Recently I purchased via ebay 4 stabilizer tubes : 0A2WA.
After measuring them and finding nothing wrong with them (only all of them are at the almost lowest side of the stab. voltage tolerance),
I accidentally heard one of them rattling while pulling it out of the socket. Then to be sure, I did some shaking and then I noticed the rattle again. So, I measured it again but did not find any problems, same stab. characteristic.
Should I be worried? Shall I not using it in one of my designs?
After measuring them and finding nothing wrong with them (only all of them are at the almost lowest side of the stab. voltage tolerance),
I accidentally heard one of them rattling while pulling it out of the socket. Then to be sure, I did some shaking and then I noticed the rattle again. So, I measured it again but did not find any problems, same stab. characteristic.
Should I be worried? Shall I not using it in one of my designs?
Last edited:
It could be a small loose piece of glass inside the tube. That's not all that unusual, nor is it a reason to not use a tube.
Check both plate (anode ) pins = 1&5 still connected together ,
,
then check pins =2&4&7 are all connected together ,
pins=3&6 help holding the the internal structure in place.
It is not unknown for the spot welds to come away.
European equivalent is the =150C4 which is a direct replacement -pin for pin (B7G base ) .
,
then check pins =2&4&7 are all connected together ,
pins=3&6 help holding the the internal structure in place.
It is not unknown for the spot welds to come away.
European equivalent is the =150C4 which is a direct replacement -pin for pin (B7G base ) .
The 0A2 is a nice tube, but if you need absolute stability, use a 85A2 and run it at approx 3mA. Tektronix (from the scopes) states that at this current these tubes can have a long term drift characteristic of less than 0.1%(!)
There are some Russian equivalents, even ruggedized ones under different part numbers, those feature ceramic insulators and are dirt cheap.
There are some Russian equivalents, even ruggedized ones under different part numbers, those feature ceramic insulators and are dirt cheap.
I used 85A2 as references in many of my regulator designs a couple of decades ago, and found they drifted a lot less than the zeners I was then using. Operating current was 3mA, and drift was typically a few hundred mV after some warm up on the 400V output of my regulated supplies. Pretty impressive.
Got to agree with the 85A2 as far as stability is concerned it was the 50,s /early 60,s "go to " tube for many military communications receivers .
Used to stabilize the FC/oscillator section ---never had to replace one ,it was so good public versions and DIY communications receiver builds used them too.
As a matter of fact I still have one ex-UK Navy B7G based communications receiver with two fitted.
Used to stabilize the FC/oscillator section ---never had to replace one ,it was so good public versions and DIY communications receiver builds used them too.
As a matter of fact I still have one ex-UK Navy B7G based communications receiver with two fitted.
My first amplifier designs used 85V supply voltage and I applied the 85A2 stab tubes for those designs.
But then I started to designing my amps with a higher voltage up to 150V.
Stumbled across the 0A2 stab tube and I am using these now.
The problem with that rattling is that I cannot have a look into that tube construction due to the fact that
the anode is shielding the inside preventing to look into that tube.
Well, I suppose it must be the anode because I never saw a construction drawing of the 0A2.
Perhaps somebody can shed more light on the 0A2 construction.
But then I started to designing my amps with a higher voltage up to 150V.
Stumbled across the 0A2 stab tube and I am using these now.
The problem with that rattling is that I cannot have a look into that tube construction due to the fact that
the anode is shielding the inside preventing to look into that tube.
Well, I suppose it must be the anode because I never saw a construction drawing of the 0A2.
Perhaps somebody can shed more light on the 0A2 construction.
The out side tube is the cathode, the central shaft is the anode (pins 1 and 5).
No idea what is rattling though...
Last edited:
I looked around a bit on the web. Apparently there are 0A2's with a mesh anode. This picture shows a metal rod as the cathode, surrounded by the cylindrycal anode.
Edit: Maybe the rattling is caused by a piece broken off of the mica spacer(s). If so, I don't think it will do harm to the functioning of the tube.
Attachments
Last edited:
Thanks PCL200 for supplying that picture.
Indeed there are tubes with a mesh or a solid cathode (according to Alan 4411).
I have one which has the mesh type (Philips). And yes, it provides a nice glow when "ON".
All the others I have are solid (Philips or RTC) .
As I wrote before, the rattling one still provides the stab curve.
Using the 85A2 and still want to have 150V supply I need 2 in series.
Don't like that because I use separate 150V supplies for each channel both channels equipped with a 0A2 🙂
Indeed there are tubes with a mesh or a solid cathode (according to Alan 4411).
I have one which has the mesh type (Philips). And yes, it provides a nice glow when "ON".
All the others I have are solid (Philips or RTC) .
As I wrote before, the rattling one still provides the stab curve.
Using the 85A2 and still want to have 150V supply I need 2 in series.
Don't like that because I use separate 150V supplies for each channel both channels equipped with a 0A2 🙂
Yes, I was wrong about the postions of the cathode and anode, Allan4411 is right. Sorry about that. The good news (for me): I learned a bit more.