American Agriculturist, September 15,1923 
183 
What Kind of Tube Shall I 
A Problem of the Amateur Radio Fan Answered 
T HERE are so many vacuum tubes 
advertised for radio reception these 
days that the newcomer into the radio 
field is rather bewildered. Tubes are 
expensive, too, so that it is important 
to know just what tube is best suited 
for the particular receiving set with 
which it is to be used. 
The type of receiving tube which is 
lighted from a dry battery instead of 
from the old storage battery is rapidly 
coming to the fore because of recent 
improvements in dry cell tube construc¬ 
tion.- Yet where great volume of speech 
and music is wanted, so that a loud 
speaker may be worked with sufficient 
strength to fill a large room or hall, 
the storage battery tubes are the only 
' ones really suited. 
But when it comes to a single tube 
receiving outfit, where the headphones 
are going to be 
By BRAINARD FOOTE 
of a small flashlight battery inserted 
between the “F-” binding post of the 
audio amplifying transformer and the 
negative side of th§ filament battery, 
instead of the straight wire connection 
usually made between those two points. 
The little flat types of battery are just 
the thing, and they will last for five or 
six months, since practically no current 
is required of them. 
In the first stage of amplification, a 
two-cell battery is 0. K., while in the 
second stage, a three-cell unit should be 
selected. The long spring is the nega¬ 
tive, and should be connected to the 
“F-” binding post. On some trans¬ 
formers, this post is labeled “S-2.” The 
“C” battery may be made of separate 
small round cells connected end for end 
(in series) and 
used exclusively, 
the difference be¬ 
tween the results 
obtained with the 
two types of tubes 
is so slight as to 
give rise to fre¬ 
quent argument 
among radio fans 
as to which is, in 
truth, superior. 
“What is the 
best detector tube 
available to¬ 
day?” one may 
ask. Probably 
the UV-200, op¬ 
erated from a 6- 
volt storage bat- 
t e r y , although 
the WD-11 and 
WD-12 tubes are 
for all practical 
purposes as good 
If In Doubt, Write! 
T O the amateur there seems to he a 
veritable jumble of figures that rep¬ 
resent the various styles and sizes of 
vacuum tubes designed for radio re¬ 
ceiving sets. In this article, Mr. Foote 
not only gives the application of the 
various tubes to radio reception, but 
also gives their advantages as well as 
their shortcomings. Mr. Foote is one 
of our foremost radio experts, and 
this story is one of the series started 
last January, which he has written 
especially for American Agriculturist. 
If you are experiencing any difficulty 
with your receiving set or desire in¬ 
formation relative to building one, 
write American Agriculturist. 
in that case it 
should be pointed 
out that the 
brass cap in the 
center of the bat¬ 
tery is the posi¬ 
tive contact, 
while the zinc 
casing itself is 
the negative. 
Perhaps the 
most talked of 
tube at this writ¬ 
ing is the UV- 
199, a G. E. prod¬ 
uct. It is truly 
remarkable in 
several ways. 
The filament cur¬ 
rent is six one- 
hundredths of an 
ampere, or about 
one-seven teemth 
as much as 
Since the various tubes mentioned 
are different in construction and in 
filament current, a special socket and 
rheostat are required, and one should 
be guided by the advice of the dealer 
or mail-order house where apparatus 
is purchased. Rheostats needed are as 
follows: UV-199, 30 ohms; WD-11, 
WD-12, 6 to 10 ohms; UV-201-A, 10 to 
20 ohms; UV-200 and 201, 6 ohms. The 
WD-11 and WD-12 tubes .are identical 
in build, although the latter employs 
a socket of standard design, whereas 
the terminals are differently arranged 
• for the WD-11. 
One may wonder whether or not it 
is permissible to arrange a combina¬ 
tion of tubes, using each where it is 
best suited, and such a plan is certain¬ 
ly advisable and to be recommended. 
There might, for instance, be an en¬ 
semble where UV-199 tubes are used 
for the radio frequency part of an out¬ 
fit, WD-11 tubes for the detector and 
first stage of amplification, and a UV- 
201-A for the second stage. Naturally, 
one must be careful with the “A” bat¬ 
teries in such schemes, so that no more 
voltage than is safe is applied to each 
tube. Separate “A” batteries are pre¬ 
ferred for each set of tubes, although 
the same “B” battery may be used for 
all of them provided the negative side 
of all the filament circuits are con¬ 
nected together. 
is 
both for distance and strength of broad¬ 
casting received. Amplifier types ot 
tubes are seldom quite as good detectors 
as the others, but with a higher B 
battery voltage very nearly equal them. 
