22-02-2011, 08:21 AM
For those sad like me that find big old bottles pleasing to the eye, here we have 5 large early 1950's TV valves.
From the first pic left to right.
Valve 1. You've already met the 6BG6G which is a beam tetrode and was designed as a line output valve for television
Valve 2. A 20P4 the last digit is rubbed off but I'm fairly confident, the 20P1 is a purpose designed self oscillating television line output valve
Valves 3,4&5 The U801, a television HT rectifier and efficiency diode. The rating is given as 1,500 Volts PIV. The unusual feature is the fact that the construction is as a pair of full wave rectifiers within the envelope. The general belief is that the U801 with its very high heater rating was unreliable due to the fragile heater. Additionally it seems to have been prone to shorting out.The four anodes were supplied each with a 100 ohm surge limiter resistor and this caused problems. One would go open circuit putting the HT load across the three remaining anodes to produce a run away fault with final destruction of the valve and all remaining limiters in a mass of sparks (info courtesy of the valve museum)
Pictures 2 & 3 are close up shots of the U801 Each of the four rectifier sections.
Picture 5 is the PL519 Line output valve, This example is of late and probably the last to be produced before transistors took over the role.
What intrigues me is and maybe someone will know what is the significance of the "SH" & "LS" as can be seen in picture 4 on the two U801's
So come lads get yer favourite bottles out and share them (not alcoholic so no Bud's N berg's lined up)
Chris
Edit: Yep that was a 20P1 I had a rummage and found a NOS Mazda of the same see pic 6
From the first pic left to right.
Valve 1. You've already met the 6BG6G which is a beam tetrode and was designed as a line output valve for television
Valve 2. A 20P4 the last digit is rubbed off but I'm fairly confident, the 20P1 is a purpose designed self oscillating television line output valve
Valves 3,4&5 The U801, a television HT rectifier and efficiency diode. The rating is given as 1,500 Volts PIV. The unusual feature is the fact that the construction is as a pair of full wave rectifiers within the envelope. The general belief is that the U801 with its very high heater rating was unreliable due to the fragile heater. Additionally it seems to have been prone to shorting out.The four anodes were supplied each with a 100 ohm surge limiter resistor and this caused problems. One would go open circuit putting the HT load across the three remaining anodes to produce a run away fault with final destruction of the valve and all remaining limiters in a mass of sparks (info courtesy of the valve museum)
Pictures 2 & 3 are close up shots of the U801 Each of the four rectifier sections.
Picture 5 is the PL519 Line output valve, This example is of late and probably the last to be produced before transistors took over the role.
What intrigues me is and maybe someone will know what is the significance of the "SH" & "LS" as can be seen in picture 4 on the two U801's
So come lads get yer favourite bottles out and share them (not alcoholic so no Bud's N berg's lined up)
Chris
Edit: Yep that was a 20P1 I had a rummage and found a NOS Mazda of the same see pic 6
