When it comes to cooling, don't forget that one of the huge differences between tubes and transistors is that tubes run a lot hotter. More (delta T) more heat sink surface area and/or more air flow.
Transistors are limited to a much lower temp than any part of a power tube, so even if you could get the same kind of connection, you would be unlikely to be able to keep the transistor cool enough.
Welll... I did a bit of searching and near as I can tell the Pacific/Oceana price is on the order of $719 ea or if you purchase 25 or more it drops to $621 ea. I didn't find a US distributor with a l
We (Steve G8GSQ) and myself are in the process of putting together a 2m amplifier with two BLF578 devices (not 578XR) at the moment. Big heatsink = 350mm (L) x 250mm (W) x 80mm (H) and two copper spr
This email describes what I've learned from looking at these modern transistors for the last few months. It seems to me like a fundamental crossover point has been reached. Silicon processing technol
Hello there The method you describe is the good one with the small tub for these devices. I do not have a mechanical tool shop like you guys my means are limited I polish the copper slaband use an co
Yep, ask the Lasers community about that little gotcha. You think power FETs are a pain to cool, you want to try a high power laser diode bar array.... Not only are they temperature tuned to match th
Paul, That's only half of the picture. The other half is that it needs to be kept very much cooler than a tube! In some cases, comparing the more compact tubes with the larger transistors, that could
Hello Jeff, Any pictures available of the copper heat spreader, aluminum plate, etc?? -- 73, Gary K9GS Check out K9NS on the web: http://www.k9ns.com Greater Milwaukee DX Association: http://www.gmdx
Gary... Some YouTube videos... http://www.youtube.com/watch?v=02v58cnb41o&feature=relmfu http://www.youtube.com/watch?v=-EACUpIhpac F1JRD also has an article in Dubus http://www.qsl.net/f1jrd/MRFE6VP
Unless something has changed we used to run the core temps of Silicon power transistors and CPUs as high as 90C, but how well that works depends on the doping and construction techniques of the Silic
So how much already ?? ... i just found a power supply that delivers 50V @ 60A ..... Mike KC7NOA _______________________________________________ Amps mailing list Amps@contesting.com http://lists.con
The only prices I could find were on foreign sites, but it "appears" they run about the price of an imported 8877 or between $700 and $800 each. At least that's according to what I could find. I'd se
Author: "Dr. David Kirkby" <david.kirkby@onetel.net>
Date: Sat, 13 Aug 2011 09:49:02 +0100
These is an equation, based on the physics of semiconductors, that shows: P f^2 R = constant. P = power f = frequency R = output impedance I can't recall the derivation of that, but could dig it out.
I've never heard of this, but I see no theoretical limit problem, we can tolerate any output impedance if we are allowed to use a transformer/s. -- Ron KA4INM - I've been carving my initials on trees
meanwell makes switchers that can stack to 9KW @ 48V _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
I have no pricing on the BLF578XR but new BLF578 (genuine, not Chineese copies) were available on ebay.co.uk for GBP £85.00 each... I purchased some for my QRO 144MHz amp and they're fine. The Freesc
I have a couple of the older versions (MRF6VP41KHR7) that will go up to 500 MHz. Now all I need to do is find a piece of copper stock (that doesn't require a second mortgage !!) and I'll try them out
<snip> There are physical limitations, but I'm embarrassed to say that although I used to teach semiconductor circuit design It's been so long that I do not remember any formulas. The limitation bein