The Washington times., 1923-03-04

/ much how they are obtained, but q
simple method is, Of course, better
than a complicated one.
My circuit maintains these oscil-
atoms, but doesn't use any coils Cfor
inductancel except those ordinarily
used for tuning and securing regen-
Grafton. The inductance is provided
by the telephone receivers, which
with the coils for tuning and ordinary
regeneration give all the amplifica.
ton that can be obtained from one
tube.
COndensers Used.
"The circuit depends for its action
upon the condensers, tuning coils
and the 'impedance' that the wind
ings Of the telephone receivers con-
tain. 1t is possible, as many radio
fans know, to set up a super-regen-
erative circuit If the proper capacity
value is used in the filament end Of
the inductance, but this proves gen.
orally unsatisfactory.
"But by so arranging the correct
condenser values in their proper
places one can get the circuit have
obtained. The diagram practically
suffices to tell the story.
"The three fixed condensers in a
Il
the three are not critical. In other
words, it is not necessary to draw
their values down to the point of
fine measurement. / have found in
some cases that I could use .OO6 mid.
capacity. In the diagram will be
| seen two leaks The grid leak GRID
is critical and Of the relatively high
value of perhaps to i y megohms9
This value, however, will vary &C.
cording to various other constants
of the circuit. The. grid condenser
value is .O0025 mid.
Leak Resistance Controls.
Variation of the low frequency
whistle noticeable in super-regener-
ative sets can be made by changing
the resistance Of the leak in the new
circuit. If the tone proves TOD low or
prominent, increase the resistance
value; If too high, decrease the re-
sistance value.
Across the condenser C5 is the
second leak. which is not critical,
and the value is very low. A solid
conductor can replace this in ampli-
fication with but small loss, omit
ting condenser C5 at the same time.
Power tubes give shade better
amplification than radiotrons wv
201. There is rather wide range
of plate voltage over which l have
found the circuits will operate. The
set has operated on from Is to $50
volts potential with a UV-2O1 tube.
Amplification directly increased with
increasing voltage, being fair at so
volts. Approximately 10 volts on
the plate seems to be giving about
the best results.
Uses and Applications.
You will not get as much ampli.
fication as with the Armstrong su.
per-regenerative two-tube circuit, but
IL In much greater than can be OBJ.
tanned with ordinary straight regen-
eratiVe circuits.
Applications are many and va.
ried, from using without a ground
on an aerial, without an aerial on a
ground, on closed loop aerial on
one side of a loop, or used with moth
ing but the wires connecting the ap-
paratus for an antenna-all depends
upon the distance of the station de-
sired for reception.
Local stations may be tuned u.s.
ing nothing but the set itself, al.
though perhaps four or five feet of
Best reception, I have found, is, as
with the Armstrong two-tube set,
obtained by use of the regular aerial
outdoors, but with no ground. But
whatever method is used, it should
be connected with the grid side of
the inductance, whether loop, an.
tenna or ground method.
Tuning Inductance Values.
ANY type of tuning can be used,
| providing that it conforms to the
wave length desired for reception.
Frequently close coupling is neces-
sary. If the condensers and tuning
inductance have sufficient range to
compensate for the difference in in.
ductance values and capacity of the
different methods of energy recep.
ton, aerial, loop or ground, the grid
leak can easily be rearranged until
the proper value is found. Then the
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