The Challis messenger. (Challis, Idaho) 1912-current, 1925-09-02
BY HERBERT E. HAYDEN, In New
York Herald Tribune


York HeraId-Tribune.
A circuit Of general usefulness
the one shown In the diagram, for
Will operate fairly well even undo
most unfavorabIe conditions and
safe In the hands OF the novice. Lik
the neutrodyne, 1t has three controls
and the set may be logged--thnt Il
once the settings for a given static
are determined they will always be tn
same unless the aerial Is changed
One Of the chief advantages Of tn
~neutrodyne Is 1t may be readily adapt
ed for family use. Anyone who "knev
the combination" could hear the sta
lions. Normally, this Is not true o.
regenerative sets. There Is an ele
ment Of great uncertainty of setting ir
the regeneration control dial. To over
come this, yet retain the advantages
Of regeneration, this circuit was de.
vised. 1t Is a modification of Wea-
gant's x circuit the so-called divided
circuit, and embodies stage of tuned
radio-frequency application, tuned
detector input, capacitatively coupled
regeneration In the detector stage and
two steps Of transformer coupled
audlo.
Preventing Radiation.
This circuit has as small tendency
to radiate as any of the regeneratlve
hook-ups, and radiation may be effec-
lively prevented by connecting mid
get condenser between the grid and
plate posts of the r. #. tube, the one
at extreme left. The setting of this
condenser Is varied until the signal is
barely audible, or preferably inaudIble
when the r. F. tube is barely lit. Then
the setting of this small condenser,
not shown, Is left In that position.
The hook-up In performance Is as
good at "dIstancegetting." The pres
ence of regeneration much more than
makes up for the absence of an extra |
tube. This is true absolutely If |
good outdoor aerial IS used, but If an
Indoor antenna Is employed, or even
a plug for the light socket, the circuit
still Will perform exceedingly well,
the distance being cut down somewhat,
Of sound being all-sufficient for speak
er operation. The ground connection
may be made to the radiator. Thus
The circuit, while primarily working
better under the more generally avail
able advantages. will do its duty with
idelity under makeshift conditions,
'uch as used in hotel rooms, on coun-
nv trips, ETC. The set was operated
III last winter IN a local hotel and
turing the summer weeks to date, the
ground connection being made to
'adlator and plug used In the light
ng main for an aerial Selectivity
vas splendid. even, WIN, less than
lalf a mile away, being tuned out
within five degrees of the dial and
asily separable from WIZ, an eighth
t mile farther away. both powerful
tatious. Very few stations outside
he metropolitan area were heard, but t
he receiving conditions, one must ad-
nit. are about as bad as In any part I
the United States
condensers Used.
To facilitate tuning on the low
'aves 1t is well to use condensers that
re modified go as to cause the dial II
,adings to be wider apart for given :,
ations on higher frequencies. These :,
ould be what are termed straight :
ne wave length. straIght-line fire. "
iency or like condensers. The usual -
'ndenser varies as to capacity, which q
nds to crowd the stations close to- >,
'ther In dial position on the lower !,
visions. due to the changes In ca a,
lcity at those points representing so ,s
uch greater frequency difference. :,
ne idea may be popularity expressed a,
saying that an ounce OF capacity :,
the lower end makes ten times as =,
eat difference In frequency as a =,
und of capacity at the upper end ~ ~
the dial. ~
The condenser used In the set was :.
e Remler Twin Rotor, which. when -
operly connected, eliminates BODY :.
pacity effects In tuning. The rotor o.
the condenser tuning the r. F. -
age should go to minus A, the stator -,
the detector input tuning condenser ~,
ould go to grid condenser, and the o.,
'or OF the feedback condenser should -,
TO plus A. eu'
CONSTITUTIONAL Data on Coils. tbe
n choosing the coils for the set one GOO
y be guided by his own particular VIII
ferNnce in design. or may follow VIII
directions for making the diamond Gle,
ave cola shown. These are wound cal,
forms having an odd-numbered aud
up OF removable radiating arms or the
kes, 3-16-fnch dowel sticks, on a sert
ular bub, Inches In diameter. viii
1g No. % double silk-covered wire, tap.
q ten turns halt, then pick I'D T
We feet ofsthe same kind of wire. best
wind this along with the remain the
OF the other or secondary wind ! celle