The Challis messenger. (Challis, Idaho) 1912-current, 1925-09-02


nections inside the set. Up to tn
3 point you will have wound ten Pill
about eleven, or about twenty-on
r turns Of the secondary, and will hay
J completed the primary, the twelve-fo'
, length. Now continue winding tt
secondary until thirty more turns al
put on, whereupon this winding, to-
Is terminated. Thus you will have fiji
ished a coil with an eleven-turn pr
mary and fifty-one-turn secondar.
One more turn or less on the Sc,
ondary Will not matter. The sec
ondary Is to be tuned by a 0O05 info
variable condenser.
That was L1L2. Now wind L3L
exactly the same way, except tina
when you reach the fortieth turn picl
up ten feet of the same kind of wir,
and wind this as II it were a specia
primary, side by side with the con
tinued secondary. then go 1t alone will
the secondary to the end. Now vol
have L3L4L5.
The aerial transformer is connected
so that the adjacent terminals Club
end OF primary and hub end Of sec
ondary) go to ground and minus A re-
spectively. The hub side, that Is, in
side terminal, of LIB goes to B plus
67a volts, and this B battery should
be separate one for best results, al
though the set will work well on a
common battery block. The minus
OF this 671A-volt block. by the way,
goes to plus A, too.
The terminal Of the secondary. LA.
that goes to the grid condenser Is the
end at the outside diameter, while the
outside terminal of L5 goes to plate.
The circuit diagram shows how the
condensers are connected to these
coils. The ticker, LIS, Is not rotable.
OF course, and that explains why 1t Is
possible to chart the regeneration con-
troll.
Both audio tubes have grids biased
~ volts negative This usually means
the three-volt post of standard G
battery will be used as the nearest
approach, If the exact Az volts aren't
accessible. There is q one-volt mega
I've bias Impaired by the grid return
o minus A (say, six volts at this
'oint), as compared with the five volts
It the other side of the rheostat. Ala
nent minus, whence all voltage reck-
ming proceeds. Indeed, the drop in
he rheostat may be little more than
volt. Hence. only three extra or ex-
ernal volts are needed.
In figuring the plate potentials. the
ommon lead. A plus and B minus,
aust be counted, too, as adding the
oitage of the A battery to that of
he b battery at the plate. The series
onnection Is obvious-minus six TO
lus six Is SIX volts, hence with 3
linus connected here you start of
18th premium of six volts. A 22h
oft tap off the B battery would real
be 28A volts. These allowances
ust be made, especially when using
lbes that are critical as to plate volt
sc, especially the C-30O and Uy-2OO,
'e most sensitive detector tubes
nown, though they do draw one
hole undisputed ampere.
AudIo Hook-Up Is Standard.
The audio lookup Is standard. ex-
'pt for the filament control lack
hose not familiar with It's operation
VI see from the diagram that adjoin-
g springs or the Jack are connected
spectively to B plus and plate. |
hen the plug is inserted it pushes |
the springy leaf already connected,
the other one Is the very stiff 7
ime. Notice that there Is a piece of
suiation between the plate spring D
q the adjoining one above 1t. This S
both the safeguard against short d
cult and the lever used to close the q
lment circuit. 1t viii be seen that "
otherwise continuous filament
nus iead-in Is interrupted by being
ssed from detector tube to the seq c.
! spring from top, in F. @. ]. The fl
itch 3 may be used for turning the OF
on and Off as unit. al
Is the three amplifier tubes-one W
ITO and two audio-are operated al
m one control, 1t should be power tn
ostat, If wire-bound, otherwise ons nj
the compression or decomposition tn
e. The ordinary run of rheostat be
hms' Will heat up under this heavy
rent. m,
douole-circuit Jack ] Is used In or
nrst audio output, as this is q In
place to listen to DIX stations IN In
ter (and in summer, when. IL and pr
re possible), and provides suffl. tire
I speaker volume from some To- pa
The change from first to second ma
o output is made simply by pulling chi
plug out Of the one Jack and in. the
ng 1t In the filament control lack. ho'
n lights the last audio tube and Alt
plate and B plus. mo
le C-301A and UV-2O1A tubes ara far
Tor this circuit. although any of bra
Try cell tubes may be used to AZ abe
ut advantage F