New-York tribune., 1922-07-30
Coils
Will Increase
Wave Range
Loading Principle, Although
Simple. Must Be Followed
Properly to Give Success
on Long Wave Reception
Load Coils Arc Tuners
On Double Circuit Receiver
Secondary Must Be Load
ed a. Well as Aerial Coil

There isa growing desire on The part
m the radio fans 20 listen in on stations
using the longer wave-lengths. such a.
the naval stations and the iran'-At'an-
tic stations. In addition 10 this. there
are few of the government operated
broadcast stations working on 1850
meters. which is above the normal
range Of the receivers now being gen
orally used.
The question which troubles the ian
BE- lust what additions he must make
fo his short-wavc receiver in order to
tune in 20 the longer wave stations.
I'm WAY the nnfwcr 10 this question
+. simpie enough. but it varies great
deal in accordance with The type oi fo-
coivcr that is being used.
In an cases the wavc-lenEtn range
o. tho receiver is increased hy means
Of loading the induciancef. This means
fhaf more irductance must BE- added io
.hc irductance ALREADY in the circuit
or. in other wordr. adding another tun-
inc coil large enough to BRING in tnc
desired station.
Two Main Types Receivers
Now there are TWO main types Of re-
ceivcrr boz use. and they can be ciassi-
Ged roughly as single and double CIR
r..t receiver. Of course. when
eacrum tubes arc ufed ther can also
q. rcgcncrat.vc in both cascf
Tho advantage OF tho two types o..
circuit have been previously described
iu this rapcr. and or we are now con
ccrrcd with.fhr hcst method o. io1o nc
we viii commence with the single cir'
cult type OF receiver.
Most OF these single circuit snort
wave sets CONSIST OF e condenser anel
tuning coil in series with tnc aeFlai
and ground. with the dctcctor snunted
around the coil. ln order 90 tune up
90 tho LONGER wave 10 will De nccfs-
ssrr to do fwo things: nrff. add an
other tuning coil of efficient mum
bor OF turns depending upon the maxi
MUM inductancc of The regular coll in
tho ec.I. and second. 90 rc-wire the
condenser so that DO is shunted across
both coils instead oi being in series
with them. The detector circuits must
also be shunted across both coils, ana
this applies equally Co the vacuum tune
and crystal
Ticker Must Re Loaded
n the circuit uses q vacuum lube 10
conjunction with a ticklcr coil, maAih- =
it single circuit rcgeneratift sell
then 30 viii De neccssary 20 load ul
tbo ticker coil also. There is anothsf
important roint thst must be rem en-
bored in circuits of th's tyne and ma,
is thc TWO loading coils must be placed
in an inductivc relationship "iin taeh
other Their closencss 20 each otncf
viii have Go be determined by cNpeT-
meut.
solute!y necessary % lead up inc sec
ondarv inductauce as well a. the aef'al
induc:ance. The secondary loading
coil must br properly designed Win
thc requisite number Of turas on u lh
ordet 90 get the nroper results ana u
this case also the two load cons shouiu
be puf into inductirc relationship WIZ
each other. As BOO the case OF inc SIN
Gle circuit receiver, % may De neees-
.arv 20 place The aeria! tuning CON
dcnser in parallel with inc atflai l"-
ductance. This dcpcnos 'ni le't upos
the range Of wavc-lengihs ii i' Hesiieu
TO listen Tor. but 10 is Imperative DO
thc. ease of thr transatlantic stations.
When We come GO rcgcnerativ, sets
4 emplovine the double circuit system
Inc question of loading zap FOR th'
longer wave lcrgfhs is little more
difficult because ;hrce loading IN
cucfarccs must be used one ior the
urinary. one for the secondary and onr
for the ticker or regencraure circuit.
Long Waves Interesting
I'm the wave length bands above The
normal range OF the short wave re-
.oi,er. there are quite ioi OF inter.
4 rstinc things 20 be- heard. but of
coufs. the majority OF them are in
dots and dashcs ~ fhc Continental
code. aside from fhc gorcnment
broadcast stations such as Fort Wood
mentioned abovc.
The range between coo and 500
meters BE- reserved for general gov
cfnmcntal usage Two Of the most
interesting are the radio compass sig
+ rails and the radio beacon signals. The
former operate on 500 meters and thc
f latter on 1000.
The wayc-lenFih band between i.6O0
ard $500 meters is assigned 20 long
distance communication with ships 20
ea and Dc is on these wave lengths
tha. quite a lot OF news matter is tcle-
craphcd. Those waves above 5000
meters are FOO Use by the big trans
Atlantic stations.