The Challis messenger. (Challis, Idaho) 1912-current, 1925-04-22
BY r. M. RUSSELL


When a radio receiver Is to be useC
In the home where 1t is operated by
all members Of the family, both young
and old, 1t should possess certain fea
lures such as simplicity In operation
perfectly clear and howlless reception
good receiving range, loud-speaking
output, and logged dial that elimi-
mates the guess-work of tuning and
makes 1t possible for one who never
saw or heard the set before to get any
station desired with 1t, by referring to
the dial reading.
Inc little two-tube set Illustrated
Will do all the above things In an
efficient manner. This Is due to the
circuit used which Is simple to build
and simple to operate, but incorpor-
ates several unique features that give
1t qualities seldom found in even
two-control outfit. 1t has automatic
or spontaneous regeneration and an
aperiodic primary. The regeneration
Increases volume and receiving range
and the aperiodlc primary makes the
set selective and allows logging of the
single tuning control.
Never under any circumstances will
the set howl If the parts are arranged
correctly and the values are as speci-
ned. The secret of this Is In the
method Of obtaining regeneration and
the fixed condenser across the audio-
frequency transformer.
The readings Of the variable conden-
ser dial, which Is the only control. are
permanent. If a station Is once re- |
celved at say 20 degrees 1t will al /
ways be received again at that point.
Ihis applies to distant as well as local |
stations.
Parts Used.
The above results are obtained by
virtue OF special tuning unit In the
form OF a coupler. 1t consists Of two
'piderweb coils, one Of five turns and
me OF 40 turns. The five-turn coil ia
he aperiodic primary and the other Is
he combined plate and secondary coil.
I Is not difficult to build the unit
spiderweb coils of the proper size
an be purchased at a radio store or
hey can be home wound on a card
oard or wood frame This should
ave IL. ID or Is spokes. The wind.
,g method is two over and two nm
er, In other words. the wire Is first
'oupd under two spokes and then
YER two spokes. etc. About one 9
alf pound OF No. % double silk or
'tton-covered wire Is necessary for .
lis. Do not use enamel
To Construct. :
Mount the coils when finished as :,
own In the illustration. The con- 4
Ing between them may vary any, n
here from one-quarter to one-half q
en- according to the selectivity de- II
red. Lay out the sockets, trans ii
rmer and the rest of the apparatus
shown and wire with the direct
method. that Is, make all s
INJECTIONS direct from terminal TO
minal in the shortest possible man.
T. This may not look pretty" but
VIII reduce the resistance and inter of
cult Interference, and make the set Sc
re efficient After all It's results di
want. not beauty. te
he parts necessary to construct the ne
aside from the special coupler are tn
follows DIR
me OOO5 variable condenser. ms
me geared vernier dial for con- by
ser. or,
ne low ratir audio frequency trans the
ner tur
me .OO1 fixed mica condenser. ser
wo 199-type sockets. as
ne 25-ohm rheostat. aer
ne to 5-megohm grid leak and I
70 liked condenser. tun
ne by ii panel. der
ne single-clrcuit Jack. mi,
'seboard. binding posts, screws. rec,
J. etc. 81,
ne ratio Of the transformer should tica
nywhere from three to six to one. eff,
not higher. The set will distort onl,
lis Is violated. The variable con- not
er also must be of the proper gro,
city. Any smaller or larger will inc
4 not allow the reception OF cor. bo,.