Drake Q-X'er Service manual
INSTRUCTIONS
for
'
QX
er
R.
L.
DRAKE
The
Q-X’er
to help discriminate between the wanted signal and interfering signals.
purpose is the same as for a crystal filter
much more effective device.
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 receiver to eliminate an, interfering carrier or heterodyne.
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 signal. See Fig. (1).
2. BOOST
the general shape of the receiver pass band is unchanged (though
lower in amplitude) but a sharp spike is imposed on top of the response.
single frequency.
switch is used to boost the carrier of a weak phone or broadcast
station to prevent distortion due to selective fading, etc.
COMPANY
I. GENERAL DESCRIPTION OF
is an attachment for a radio receiver.
but the Q-X’er
Three modes of operation are provided for as
-
With the selector switch set in the BOOST position again
This spike may be tuned across the pass band to boost any
See Fig. (2). Generally, this position of the
Q-X’ER
Its main purpose is
in operation is a
The gen-
The
3. PEAK
of the receiver is narrowed to a very selective response only a few
hundred cycles wide. Fig. (3).
The
tuning in the signal.
note).
In principle of operation, the
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.
Q-X'er
tiplier circuit.
mately 3000.
achieves its performance through the use of an efficient, stable Q mul-
-
With the selector switch in the PEAK position the pass band
This is ideal for C. W. reception.
Q-X’er
This accounts for its sharp peak or notch.
TUNING control can be used for a fine adjustment in
(Tuning here does not change the Beat Frequency
The
Q-X’er
Q-X’er
acts just like a resonant circuit with a Q of approxi-
-1-
is simple.
It is a two terminal de-
The
It should be noted here that there are three tuned
circuits involved in the operation: (1) in the I. F. transformer of the receiver,
which tunes out the capacity of the coax cable, and (3)
the
Q-X’er
important that these three circuits be tuned to the same
frequency.
tuning circuit.
Follow the installation instructions carefully.
II. INSTALLATION INSTRUCTIONS
(2) the input coil of the
For proper operation it is
Q-X’er
Connect power to the
1.
Green wire to one side of
White wire to other side of
Note:
Red wire to B-t 100 to 300 VDC
Current required is
Black wire to Ground or B-.
This
power can usually be taken from the accessory socket of the
receiver or slicer.
plug and socket
When a power or accessory socket is available, remove the 4 pin
plug which is supplied and replace it with one to match the acces-
sory socket.
Turn on receiver (if it has variable I. F. selectivity, set for most
2.
tive position.
center a steady carrier.
tuning again until
Slightly turn in each direction the adjusting screw on the 455 KC I. F. cir-
3.
cuit to which the
to the rest of the set.
of the mixer tube.
such as the grid following a crystal filter or the plate or grid end of a
mechanical filter.
for
DO NOT connect coax cable yet.
If it has a crystal filter,
Q-X’er
Neither green nor white wire is grounded
in the
ter tap ground or one side ground is 0. K.
Current required is
The
use when accessory socket is not available.
Q-X'er
Q-X'er
This tuned circuit is preferably the one at the plate
Do not connect the
as follows:
6.3
V. heater supply
6.3
V. heater supply
Q-X'er so a
Q-X’er
("S"
is adjusted.
is to be connected to see that it is exactly peaked
cable is supplied with a 4 pin
meter will show a peak.) DO NOT change
heater supply with cen-
.3
amps.
.25
to 2 ma.
leave it off. ) Carefully tune in and
Q-X'er
to a low impedance point
.
selec
-
Connect the I. F. coax cable of the
4.
As stated, the mixer plate is ingeneral the best spot.
tube is used, the connection can be made by removing the tube from the
socket, slipping the loop on the cable over the plate pin, and replacing the
tube in the socket.
be made by soldering directly to the socket under the chassis.
the coax direct; do not use a series condenser.
If a miniature tube is used, the coax connection should
Q-X'er
-2-
to the tuned circuit chosen above.
If an octal based
Connect
5.
Ground the shield of the I. F. coax cable to the chassis unless the
receiver has a “hot” chassis as in an AC-DC set.
receivers do not connect the shield; cut it off and tape the end to
prevent accidental connection.
6.
Remove two nuts on back of
Q-X’er
and pull off back cover and case.
In “hot” chassis
7. Set
8. Set
9. Replace cover and case.
Finding the Notch
trouble locating the notch.
ment for which there is only one correct setting.
mum rejection for all conditions.
trol must be set to within about
Q-X’er
L2 (see fig.
Q-X’er
below oscillation.
(maximum “S” meter reading).
Q-X’er
the
shielded coil,
switch to “OFF” position. Carefully adjust input coil,
5) for maximum
switch to PEAK.
Rotate
tuning range.
Ll
(see fig.
Note
Changing length of I. F. coax cable will cause detuning
of
tuned as in Step 7 of “Installation Instructions”.
recommend that the unit be adjusted and operated as
shipped before a change in cable length is attempted.
These two coils in the
:
455 KC. Your adjustment takes care of any small devia-
tion from 455 KC in the receiver I. F.
L2.
If the length must be changed, L2 must be re-
III. OPERATING INSTRUCTIONS
-
When you first use your
The NOTCH ADJ. control is a balancing adjust-
“S”.meter
Set PEAK ADJ. control to a point just
Q-X'er
If it does not, adjust the screw on the
6),
to peak the carrier at this point.
Q-X’er
For good notching, the NOTCH ADJ. con-
l/16”
reading.
TUNING knob to peak carrier
This should occur at the center of
Q-X'er
is now ready for use.
of this point.
are factory adjusted to
Q-X’er,
-
We
you will probably have
This setting will give maxi-
set NOTCH
To
Locate the approximate setting of the TUNING dial for some stable
1.
heterodyne by using the BOOST or PEAK position.
Turn switch to NOTCH and carefully turn the NOTCH ADJ. control
2.
until some rejection of the heterodyne is observed.
Slight adjustment alternately of TUNING and NOTCH
3.
maximum rejection of the heterodyne.
Leave the NOTCH ADJ. control set at this position.
4.
notching over the entire tuning range of the
never need to be changed very much.
ADJ.
control for the first time follow these instructions:
ADJ. will give
It will give best
-3
Q-X’er
-
and probably
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