The Washington herald. [volume] (Washington, D.C.) 1906-1939, 1922-04-06
Questions and Answers
,Potentioneter Circuit.

Q. Could you please give me d.
-ections for a potentiometer. how
to make 1t and how to connect 1t
to a crystal >detector set. including
a tuning coil. 3.ooo-ohm phones and
fixed condenser H. s. B.
A. The potentiometer and its use
were fully described in The Herald
of April 4: also the proper hook
up for connecting 1t to a crystal
detector. As you have a single In
ductance coil double slide. you may
get best results by connecting your
antenna lead near the loose end OF
the coil; your antenna lead midway
of the coil. This will enable you
to vary your coupling without vary
ing wave length. See figure l-b
in Tuesdays Herald. You can avoid
the use OF the potentiometer IL you
change your carborundum crystal for
silicon or galena. which are equally
good for receiving sets mot sub
ject to excessive vibration or mo-
ton.
whistIing In Receiver.
Q. a. We have just purchased large
Acmefone and would like to know
what causes a loud whistling SOUND;
this is so shrill at times We can
hear no other sounds.
b. Where can l secure books list
ing radio calls? What are QXJR;
sXJ; UXR: wDL and WIZ?
II. w.B.
A. The briefest answer to this
question is the fact that difnculty
has been experienced with certain
sets employing high application to
get rid of this whistling and sing
ing effect. 1t is due to poorly regu-
lated oscillations between plate and
grid OF the vacuum tubes. This can
be partly avoided by reducing the
ticker coupling indicated on a knob
on your set. AS amplification Is in
creased. regenerative effects result;
disturbances are amplified as are the
usual signals. Shielding the receiv-
ing mechanism by a metal casing is
another method of cutting down
noises.
b. The books listing radio calls
are: Amateur Radio Stations of the
United States" and Commercial and
Government Radio Stations of the
United States" both obtainable from
the Superintendent Of Documents,
Government Printing Office. The
new editions will be available soon.
In yesterdays Herald an explana-
ton was given of how to determine
radio calls by noting the letter and
combination. QXJR Is a code alb
breviation. as are all calls starting
with Q. 2XJ Is a special land sta
ton at Deal Beach. N. ]. You
may hear this station today because
1t is conducting radiophone tests
with the steamship America, now ap-
preaching New York on its way
from Bremen. UXR Is an Italian
ship. distinguished by the letter U
and the fact that the three-letter
group falls between UPA and UZZ.
WDL is the steamship Lakeland, Of
the Tri-State Steamship Company.
WIZ is Newark. N. J.. westinC-
house electric station. See In the
Air Today" schedule.
O. Can you tell me where I can
obtain Instructions for a home
made receiving set? J. H. r.
A. Inquire at local electrical
shops handling radio equipment. or
read instructions published in The
Herald March 5 and 6.
Q. What will a small receiving
set cost? RI
A. In the article described in the
question above you will find a means
of making a set for a few dollars.
This would be a crude crystal set.
without a great range. Modern
vacuum tube receiving sets cost
from $40 to s596, depending on the
service desired. Money is wasted in
buying cheap sets.
Light Wire Aerial.
Q. Do I understand that by Gen
Squier's hook-up broadcast mes
sages are first picked up by a pow
erful receiving station. amplified
and then relayed through the cleo
tric-light circuit? How is the re-
ceiver connected to the electric
light Circuit and what apparatus is
necessary to prevent blowing up OF
the fuses? CHAS. C. s.
A. The last question will be an
swered first. namely to. avoid blow
ing up the fuses wait for further
data concerning Maj. Gen. Squier's
development before attempting a
hook up. The plan is not com
mercially practicable as yet. hence
should not be tried by novices. A
letter published in The Herald
April 8. gives the explanation OF
Maj. Louis ]. Bender. Signal Corps
U. Sra. which is the only stateme Mt
for publication at present.