Professional 625 -> 405 Convertor

[ppppenguin]

Perhaps the '509s were first used at unmanned or minimally manned sites where reliability mattered more.

[Heatercathodeshort]

I can only say that the results from the Crystal palace 405 line transmitter BBC1 were nothing short of superb. You may have had problems with the maintenance at the transmitter end but the results on good domestic receivers was at the top end. J.

[frank1471]

Originally Posted by Ray Cooper

What you may not appreciate was, that at any given station, there'd be two of the things running in parallel, with a bloke constantly on hand to switch from one to the other if the 'service' unit started to display eccentric tendencies, which they certainly did on a weekly basis and sometimes daily. In bad periods, it could be a struggle to keep even one of the units in good working fettle. However, with a mixture of experience and deep cunning the service was usually maintained to an acceptable standard.

I too was involved with keeping these going at Holme Moss.
We had an auto changeover system which used a "roving pulse". A narrow pulse on one line in the blanking interval which slowly moved along the line to detect store faults.
I have fond memories of those massive store cards on a huge extender and using a "wet finger" to find the faulty store. Also the "bar sinister" test waveform for quickly checking them.. the standby one of course.
The biggest problem was the edge connectors on the store cards. After a few insertions the gold plating had gone and they were always either being replaced (if we were keen) or cleaned towards the end of their lives.
Mostly just re-seating the store cards worked for a while.

Frank

[murphyv310]

Certainly from the receiving end I can vouch that from Kirk 'o Shotts & Black Hill the results on 405 were always superb!
I wonder though how the Aurora would compare with the the old technology, I bet no one could tell the difference!