Vilas County news. [volume] (Eagle River, Vilas County, Wis.) 1896-1927, 1923-01-24
INTERFERENCE OF
RECEIVING SETS
Each, When Tuning for Distant
Station, Acts as a Continuous
Wave TranSmitter.

tons, was due 10 a combination or
the carrier waves OF two stations
which were very nearly on the same
wave length. There is another series
OF whistles always present which very
much resemble the whine OF q mos
quito both In tone and amount Of an
noyance produced. These are caused
by the receiving sets OF other listen
ers. Every receiver using a vacuum
tube detector with a regenerative cir
cult is a potential transmitter. In
fact Il contains all the essentials Of
a radiophone transmitter on a small
scale.
The detector tube when oscillating
produces oscillation exactly similar 10
the carrier wave Of the radlOphone
stations. The frequency or wave
length Of this wave can be varied by
changing the tuning Of the receiving
tuner.
The usual procedure In tuning for
a distant phone station Is as follows:
Put the detector tube In an Oscillating
condition after the tuner has been adj
justed near the point where expert
ence has taught us to look for the
brOadcasting stations, then move the
dial slowly across the approximate
point where the stations are usually
heard. The carrier waves are located
by whistle which starts at the upper
limit OF audibllity and goes down the
scale until IL becomes so low that II Is
no longer a note. At this point the
set is in exact resonance. and If the
ticker. coupling. or plate tuning In
ductance Is decreased until the detec-
tor tube stops oscillating, the very
best adjustment is obtained for recep-
ton OF that particular station.
Unfortunately while this listener is
going through this operation his re-
ceiving set is acting MS a continuous
wave transmltter, and Is producing
some inharmOuiOus walls I'm the
phones Of his neighbors who happen
20 be already on the wave Of the same
station. The continuous wave sent
out by the receiver combines with the
carrier wave OF the transmitting sta
ton, producing an audible note. IF
the operator could tune his set as sim
ply rs was described above there
would be very little interference, but
he usually whistles back and forth
across the wave OF the transmitting
station several times. often several
listeners who have been getting the
concert perfectly viii get restless be
tween selections and get their tubes
10 osclllating and whistle up and down
a few times.
All listeners should be very careful
10 keep their detectors In a nOn-OsciI-
lating condition as much as possible
10 reduce this annoyance OF Interior
ence between receivers.
Opinions seem TO vary considerably
In regard TO the comparative amounts
OF energy indicted into the antenna by
the "single circuit" or conductively
coupled, and the "three circuit" or
inductively coupled receiving set.
Previous TO the Introduction OF the
single circuit very little trouble had
been experienced with beat notes
from receiving stations. This was no
doubt due 10 the fact that receiving
sets were rather few and far between;
also up until a few years ago there
was a very small percentage Of c. W.
telegraph and phone stations so that
there was no reason why an amateur
should keep his tube In oscillation
condition. On the contrary, he was
very careful TO keep 1t just below the
osclllating point, that being the most
sensitive adjustment for spark signals.
With the telephone and C W. tele-
graph transmitting stations, 1. e., tube
transmltters, came the single circuit
tuner with its extreme simplicity OF
adjustment. which was SO well adapt
ed TO the very sharp tuning of the
new transmitters. And with the ad-
vent OF these new transmitters came
the necessity for making the detector
tube oscillate In order to locate a sta
ton on the scale OF a receiving tuner.
Naturally then the Interference be-
tween receiving sets became notice
able az about the time that the single
circuit sets became numerous, and this
helped TO prejudice the minds OF the
radio public against this type OF re-
ceiver. However, the fact that the
single circuit arrived az about the
same time with the Interference was by
no means the only reason for believing
this tuner 10 be the main cause of
the trouble.
For instance in constructing a single /
circuit or conductively coupled tuner
the difficulty IS IN obtaining regenera-
tlon at all points on the scale. This
seems TO show that there is more re-
sistance In this circuit than in the in
ductively coupled type. The main
point OF difference Is the close |
coupling 20 the antenna. Being con-
ducuvely coupled. the coupling 70 /
the antenna circuit is at maximum |