The Washington herald., 1922-04-21
Questions and Answers
Resenerativc Hook-Up.

r. NJ I nave reSeherdtiNe SCI ~
variometers and variocoupler) oi
homemade material. wired a,
shown by diagram herewith. Using
one tube 1 get Newark, Pittsburgh
and other stations any night and
often during daytime. However
when / touch post shown tplate
in secondary. lead) I get an audio
afnpltflcations OF, at least 500 per
cent. 1t seems to me that there is a
loss of efficiency somewhere which
| could be remedied by placing a con-
denser at the proper point. AS ]
| wish to install a two-step and have
a Murdoch .001 and Conn. .O0l:
a. Where best can these two
condensers be placed?
b. This morning while telephon
ing ! heard distinctly spark signals
by phone Irregular wire telephone).
" was not NAA. How is this pos
sible?
C. expect to put up an aerial
225 feet long, single wire. 70 feet
high. running in NNE and SWW
line. but with open end toward
NNE. l. type. AS Newark is the sta
tion I want to get and the open
direction will the length and height
counteract this directional effect: ]
is impossible to bring the lead-in
from the other end unless l have
long slanting lead-in.
d. Can l use a five watt tube for
final stages of ampliflcation with
Baldwin type phone as loud speak
er without harming the delicate di-
aphragm of receiver II use but 100
volts on tube? II so, will 100 volts
be. enough to warrant the use, Of
such a tube? Thank you very much
for answering these questions. l
certainly do appreciate your radio
page. I. F. H.
A. a. Your first question is best
| answered by reference to the hook
up of standard regenerative re-
ceiver published in The Herald of
April 9. You will notice one fixed
condenser is used as grid condenser
(Omitted in your diagram) shunted
by the grid leak. The other. vari-
able condenser, Is shunted across
your phones and negative of the B
battery.
b. This occurs often. particularly
when a spark station Is near by.
The phone transmitter acts as a de-
dector and the phone lines as an an
tenna. You then receive the spark
signals on the phone line by induc-
tion. This is very noticeable near
Navy Yards or government trans
mitting stations. The strength of
these signals at times interferes
with ordinary conversation.
c. Your present arrangement will
work satisfactorily. but facing II as
you suggest would be the proper
way.
d. Yes. This tube will stand from
$50 to 500 volts. Your phones will
not be injured unless exceptionally
strong signals are received. 1t would
be best not to listen in on nearby
nigh power Transmitting stations.
Unless you request it. will not re-
turn the diagram you enclosed as
question.
Testing Head Phones.
Q. How can I test out my head
phones to make sure they are in
working order? N. H. r.
A. a good testing circuit is a
dry cell and an inductance or short
coil, all connected in series. The
circuit is opened and closed by
means of the phone leads. IF a
click Is heard on closing the circuit
the phones are in good order. II
no click is heard it is possible that
the coil you have in series is of
too high resistance. Then try
smaller coil.
PHotron Tube.
Q. What is the so-called Pliotron
tube?' F. K.
A. This tube is a tube of two or
three elements and of very high
vacuum. Very large tubes Of thi.
design are used to generate audio
or radio frequency currents. 1t has
proved efficient for frequencies up
to 1000 kilo cycles per second.
Transmitting License.
Q. Is a license required il I op-
crate a small spark set? MIR.
A. Yes. A license must be taken
out for every transmitting station.
Communicate with the radio inspec-
tor, Customs House, Baltimore, Md.
Musical Note TrnnsmIttcr.
Q. have heard that some trans
mitting stations cut down static
interference by some process. Is
this correct? D.L.J.
A. Some transmitting apparatus is
designed to send tones of nearly
musical pitch. Tac s!atic is 7ut out
in the sense that the dots and
dashes sent at this peculiar pitch
and frequently are so readily distin-
guished from the intermittent
breaks of static. II is difficult at
fit 81; by :he way, 20 become used Io
this rIusical tone in rece.viag Tr:ii
bit of exparierSc Is gained tfe
lots seem to hlond ,nto the Gashes.