Ten-Tec 243 - Page 3

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6.) When the Model 243 is not connected, jumper VFO IN and VFO OUT on the
rear
apron
of
your
@MNI
to
restore
normal
operation
with
cable
supplied.
7.) When using Model 244 Digital Readout with Model 243, use the two phono
jacks on the rear apron of the Model 243 to access the mixed local
oscillator and +12 VDC.
CRYSTAL INSTALLATION
1.) Remove Model 243 bottom cover.
2.)
Sockets
(4)
are
located
on
the
CRYSTAL
OSCILLATOR/SWITCH
Board
with
a
trimmer
capacitor
for
each
socket.
The
socket
on
the
outboard
side
is
for
X-1.
3.) The trimmer capacitors allow for a slight trimming of each crystal fre-
quency. The amount of frequency deviation depends on the crystal's cut,
frequency, case capacitance, and other characteristics, but nominally is
about +1.5 kHz.
4.) After frequency is trimmed, replace bottom.
CRYSTAL OPERATION
TEN-TEC, Inc. does not supply crystals for fixed frequency operation since
there are an infinite number of frequencies that may be selected. It is recom-
mended that crystals for your desired operating frequencies be purchased from a
reliable crystal manufacturer, to the specifications outlined below. It is not
necessary that all four positions be filled with crystals.
Out-Of-Band Limits
Band Frequency Range
160 1.7 to 2.10 MHz
80 3.4 to 4.10 MHz
40 6.9 to 7.40 MHz
20 13.8 to 14.55 MHz
15 20.8 to 21.65 MHz
10 27.8 to 30.00 MHz
Crystal Specifications
Case: HC-18/U.
Terminals: .041" diameter on .188 centers.
Mode: Fundamental only. Parallel resonance.
Load
Capacitance:
20
pF.
(At
32
pF,
frequency
is
slightly
higher.)
Frequency:
For
160,
80,
40,
and
20
meters,
use
a
crystal
cut
for
5
MHz
‡
kHz
from
lower
band
edge
of
segment.
For
10
MHz,
15
and
10
meters,
use
a
crystal
cut
for
5.01
MHz
+
kHz
from
lower
band
edge
of
segment.
For
example,
a
crystal
cut
for
5.050
MHz
will
operate
at 1.850, 3.550, 7.050, 10.040, 14.050, 21.040, 28.040, 28.540,
29.040
and
29.540
MHz.
A
crystal
cut
for
4.960
MHz
will
operate
at
1.760,
3.460,
6.960,
9.950,
13.960,
20.950,
27.950,
28.450,
28.950 and 29.450 MHz. Frequencies on or near the 10 MHz segment
will operate in the receive mode only. Frequency so determined
is
the
receive
frequency
in
only
the
SB-N
and
CW
positions.
Refer
to Page 2-10 of the @MNI Owner/Operator's
Manual
under Operating
Hints,
paragraphs
7 and 8 for further
explanation.
DIAL POINTER ZERO SET
When
calibrating
at
any
100
kHz
point,
the
slide
rule
dial
pointer
may
be
set
exactly
to
the
scale
marking
for
this
frequency
with
the
aid
of
the
serrated
disc
knob
protruding
from
the
bottom
of
the
case.
It
is
located
between
the
main
tuning
knob
and
the
MODE
switch.
This
adjustment
need
be
made
only
occasionally
as
the
string
system
ages,
since
the
pointer
is
not
intended
for
exact
indications
of
frequency,
but
rather
as
a
segment
indicator
telling
in
which
100
kHz
segment
you
are
tuned.
Accurate
frequency
determination
is
made
by
the
use
of
the
0-100
dial
skirt.
6L-V
EPT-T