Refer to Pictorial
12
for the following steps.
( )
Secure the cabinet top in place, using
#6
lockwashers and 6-32 nuts on the spade
(
)
Now position the cabinet top between the bolts.
sides of the cabinet bottom. Carefullvguide
the phone jack under the circuit boa"& Be
sure the 4-wire cable
is
positioned
as
shown.
(
)
Check to see that the key lever
is
centered
in the slot of the cabinet tou.
If
the lever
hits the cabinet top, repeat -the key lever
(
)
Position the spade bolt of the cabinet top
adjustments on Pages 17 through
19.
into the notch of the cabinet bottom.
(
)
Carefully pull the line cord knot against
(
)
To open the cabinet, remove the nuts and
screws indicated by the arrows in the inset
the inside rubber grommet.
drawing of Retail 12A. Then lift the cabinet
top and circuit board out of the cabinet
Refer to Detail 12A for the following steps.
bottom.
(
) At the key lever end, swing the cabinet top
between the sides of the cabinet bottom.
(
)
Carefully peel away the backing paperfrom
Be sure none of the cables are pinched the blue and white identification label. Then
between the metal parts.
press the label onto the rear of the cabinet.
Be sure to refer to the numbers on this
(
)
Pit the spade bolts of the cabinet top into
label in any communications you have with
the holes of the cabinet bottom.
the Heath Company about this kit.
INSTALLATION AND OPERATION
PROPER TRANSMITTER VOLTAGES
CAUTION:
The key jack of the transmitter, to
which the
KEYED
LINE
of the Electronic Keyer
will be connected, must not have open circuit
or spike voltages
in
excess of -105 volts. Also,
the key circuit current must be less than 35
milliamperes, Most transmitters are well with-
in
these ratings, however, the transmitter should
be
checked before connecting the Electronic
Keyer.
If
the transmitter voltage or current
is
in
excess of these ratings, the 2N398A tran-
sistor may be damaged. Also, any positive volt-
age applied will immediately damage the 2N398A
transistor at Q10.
These transmitter ratings will be checked in the
following steps.
(
)
Connect a standard key to the transmitter
and place the transmitter in operation.
(
)
Next, connect a milliampere meter across
the key contacts (key-up). This current must
be less than 35 milliamperes.
The following step
is
to check for spike volt-
ages in excess of -105 DC volts to ground or
any positive peaks.
(
)
Connect an oscilloscope across the key.
Then operate the key while observing the
oscilloscope screen.
If
the open-circuit voltage
is
too high, it can
usually be reduced by connecting a suitable
value resistor across the key circuit. Normally,
a transmitter will require approximately 50 volts
to obtain proper keying bias. Higher keyingbias
voltages are sometimes used, as they are read-
ily available from transmitter power supplies.
Try various values of resistors until a safe key
circuit voltage
is
obtained, and satisfactory
transmitter cutoff
is
maintained.
(
)
Check the open-circuit (key-up) voltage
If
the spike voltages are too high, refer to the
across the key contacts. It should be less ARRL Handbook under the use of key-click,
than -105 DC volts (measured with a VTVM).
TVI, and
BCI
measures.
To Next Page
Loading...
