> My engineering background and professional experience are in digital
> design and software engineering, not RF design. Disentangling their
> technical arguments would take more effort than I care to spend.
The arguments aren't all that tangled.
My conclusions are based on my experience and
measurements...and knowing what fails in the field as a percentage
of what goes out based on feedback over the past twenty years
My conclusions are all rooted in provable documented science, and
not based on any personal issue.
> my amplifiers (AL1200, SB220, SB201) has ever flash-banged, so I'd rather
> spend what free time I have chasing DX or writing station automation
> software. But a competent RF engineer should have little difficulty,
> particularly with the tools available today:
That's true.
> 1. select an appropriate circuit modeling program
Why model when you can measure?
> 2. construct a model of the tube in question, parametizing manufacturing
> variances
Why model when you can measure?
> 3. construct a model of an amplifier circuit in question, parametizing
> component tolerances
Why model when you can measure?
> 4. discover combinations of parameters, if any, under which VHF
> oscillation occurs
That can easily be done, through measurements and an
understanding of basic RF systems.
> 5. construct models of alternative VHF oscillation-suppressing circuits,
> and evaluate their effectiveness and side-effects
N7WS ran calculations and reached an independent conclusion.
After he reached the conclusion and published an e-mail asking
him to change his position by one of the parties in the debate, he
was personally attacked.
Anyone doubting this can ask N7WS directly.
> does not oscillate. Evaluating the effectiveness of suppressor circuits is
> a similarly-objective excersize.
It isn't that complicated. Models are useful for a system that is too
complicated to be measured and analyzed as a real system.
Models are shortcuts.
> I suspect that neither combatant is truly interested in resolving the
> underlying technical issue; doing so would terminate their righteous
> justification for continuously elbowing and needling each other. It won't
> stop until Rich publicly admits that he profits by selling unnecessary, if
> not harmful, add-ons to ignorant amplifier owners,
Profits come from more than cash. Some profits are in the form of
notoriety. The nichrome isn't harmful, it is the theories that ruin the
ability of people to understand the complex workings of a PA that
are harmful.
There are harmful mods he suggests, such as removing grid
protection circuits. He suggests using resistors for fuses to protect
grids. He also suggests increasing the size of equalizing resistors
in amplifiers, when those resistors were selected to have the
maximum possible resistance to do an effective job. Those
changes are harmful.
or until Tom admits
> that he intentionally designed self-destructive amplifier circuits on
> behalf of his quality-insensitive employers and hid this malfeasance by
> using the influence of those employers to suppress Rich's whistle-blowing
> ARRL handbook article. We'll be reverse-engineering humans from their
> genomes before either of those things happens.
I suppose that could be correct. This is how it would have to have
worked:
I would have had to have been ordered to design amplifiers to fail so
the manufacturer's could spend extra money on warranty service.
Dick Erhorn would have to have decided to design amplifiers that
ate 8877's in the 80's, just like I was order to do, just so the
companies would get returned products and service headaches,
and lose sales.
Eimac had to be part of this conspiracy, since they covered up the
manufacturer's intentional flaws by issuing hundreds of thousands
of dollars of credits for defective tubes that really weren't defective.
Eimac had so much fun doing this, they dragged it out for years
spending millions of dollars just so we could all make Rich "look
bad"!
or...... the case could be this:
Eimac had repeated problems with materials that they had a hard
time curing. At first they though it was air pollution in the plant at
Salt Lake City, then they thought it was a heat dam problem
causing the grid to become misaligned after many thermal cycles.
What did I do? I built a tester that cycled the filaments of 8877's in
batches of about 10 tubes. The tester had a SCR latch and a light
bulb that detected momentary grid shorts as the filament cycled.
About 90% of new 8877's failed after two days of filament cycling,
but I suppose it could have been a parasitic. After all, the grid had
12 volts negative voltage on it. I suppose it didn't matter that the
anode was at zero volts, it had to have been a parasitic!!
So here's the choice.
1.) The entire manufacturing world has a conspiracy to discredit
Rich, no matter what it costs.
2.) Rich has an agenda to discredit the entire manufacturing world.
73, Tom W8JI
w8ji@contesting.com
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|