Emmons County record. [volume] (Williamsport, D.T. [i.e. N.D.]) 1884-current, 1922-07-06

Se.O >.>9NS~'O
applied to the grid in order to reduce
the plate current to zero. The value
Of F, which is the positive grid poten-
ttai that will cause the maximum or
saturation current to flow in the plate
circuit, is also determined by the rela.
tive position of the grid with respect
10 the filament and plate. If the grid
is of very fine mesh, the value Of E,
rs small because the electrons In pass
ing through the small mesh Of the
grid on their Journey from the fla
ment to the plate will negatively
charge the grid and will be repealed.
Similarly a small positive charge ap-
piled ito "a fine mesh will tend TO &C.
celebrate the velocity Of the electrons.
In case Of very coarse mesh grid,
the electrons can pass through the ap-
tertures in the grid without coming in
80 close to the charge ON it and q
relatively high potential will be re-
4utred on the grid to control the ,elec-
'tF0n stream, or in other words, the
current flowing in. the plate circuit.
Referring to Fig. VIII, O-G, IL the
cnrrent that will flow in the plate cir
cult when there Is no potential .ap-
nlted Ito the grid. Suppose positive
potential as OF Is applied to the grid,
The ,correspo nding plate circuit current
will he I'D or BID, more than 1t was
when the grid had no potential ap-
piled to it.
A negative potential Of OH q nsw
applied to the grid where OH Is equal
in value to OIL, hut opposite in sign.
The application Of the negative DO
tenttal when applied to the grid will
cause the plate carrent to be reduced
to "a value nc or A-C, less than It
WAS when there was Ito potential ap-
Piled to the grid. So 1t Is seen that q
negative potential when applied to the
grid does not reduce the plate circuit
current as much as the, same positive
potential increased the plate circuit
current. This irregular conductivity Of
the tube .is made use Of when the tube
is used as a detector or rectifier of
radio kignalA
The inoapfhg radio Signal Is high
frequency alternating current. Let US
apply an alternating difference, Of po-
tential whose maximum positive val.
/ ne is equal to OF and whose maximum
negative value Is equal to Oh, to the
grid Of the three-electr0de tube
whose Characteristic curve IL the same
as that shown IN Fig. VIM. n Fig.
TX is shown the alternating difference
OF potential applied to the grid.
Through the nrst quarter Of cycle,
from zero at to 4 maximum mega
tive value at K, equal to Oh, the
platl hircuit current will vary from
sO0 value At P when no grid po-
tent applied to value at Q equal
During the next quarter Of q cycle
tAe grid potential changes from q
maximum negative value at Il to zero
ut e The corresponding values q
Splats circuit current are shown by the
sporno0 Of the plate current curve
During the next or third quarter
sof cycle the applied grid potential
increases from zero at L to maxi.
mum Dosittve value at II, equal to
S!Ql and scauses the plate circuit to In.
|! e.sease feom I-B. its value when the |
plate potential ID zero. TO I'D, IN n.
s.Eess In plate current equal to. BID.
During the remaining fourth quar-
ter ~ q cycle 20 the applied srid po- !
sstenfisl varies from 4 maximum posi-.
tive valne at n 10 zero atm. the plate
ctrcuif cuIfsht. vaItes, from value 8
% q. y 81 HI 4; 81
Assuming that tie characteristic
ientys ssAhown II zig; VIM and Fig. |
,l y. - Nth 81 potential Of % volts |
On the plate thent IL the plate current
I. 70 be reduced 10 zero by i varia.
!, don ls. q plate yoltage no poten.
~ 81 applted to the sEtd the plate
voltage must be reduced 70 zero or q |
.rsductf Of % volts must be made.