Need help selecting a VR tube

phrarod · 3rd August 2009, 10:41 PM

I have a regulated tube power supply that I choke loaded. Due to this I need to get some more voltage out than normal when it was capacitor loaded.

It calls for a 0C2 tube which gave me way too low voltage at HV+ output. About 65VDC low. I put in a 0A2 which jumped the final HV+ about 80VDC

I need something a little less than the 0A2 so I can set the trim pot with a decent range.

Anything between the two of these?

Merlinb · 3rd August 2009, 10:46 PM

0B2 and the 85A2 spring to mind.

phrarod · 3rd August 2009, 11:07 PM

If the 0C2 is 103VDC and the 0A2 is 150VDC the something like 130VDC?

I checked the data sheet right now and it list the 0B2 as 108VDC unless I'm reading it wrong?

Just found an 0B2 and WOW the highest voltage output yet! OK that won't work.

BTW the tube is being loaded with a 30K resistor. Maybe I can change the loading resistor? Its being loaded from the plate (pin 1) of a 12AU7

Wavebourn · 3rd August 2009, 11:20 PM

Check for neon bulbs and cold cathode thyratrons, they may be in the range you are looking for. One of neon bulbs is used in BC-438 tube receiver I have in my living room currently.

phrarod · 4th August 2009, 12:23 AM

Looks like I need a VR tube with a reference voltage of 130V

thevoice · 4th August 2009, 04:25 AM

Some of the European STV tubes are around there, like the STV240/40 or STV240/80. Unless you know of a source you may have trouble finding some though.

phrarod · 4th August 2009, 04:27 AM

Thanks everyone. I gave up and just changed the voltage divider network. Everything works fine now although one filament supply is running 10 degrees hotter than the other and I'm getting some new noise. Have to look into that.

Merlinb · 4th August 2009, 09:40 AM

Quote:

Originally posted by phrarod

Just found an 0B2 and WOW the highest voltage output yet! OK that won't work.

Ok, two 0C2 in series!

Wavebourn · 4th August 2009, 04:46 PM

Quote:

Originally posted by Merlinb

Ok, two 0C2 in series!

With 510K resistor in parallell to one, in order to get them started.

3rd August 2009, 10:41 PM	#1
phrarod diyAudio Member Join Date: Aug 2005	Need help selecting a VR tube I have a regulated tube power supply that I choke loaded. Due to this I need to get some more voltage out than normal when it was capacitor loaded. It calls for a 0C2 tube which gave me way too low voltage at HV+ output. About 65VDC low. I put in a 0A2 which jumped the final HV+ about 80VDC I need something a little less than the 0A2 so I can set the trim pot with a decent range. Anything between the two of these?

3rd August 2009, 11:20 PM	#4
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	Check for neon bulbs and cold cathode thyratrons, they may be in the range you are looking for. One of neon bulbs is used in BC-438 tube receiver I have in my living room currently. __________________ The devil is not so terrible as his mathematical model! Wavebourn: We Create Creativity!

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3rd August 2009, 10:46 PM	#2
Merlinb diyAudio Member Join Date: May 2006 Location: York	0B2 and the 85A2 spring to mind.

3rd August 2009, 11:07 PM	#3
phrarod diyAudio Member Join Date: Aug 2005	If the 0C2 is 103VDC and the 0A2 is 150VDC the something like 130VDC? I checked the data sheet right now and it list the 0B2 as 108VDC unless I'm reading it wrong? Just found an 0B2 and WOW the highest voltage output yet! OK that won't work. BTW the tube is being loaded with a 30K resistor. Maybe I can change the loading resistor? Its being loaded from the plate (pin 1) of a 12AU7

4th August 2009, 12:23 AM	#5
phrarod diyAudio Member Join Date: Aug 2005	Looks like I need a VR tube with a reference voltage of 130V

4th August 2009, 04:25 AM	#6
thevoice diyAudio Member Join Date: Mar 2005 Location: Melbourne Again	Some of the European STV tubes are around there, like the STV240/40 or STV240/80. Unless you know of a source you may have trouble finding some though.

4th August 2009, 04:27 AM	#7
phrarod diyAudio Member Join Date: Aug 2005	Thanks everyone. I gave up and just changed the voltage divider network. Everything works fine now although one filament supply is running 10 degrees hotter than the other and I'm getting some new noise. Have to look into that.

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