American Agriculturist, February 3,1923 
103 
A More Sensitive Radio Set 
How to make a Regenerative or Vacuum Tube Outfit 
W HEN one wishes By BRAINARD FOOTE 
to receive radio 
over distances upwai'd of 20 miles, it be¬ 
comes necessary to use a more sensitive 
form of detector than the crystal. A 
vacuum tube detector is then needed. 
In Figure 3 appears a single tube re¬ 
ceiving set which for simplicity and 
results cannot be excelled. Moreover, 
should the builder of the set wish to 
add amplification later on or to try 
another “hook-up,” the parts are all 
necessary and eas¬ 
ily adapted. 
What can be ex-' 
a common dry bat¬ 
tery, such as the Red 
Seal, is the “A” battery. The “B” 
battery should then be 45 volts. Re¬ 
sults will be as good as with the other 
tube, but there is this to be said: 
Should it be desired to add an ampli¬ 
fier later on, results will not be quite 
as good with the WD-11 tubes, as far 
as the amplifier is concerned, although 
they may be used with considerable 
success. Fig. 4 is a rear view, indicat¬ 
ing the approxi- 
A 
G 
pected from such 
an outfit in the 
way of distance ? 
So much depends 
upon the height 
of the aerial and 
the location that no 
definite statement 
can be made. It is 
safe to expect 
clear daylight re¬ 
ception of 30 or 40 
miles, and dis¬ 
tances at night of 
at least 200 miles. 
However, practically every one using 
such a set often hears stations over 
1,000 miles away, and those in country 
locations report even better results. 
The farmer has far the best of radio in 
his location, for at least a score of 
miles from the nearest broadcaster, he 
can pick and choose at will among the 
dozens of programs sent out every 
evening. 
The parts needed for the set are as 
follows: 
.001 mfds. variable condenser; vari¬ 
ometer; tube socket; rheostat; grid 
condenser with grid leak; phone con¬ 
denser; 8 binding posts; hard rubber 
or bakelite panel, 6 x 12 inches; wooden 
base; vacuum tube; telephone headset, 
at least 2000 ohms; “A” battery; “B” 
battery; 100 feet No. 14 aerial wire; 
ground clamp; % lb. bell wire for con¬ 
nections; 2 antenna insulators; 1 por¬ 
celain lead-in bushing; 2—3 inch dials. 
It is advisable to pay a fairly good 
price for everything purchased, to in¬ 
sure good results. There should be no 
(\ TTcklcr-^ @ 
^^RhcosTot 0 
Single Circuit Regenerative Realver 
FI6- 3 sf 
m ^ t e placing of 
the parts on the 
panel. The vario¬ 
meter may not be 
wired e x ac 11 y as 
shown, but it 
should be altered 
so there are two 
distinct parts: the 
two fixed coils con- 
n e c t e d together, 
and the rotary 
member. The flexil 
b 1 e leads coming 
out from the hol¬ 
low shaft are the 
connections to the 
rotor, while the other two are for the 
fixed coils, or stator. Bell wire is 
suitable for joining the parts and all 
joints should be tight. If possible, 
they should be soldered. The binding 
posts are all marked: “T” for tele¬ 
phones; “B” for the “B” battery, of 
which the red wire is positive and con¬ 
nects to the phones; “A” for “A” bat¬ 
tery, with “positive” connected to the 
variometer and “ground” ; “A” for aerial 
and “G” for ground. The appearance of 
the set from the front is given in 
Figure 3. 
Operating the Set 
The working of the set is simplicity 
itself. First the tube is inserted in 
the socket, and the rheostat turned on 
sufficiently to illuminate the tube and 
produce in the phones a bell-like ring¬ 
ing sound when the tube is tapped 
lightly with the finger. Care should 
be taken never to interchange the “A” 
and “B” batteries, for fear of burn¬ 
ing out the vacuum tube. The rotor 
Layout for Regenerative or Vacuum Tube Outfit 
chance of leakage due to poor sockets, 
poorly insulated condensei’s and the 
like. Hence it is well to insist upon 
products stamped with the manufac¬ 
turer’s name. Everything required may 
be ordered from a mail-order catalog, 
}f a radio dealer is not available. Amer¬ 
ican Agriculturist will advise you 
where parts may be procured.. 
If the standard , vacuum tube is se¬ 
lected, such as the UV 200, the socket 
will have terminals arranged in a dif¬ 
ferent manner from that illustrated, 
but the connections should be made to 
posts lettered as shown in the sketch. 
In that, case, the .“A” battery is a 6 
volt storage battery, and the “B” bat¬ 
tery is a 22 Vz volt block battery. There 
on the market 1 a tube called the 
WD-H, which is operated on 1% volts, 
the type of socket shown is fbr this 
tube. Much lesiS, current is needed, and 
of the variometer, which in this set is 
the “tickler,” should be set at right 
angles to the stator, as shown in Figure 
4. The variable condenser is then 
turned slowly from a zero position with 
the plates all out, to the 100 degree 
point, where the plates are all meshed. 
Throughout the process of moving the 
condenser, the tickler should be moved 
along with it, keeping the two instru¬ 
ments in such a relative position that 
“oscillations” are just on the point of 
starting. This is indicated by a soft 
rushing sound as of water, and is the 
point of regeneration. Transmission 
from a broadcasting station is indi¬ 
cated by a whistling sound which 
“chii’ps” like a canary as the wave 
length is passed on the condenser. This 
should be brought in as loudly as pos¬ 
sible, and the tickler turned back to 
{Continued on page 106) 
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