[Maritan]

I recently acquired a Decware ZP3 phono amp that calls for a 0A3 regulator tube (among others). The preamp came with a 0C3A instead. While I have confirmed with the manufacturer (Steve Deckert) himself that 0C3A will work just fine, he also suggested I get a 0A3 and see if I preferred the sound of one to another.

Cool, so I hit my local tube store up and picked up a GE 0A3 on Wednesday (Thursday?). I plugged it in and gave the turntable a listen. Sounded good, but I will reserve judgement since the whole chain from source to speakers are breaking in.

Anyway, I fired up the phono preamp last night and the 0A3 started blinking - kind of like the indicator light in our car when we're making a turn. (The first night I used it, it didn't do that.) Music still made it through despite the blinking 0A3. I plugged in the 0C3A and it didn't seem to blink - but the 0A3 is a much brighter tube than the 0C3A and any lessening of brightness is immediately noticeable.

Has anyone had an experience like this? Bad tube? Bad phono pre? Any ideas would be appreciated.

[FullRangeMan]

Anyway, I fired up the phono preamp last night and the 0A3 started blinking -

Seems bad contact inside the tube or the tube pins dont fit perfectly in the socket.
A good socket is very important.

Would be useful find what is blinking, the filaments/cathode, grid or plate.
The problematic tube fit firm in the socket??

[Maritan]

FULLRANGEMAN - I'm actually not familiar with the construction of vacuum tubes, much less the 0A3 specifically. Here's a very short video of the blinking -

http://youtube.com/watch?v=XRqh9sfjmqU

I tried to seat the tube more securely, tapped gently on it but neither stopped the blinking or made it worse really.

So, what is blinking? Filament? Grid? Plate? Given what you see, any additional input?

[FullRangeMan]

No possible see what exactly is blinking as there is plenty of light.
Seems a defective tube to me, I would ask a replace tube from the vendor if possible and ask the expert opinion from Steve Deckert also.

[FullRangeMan]

This is a cold cathode tube, hence the 0 prefix(zero volts) in the tube name, in this datasheet there is some suited comments in the General Operation paragraph.
It mention this is a glow discharge tube whatever it is.

http://www.mif.pg.gda.pl/homepages/frank/sheets/141/g/GL874.pdf
Looks good wait Steve opinion before ask warranty to the tube vendor.

[Maritan]

That's good info! Thanks FULLRANGEMAN. I'll call Steve tomorrow and talk to him about this first.