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# Interesting curves...

B

#### Bill Sloman

Jan 1, 1970
0
Which is another job idea: offer to proof-read peoples's data sheets.
That would be the ideal job for some older guy who knows everything
about everything.

John Larkin furthers his claim to be our most out-of-touch-with-
reality poster.

I've never made any claim to be particularly expert with RF parts.
I've certainly used wide-band transistors at frequencies close to
1GHz, but strictly as wide-band amplifiers, and I'm aware that there
are lots of fun aspects to their narrower-band use where I know very
little - possibly even less than John Larkin.

J

#### Jamie

Jan 1, 1970
0
John said:
How annoying. No Idss spec, no DC curves. RF people are like that:
just fiddle with the bias until it works.

Since the abs max range of gate voltage is -8 to -2, it's presumably
destroyed in shipping. Unless they ship it with a battery attached.

Abs max supply voltage is 48, but leakage is tested at 175.

The forward transconductance spec is clearly wrong.

Pitiful. We use phemts in pulsed time-domain applications, and usually
have to test them ourselves to get basic specs. Even the manufacturers
often don't know basic stuff about their parts. A Spice model, or even
basic DC curves, is rare for RF parts.
Don't feel bad, the other day I discovered that we have a tube of power
mosfets 18 amps, 500V out of a batch we order with a different date code
on them that does not pass the 500V break down test, they're good for
only ~250v before they start to break down. These were purchased all at
the same time but this particular tube seems to be older stock.

Not only that, I notice the package, although the same type, looks
like they were made else where on the planet, they don't seem to have
the same exact mold shape. I wonder if I got rebranded or defective parts?

It's not a bug deal, we just put those assigned with a note on them,
they now are test fets, but these fets are not cheap and it's a good
thing I didn't pay for them..

Jamie

F

#### Fred Bartoli

Jan 1, 1970
0
Vladimir Vassilevsky a écrit :
Well, it is clear why. However the one who prepares datasheet doesn't seem
to have a clue.

I meant the small hook at the curves upper right extremity.

I'd be curious to know what so obvious about these...

R

#### Robert Baer

Jan 1, 1970
0
Jamie said:
Don't feel bad, the other day I discovered that we have a tube of power
mosfets 18 amps, 500V out of a batch we order with a different date code
on them that does not pass the 500V break down test, they're good for
only ~250v before they start to break down. These were purchased all at
the same time but this particular tube seems to be older stock.

Not only that, I notice the package, although the same type, looks like
they were made else where on the planet, they don't seem to have the
same exact mold shape. I wonder if I got rebranded or defective parts?

It's not a bug deal, we just put those assigned with a note on them,
they now are test fets, but these fets are not cheap and it's a good
thing I didn't pay for them..

Jamie
Maybe counterfeit parts..a lot of that going on.

R

#### Robert Baer

Jan 1, 1970
0
John said:
I keep making great suggestions about fun and useful things that
geezers could do, and geezers pop up and tell me what they don't know
and can't do.
Maybe they were shot down by those big companies that need expertise.
HR takes one look at them and instantly determine they are 40 or
older and kick them out as being "overqualified".
The companies would rather hire two greenies fresh out of college and
$$pend even more money in training for a year or so to get them to be useful.. K #### [email protected] Jan 1, 1970 0 Maybe they were shot down by those big companies that need expertise. HR takes one look at them and instantly determine they are 40 or older and kick them out as being "overqualified". The companies would rather hire two greenies fresh out of college and$$pend even more money in training for a year or so to get them to be
useful..

Absurd. It's just the opposite, in fact. Recent grads are living in
mommy's basement, playing the XBox.

B

#### Bill Sloman

Jan 1, 1970
0
I keep making great suggestions about fun and useful things that
geezers could do, and geezers pop up and tell me what they don't know
and can't do.

It's the contrast between ill-informed fantasies and objective
reality. The US electorate seems to have preferred the latter.

L

#### legg

Jan 1, 1970
0
Which is another job idea: offer to proof-read peoples's data sheets.
That would be the ideal job for some older guy who knows everything
about everything.

It doesn't pay.

A typo in the hand is worth two proofs in the bush.

RL

L

#### legg

Jan 1, 1970
0
On the previous plot, they have output power vs input power. The output
power decreases after passing maximum due to overexitation. They just put
sequential numbers of the output power from that plot into drain efficiency
calculation. So, after maximum reaching maximum power, the graph makes a
hook.

Vladimir Vassilevsky
DSP and Mixed Signal Consultant
www.abvolt.com
Can't blame the spreadsheet software.....

Actually, Excel used efficiency as the dependant coordinate for
drawing the line connection sequence. Efficiency should drop with
over-exitation, if input drive power is included in total power
consumed.

There are valid bistable graphical plots, but this isn't one.

RL

J

#### Jamie

Jan 1, 1970
0
Bill said:
It's the contrast between ill-informed fantasies and objective
reality. The US electorate seems to have preferred the latter.

You'd make a perfect politician, never getting the facts right and
always twisting the truth, if you really knew what the truth was.

Jamie

R

#### Robert Baer

Jan 1, 1970
0
Vladimir said:
On the previous plot, they have output power vs input power. The output
power decreases after passing maximum due to overexitation. They just put
sequential numbers of the output power from that plot into drain efficiency
calculation. So, after maximum reaching maximum power, the graph makes a
hook.

Vladimir Vassilevsky
DSP and Mixed Signal Consultant
www.abvolt.com
..here come de puns..
Well, it was obvious as to the why and what, but the giraffe had its
neck broken by the plodding idiot by interchanging the axis.
Just rotate the giraffe 90 degrees so it will be standing on its legs
and thus have no broken neck..

R

#### Robert Baer

Jan 1, 1970
0
Absurd. It's just the opposite, in fact. Recent grads are living in
mommy's basement, playing the XBox.
I was talking about the job market before His Changeness.

R

#### Robert Baer

Jan 1, 1970
0
Phil said:
Sure you can. There's nothing inherent in the idea of an amplifier that
prevents the output power from going down as you increase the input
power, past a certain point. All you need is a bias shift.

Cheers

Phil Hobbs
Yea, yea, yea. Bot the presentation is absurd; rotate the graph 90
degrees..

K

#### [email protected]

Jan 1, 1970
0
I was talking about the job market before His Changeness.

It's been true for some time. It's hard for script-kiddies to find
jobs. Experienced design engineers aren't having a lot of trouble
finding work. While I have experienced some age discrimination, it's
just as often been reverse.

B

#### Bill Sloman

Jan 1, 1970
0
It's been true for some time.  It's hard for script-kiddies to find
jobs.  Experienced design engineers aren't having a lot of trouble
finding work.  While I have experienced some age discrimination, it's
just as often been reverse.

You've persuaded other people that at least some of the elderly should
be discriminated against?

I'd prefer that you hadn't gone to the trouble, particularly in your
posts here.

B

#### Bill Sloman

Jan 1, 1970
0
BillSlomanwrote:

You'd make a perfect politician, never getting the facts right

Find the fact I've got wrong.
and always twisting the truth, if you really knew what the truth was.

I've probably got a better idea of what is true and what isn't than
you and John Larkin put together (and that's a depressing image).

K

#### [email protected]

Jan 1, 1970
0
You've persuaded other people that at least some of the elderly should
be discriminated against?

A sane person couldn't come to that conclusion with a dart.
I'd prefer that you hadn't gone to the trouble, particularly in your
posts here.

Slowman, NO ONE cares what you'd prefer. Really!

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