On 6/7/25 06:16, Bret Busby wrote:
On 7/6/25 17:26, gene heskett wrote:
On 6/7/25 02:52, Bret Busby wrote:
It is all relative...
Yes it is, but you would be amazed at the supposedly intelligent
people who will argue the a 5 foot long low uhf band klystron
amplifier as used until the 1985 time frame, is immune to E=MV2 math.
extremely off topic, but possibly educational:
It can be a very high gain amplifier, turning a 1 watt drive at the
top of the tube into 30kw at the bottom, nominally 5 feet away. But
the output has a horrible time vs power level distortion. We did not
then know, and most assumed a non-linearity in the amplitude domain,
but it was actually in the time domain because the electron beam was
traveling at a voltage differential of 19,700 volts, the variable
mass of the electron changed because it could be slowed at the lower
mass but speeding it up raised the mass, so the average velocity was
reduced, increasing the transit time by around 120 nanoseconds at
30kw (ntsc sync tips) vs 1kw (at ntsc white.) This put horrible
spikes on both edges of the sync.
At that time we did not know how to predistort the drive to
compensate that in the time domain but obviously we have learned how
now or we would not have our working hidef digital tv we have today.
I am glad that tech has been replaced with better stuff as the
klystron amplifier has a hell of a power bill, needing 113kw of wall
power per tube.. Do able when electricity was 2 cents a kwh, at 20
cents most early uhf stations went dark, squeezed by the power bill
into bankruptcy. That and a tired tube was about $125,000 for a fresh
one. Certified check no time payment plan.
Here's one for you, in terms of relativity...
When I was at secondary school, we had an interesting physics teacher
(he was a pom, and so we had some amusing banter), and he found an
interesting way of telling us of relativity and relativistic mechanics.
According to the Doppler theory (I believe it was - this is from some
decades ago), if you would be travelling toward a set of traffic
lights, at the speed of light, and the traffic lights were red, the
Doppler effect would cause them to appear green, and, so you could
travel through them; and, if you hit anything, it would not matter,
because, at the speed of light, you would have infinite mass, and so,
whatever you hit, would be obliterated...
:)
I still remember the teacher's name - he was an interesting teacher,
who taught using various methods, including learning things from errors.
One of the aspects of science, when it goes beyond classical science,
like going beyond classical physics, is that it can become like a
mathematics lecturer once said of pure maths (he taught pure
mathematics and differential equations) - the further a person goes
into it, the more a person can lose a grip on reality;
Define reality. . .
it is like the question of "the universe" - it is said to be
constantly expanding and contracting - if that is correct, then,
something must exist outside the border of "the universe". If that is
correct, then, how can what we regard as "the universe", be regarded
as a universe, when it is not all encompassing?
We've got people working on that. But . . .
The JWST is showing us stuff that does not fit our big bang theory's.
So is CERN. What theory will we wind up with 150 years hence? What
vaporous stuff is this force we call gravity? It refuses to fit neatly
into the theorists pronouncements.
It is like Danny DeVito's reference to "Military Intelligence".
Chuckle, that teacher was an excellent teacher. People who make you
actually think are the best. Not because they teach facts, but because
they make you think and reach your own opinion. And Danny was right.
Classic oxymoron.
I recall an instance in G.J. Colorado where I was once sent to "put out
the engineering fire" at the KREX-tv complex, and found a cable
reconnected that I had unplugged as it was a double termination with a
200' cable, creating a huge video echo. I hunted up the EE who had
plugged it back in screwing up the video at both locations. And gave him
an example of my 15 minute monologue that included some unflattering
comments about his personal "finding his roots". I thought at one point
in my tirade he was going to take a swing at me. But when I had finally
run down, he stood there for probably 20 seconds, and then said he "now
I understand the double termination effects, VSWR in general and why the
hell wasn't I teaching someplace?" Answering that was easy. I'm self
educated. and there is no way in hell that I could ever teach in an
academic facility if I only had an 8th grade education. TPTB wouldn't
tolerate it. I was invited to quit school as I was disturbing the
senior physics class by correcting the teacher's faulty knowledge about
Newton's 3rd law of motion. This was about a year after I had scored 147
on the Iowa IQ test in the 7th grade. So I did quit and went to work
fixing them newfangled things called tv's in 1948. Pure serendipity has
put me in some interesting places in the last 75 years. It's been one
hell of a ride. But at 90, the end is in sight, but I can say I'd do it
again. It was/is fun. And getting more complex by the day. Thank you Bret.
..
Bret Busby
Armadale
West Australia
(UTC+0800)
..............
.
Cheers, Gene Heskett, CET.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
