on 5/11/01 10:21 PM, Wt8r@aol.com at Wt8r@aol.com wrote:
> Now that that is cleared up, Jon, please explain "side affects".....I don't
> understand them.
One "side" affect is from laughing so hard at your drivel that my stomach
aches!
I think the original question to explain "side" effects (and it should be
effects not affects) revolved around my analogy of going to see a doctor and
getting a wrong prescription for something. Here is the original quote:
> However, we still don't know enough about the original problem just to start
> throwing in a lot of cures w/o understanding the mechanisms behind it. It's
> like going to the doctor with a stomach ache and him giving you pain
> relievers, anti-ulcer medication, etc., when all you needed was a good
> antacid. Sure you might get better, but you don't know why and side affects
> from the treatment may eventually cause other problems.
If you go to the doctor complaining of an aching stomach, and he gives you a
medicine than you need when all you need is an antacid, you may have other
problems. You may have an allergic reaction. You may get more sick. All
sorts of things may or may not happen.
The same is true for just throwing "cures" at a problem in an amplifier or
any kind of engineering project w/o understand the "why" behind it. One can
just get lucky, with various things, but the problem may come back.
In the original design of my amp (as it came from the estate sale), I had
more of Rich's nichrome in that piece of crap than you could shake a stick
at (have pictures to prove it). Amp kept oscillating. Felt and was
convinced in those days that Rich was right about nichrome. Kept adding
more and more. Had the biggest oscillation with my amp with all the
nichrome. Blew up a couple watt <1 Ohm resistor rich had recommended going
from the plate choke to the anode line. Called Rich on the phone and asked
him about it. He said, "I have no idea. Just short that resistor out and
don't worry about it."
That was my first clue that I was just throwing sh*t on the wall hoping some
would stick. Here was this person who supposedly had all the answers on
parasitics and all these solutions he came up with. Then he tells me just
to bypass one of his solutions and not use it (This is not besmirching Rich.
It was what happened. Many other Rich ideas wound up in my amp.).
Something told me that I had to sit back and take a better look at what was
going on and why.
The "side effect" of just randomly adding nichrome was more instability.
So I completely gutted the RF section of the amp and rebuilt it with a new
layout, new components and so forth. I began to take a systematic look at
things to determine the solution to my problem. Even at this time, I still
felt nichrome suppressors would be a good idea. So I got the amp stable and
tested out the suppressors. The kept burning up. Not due to instability,
but to high circulating currents on 10 meters that flowed through the tube
(Oh yeah, I remember you saying that circulating currents don't flow the
tube. I'll have to make a note of that and try to figure out why they don't
when experience proves otherwise.).
Removed the nichrome. Removed the resistor from the parasitic suppressor as
well. It all worked due to a good layout and some other designs in the tank
circuit I won't go into here that have already been covered. Three years
later and never a hint of oscillation.
The "side effect" of having nicrhome in a place where it wasn't needed was
burnt up resistors and excess heat. Even if the resistors hadn't have burnt
up due to circulating currents, the heat generated by the nichrome was
incredible. It glowed the the element in a toaster oven on 10m.
Systematic approaches to any problem are the best solution rather than hit
or miss band-aid cures.
That's all.
Now, Dave, do I need to pull Webster's dictionary to look up the term for
you?
Ad Rich would say,
cheers!
-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)
Member: ARRL, AMSAT, DXCC, NRA
http://www.qsl.net/ke9na
"A life lived in fear is a life half lived."
--
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