INSTRUCTIONS
for
Q X' er
R.
L .
DRAKE COMPANY
I. GENERAL DESCRIPTION OF Q-X’ER
The Q-X’er is an attachment for a radio receiver. Its main purpose is
to help discriminate between the wanted signal and interfering signals. The
purpose is the same as for a crystal filter but the Q-X’er in operation is a
much more effective device. Three modes of operation are provided for as
follows
:
1. NOTCH - With the selector switch set in the NOTCH position, a very
sharp rejection notch may be tuned across the pass band of the re-
ceiver to eliminate an, interfering carrier or heterodyne. The gen-
eral shape of the receiver pass band is unchanged and the notch is so
sharp that it is almost imperceptible in the audio of the desired sig-
nal. See Fig. (1).
2. BOOST - With the selector switch set in the BOOST position again
the general shape of the receiver pass band is unchanged (though
lower in amplitude) but a sharp spike is imposed on top of the re-
sponse. This spike may be tuned across the pass band to boost any
single frequency. See Fig. (2). Generally, this position of the
switch is used to boost the carrier of a weak phone or broadcast
station to prevent distortion due to selective fading, etc.
3. PEAK - With the selector switch in the PEAK position the pass band
of the receiver is narrowed to a very selective response only a few
hundred cycles wide. Fig. (3). This is ideal for C. W. reception.
The Q-X’er TUNING control can be used for a fine adjustment in
tuning in the signal.
note).
(Tuning here does not change the Beat Frequency
In principle of operation, the Q-X’er is simple.
It is a two terminal de-
vice shunted across an I. F. transformer ‘in the receiver to act as a gate letting
through the desired frequencies and stopping the undesired frequencies.
The
Q-X'er achieves its performance through the use of an efficient, stable Q mul-
tiplier circuit. The Q-X’er acts just like
a
resonant circuit with a Q of approxi-
mately 3000. This accounts for its sharp peak or notch.
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