Re: Getting indication of rf


John E. Beech
 

Hi Andy,
My comment was a bit tongue-in-cheek, but it has taken over seventy years of semiconductor development and expensive equipment to get to where we are now whereas a moving coil meter can be made or repaired by a competent watch/instrument maker with hand tools and a simple lathe. ( trouble is finding one these days!) You can also see when a MCM isn't working. I've managed to destroy no end of semiconductors in my time & a lot of them didn't look as though they were damaged. But as you say semis are so cheap to buy now you can incorporate as may as you like for protection. Incidentally the protection diode in my L 23 TVTR did its job of reverse voltage protection ie blew the fuse but failed itself in doing so as it went short circuit. So much for 100's amps peak non-repetitive current!

de John G8SEQ

-------Original Message-------
From: Paul Randall G3NJV <paulfrandall@hotmail.com>
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] Getting indication of rf
Sent: Jun 04 '20 23:30

"What's this got to do with"
Maybe nothing, but .... keep the lines open so anyone can post without
fear.

-------------------------

FROM: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of
Andy G4JNT <andy.g4jnt@gmail.com>
SENT: 04 June 2020 22:47
TO: UK Microwaves groups.io <UKMicrowaves@groups.io>
SUBJECT: Re: [UKMicrowaves] Getting indication of rf

But one purification cycle gives the raw materials for tens of
thousands of chips. May even be 100s of k devices - does anyone have
figures?
So it's hardly a 'lot' of energy.

When the design already exists and the IP is made available, they're
pretty easy to get made too. Look at the story of the reincarnation of
the old SL6270 VOGAD chip.

And this myth about static sensitivity.
OK, back in the dark ages of the 1970s, perhaps into the 1980s even,
devices were susceptible and manufacturers weren't as careful as they
should have been, but since then they've become orders of magnitude
better. It's not just hearsay, I know someone who has worked in the
highly specialised field of semiconductor static testing since that
era and he has benn very closely involved with and explained the
progress made over the years with testing techniques and built in
protection.. (He may even be a member of this Group now. Paul, are you
there ....?)

It's really about time some of these myths of decades ago were
forgotten and people looked at the real state of electronics today.
Trouble is, there are so few young electronics graduates in our Am.
Rad. ranks now to tell the story ...

BTW, I connected a chunky 5V power supply the wrong way round to a PIC
processor once. It current limited at 3A and current must have passed
for perhaps half a second, most of i- going through the device WHICH
SURVIVED to carry on working. What happened is that every I/O line and
there were over 20 of them had reverse biassed diodes (for transient
and over voltage protection) to ground and the supply rail. With the
supply reversed all these diodes forward conducted, in parallel, and
were able to able to sink that 3A for the duration. But longer and
bond wires might have popped. But the chip subsequently worked.

What's this got to do with the subject line of RF Indication - I
dunno, but it's a good waffle anyway. Back to the G+T

Andy
www.g4jnt.com

On Thu, 4 Jun 2020 at 22:11, John E. Beech <john@g8seq.com> wrote:

> Problem is that most silicon is locked up as silicon dioxide.
> Extracting it and purifying so that it can be made precisely impure
> enough to make it semi-conduct takes an enormous amount of energy
> and effort and exactly how robust are they? They don't like it up
> 'em Mr Mainwaring! Voltage spikes that is.
>
> de John G8SEQ
>
>> -------Original Message-------
>> From: Andy G4JNT <andy.g4jnt@gmail.com>
>> To: UK Microwaves groups.io <UKMicrowaves@groups.io>
>> Subject: Re: [UKMicrowaves] Getting indication of rf
>> Sent: Jun 04 '20 14:42
>>
>> Think of it in terms of cost and effort instead.
>>
>> Transistors and anything inside an IC is only silicon - one of
> the
>> most abundant elements on Earth. ICs churned out by the
> quintillion
>> each day
>> Compare that with the cost, setting up, delicate mechanism, easy
>> damage of an analogue meter
>> Who'd ever choose the latter, again

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