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; 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?
It is like Danny DeVito's reference to "Military Intelligence".
..
Bret Busby
Armadale
West Australia
(UTC+0800)
..............
