CTV Tubes - UK Vintage Radio Repair and Restoration Discussion Forum

Hunts smoothing bomb · 11th May 2006, 10:57 am

Greetings,

Just a quick question, Does anyone know when the phosphors on CTV tubes changed from being round to rectangular?

It's just one of those pointless questions I felt I needed the answer to.

Kind regards

Lee

newlite4 · 11th May 2006, 11:56 am

The original Delta "triple dot" formation gave way to the "in line" formation with the introduction of the Philips "AX" series tube around 1974. Although the Sony Trinitron system with "in line" configuration arrived in around 1970, this was a different type of system entirely.
Neil

slidertogrid · 11th May 2006, 11:04 pm

The Thorn 9000 was the first set I saw with a PIL (Precision in line) tube, this was where the phospher was arranged in coloured rectangles, previous tubes were delta gun where the phosphers were arranged in triangles .I think the 9000 dates to around 1973/4.
I remember the early pil tubes didnt last long, Hitachi had a real problem with a directly heated cathode pil tube they lasted on avarage 10 months! but to give them their due Hitachi replaced every one

even when the sets were out of gurantee, cant see that happening nowdays

Welsh Anorak · 12th May 2006, 5:40 pm

Hi
Yes - the first non-trinitron tube was in the Thorn 9000, closely followed by the (much longer lasting) ITT CVC20, and a most odd 110 degree 20" pil tube in the Rediffusion Mk3 which seemed to last for ever! The 20" seemed (at first anyway) to be much longer-lasting than the larger sizes.

slidertogrid · 12th May 2006, 10:03 pm

The Decca 80 used a early pil tube that was notorious for going flat after a few years, I think the heaters were underun from new and many sets were looking sick at 3/4 years old, the practice with these (rental) sets was to unsolder one of the wires on the lopt heater winding pass it throught the core and resolder it! this added about 1/2 a turn to the heater winding and in some cases gave the sets another 5 years! happy days! Dont ask what we did to the G11! the "heater mod " we devised for that would make Len Briggs Turn in his grave!

Brian R Pateman · 13th May 2006, 12:19 am

Quote:

Originally Posted by Welsh Anorak

Hi
Yes - the first non-trinitron tube was in the Thorn 9000, closely followed by the (much longer lasting) ITT CVC20, and a most odd 110 degree 20" pil tube in the Rediffusion Mk3 which seemed to last for ever! The 20" seemed (at first anyway) to be much longer-lasting than the larger sizes.

Yes, funny that, the Mullard 20" tubes in Philips sets of the same era lasted no time at all!

Regards,

slidertogrid · 15th May 2006, 12:02 am

We devised a terrible "heater mod" for the G11 ,which I hasten to add were rental sets towards the end of there usefull life at the time, first you cut the print between the heater fuse holder and the lopt, then you soldered a wire to the lopt pin , passed it through a convienient hole in the line panel( near the lopt) passed it through the core of the lopt and soldered it to the fuse holder, the fuse was then removed and a resistor soldered across the fuse holder on the back of the print, the it was a 5watt ww and the value varied from 3R3 to 1R5 depending on how flat the tube was, if it was really duff you could always refit the fuse!this usually brought the tubes back to life for a while .PIL tubes never seemd to reactivate well , the old delta gun tubes would boost and last, but "bump " a pil and it usually killed it! hence the heater mod ! Happy days!!

Brian R Pateman · 15th May 2006, 10:05 pm

Quote:

Originally Posted by slidertogrid

We devised a terrible "heater mod" for the G11 ,

Yes, I remember doing something similar to sets in my own rental fleet in the 1980s.

(I always had a soft spot for the G11 despite the dry joints).

as for rejuvenating tubes I found it made a difference which type of tester / rejuvenator you used. The most effective for me was the Leader. Mine was bought secondhand from Stewarts of Reading and worked well on most tubes, even PIls if caught early enough.

Those were the days!

Regards,

11th May 2006, 10:57 am	#1
Hunts smoothing bomb Octode Join Date: Oct 2005 Location: Wimborne, Dorset, UK. Posts: 1,407	CTV Tubes Greetings, Just a quick question, Does anyone know when the phosphors on CTV tubes changed from being round to rectangular? It's just one of those pointless questions I felt I needed the answer to. Kind regards Lee __________________ Lee

11th May 2006, 11:56 am	#2
newlite4 Octode Join Date: Nov 2003 Location: Bath, Somerset, UK. Posts: 1,805	Re: CTV Tubes The original Delta "triple dot" formation gave way to the "in line" formation with the introduction of the Philips "AX" series tube around 1974. Although the Sony Trinitron system with "in line" configuration arrived in around 1970, this was a different type of system entirely. Neil

11th May 2006, 11:04 pm	#3
slidertogrid Octode Join Date: Apr 2005 Location: Peterborough, Cambridgeshire, UK. Posts: 1,898	Re: CTV Tubes The Thorn 9000 was the first set I saw with a PIL (Precision in line) tube, this was where the phospher was arranged in coloured rectangles, previous tubes were delta gun where the phosphers were arranged in triangles .I think the 9000 dates to around 1973/4. I remember the early pil tubes didnt last long, Hitachi had a real problem with a directly heated cathode pil tube they lasted on avarage 10 months! but to give them their due Hitachi replaced every one even when the sets were out of gurantee, cant see that happening nowdays

12th May 2006, 5:40 pm	#4
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,918	Re: CTV Tubes Hi Yes - the first non-trinitron tube was in the Thorn 9000, closely followed by the (much longer lasting) ITT CVC20, and a most odd 110 degree 20" pil tube in the Rediffusion Mk3 which seemed to last for ever! The 20" seemed (at first anyway) to be much longer-lasting than the larger sizes.

12th May 2006, 10:03 pm	#5
slidertogrid Octode Join Date: Apr 2005 Location: Peterborough, Cambridgeshire, UK. Posts: 1,898	Re: CTV Tubes The Decca 80 used a early pil tube that was notorious for going flat after a few years, I think the heaters were underun from new and many sets were looking sick at 3/4 years old, the practice with these (rental) sets was to unsolder one of the wires on the lopt heater winding pass it throught the core and resolder it! this added about 1/2 a turn to the heater winding and in some cases gave the sets another 5 years! happy days! Dont ask what we did to the G11! the "heater mod " we devised for that would make Len Briggs Turn in his grave!

15th May 2006, 12:02 am	#7
slidertogrid Octode Join Date: Apr 2005 Location: Peterborough, Cambridgeshire, UK. Posts: 1,898	Re: CTV Tubes We devised a terrible "heater mod" for the G11 ,which I hasten to add were rental sets towards the end of there usefull life at the time, first you cut the print between the heater fuse holder and the lopt, then you soldered a wire to the lopt pin , passed it through a convienient hole in the line panel( near the lopt) passed it through the core of the lopt and soldered it to the fuse holder, the fuse was then removed and a resistor soldered across the fuse holder on the back of the print, the it was a 5watt ww and the value varied from 3R3 to 1R5 depending on how flat the tube was, if it was really duff you could always refit the fuse!this usually brought the tubes back to life for a while .PIL tubes never seemd to reactivate well , the old delta gun tubes would boost and last, but "bump " a pil and it usually killed it! hence the heater mod ! Happy days!!