The Washington herald., 1922-06-28

a. from your sketch IL Is haro
to Judge the results you might
expect. A diagram for use with
two tubes is being forwarded. The
tuning coil you have Is not sum
ctent for this set. Honeycomb coils
for inductances are suggested.
Variable Condenser Eject.
Q. The enclosed sketch illustrates
my hook-up. The variable con-
denser was added recently and
has been Of no value. understood
that the object of a variable con-
denser was to enable sharp tuning.
Does this necessarily mean louder
signals? I have no difficulty hear
ing WMU, VIII and NOF plainly.
/ also hear WPM. but only occa-
sionally. My trouble with the
Church of the Covenant Is that ]
do not get anything that Is said.
Can you suggest any change that
will enable me to hear the last
two stations celarly? / can't get
WEAS at all. H. L. II.
A. Your hook-up is correct and
the set should give you satisfac-
tory results. Try inserting the
variable condenser in the aerial
circuit between aerial and primary
| of loose coupler. Several other
possible hook-ups are being for
warded to you. Your aerial may
be largely to blame for the poor
results obtained. l would suggest
that you extend three or four wire.
around the ceiling of the room.
spaced four inches apart.
variable condenser across the
secondary may increase the sensi-
| tiveness OF your set. Its object
is to provide the correct capacity
to correspond with the inductance
| in the circuit so the receiver is in
resonance with the distant trans
mitter. The problem OF getting
loud signals through a crystal de-
tector set is largely one OF tuning
correctly. II you are tuning, saw
to $50 meters, start with most or
the inductance on the secondary
cut in. and small capacity. Place
the secondary almost entirely
within the primary Cclose coup
ling). Adjust the primary slider
until signals are heard, then make
sure the detector Is on its most
sensitive point Now gradually
pull the secondary coil out from
the primary Ooose coupling) then
move primary and secondary con-
facts and re-adjust the secondary
condenser. Repeat the operation,
using different values Of inductance
and capacity. For your apparatus.
tuning in this manner should
bring in local stations more clearly.
| Low power and the fact that YOU
have a crystal set that Is not sensi-
tive accounts for weak signals
from the stations mentioned.
| Receiver-CrystaI Set.
Q. I wired a crystal set from the
Bureau OF Standards plan and as
yet have not been able to receive
anything. Had to string an inside
antenna. as l can't get permission
to place one outside. / first strung
| single stranded wire forty feet
through my apartment. then
strung my antenna as enclosed
sketch.
ta) Which should be best. the
| above or the single wire? Or can
they both be improved7
tb) One block away is the ThIr-
teenth and d street power station
VI 'he w. ~ r.. GO. would this
effect receivinge
(c) Am using lamp cord from sill
to cold water pipe for ground. Is
this OK?
Id l wound a tuning coil with
No. 22 double cotton covered wire.
| Would No. "a enameled wire be any
better.
| (e) Am using a fixed condenser
across the phones. which are 1000
ohm Stromberg Carlson. and a de-
| tector set with the crystal and cat
whisker enclosed in a glass tube.
O Should I use a slide, tuner or
a variometer or a variable con-
denser to get results.
| Any information you can give me
will deeply appreciate L-V.
A. The aerial problem answered
| in the question above is very sim
liar to your own.
OBJ The nearness of the power
lines will undoubtedly give YOU
some trouble. Try extending your
aerial wires lengthwise of the room
at right angles. To these lines. The
Bureau OF Standards set has In most
instances given very satisfactory
| results.
(cl IL the ground wire is soldered
or tightly clamped to the water
pipe the connection Is all right.
(d) Without knowing the size Of
the tuning coil ] could not estimate
the inductance from the figure you
have given In general. either size
of wire mentioned Is satisfactory.
(e) This apparatus Is correct.
| f) In your case 1 believe the
slide tuner will work more salts
factorily. A number of crystal de-
tector diagrams are being for
warded with which you may expert