New-York tribune., 1922-06-04
Is
Useful Part
I'm Receiver
f. Easily Made and Permits |,
: Inductance To Be Varied
without Any Break in
Continuity of the Circuit
Better for Short Waves
Tune. by Varying Inductive
relationship of Windings
on the Rotor and Staior

-. ado receiving set is the vario-
RS most Efficient on short
-. .,. and as the broadcasting sta
- A., All operating, by government
~. 80. v,on $50 meters, the yariometer
~. - vsrv large sphere Of usefulness
~. -. ,ssiophone system. 1t affords
a.. o, getting continuous variation
80, ,ndue,anee in the radio fre-
-, circuits without the dissdvan-
81. =, sliding contacts or the multi
-. witches that are used in other
-, Z A. induetanee. It also has the
.a.,..,s. that it can be readily and
simply constructed
49,, when used with the vacuum
a., M cots is the fact that its Pc
10, nature permits the varia-
-, n its inductance without any
,.,,t in the continuity Of the circuit.
-. svery importan, in vacuum tube
r,,t because with the multi-point
.~,,,.., used in other induetanees,
r,l,,. they are very carefully designed
,,s constructed, the circuit is apt TO be
lroken while the adjustments are be-
,,y made. and in some cases this VIII
,,s5 70 paralyze the vacuum tube
co..;sts ~ stator and Rotor
barometer Is constructed in two
s.,,iops-one known as the stator ana
-. other As a rotor. The siator' as
ns name implies, is stationary wind-
re in a suitable form, while the rotor
"a winding upon a coil which rotates
u,on is axis inside Of the stationary
vnding.
The operation Of the variometer is as
follows: II the rotor is turned in such
manner that is plane comedies with
.se plsne Of the stationary coil, the
,s,ren, will circle through both wind
irss IN the same direction and their
nsrs,ic helds will add 10 each other.
The ulf.irduet.on OF the vsriometer
thsr A. is maximum point.
ssould the rotor be turned complete
lv sround. the current will then Aow
through the two coils in opposite direc-
IONS snd the result will be that the
;vo magnetic fields will oppose each
o,ber and the self-induction Of the
10 MI rTsfI NJ
rneiitslly zero. OF course, II the
w'or coil is al any other angle, we
tiain varying degrees Of self-induc-
son, snd it is By this means that tun-
rr is affected with the variometer.
yariometers Standardized
In the past couple Of years. the
iifoneters used in receiving circuits
lave become more or less standardized,
ri the forms upon which the two
vrirgs are laid can be obtained
riiy-made by the radio fan. They
variable come in three pieces-two
q ne pieces representing sections OF
10 s.ator and the third piece being the
, ro.sr The latter IS invariably made
n ball form.
Fu the novice who desires 70 con-
| Frsci his own variOmeter without OBJ
aifrg any Of these standard parts, the
/ tr,ring instructions should be fol
| krtd. obtain two cardboard tubes
ms inches in diameter and the other
| inthes in diameter, both being
,tkss in length. Upon these wind sin
IL layers Of No. "a 5. c. c. wire. Th'
r,tine will not be continuously made
:sause in the middle Of each tube ?
l;s,e Of one-qusrter inch must be left
- ias, the shaft which revolves the
rotor can be passed through both coils
The ume amount Of wire should be
Placed on each tube, completely hiling
re tsbe with the exception Of the one
l e-srtr inch space in the middle and
ilght space on each edge.
The outer tube can be mounted on a
vtoten frame after hole has been
| t1lled sufficiently large enough 70 take
- piece Of quarter-inch round brass
nd /; inches In length. The inner tube
isorld be fastened TO this brass rod so
rat il will revolve with II. One end
rihe rod will have an adjusting knob
tashsd 10 10. A scale can be added
desired. The turns should be thor
lgtly shellscked after the winding Is
'srls'e, in order TO prevent that from
r'Rning up.
4 standard Blocks Can Be Used
1 With the standard wooden blocks or
Nzposiiion blocks that are sold for
Hnensier purposes all that will be
'Ssitary is 20 wind the spaces left for
Il nsing with No. % D. c. c. wire, so
a' The entire space is filed up. AZ
II = Inst glance II will look as though
Il ASK Of wiring the stator section
Il ,l Be extremely difficult, but II these
/ 1isetions are followed IL will not be
II ny hard task.
4 NFei the sections OF the stator with
Il or Of shellac and before this dries
yoat winding upon II, seeing that
i tinding Is snug and tight. After
| -. Is completed cover with another
N shellac and force the windings
Position and then allow II 10 dry.
/ -. assembling the variometer, the
L 4" the stator winding will be car
49, "a and connected 10 the beginning
- io,or winding. In this case. how
ne1ible connection OF sufficient
"a must be left between the two
order 20 permit the rotor TO be
completely around without
.rg the connection. Another way
e the brass shaft as a means Of
s,.'suhg the two coils together. so
sr.,.e He rotor coil can be spun COM
II ~y around.