[Boatanchors] 813s and the entire power morass

[rbethman]

All,

I don't claim to be the end of all knowledge by any means.

I commented that vertically mounted 572Bs and 813s is "more 
intelligent".  This doesn't mean that anyone whom does otherwise isn't 
intelligent.  It is my way of saying "common sense" rules. Mount 
something that requires given tolerances, and it reminds me of so many 
things we have seen in life where the "Engineer" that designed it should 
have had to work on the things he designs *before* he designs pieces of 
equipment.

[ Remember the Ford Pinto series!  Ever try to change out the clutch? ]

What I base it on is over 30 years as an Amateur Radio Operator, having 
used Yaesu Amplifiers with the tubes horizontally mounted, even a 
Heathkit SB-201.  I also have built GG-813 amplifiers.

None of us can predict what any particular run of tubes will be like, 
nor can we predict how close the tolerances were at the time of 
manufacture.  I do my best not to tempt fate!  Murphy's Law seems to 
apply more often than not.

I look at simple common sense and that hasn't done too bad for me.  Any 
manufacturer can indeed say that you "can" mount the above tubes in the 
horizontal position, and tell you which pins to place in which position 
when you do so.  That doesn't mean you "have" to.  I prefer to eliminate 
one additional

I found the old Yaesu FL-2100B to be a bit flaky early on.  Just my 
experience.

The Heathkit SB-201 was definitely better made than the Yaesu.

Between those two amplifiers, I home-brewed a pair of 813s in Grounded 
Grid.  I mounted the bases and the sockets below the chassis on 
porcelain stand-offs to allow for convection air flow. It also helps to 
keep the greater RF field away from the filament circuit.  Perhaps I was 
just being overly cautious, perhaps not.

I also used a microwave oven transformer and a microwave squirrel cage 
blower for this project.

I went through the old strings of diodes with capacitors and resistors 
for equalization.  Ended up with around 2200VDC on the plates.  Even the 
tables in the West Coast Handbooks indicated the voltage range was in 
the ballpark.

I never heard about PEP until the FCC changed the rules and regulations.

I DO know that the basis used by Terman indeed is laid out with a sine 
wave, (symmetrical wave), modulating the RF.  Why does this method get 
used?  It makes numbers work easier.  It also is easier to actually see.

I can't afford to go out and buy a "storage" type oscilloscope.  I have 
a plain Jane Hitachi V-212 that does what I need.

The GG-813s in that old amp never got overheated, never shorted out, and 
stayed a workhorse up until an overseas duty assignment. They were built 
in an SX-28 cabinet.  No, I didn't trash one.  I obtained one that was 
already toasted!

Anyway, the moving folks managed to shorten that cabinet by over 2"!  
How in the world they did that I will never know.  However, that was the 
only reason I bought the Heathkit SB-210.

That kit I could get overseas.  I couldn't scrounge all the parts to 
build another GG-813 amp over there.

The gist of all of this is simple.  Paul has one nice looking design.  
It reminds me of a Heathkit Cabinet, with a bunch less room inside.  My 
hat is off to him!  I never had any intent to denigrate his design or 
abilities.  If it has been taken that way, I definitely apologize!  Such 
was never the intent of this long thread.

He and others make their projects look absolutely wonderful!  I have 
never put the effort and time into my projects to make them great 
looking.  I go for the sturdy, solid, and lasts for a long time projects.

I also use a old Military Dummy Load/wattmeter.  It is the ME-165.  Good 
old fashioned non-inductive resistors.  Buy them now and you pay dearly.

This thread has altered in so many ways and manners that I don't think 
we can tell what started where.

Paul, you had, if I still recall correctly, a short to grid in a GE 
manufactured 813.  All of us know that GE, Westinghouse, and any other 
U.S. manufactured tube has been around for quite awhile.  It has been 
quite awhile since any vacuum tubes have been made here.  The boxes are 
slowly getting empty for many of us when it comes to power tubes.

I've still got one of those Westinghouse 813s in one of my boxes of tubes.

Regardless, this has gone from a short issue and realm to wider areas 
that don't belong with Paul's part failure.  Paul - I hope it didn't 
ruin anything other than that one tube!  Work of that quality doesn't 
really deserve to get burned up!

I'll say that it has remained civil.  That is great!  Too often a list 
will get off on the wrong foot about this stage.

Let us all get back to the normally scheduled "programming".

If anyone has a "real" useful idea or suggestion, go for it.

I'm going to go back to my interests and latest projects.  I've gotten 
myself into giving SDR a shot.  I have the Raspberry PI, a DVT Dongle, 
and a "RANverter".

Some assembly required!  Fortunately not much at all in the SMT arena.  
My eyes can only take so much before I get a headache!

Regards, Bob - N0DGN