New-York tribune., 1922-12-10
Radio Frequency Transformers,
With Hints on Their Use

Asne Radio Frequency Transformer
When n receiving set begins 10 grow
il srovs outward from the detcotor
tube. The tendency at present ID for
the growth 20 start with on ofshoo'
OF audlo frequcncy, which may eytend
for two or three stages before eiBtor-
ton or circuit noises discourage a FUR
ther extension IN this direction. Then
from The other side Of the deteetor
tube there IA likely 20 appear 4 sprout
cf radio frequency. j.,
Radio frequency is not o. rugged and
easily slapped together" % tie. sudio
end. Engineers tackled the problem OF
designing radio frequency transform
ore cautiously. and Il was only after a
great deal of experimentation that
they succeeded In evolving a device
that would handle the high frequency
carrier currents with the desirable
cfsciency. Evca yet the aveeess oi Fneh
device depends ~ 10 small degree
upon the way u is connected into the
circuit. short leads and separation OF
conductors arc both pccesssry. But II
q radio-freducney transforrier that i5
inherently good 70 correctly connected
into the Circuit and used o. the range
Of wave lengths fog which Il wes de-
signed Il will prove q satisfactory in
vestmen,. The fact should be kept in
mind, however. that the value OF radio
frequency e. more in the distance pos
sibilities than IN increased volume for
the local statious.
Acme radio frequency transformer
are built in several different types 70
accommodate The ordinary znge Of
wave lengths and various conditions
Of operation IN different parts OF a
mu.ti-staRe set. The clements Of
these transformers arc inclosed In 2
hard rubber case three inches long and
one and oae-cusrter inches in width
and height. These clements consis.
Of the primary and secondary Winding.
so separated as 70 reduce the mutual
and individual capacity effects which
play su important part u the Coeign
problem az such high frequencies. EX-
tromely fne silk-covered wire 10 used
Tor the secondary windings. and equally
fno cotton-eovered material on tAc pri-
mary fido. The core consists Of a
block tao and one-half inches long and
n haif-ineh square built up OF lamina-
tions that are very much thinner than
;hoso used In the ordinary agdio fre-
Cuency trRnsformer.
Leads from the primary sud second
airy sides are soidered to the screw
heads os the four terminal posts
mounted IN 3 row along the cover Of
tho case. The type number 10 also
given 10 that there is 10 danger of
connecting in the wrong sequence If
the directions arc followed. 1t is
necessary 20 use G potentiometer for
maintaining a fno adjustment Of grid
bias when using radio frequency. One
pctentiometor can sc used TO regulate
the grid Of the Arst stage and the sec
ord may be connected direct to the
negative side OF the iilsment battery.
Al additional advantage is gained IN
using & poteutiometer AZ the negative
end OF the plate battery SO that close
regulation oi plate voltage may BE
obtained.
Type RI las Z wave length range
of 100 70 go METERS. R-2 has a
range of $50 10 600 meters. For the
second and t5ird stages 20 be used in
conjunction with R-2 are the types
R-3 and "a respectively. Manufac-
tured b2 Acme Apparatus Company,
Cambridge, Mari.