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Re: Big Daddy Vacuum Tube




    Look inside the tube if it's made of glass because this pinout doesn't
sound right.  It should be Filament 2 wires, Cathode 1 wire, Grid 1, 1 or 2,
Accellerator Grid 2, 1 or 2 wires.  On a 5 pin one of the pins has no
connection on a Triode.  Typically pins 4, and 5 are the filament.  1 is the
Cathode, 2 is the grid, and 3 is the anode, and this is a standard.  If they
are lettered G is the Grid, P is anode, and K is the cathode.  Look for the
part number, it should be around the base next to the pins.  Unless, you
tell me, I doubt much about a psychic part number.  There are way more than
just one kind of 5 pin triode out there.  For one, some are UHF, others are
RF, and some are condidered audio, and that has to do with grid capacitance.
As a whole, the most comparable solid state component minus the heating
element as far as impedance characteristics are concerned is a MOSFET.  As
far as gain characteristics, they are comparable to a voltage controlled
transistor, and the output gain ratio is linear up to a point that either
the wire that the cathode is made from gets so hot that its resistance goes
up, or the anode, which is usually not the anode but, the cathode by design.
The cathode is a piece of wire that is wrapped around the heating element,
if it's a glass tube, you can see which pin it's connected to.  The filiment
is simply a loop of wire like you would find in a lightbulb, but it
typically stands on end, and is held vertically, not horizontally.  The
cathode should read infinite to every pin, the grid infinite to every pin,
and the anode infinite to every pin.  Only the filimant has a second pin
that when cold will measure any low value of resistance.


    So, three pins should read open in respect to a VOM, or DMM measurement
when tested against every pin except the filimant.  Until, you heat up the
filiment this will not change.  Then between the grid, and the anode will be
the first place you can read a resistance.  Most of the current handling
capabilities of a vacuum are totally dependant on wire diameters.  So
actually if you have an eye for when diameter of wire will heat up, then you
know how much power it can handle if its glass.  If you use a split bench
power supply, then you will need to do a linear test,of the tubes gain, and
plot a graph.  When the gain begins to curve down as you turn up the grid
voltage a half volt at a time, when the cathode wire begins to heat up, and
the gain ratio starts dropping then the wire that the cathode is made of is
actually getting hot, and the maximum current it can handle is the linear
part of the graph, or the straight part of a line plotted on a graph for the
grid voltage, and not where the gain begins to drop off because that is
where the wire is starting to get hot enough to melt...  The grid is for the
most part open, and the anode, or plate is typically a metal plate, and not
a wire cage.  The cathode, and the grid are wire cages but, the grid is so
close to open, and only has a biasing voltage that is required to control
current flow, that it just never really recieves enough power in watts to
heat up.


    James.


This pinout doesn't look right at all, because the grid is seperate of the
cathode, and the anode, or plate is seperate of those, and only the filiment
is reversable.  The filiment can use direct AC, and that is why they have a
cathode.  The cathode replaces a filiment that has, or does the work of the
cathode.  Biased properly there are two voltages on a single filiment if
there is no cathode.  On is a DC heating voltage, and the other is Cathode
to Plate, or anode voltage.  The heat itself mobilizes the electrons, and
reduces the resistance of space, or the vacuum.  In vacuum tube terms the
heat boils off the electrons from the cathode in standard terms.  Most of
the schematics have current flow from the postive pole to the negative pole
in vacuum tube type diagrams of the old era of old fashioned electronics,
and ideas, an electron is a postive charge.  Later, in history, it was
proven that electrons were actually negatively charged particals, and that
is the difference between conventional current flow, and actual.
Semi-conductor theory was written with actual in mind, and not conventional.
Now, most of that is forgotten.  If you have a glass triode, the pinout is
going to be the same.  On mine there is a pin that has a space on either
side, and has the greatest distance between all of the other pins, and it is
the control grid, which should be biased negative in respect to the cathode.
Looking down on the pins, with the tube upsidedown the cathode is the first
pin on the right.  The next two pin working clockwise are the filiment, and
the last pin is the anode, or the plate.  The pins on my tube are not
numbered or lettered, and marked by the off center pin which is unequally
spaced to fit into a socket only one way...

>1-5..................fil

>2-4..................grid 2
>3......................grid 1
>
>uses Eimac HR-8 plate connector and SK-500 forced-air socket
>
>typical operation for one tube up to 110 mHz:
>


The plate has it's own pin, and pin number or letter.

>plate V............................5000 V
>screen V........................  500 V
>grid V.............................. -200 V
>plate current..................  700 mA
>screen current..............   147 ma
>grid current....................     45 ma
>plate diss.......................1000 W
>screen diss...................     73 W
>grid diss.........................       7 W
>
>A 1991 price from Richardson Electronics is $895.
>I would hold it with both hands.    :-))
>
>Cheers,
>Ralph Zekelman
>