New-York tribune., 1922-10-22
Set
With Only Two
Control Dials
sapcr. Regeneration With
the Minimum Number of
Parts Is Produced After
Much Experimentation
Has One Air Condenser
Variation Of the Remaining
Capacities Obtained by
Adding Fixed Condensers


ducine super-regenerative receiver
With two controls only. The set lie the
one recommended by Major e. H. Arm
atrong as the circuit best suited for
the reception of music and speech and
employs two vacuum tubes for super
regeneration, and an additional tube
for audio-frequency amplifcation.
The complete set stands on base
board Of hakeiite, measuring nineteen
Inches in length, fourteen inches in
width and eight inches high. The wir-
ias is entirely concealed beneath the
dashboard, which stands on q wooden
mount 4 small bakelite panel seven
! inches high Is mounted on the front
10 take the two controlling dials.
In designing the set the purpose in
yisw was to make as many Of the
ssrts fixed In value ae possible and to
illninate all unnecessary apparatus.
This is entirely practical, but slight
Gcepticn 10 necessary, as will be ex-
ralned.
Rheostats Unnecessary
Ths first thing that should be re-
rendered In the super-regenerativ
gssem is that the first two vacuum
hbes are required to be In the oscil-
isting state all Of the time and conse-
suensly the filaments should be full
o.. Under these circumstances the
and have been eliminated completely.
70 understand the reason why the
Two tubes should be in the oscillating
,tate 1t 10 necessary to explain their
iuncsioning. Tho second tube produces
cscillasions at certain definite fire.
auency which Is determined by the two
large duo-lateral coils in its grid and
plste circuit, as we'll as by the con-
aensers about the coils.
The first tube acts as the regene-
rstye amplifier of the weak currents
shat are picked up by the loop aerial.
Mit is really in the oscillating state
sish the filament fully turned on, it
could not under normal circumstances
trassion without distortion. AS mat
tei " fact, however, it Is only in a
shss,s.ical state of oscillation, be-
Gauss the lower frequency produced
BY the second tube is impressed upon
u and counteracts the real effect of
aseaiation. In other words the second
tube acts as an automatic switch, cut
ting out and switching in the first
tubs at a sufficient number Of times
per second to prevent 1t from pro-
ducing sustained oscillations. In this
manner the full amplifying possibili-
ties Of the tube are realized.
Switches Also Eliminated
The next step that was undertaken
vas to determine whether 1t was pos
dble to eliminate the switches and
switch points on the primary Of the
sario-coupler. This has proved entire
ly satisfactory.
The vario-coupler is wound on xour-
inch tube with seventy turns Of No. "a
silk-covercd copper wire. All of these
turns are in the circuit, Joined in
parallel with the loop. The rotor Is
wound on q tube three and half
Inches in diameter with seventy-five
turns OF No. 80 enamel covered wire,
The dial connected TO the rotor gives
control Of regeneration.
Only one variable condenser Ia used
tn the circuit, and this is shunted
across the loop in order to tune for
save. length. 1t is Of the conven-
tonal 2S-plate type, with a Vernier
attachment for close tuning.
The remaining parts are all fixed,
$pa follow in detail the diagram pub
nshsd IN this paper last July. There
y, n,aoweyer, one exception. Wherever
condenser Is in the circuit, the fa-
nr mlllar nicadons were used. These are
aa,e, nssie liked condensers OF various ca
psciles, which have two eyelets for
Connections
Condensers Mounted on Screws
~ was found that they were very
sss1aseaient ss for fixing the capacity in
sas circuit, and thus eliminating the
Ysr ar condensers. The manner in
na'ea rney were assembled was as fol-
""s. Two screws with nuts were fixed
" .he oakeiite Dashboard in such way
nas .ne micadons could be slipped
Mst them, and then screwed down
4 isn.ly with the nuts. In this manner
..n !. was possible to add capacity by put
Ing more micadons on, or reduce ca
pagTasy Tay bg removing them.
+,s as constants for the condensers In
Acro.Ap governmental set were as follows:
csnsss. .,oss the 1850 turn coil, .0o25 MID.
I 5oo ~ between tho 400 turn and
nana.,. urn ouo-iateral coils, .0005 MID.
and ~ between the 1900 turn coil
oos rss sse common lead of the circuit,
of tba bis;, 81, IN series with the choke coil
!. ns ill niter circuit, .00I MID.
ha.. WIZ De found that the condenser
ne.Ween % the 400 and 150o turn coils
10 aase TO be varied in it's capacity
nee. - aeet the characteristics of the par
Il !. .uoe used in the second socket.
fast ~. ~. snls reason that a hard and
pacisy cannot be given.
- C' Battery Is Critical
ssttss me experiments showed that the &C"
cr;t;s.fs on the second tube was very
slsrasi, varying from six volts to
ws, h. ;solls, according to the tube that
har. s 'e'ng used. The first tube should
a's aa =. negative potential of six volts
hapa 80 o.g,fd .g,rfid, and the third tube should
NJ volts for this purpose.
sss. .ne Plate circuits, it was found
arst ~ ~ volts could be used on the
Is yoSs. TWO tubes, and as much as 22o
snnl;.. ~ .he third tube. This, Of course,
Il. pss.ss wno to Eve watt tubes. of which
rssu,s. = was found to give the best
..,a, unce the set has been fulIv mas
a. Dy series Of experiments it
roe 20 get permanently at 500 or 400
Nsesa. according to the necessities Of
NAV. .t'caiiSy, and the simple arrange
tive ias ,oi 81 battery switch in the mega
rli s .saos OF the A and b batteries
Il permit the. user to switch in the
lns c,ose it down. It Is very strik-
ns.ts y Just push a button and i'm
les,a lesaateiy hear the music come in on 4
'sue speaker. s0''s 80 oA Z
AauiO central I'm Icrtloy