Heat sink for these transistors

[TinCanAlley]

Originally Posted by zeno

IIRC the heat sinks were on the 9-121 & 9-155 CRT modules.
maybe also on 9-89 but its been years.
BUT I dont think the fat leads will go into your sockets.
I would leave well enuf alone, they were quite reliable.

73 Zeno

You're right. I pulled the sinks off an old video driver board from my other CCII. That board also uses the 121-868 output transistors I'm trying in the Avanti, so they're the right clips and the same as sold at Radio Shack.

Now the specs say the max junction temp is 150C. I don't know what that means for external temp. I do know that with the clips they run between 105 and 130F, or 40 and 54C. That's about 20% hotter than the TO-39s with the stock heat sinks. I don't know if these naturally run hotter. I do know they have a composite or silicone type case and the old ones are metal. That might account for the heat difference. I imagine the metal dissipates heat better.