The Washington herald., 1922-07-30
Questions and Answers.
Tuning Coil Connections.

Q. I have a double slide tuning coil
for use with my crystal detector set,
but cannot hear music on $50 meters.
Is there any way to connect with a
straight aerial so as to hear local
music especially?-N J. L
A. 1t is possible that you have made
the wrong connections from tuning
coil slide to the apparatus. Follow
the diagram shown with tube detec-
tor above and make sure the ground
and aerial leads are correct. With a
crystal detector set you will not re-
ceive some of the local stations. l
have no idea what other apparatus
Is Is your circuit so cannot suggest
now TO make your set more selectiye.
Ticker Collaborating.
Q. What is suitable for a ticker
coil and where is it placed on the set i?
L. X.
A. Honeycomb coils are very suit
able for ticklers and are mounted
with the primary and secondary
coils. The ticker and primary are
usually moved at varying angles to
the secondary.
Wave Length Range.
.. What will enable me 20 tune-in
WN->. Postoff1ce, on my c..yral set
s.. : can ear III, reports aud mar
ECt staten chts?- II. ]. K.
A. You may increase the wave
length range to your set by adding
a loading coil between the aerial and
primary of your loose coupler. A
condenser shunted around this coil
and the primary will then give YOU
The Necessary capacity for ma:ntaIn-
ing a proper ratio of inductlnce and
capacity in the circuit. 1t is possible
tnat you may hear WwX without
making these changes. although
cannot Judge without a diagram of
your apparatus. WWN sounds on
ileo meters. but has a harmonic in
the neighborhood of $50 meters. This
harmonic wave is being received
quite regularly by many operators.
Potentfometer-B Battery.
.: Is there any advantage in using
battery potentiometer, and how
can person know IL the filam
rheostat is at the proper place in a
NJ. K. H
A: Practical operating hints vary
with each make of set. There are
however. certain fundementaIs
which apply to nearly. all sets.
There is an advantage in using a
battery or plate circuit potentio-
meter, because the plate voltage In
critical for best operating results.
A potentiometer is placed across
tne battery, and provides a slid
ing contact for taking current off
the resistance at any setting. The
advantage then is sensitive con-
troll. For adjustment of the A bat
terry current lighting the filament
turn the filament rheostat to a.
point where a kissing sound is
heard In the head phones. Now
turn the rheostat back and an.
proach this point again. leaving the
rheostat fixed at a position iust
ahead of where the Kissing sound
IS heard. These. suggestions will
help in the operation of a non-re-
generative' receiver as Judge your
set to be.
Rotary spark Gap.
Q. During a visit to NAA, Airing
ton station some weeks ago. a
group of boys were shown the ro-
tary spark gap. but I didn't un-
derstand its purpose and have heard
sum gaps are uSeu ABOARD Sn1DS.
Can you give, me some Information
on this? B. H. ],
A. The name rotary gap Is some
what misleading. The gap is be-
tween a stationary electrode and
the points of rotating wheel. The
wheel is reyolved very rapidly and
spark is passed each. time a. point
or spoke" OF the rotating wheel
passes the stationarys@felectrode.
The wheel is rotated at very high
speed. and gives of correspono-
'ingly high pitched note. The more
efficient sets now in use for high
frequency currents are synchronoua
rotary gaps meaning the spark. dis.
charges are very regular and pro-
duce an even, musical note. The
timing OF the rotary gap wheel In
this instance. 10 such that the al /,
current voltage In the cos