Validating the performance of my TO-3 to TO-3P transistor adapters

Posted on by hoppesbrain

Logically, I believe my adapters must have better thermal performance than simply bolting a TO-3P straight to a heatsink drilled for TO-3. There is simply more copper heat-spreader, and more surface area in contact with the heatsink. And the double-thick copper sandwich (3.2mm) is a lot more copper mass than even a regular TO-3.

But if course I need to SCIENCE this hypothesis to be sure! I don’t sell untested assertions.

Continue reading Validating the performance of my TO-3 to TO-3P transistor adapters

A Marantz 1060 with Sanken Outputs!

Posted on by hoppesbrain

I’m trying out my new TO-3 to TO-3P adapters on this Marantz 1060 that’s been sitting around my shop, 90% complete for the last few years. They look so cool!

I think these Sanken 2SC4468’s —that I found in my junk bin— are going to be a better fit for the 1060 than the usually recommended ON Semi MJ21194. The MJ21194 is a super high-power device, 250W, with a big 5.5mm die, and big Cob and Cib to go along with it. And only 4MHz. (Minimum spec, it’s probably more like 10MHz) The original Hitachi 2SC897’s are only 60W, with a much smaller die, and low Cob. This is only a 30WPC amp, so why use a 250W transistor? The Sanken 2SC4468 is 100W, 250pF Cob, and its 20MHz Ft is a closer match to the 15Mhz of the 2SC897.

The 1060 is a well-compensated amplifier, I’m not too worried that it will oscillate with these slightly faster transistors. But I have yet to actually test it, this amp still needs work!

This is so cool, the selection of transistors that could be fitted is vast! Not just MJ2119X. Pick the best transistor for the job. And soldered to an adapter, even better thermal performance! (I’ll be doing experiments to test this assertion soon.)

Update 2024.04.20

Changed my mind! ST 2SD1047 instead. Even lower Cob, 150pF… If I’m going to test the concept of using lower capacitance devices in the 1060, well these are even lower.

TO-66 to TO-220 Adapters coming soon!

Posted on by hoppesbrain

Got another one! TO-66’s are even harder to get replacements for than TO-3. Again the usual solution is to bodge a TO-220 in place, but the TO-220 tab is much smaller than the TO-66 case, the thermal performance is not as good. This copper heat-spreader + TO-220 transistor should actually offer better thermal performance than the original TO-66; there’s more copper mass overall.

They’re on the way from the fabricator, they should be available in late April.

TO-3 and “BatWing” transistor adapters coming soon!

Posted on by hoppesbrain

On the heels of the launch of my MT-200 Adapters, these solid copper adapter plates adapt new transistors to old formats. Available soon! I just need to test them, but there’s zero reason they won’t meet expectations. Actually these adapters should offer better thermal performance than the original devices. There’s more copper mass overall, so the heat-spreading action should be superior.

MT-200 to TO-3P adapters are live!

Posted on by hoppesbrain

Introductory offer: FREE! (If you can help)

I need some help from my customers! I have not yet tested these adapters in any actual amplifiers or receivers. But I have every reason to believe they’ll work perfectly. If you succeed in installing these adapters in your amp or receiver, and can provide me with clear pictures of your install that I can use on this product page, and some user-experience feedback, you will receive a refund for your purchase, up to $45 (8 adapters). Also, if you find you cannot make them work, you’ll receive a refund. I can provide support though the process; you can call or email me about it. We’ll figure it out. If it doesn’t work, it doesn’t work, and that’s the deal. (But it’s probably gonna work.)

MT-200 to TO-3P / TO-247 Transistor Adapters / Heat-Spreaders