[Amps] EIMAC (8877 TYPE)

[Tom W8JI]

> On all the reflectors that I subscribe to, there is an
> abundance of misinformation.  We all come biased.

Sometimes people get carried away also, and read things into 
things that are not said.

> It is
> obviously important to be able to separate the theory, 
> myths
> or crap from the jewels of information.  I continually
> support my philosophy by the experience factor. 
> 'Experience
> trumps theory every time.'

Not actually.

What does happen is sometimes people misunderstand or misuse 
information. That's quite often where the problem is.

For example? My comment that I wouldn't gut and modify an 
SB220, or in particular an SB200, for six meters is based on 
the fact you have to be careful running a 3-500Z on 50MHz. 
What we get away at on HF just doesn't fly up there unless 
you have a lot of dumb luck, and it basically will ruin the 
amp for any other use.

On the other hand with a reasonable layout in an HF amp like 
the AL800 with a 3CX800A7 we can move the ten meter tap, 
redo the input for ten to six, and have a bandswitched amp 
that will work 160-15 and 6 meters and run 900 watts or more 
if you don't mind hammering the tube a little.

This wasn't a reflection on anyone's ability, it's just a 
simple fact. If I wanted to convert or build a six meter 
amp, I'd use a tube that is easy to manage on six meters.
I've made 4-  6MJ6 sweep tubes amplify on six meters with 
400 watts out... and I could easily repeat that trick over 
and over...but I'd never crow about how great an amp that 
makes or advise people to try that at home. I'd never 
pretend it was "more stable on six than on twenty meters".

People are often like toggle switches. They are either on or 
off, and assume because one thing is not the best idea or 
one claim is wrong everything is wrong. Case in point, Lou's 
3CPX1500 tubes. People had them hitting the case, failing 
from low heater voltage, and all sorts of things. The fact 
is that tube is actually a good direct plug in for an 
8877...and if the top hits the case of the amplifier whoever 
built the sheet metal was an absolute moron to have it so 
close in the first place.

This reflector, like antenna reflectors, has a tendency to 
go off on long meaningless tangents and the entire initial 
point is lost in all the opinions. Because something doesn't 
work like people think or as well as people might imagine 
certainly doesn't mean it won't work at all.

73 Tom