Why did 405 look so good?

[colly0410]

Reading an article (Practical Television March 1965 page 276) on mean level AGC & it's infamous effects on 405, it says "Of recent years the effects have become so noticeable that that TV producers have been forced to take them into account & to avoid televising scenes of very low illumination level.) I suppose the widespread use of AC coupling didn't help matters. Mean level AGC = another 405 negative?

[Murphyv310]

That wasn't the fault of the 405 line system though. It was penny pinching by the manufacturer.
Comparing the likes of the 1953 Pye V4 and many later sets there is a big difference in the picture quality.
Actually as I've mentioned before non AGC sets were remarkably good.

[peter scott]

Of course the the complaint is very much more obvious when there are different approaches for UHF and VHF in the same set as in Sony 9-90.

   

Peter

[Murphyv310]

The 9-90 is particularly bad on 405, it can be improved but it is horrible to work on, fortunately a very reliable set.
The Perdio Portarama and Philips T-vette perform very well but reliability is no where near the standard of the Sony.

[ppppenguin]

In the professional/broadcast TV world one of the standard test waveforms has switched APL (average picture level). So a ramp or staircase on about 1 in 5 lines, the remaining lines switching from black to white every half second or so. This shows up any black level clamping weaknesses quite dramatically. I've never converted it to 405 and fed it to any TVs. Not sure I'd want to see the results

[colly0410]

That wasn't the fault of the 405 line system though. It was penny pinching by the manufacturer.

Very true, Mr Blumlein didn't foresee the skinflintness of the TV makers when he invented the 405 line system...

[Geordie McBoyne]

I must fire up this monster 405 line TV set. It's a 24" Kolster-Brandes model housed in a special custom made cabinet.
The CRT is a Brimar C24KM which was imported from Europe. It's likely an MW61-80. Tube has a pentode gun assembly similar to that fitted in the MW43-69.
Made in 1958 the KB PV100 was the largest screen TV available in the UK.

Geordie McBoyne.