New-York tribune., 1922-06-18
Useful Points
WhichPrOduce
Best Results
Fans at Long Distance From
Broadcasiing Station Can
Improve Results BY Using
Five.Watt Vacuum Tubes
Act a. Power AmpliGcr,
Care Must Be Taken 10 See
Transformers Will With.
stand Voltage Required

In the lssi few days have received
. number ~ requests from radio cans
fesiding .n Isolated eommun.t.c7. u-g-
.ne me 20 advise them just what ad
dit.onAl apparatus they can employ .n
order to obtain better results over the
long distances that they are located
from the broHdcsstng stations. II IS
my purpose. therefore. In this article.
10 outline one or two little change
that can be made 20 improve che rr-
osp,ion a. these distant poln'F.
Of eourse. the ideal set for inoss
radio fans - the new Armstrong cir
cult. known as the supcr-rcgcucratiye
receiver. but. ~ course In thc natY-a
course 80 events. 10 will be ma1y
months before this apparatus IS avail
able for general use. ard it is Tor that
reason that an giving tho following
hints 10 improve reception with exist
ing instruments.
Amplines Only Detcotor Signals
Most of tho radio fans living o.
some distance from a broadcasting sfa
tion are utilizing e detector ard two
stages o. audfo-frfqrenct amn| 'N.''
Vow. with this type ~ circuit ffc only
thing that can be- ampiifrd tnr'
which passes through the defccfor. ln
other words. u che energy received
upon the serial il TOO weak 90 aetna
the de'ector. there cannot hr any ann
piifcation of that particular gnai
There are. however. some signals
TINT ere ius' sufficiently 7'rors enough
20 be passed ,hFoucn The detcctrr. ht'
which the two stages of am0ihrafion
normally used aye insufficient % am-
plify In volume large enough '1 bc
clearly understood.
This car he overcome b. uFinr ave-
watt nower tube 70 tho isst stage oI
the sudio-freqlcrcg Before f0.re r'.
however. ihc radio ian should maze
quite sure that the trarsfoTmer 'h.eh
- IN the circuit between irr f.'. am-
p.ifying tube and the second amnifft-
inr tub. will Withstand trs voltage
that is necessary 70 be ufrd in tno
r.ste eireui. o; The fve-wst. tlae.
Must Use $50 Volts on Plate
In order % re, the best results VITA
/ the smsll power tube rated A. 5-wattf.
+, will hc neoessary - use $50 ro.is in
the plate circuit this voltage can b.
obtained BY putting a sufficient nrm
Der Of 2eis volt dr. cell battery units
in series wi:h each other. bl; care
should hs taken that this $50 volts is
only In the plate circuit of tne '-Na-'
tube and rot IN the circuit or t1c other
smplifying tube.
A great deal will depend also upon
o.
,er.es used in the set. n this conrec-
tion would sugges, ;hat tne following
fcst be made First of ait. n &c start
oil with this Fundamental fact in m.nd.
namely. that the positive plate uf the
n" batterv must b@ connected % :hs
rla,r terminal - zoe vacuum tube. no
rittske can be made. Now taho ihe
negative lead from 'he "b' battery and
try y out. arst. upon t1e positive 'cr-
minai ~ the a" battery, and lstcn -
ne signals. Then take the negative
lead and connect up 90 trc negative
lead OF tire a" battery, and note the
difference in results. NnicneFcr -
these tao connections gives tnc octtcF
results. that should BE che ana! coz
reetion used with the set.
soft Tubes Are Critical
Another important thing 90 bear IN
mind = the following; In the erer'
ira, the soft" vacuum tube is oc-
inc used as detector. OF. in otner
words. tubes equivalent @ the lN
900. II Is very necessary 20 experiment.
for the correct voltage 90 be u'ad 10
The plato circuit ~ that particular
tube. This is due 20 the fact mat no
two soft" tubes arc c.lfe in t'cir
eharsctcristics. This rnrtict'lr iir'
81 tube = very critical in .f7 operation
and each tube needs a a.ecfent ilate
voltage o. other tubes of nc same
tyne. Some u these tubes w.! olet-
ato on as low a. three volts M tnf
nlate circuit. while others VIII require
the full 22is volts. Only experiment
can tell which IS right.
In this connection, j. would not te
bad idea % use q multiple poini switen
60 arranged that ZAP is taken iEoin
eysrv eel of the dry battery to eacn
of t.. switch points IN sien manner
that any voltage can b. hrought lh'o
this circuit b. means ~ the switch
For real. stable results D. Us mlen
better 20 use hard vacuum tube Tor
deteetor purpose; in otlcr Mo.l.
TUBE similar in tyne % the w -'l.
With such tube - is uc s.nle 70 use
either 22iI yoi;s og 50 volts ~ 'n,
plate eireui. o. the ds.ector TUBE an,ii
ths results a. general average WIZ
ne much stfad.cr