple.
Remember I converted a Decca CTV22 Dual Standard to NTSC 405 line colour, hence to need for an SCRF NTSC aurora, the screen shots are on the Aurora Legacy site.
I'd like to do this again with a Sony 1310 or 1320, taming the line stage isn't an issue and initially it'll be 405 RGB from the PC.
https://www.tech-retro.com/aurora-design/sc-images.html
(11-03-2023, 11:58 AM)ppppenguin Wrote: [ -> ]All UK colour sets from 1967 to 1969 were 625/405. They didn't do colour on 405 though it would be entirely possible to modify one.
I never saw a colour set before 1970.

Quote:Divis became the UHF main station for Belfast and the surrounding area with BBC2 being the first regular service commencing on 18 March 1967. Colour UHF transmitters for BBC1 and ITV came into operation in September 1970.
—Wikipedia
Wikipedia also claims BBC 2 Northern Ireland started 11 June 1966.

We had a mono dual 405-625 TV with a continuous vertical radio-style scale for UHF, maybe since 1962 or 1963. Before that we had my grandparents' old 405 set, the second such passed on. One had doors. Every day after school I'd check if anything was on UHF. Then there were the "trade transmissions" before regular BBC2 started. Unfortunately I can't remember when that was but indeed maybe that was before June 1966.

We watched the first moon landing on it. 20 July 1969.
I guess BBC2 was in England in Mono from 1964 and then colour from 1967. I suspect hardly anyone where I lived in NI got colour till BBC1 & UTV were added. Most colour sets were rented then, as was ours in 1970.
Then from the mid 1970s I worked in the BBC. The transmitters by then did have HW for a 4th Channel. The Politicians claimed it was technically impossible to transmit RTE in NI. They meant politcally and shortly after that claim it happened by accident. RTE had added a new TX at Longford (they'd used 405 in areas where people bought TVs for BBC and 625 everywhere else, launch 31st December 1961, which is why it's PAL-i, because Ireland used the UK audio subcarrier spacing before BBC2). One night BBC closed and RTE had a late film. After feed from BH was cut for the night the Divis system would see if Scotland (Kirk O'Shots?) was live and rebroadcast it before shutting down, but it picked Longford RTE on that channel. The complaints jammed BBC switchboard and congratulations the RTE Belfast one up the road, Fanum House that had AA, near Shaftesbury Sq.

Another time the BBC NI schools was interrupted with RTE test card by accident.

They always blocked Network wide Welsh in NI back then. Can't be appeasing Irish speakers (despite Britain supporting Irish in primary schools before 1922). One day my boss swore and pulled the switch to switch from GB to testcard. I reached over and put it back.
"What do you think you are doing! We have to block the Welsh!"
"But not the Eisteddfod! Check the NI Radio Times."
He looked at it. "Thanks."

Then C4 did start in November 1982 and I left NI in Feb 1983, I probably got the best bits? We were in the MidWest, so no more UK TV till C5 on analogue satellite and then Digital satellite later with S4C only as FTA, so we lost C5 for a while when analogue ended.

A friend of mine moved from BBC Transmitters to RTE Transmitters in 1985, so he got to help turn off 405 in England and Ireland, though this part of Ireland never had 405 and only ended Band I RTE 625 in 1999. The remaining band III RTE1 & RTE2 ended with ASO 24 October 2012 (Even SD is H264 and HD doesn't use DVB-T2). In parts of the Midwest from 1996 when Teilifís na Gaeilge started on UHF, you needed a Band I, Band III and Band V aerial.
Proper 625 sets for the Irish market always had VHF & UHF tuners to suit broadcast and analogue cable.
Limerick City was fringe reception for Band I and Band III till the UHF only Woodcock hill transmitter was added in I think about 1989, but I was abroad 1989-1990. Lots of Limerick City houses still have defunct Log periodics, Band I and Band III aerials. TV3 was the the 4th channel but was meant to be 3rd, so Teilifís na Gaeilge was rebranded TG4.
The Irish channels are all on Sky, for NI or Irish subscription, but occasional programs are blanked on NI viewing cards (but some may have Irish cards). Unusually all the RTE with TG4 are also FTA on 9E Ka band, narrow spot beam. The spots on KA-Sat reuse frequencies so only bits of GB coast can get the Irish channels. Or if you have an Irish viewing sub from Sky, they all work in London.
Michael
1970 was duplication (BBC1 & ITV on 625 Colour) but BBC2 had colour from 1967, hope that clarifies it for you.
BBC1 and ITV had colour from November 1969. Not sure how long it took to roll it out nationwide.

BBC2 had colour from December 1967 officially but Wimbledon and some other programmes were colour from summer 67.
(11-03-2023, 04:22 PM)ppppenguin Wrote: [ -> ]BBC1 and ITV had colour from November 1969. Not sure how long it took to roll it out nationwide.

BBC2 had colour from December 1967 officially but Wimbledon and some other programmes were colour from summer 67.

That's Correct, For some reason I thought it was 1970 but I do remember our British Relay viewing unit having the 625 line switch firmly left on 625 before I started working with the same company on the 5th Jan 1970. Today's error
I heard BBC Northern Ireland opting out of most things in Welsh was because of a worry that Protestants might assume it was Gaelic & get angry!

Some of the Irish cities had analogue cable systems, which helped to stop the spread of large arrays of ariels, especially the ones trying to pick up British TV.
Would it be possible to re-program a standard SCRF405 to the NTSC 405 colour version?
Jac
Hello Jac,
I do remember Daryll saying he just got away with programming the FGPA for NTSC 405 colour. I believe the colour converter employs the same chip set as in the SCRF405 converter.

Geordie McBoyne.
The Motorola MC1377 PAL/NTSC colour encoder IC can with a change of some component values be adapted for 405 line colour.
The IC can be used with the sub-carrier and sync pulse generator I mentioned to in a previous post in this topic.
The burst gate is a ramp generator which consists of two comparators within the IC, access is to pin 1. This can be adapted for 405 line sync timing.
Using the MC1377 I made a successful colour bars generator for 405 lines.

Data for the MC1377: https://www.smspower.org/uploads/Develop...MC1377.pdf

Geordie McBoyne.
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