phase angle convention

Given the consequences of hooking the phases up wrong in a power plant, I'm sort of glad they do!

Cheers,

Phil Hobbs

Joerg snipped-for-privacy@removethispacbell.net posted to sci.electronics.design:

Collector of drain impedances of even small RF amplifiers are rather small, but they usually use a transformer of some kind to get to antenna feed line impedances. I still believe in the maximum power transfer theorem.

The transformer is used to achieve the desired power output at a given voltage and use the current capabilities of the device to a healthy extent and not beyond. You can easily double the output power of a modern RF amp and then one of three things happen:

a. Nothing but the circuit breaker trips all the time. b. The federales come because you exceeded the licensed limits. c. The overtemp warning light comes on, followed by a shut-down or a loud bang.

--
Regards, Joerg

http://www.analogconsultants.com/

Impedance matching, or the need for it, is probably one of the most widely misunderstood pieces of EE theory. Remember the thread in here around July

2005 on the subject? I think you said then that your Prof had screwy ideas about it.

--
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more
durable; the other is a cheaper thing, but the moths get into it."
                                             (Stephen Leacock)

Usually in the opposite order :-(

-- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)

Yes, I was thinking about the tube days. Red -> cherry red -> orange -> white -> KABLAM! (then the sound of flying glass)

With transistor amps the kablouie often comes first. But at least there is no glass flying about.

--
Regards, Joerg

http://www.analogconsultants.com/

Yep, he sure did. There was actually an assistant professor who still kept disagreeing with me. Me being the lowly student. Then I asked him whether he could calculate the final amp stage of a modern AM transmitter at greater than 85% efficiency. I gave him a datasheet of a really big one so he would believe me that this was state-of-the-art. Well, he stared at the stuff, sweat beads showing up on the forehead ...

--
Regards, Joerg

http://www.analogconsultants.com/

I've seen bits of plastic flying around. Well, I didn't actualy see it, but we found it after turning the power off. The +12 and -12 supply wires were swapped. A 1488 had a neat conical hole in the top of the package. There wasn't any smoke, but there was a loud snap, loud enough so that neither of us had any question that something bad had happened.

If I was going to do that on a production line, I think safety glasses would be a good idea.

--
These are my opinions, not necessarily my employer's.  I hate spam.