Now about amplifiers. Without ques¬ 
tion, the UV-201-A tube is without a 
peer in this class. Not only is it con¬ 
siderably better than its close relative, 
the UV-201, but it requires only one- 
fourth as much power to operate it as 
that tube. It is possible to run the 
UV-201-A from dry cells, although so 
many of them are necessary that the 
storage battery is cheaper in the long- 
run. For instance, after we note that 
the 201-A tube takes one-quarter am¬ 
pere at five volts to light its filament, 
we may realize that a series of four 
dry cells with the correct type of 
rheostat is sufficient for the tube’s 
illumination. 
But for a threedmbe outfit, there 
would be at least eight batteries, and 
prcforsibly twclvG, in n sGi’ics-imiltipiG 
connection for efficient working of the 
set from dry batteries. That, of couise, 
is a little too expensive for serious con¬ 
sideration, since a “recharge” would 
mean a new set of batteries at a cost 
of about $4.80 after approximately 100 
hours of service. A storage battery 
may be recharged at home with a bat¬ 
tery charger at a cost of about a nickel, 
or 'at a service station for about 75 
cents. The initial cost of the battery 
is in the neighborhood of $16; yet a 
few recharges would turn the balance 
and show that the storage type is more 
economical. 
For the second stage of amplification, 
with about 120 volts of “B” battery, the 
VT-2 or “E” tube is unusually satis¬ 
factory, and being larger in size than 
the other two storage battery tubes 
mentioned, operates the loud speaker 
with a shade truer reproduction. 
Can amplification be accomplished by 
dry cell tubes? Yes, and with them 
a loud speaker may quite easily be 
made to function for a few people in 
a small room. The filaments of such 
tubes are so frail and thin, however, 
that the current which such tubes can 
send through the electro-magnets of a 
loud speaker is relatively small, and 
one cannot expect the greater output 
obtained with the other tubes just 
considered. 
The same audio frequency amplifier 
circuit is used, with the exception that 
taken by the old storage battery tubes. 
Three volts are needed, so that the 
tube can be operated for about seventy- 
five hours from a large-size three-cell 
flashlight battery. Three standard size 
dry batteries will do, and they will last 
just about 400 hours with one UV-199! 
The UV-199 is not quite as good a 
detector as the WD-11 or WD-12 tubes, 
but it is far superior for radio fre¬ 
quency amplification, and in fact is 
very nearly the equal of the UV-201 
or UV-201-A for that purpose. It is 
not quite as good as either of the other 
dry cell tubes for audio amplification, 
yet it can be used with considerable 
success. 
For a single tube reflex circuit, de¬ 
scribed in the May 5 issue of the Amer¬ 
ican Agriculturist, which is reproduced 
on this page, or for that circuit with 
an added step of audio frequency am¬ 
plification, the UV-199 is just the thing. 
The tube is so good for radio frequency, 
that the range" of a reflex circuit with 
it is greater than the same circuit 
where a WD-11 is used. Of course, the 
strength will not be quite as great on 
reception from a nearby station, but 
for farm radio work, where the unusual 
clarity available with a single tube and 
crystal detector in the reflex combina¬ 
tion is appealing, the UV-199 should 
be chosen. Its “B” battery voltage 
should be about 45, 
A. A. HOOK-UP WORKS FINE 
I made the hook-up that you printed 
in the Agriculturist a few weeks ago 
and it works fine. I made mine in 
units and connected them together. 
I find this hook-up works better with¬ 
out a grid leak or condenser. I also 
am using the Paragon control unit. I 
received the following stations using 
one WD-11 detector tube: WJZ, WOR, 
WEAF, WAAM, WBS, WBAM, 
KDKA, WGY, WWJ, WDAP, WMAQ, 
WLW, WNAC, WGT, WOC, WSY, 
WHAS, WJAS, KOP, WBT. 
My aerial consists of a single wire 
75-feet long and 36 feet at one end and 
25 feet at the other. This set tunes 
nearby stations out fine. 
I hope other readers of your paper 
tried the hook-up.—Louis M. Van 
Ness, Pompton, N. J. 
SUBSTITUTE FOR WD-ll’S 
Please advise me, where I could buy a WD-11 
vacuum tube as described In Mr. Foote’s ar¬ 
ticles.— O. E. Williamson, Schoharie, N. Y. 
If you cannot find a WD-11 tube, you 
may use one of the other types, such as 
UV-200, which is operated from a 6-volt 
storage battery or a new UV-201 A 
tube, which may be operated from such 
a battery or from four dry cells con¬ 
nected in series. 
“I find the magazine so interesting 
I am subscribing for another year. No 
home should be without the American 
Agriculturist, city or country. There 
is always something to learn in the 
American Agriculturist.”—Mrs. Wra. 
Wilkening, Jr., Windham, N. Y. 
a “C” battery is always desirable to in 
sure clear amplification. This consists 
This is the layout or schematic diag 
and well adapted to 
ram of the Reflex set, easily made 
distance reception 
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