R53 Broken Bulb - UK Vintage Radio Repair and Restoration Discussion Forum

jim_jobe · 28th Feb 2015, 1:27 pm

I have an R53 thermistor but unfortunately the bulb is broken - will that affect its performance?

Radio Wrangler · 28th Feb 2015, 1:46 pm

Severely, I'm afraid.

It is a fastish-responding device for operation at low power levels and that means it has to be in vacuum.

They're getting rather hard to find.

David

jim_jobe · 28th Feb 2015, 5:59 pm

I thought that might be the case David. Thank goodness I have another one.
Cheers,
Jim

julie_m · 28th Feb 2015, 7:10 pm

This sounds like an opportunity for some comparative testing ..... !

MotorBikeLes · 28th Feb 2015, 7:13 pm

Vacuum filled or gas filled? I thought that CO2 filling was used, with its high thermal conductivity.
Of course I could be confusing things with the old Cambridge gas analyser!
Les.

Dickie · 28th Feb 2015, 8:14 pm

High thermal conductivity would slow its response rather a lot?

Radio Wrangler · 28th Feb 2015, 9:09 pm

It's the combination of fast-ish response and operation at low levels. In vacuo heat loss will be by mounting wires and radiation Stefan's constant says radiative power is proportional to Kelvins to the fourth power., so the solution seems to be a tiny bead running hot on low power input. If it's not actual vacuum, it must be very low pressure inert gas.

David

28th Feb 2015, 1:27 pm	#1
jim_jobe Heptode Join Date: Nov 2004 Location: Ripon, N.Yorkshire, UK. Posts: 782	R53 Broken Bulb I have an R53 thermistor but unfortunately the bulb is broken - will that affect its performance?

28th Feb 2015, 1:46 pm	#2
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: R53 Broken Bulb Severely, I'm afraid. It is a fastish-responding device for operation at low power levels and that means it has to be in vacuum. They're getting rather hard to find. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

28th Feb 2015, 5:59 pm	#3
jim_jobe Heptode Join Date: Nov 2004 Location: Ripon, N.Yorkshire, UK. Posts: 782	Re: R53 Broken Bulb I thought that might be the case David. Thank goodness I have another one. Cheers, Jim

28th Feb 2015, 7:10 pm	#4
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: R53 Broken Bulb This sounds like an opportunity for some comparative testing ..... ! __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

28th Feb 2015, 7:13 pm	#5
MotorBikeLes Nonode Join Date: Dec 2012 Location: Kirk Michael, Isle of Man Posts: 2,350	Re: R53 Broken Bulb Vacuum filled or gas filled? I thought that CO2 filling was used, with its high thermal conductivity. Of course I could be confusing things with the old Cambridge gas analyser! Les.

28th Feb 2015, 8:14 pm	#6
Dickie Octode Join Date: Sep 2004 Location: St. Albans, Hertfordshire, UK. Posts: 1,478	Re: R53 Broken Bulb High thermal conductivity would slow its response rather a lot? __________________ Regards, Richard, BVWS member

28th Feb 2015, 9:09 pm	#7
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: R53 Broken Bulb It's the combination of fast-ish response and operation at low levels. In vacuo heat loss will be by mounting wires and radiation Stefan's constant says radiative power is proportional to Kelvins to the fourth power., so the solution seems to be a tiny bead running hot on low power input. If it's not actual vacuum, it must be very low pressure inert gas. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done