oa2 tube substitution

[pucho812]

I should be o.k. here but want a second confirmation

I should be able to swap it with a 10W 150V zener diode....

Yes?

 

[Conviction]

Why do you want to substitute it? The 0A2 is dirt cheap - and there's still heaps of them.

A zener sub is fine, 150V is spot on. I've done it twice on some old scopes but it always felt redundant - could have just put in a fresh 0A2.

 

[Audio1Man]

Hi pucho812
If you can’t get the OA2, why not use an active series pass circuit? As the shunt type may need more power dissipation. The 10 watt Zener may or may not be temp or voltage stable and have more noise? I have attached the basic series pass circuit and the details need to be calculated.
Duke

 

[pucho812]

Why do you want to substitute it? The 0A2 is dirt cheap - and there's still heaps of them.

A zener sub is fine, 150V is spot on. I've done it twice on some old scopes but it always felt redundant - could have just put in a fresh 0A2.

availability. I can locally get the zener for a few bucks vs waiting for shipping time. 

 

[pucho812]

Hi pucho812
the shunt type may need more power dissipation.

yes there is plant to bolt it to a heatsink.

 

[trobbins]

You really should identify whay circuit it is in, and what current range the OA2 needs to shunt for acceptable circuit operation.
That would then allow the zener to be chosen correctly, especially as heatsinking would be required to avoid silicon death syndrome.