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Palomar Maxi Mod
- Thread starter Low_Boy
- Start date
You can buy sheets of insulator material made by Chromerics and you can cut your own to any size you want.
https://www.digikey.com/en/product-...41-commercial-grade-electrical-insulator-pads
They used to make TO-220 transistors with Isolated tabs on the back and no insulation was required. Just put a small amount of grease on the back of it and screw it down. In a way like the RF transistors 1446, 2879, mrf455.
I wish they would do that again. All of those ceramic insulators are primarily for High Voltage isolation and are inferior to the isolated tab transistors. Surface imperfections will break those and the high voltage isolation is gone, or if the heat sink is flexible they break.
I wish they would do that again. All of those ceramic insulators are primarily for High Voltage isolation and are inferior to the isolated tab transistors. Surface imperfections will break those and the high voltage isolation is gone, or if the heat sink is flexible they break.
One thing about ceramic insulators is if you do anything wrong in the mounting of the transistor, they are the first to let you know by cracking. You can have your heatsink perfectly flat and simply apply to much torque on the mounting screws. That causes the aluminum around the screw hole to pull up and can distort the heatsink or transistor case enough to crack the insulator during thermal expansion.That doesn't mean to abandon the ceramic insulator, it means we have to improve our transistor mounting skills.
Or (ahem) bolt them down to the heat sink BEFORE you solder the leads to the pc board.
73
73
This is the correct way to limit mechanical stress on the device and was the proper procedure in manufacturing electronics back in the days. I had to work with a manufacturer on device failures and that was one of the top questions they asked whether it was bolted prior to soldering.
I know a guy that popped the tops off of 2879s trying to install them. Some people have different ways of doing things.
We had fixtures that aligned the transistor up on the heatsink. We also used split lock washers and assembly was done with torque wrenches. When the gap on the split washer was closed you were approaching the torque specification for the mounting. We used TO-3 transistors on ceramic insulators and the were tightened in increments first one side then the other and back and forth until the torque wrench clicked.
We used REAL beefy IRF-150's and it was good for 28 amps continuous..
We used REAL beefy IRF-150's and it was good for 28 amps continuous..
I don't know how to tell you this but the "Death Star" was not operational at that time.
It was caused by one of the Super Bowl signals that originated from the "Mule Droppings" site on that planet.
Sorry buddy, but that was a swing and a miss.
Goes right in there with your "MUH Thermocouple"
Wha??? Muh thermocouple is wrong? But muh research and muh test’s. Not to mention dat video.
It’s all been a sham? A huge hoax and a lie? Not even muh surface area will save me here?
Oh lord, muh feelings.
It’s all been a sham? A huge hoax and a lie? Not even muh surface area will save me here?
Oh lord, muh feelings.