Many of the sets from that era until the first dual standard appeared gave really good performance. It seems that the makers had found the correct formula for a 405 Line TV. It just show what can be achieved in terms of picture quality on 17 inch sets. The 19 inch models were about the limit for 405, there were plenty of 21 inch sets about but unless they were viewed from across the room the line structure became noticeable.
You have a good specimen of what was achievable from the time.
Frank
The 19 inch models were about the limit for 405, there were plenty of 21 inch sets about but unless they were viewed from across the room the line structure became noticeable.
Agreed, but it was the pronounced curvature of the faceplate that made them so bad to watch at close quarters. To my mind, all 21" tubes looked ugly.
The 23" CRT, however, like its 19" partner, had a much flatter faceplate and gave perfectly respectable pictures.
When all else fails, read the instructions
Perhaps off topic but if the programme material gives you enjoyment then some pictures defects don’t get noticed by many.
The 23 inch screens were good, I’m just found the 19 inch more to my liking but on 625 the 23 inch held there own.
I have a 32 inch flat screen TV, it was given to me by my son in 2008 when he went live abroad. It’s good but I would be quite happy with a smaller screen, my daughters TV must be 60 inch flat screen, I can’t say it gives me any more enjoyment than smaller screens.
Frank
Another aspect of picture quality for me is black level clamping, or rather the lack of it on some set's. The Murphy is DC coupled so no issue there anyway though.
To understand the black art of electronics is to understand witchcraft. Andrew.
Another aspect of picture quality for me is black level clamping, or rather the lack of it on some set's. The Murphy is DC coupled so no issue there anyway though.
Many never noticed it lacking, and some even complained when Bush introduced it. I was on holiday in the Lake District, early 60’s and saw some terrible snowy ghosty pictures in various places. The locals were used to it and saw past the faults and enjoyed the content. I think they were happy to have some form of picture.
I am not saying it’s not needed but it’s surprising what some will put up with even if the results can be improved.
Takes all sorts.
Frank
In the RGD Deep17 topic I mentioned that the frame sync is obtained by using a differentiator circuit instead of the usual CR integrator.
The Murphy V280 employs a differentiator to extract the frame sync pulse but unlike the simple RGD a proper pulse shaper follows the CR differentiator.
An extract from the 1960/61 Radio and Television servicing book:
Interlace
The usual frame sync system - on the efficiency of which depends the "goodness" of the interlacing - is to feed the output from the sync separator valve to a differentiating network followed by what is termed a "clipper" or "pulse shaper" and may be a diode or triode. The object is to produce a series of frame-sync pulses of nearly equal amplitude and well defined leading edges necessary to trigger the frame timebase positively at the exact instant.
Till Eulenspiegel.
Always helps me a good circuit description, some circuits are easy others not so much, well for me anyway. ?
Frank
It just show what can be achieved in terms of picture quality on 17 inch sets. The 19 inch models were about the limit for 405, there were plenty of 21 inch sets about but unless they were viewed from across the room the line structure became noticeable.
Hi Frank, let's see what 405 looks like on that huge 1958 24" KB "Regina" when I get it working. CRT is the Brimar C24KM which is an imported tube, possibly the Continental AW61-80.
Now's there's set that must have perfect interlace.
Till Eulenspiegel.
