03-20-2015, 08:48 AM
Yes, that's pretty much it. You want to find a replacement with equal or higher voltage and current specs, and comparable physical package. The other factor is the cutoff freq rating Ft, which should be in the 2 to 10 Mhz range.
If you can't find any specs, then look for transistors with a Vce rating comfortably higher than the total DC power supply voltage. Ic current ratings are typically 8 to 15 A for small power transistors and should be suitable. If the amp is higher power, then parallel connected outputs are usually used.
Another thing is matching. Japanese output transistors specified for audio use are typically tightly matched into groups for beta and Vbe. This becomes important when you have sets of transistors in parallel for the output stage.
For the 170, I would be looking for transistors with Vce ratings of 60-80 v, and Ic around 10-15 A. What sort of package are they? Metal TO-3 or plastic case?
If you can't find any specs, then look for transistors with a Vce rating comfortably higher than the total DC power supply voltage. Ic current ratings are typically 8 to 15 A for small power transistors and should be suitable. If the amp is higher power, then parallel connected outputs are usually used.
Another thing is matching. Japanese output transistors specified for audio use are typically tightly matched into groups for beta and Vbe. This becomes important when you have sets of transistors in parallel for the output stage.
For the 170, I would be looking for transistors with Vce ratings of 60-80 v, and Ic around 10-15 A. What sort of package are they? Metal TO-3 or plastic case?
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
