Hi Folks.
I am looking for a 25" picture tube, ideally a 25NP4. This tube type seems to have been a favourite of H.M.V.
I guess almost any 25" B&W tube would do. They all had the safety screen bonded to the screen face.

Without another tube I might have to abandon the project. The set in question is a H.M.V. Windsor 25 inch with the V2 chassis.

The tube does not have to be perfect, just have about 0.5ma emission.

Regards

Wayne.

Assuming you are not going to put a lot of hours on it, have you tried increasing the filament voltage.
They used to sell inline transformer purpose made for this.
I'm sure to have one or two in my junk pile.
And they used to work well and believe it or not for quite some time.
JJ

I have one of those tubes (Thomas) in my HMV Y2-D3.

It was looking very sad but I rejuvenated it with a box I built that implements a method that was first documented on the UK forum.

Very, very successful!

Is the existing one completely dead or down to air? In other words is there hope?

The set has some issues but I hoped to have it as a working display.
The safety screen of the bonded tube is cracked. Quite impressive. It now appears (after further testing) to be down to air.

The heater was intact, and although I never saw it glow, I could feel its warmth.
My feelings are that the heater went open circuit because of air in the tube.

Unless I can get something to fit, I will have to get rid of the set. Space is always at a premium.

I have two non-bonded 23" tubes at home saved for other projects that might come along. They are not the greatest but if anyone is in a prediciment, Give me a call.

All the best.

Wayne.

Actually, no-one in Oz made a bonded 25" tube.

The only bonded (laminated faceplate) CRT made here was the 23HP4, as seen in the original Pye Pedigree and many other sets.

All the other non-naked CRTs were either shellbond or rim-banded

A shellbont tube is basically just a naked CRT glued into a pressed metal shell with epoxy. This holds the faceplate in compression and avoids implosions that might be caused by blows to the front.

A rim-banded tube is the same thing but done with a steel compression band, much like a packing crate band but with mounting lugs fitted to the corners. I often wonder how many tube implosions they had while setting up the machine that tensioned and clamped that band!

None of these tubes actually have two layers of glass on the faceplate,

I actually had a factory-fitted Thomas shellbond tube in an HMV once that carried the part number of a naked tube but someone had hand-written on it "Shellbond".

Like my Calstan!