Heat isolation, gain, and part longevity.

[Thecomedian]

Has anyone tried using heat sinks or heat "blocks", to retain heat on a transistor and push it's gain farther? The russian MP25B specs show a gain of 140 if you can push it's heat up to a K value that is equivalent to 69C or 158F.

This is below the 75C max temp rating. How much shorter would their lifespan be? Are there any simple solutions for heat regulation that would allow you to do this? Are there any objects like heat sinks or "blocks" which will allow you to push their heat to the required level for that gain?

[amptramp]

You could insulate the transistor in polystyrene foam.  It is true that hfe increases with temperature, but so does noise and the failure rate doubles for every 10°C rise.  Leakage also follows this rule, so germanium transistors are likely to exhibit bias problems.  You are best off using higher gain circuitry and feedback to minimize the effect of transistor gain on circuit performance.  This is what has made op amps so popular.

[R.G.]

Small device ovens used to be done for keeping the temperature of a crystal or some such at a constant temperature.

It's not hard to do, but as A.T. notes, it's a poor choice to try to raise gain in a transistor. Best to find a better transistor.

[Thecomedian]

so are those specs meant to mean that if the temp isn't stable, your gain will be so high and it'll throw off the Q? As sort of a warning about stability?

I guess that leads to my next question of why we need such high gain in devices. If we have a gain of 2 in a signal, and that doubles it, why is that not good enough when you feed a signal with twice as much amplitude as the original into an Amp/speaker setup? Is it because when we talk about gain, we're talking about exceptionally tiny values being made 100x less tiny? As in, if you had 1ml of fluid, and you took 100x 1ml, it's still a relatively small amount of fluid compared to how much a person needs to drink daily? The analogy I suppose is meant to say that the gain of the signal is really not that much compared to how much the amp can use or wants. Would this analogy be correct?