HRH Queen Elizabeth 70TH Jubilee

[Panrock]

Tell me about it... I am no stranger to the use of mirrors in an effort to see the picture whilst carrying out some adjustment or other, in this case craning my neck around the sheer bulk of the cabinet in order to see... anything.

In the Bude, the worst thing is trying to adjust the frame linearity while attempting to see the picture -in the mirror - at the same time. It is physically impossible to see where one is putting one's hand at the same time as seeing the picture. And there are - jagged - live parts nearby to touch as you do it.  Moreover, on the TV24A chassis used here there are two controls, which interact. The last time I attempted this operation I inflicted on my left hand repeated electric shocks... but I wouldn't give up! I still have the deep, RF-like, burns in the flesh to show for it.

Incidentally, if anyone wants to do a tutorial on the TV24A's multivibrator frame timebase, I would be an eager pupil.  I still haven't got it as good as it should be.

Steve

[Murphyv310]

Hi Steve.
Try a 30PL1 instead of the ECL80 in the frame. It improves it and gives far better linearity. It's plug and play in these sets.

[Panrock]

Thanks for that Trevor... it wouldn't have occurred to me. I see I have stock, so I'll try it.

Steve

[peter scott]

The 30PL1 is a cleaver substitute. Like Steve, it wouldn't have occured to me either. It drops a few more volts in the heater chain and has a lower anode voltage spec but can pass substantially more anode current. Given that the ECL80 is running off a 370 volt boost rail its 200 volt anode rating sounds a bit low and the 30PL1 at 170 volts even more so but I guess if they don't flash-over then all is well. I don't have one to try but if my NOS ECL80 proves inadequate I might have a go.

Peter

[Murphyv310]

The first thing you will notice is a big increase in available height, linearity is improved and interlace is less dependent on frame hold position.
The ECL80 can withstand over 1kv on the pentode anode before flashover.

[peter scott]

p.s. I've just found one and it does look better than my ECL80s although it was probably been swapped out for being a bit down. The one I have is about equal with my best ECL80.

Thanks,

Peter

[Panrock]

I found I had only one 30PL1 and it clearly had been used, with a 2.5 Mohm h/k leak on the tester (this turned out not to matter).

On fitting it - more height in hand as Trevor had predicted and the linearity is better too. A top tip!

[Murphyv310]

Hi.
The other valve that'll get you out of trouble when the customer is nipping your brain is a PCL83, a horrid little valve and guaranteed to fail in a month but it does work. A new 30PL1 does indeed work well and also lasts better than the ECL80.

[peter scott]

I thought it looked a bit long for video so just a few stills.

   
   
   

Peter