Power horizontal deflection transistors work fine in output stages ?

[aldovan]

Friends

Is possible use a power horizontal deflection transistor in a output stage ?
A BU208A, per exemple, can work fine in a output stage ?
This transistor is fast switching, but the gain is small.
I think in make some experiences...

Aldovan

[longthrow]

Originally posted by aldovan
Friends

Is possible use a power horizontal deflection transistor in a output stage ?
A BU208A, per exemple, can work fine in a output stage ?

hi aldovan,

do you mean as an audio power output?
if it is,i doubt it..that maybe fast but thats not the only concern in audio application..

[Giaime]

They have strict limits in collector current, too high Vce(sat), and almost no beta at normal currents. I tried S2000A and gave it up...

[ilimzn]

The simple answer is no.
The gain is normally too low and the DC SOA is way too small - not a problem in their original application where they work as switches.
That being said, although these are generally marked as 'BUxxx' for Euro type markings, it does not follow automatically that all BU marked transistors are for that purpose. You should check for speciffic types.

[aldovan]

I have the BUY 20 and BUY84.
This two transistor is fine for output or no ?

Aldovan

[Conrad Hoffman]

I used to use HV deflection transistors in commercial HV amplifiers, up to 1200V. As mentioned above, the beta can drop to one or two, and SOA is limited. They are not robust in anything other than their designed application. For the HV amps, drive current isn't a problem because any simple LV stage can come up with enough current, even if the beta dropped below one, when you consider that the needed output current is very low. Not so for audio. What the transistor gets you is the HV capability, but they aren't fast. If you got a pile of them for free, maybe you could wire a bunch as parallel darlingtons, and force a design, but performance wouldn't be very good for all the effort involved.

[AndrewT]

But, the high definition CRT display transistors make excellent audio VAS and Pre-drivers.
2sa1405/6/7/76/77/78/80 and dozens of others, that are cheaper.

[jackinnj]

I've used them in HV regulators --