The Holly chieftain., 1924-03-27
BY ARTHUR u. EDDY

If you engage yourself In CONVERSE
tiOn with the average amateur con-
corning his radio receiving set it will
not he long before he will bring up the
question Of maximum range of re-
ception, which would be the para
mount topic of discussion. 1t is thus
that we have grown into the habit of
judging the relative merit of re-
ceiving set by the range that 1t can
cover, and although this method of
judgment is not altogether fair and
just to all types of outfits. vet for the
average beginner or radio expert
menter 1t does form good basis of
quality. The standard range of the
regenerative receiver is quite an un-
known quantity, for amateurs and ex-
perts having, almost identical circuits
and antenna conditions give very CON
fiicting claims. But still, If we are
to base most of our claims on dis
tance, on everyday possibility of re-
ceiving certain broadcasting sta
ton, 1t would be very near the truth
If we should limit the regenerative re-
ceiver to approximately a range of 100
miles when using rather sensitive
detector tube.
Most amateurs realizing this have
endeavored to augment this distance
by the use of a combination of audio
and radio frequency amplitiers-in
other words the reflex circuit. With
the former type success was assured
where the sensitivity of the detector
wassereat enough to detect the signal,
soft tube-that is. n tube that Kisses
at critical point-the number of
audio frequency stages is somewhat
limited. To adapt radio frequency
amplification to a regenerntive re-
ceiver after once 1t has been con-
structed is by no means an easy task.
Yet some amateurs have not only ac-
complished this. but have obtained re-
markable results.
For the vast majority Of beginners
the true answer. to the problem of
building long distance receiver is not
the regenerative receiver with audio
and radio frequency ampliflers nor the
ceiver which is combination of audio
and radio frequency units in the cir
cult. This type of circuit will not only
have the desired range, but will be SO
compact that 1t will he readily port
able and so simple and efficient In Its
operation that the beginner can oper-
ate it as satisfactorily as the expert.
t. hut J, ali,
described in peculiar ways with
peculiar names. This is at once an
evidence Of evasion. for the simple
reason that at the end Of the story
the whole thing will he found to be
the original reflex circuit.
A reflex set can be made from
single tube and crystal detector. the
single tube serving for both audiO
and radio frequency amplification. If
1t Is desired to operate loud speaker
we must resort to a two or three tube
reflex circuit. Here the first two tubes
serve as radio amplifiers and audio am
plifiers, with the crystal rs detector.
The schematic diagram shows num-
ber Of two-tube reflex circuits.
If amplitier tubes are used In all
stages the 3 battery should be regu-
lated so that the proper battery
voltage is applied to their respective
plates. This is accomplished by ex-
pertinent. Usually between forty-five
md seventy volts are found best for
the plate voltage.
In the actual application Of the cir
cults there are several difficulties to
be overcome. The tubes, for instance,
must be coupled for both radio and au-
dio frequency amplitication. but placing
the audio frequency amplifier in cir
cult where radio frequency currents are
flowing, the windIngs of the secondary
act MS a choke coil and prevent the
radio frequency currents from pass
ing. To overcome this condenser is
shunted around the windlngs so the