There was a recient request for a CW keyer ckt. This is one that I
pulled from a very early version of CT. This could be the same circuit
that K6LL
sent.
SENDING CW
Morse code is sent by keying the DTR line of COM1, COM2,
or the STATUS line of LPT1 or LPT2.
The circuit needed to key positive keyed radios from COM1 or
COM2
is a 1K resistor from DTR (pin 20 on a DB25, pin X on a DB9) to the base
of
an NPN small signal transistor (for example, a 2N4400, a 2N3904, etc.).
The
emitter of the transistor and the ground lead of the transmitter keying
cable
are connected to SIGNAL GROUND (pin 7 on a DB25, pin X on a DB9).The
collector of the transistor is connected to the transmitter keying cable
(hot, not ground side).
The circuit needed to key positive keyed radios from LPT1 or
LPT2 is a 1K resistor from SLCT (pin 17 on a DB25) to the base of an
NPN
small signal transistor (for example, a 2N4400, a 2N3904, etc.). The
emitter
of the transistor is connected to STROBE (pin 1 on a DB25). The ground
lead
of the transmitter keying cable is connected to SIGNAL GROUND (pin 18 on
a
DB25). The collector of the transistor is connected to the transmitter
keying cable (hot, not ground side).
****************************************************************************
KEYING CKT
DB25| 1 k __________________> Tx key
| | / C
20|___ /\/\/\__b|/
| |\
| \ E
|_ _____________\________________________ Tx grnd
Universal Keying Interface
by Art Boyars K3KU
Here's a circuit which will key either positive or negative voltage
lines (i.e., either your +12 VDC transistorized rig or your -60 VDC grid
block transmitter).
For -VDC (grid block) keying, when Q2 is driven (ON), it sinks
base
current from Q1, which switches on. With both transistors saturated,
the
key line is within a few tenths of a volt of ground. R1 is chosen so
that enough emitter current is supplied from the Vcc source to drive the
key line, typically about 2mA for grid block keying. For example, for
Vcc=+5V and i=2mA, R1 should be about 2.2k or so.
For +VDC keying, Q1 does not act as a transistor! It's
collector-base junction just acts as a diode, conducting key line
current
down to the Q2 collector. The small penalty is that Q2 also has to pull
the Vcc/R1 current. This wasted current won't matter unless you are
trying to run flea power. R2 is chosen to get enough base drive to
saturate Q2. It doesn't take much, and even a CMOS output can probably
do the trick. Q1 has to have a high enough breakdown voltage rating to
handle the VDC. Q2 only has to be rated at the +VDC.
If you have a negative input signal and negative Vcc, just make Q1
NPN and Q2 PNP. In that case, both transistors need to handle the
higher
voltage.
(Reprinted from the PVRC Newsletter, February 1990. Thanks to KM3T
for
help in obtaining this circuit and description.)
Schematic for Universal Keying Interface by K3KU
R1
+Vcc O-------/\/\/\-----\ Q1 /-------------O key line to
rig
\(PNP)/
> /
-------
|
|
/
|/
R2 |
O------/\/\/\------| Q2 (NPN)
|\
\
>|
|
|
|
__|__
___
_
Notes:
Will key either transistor or grid-block keyed transceivers.
+Vcc is 5-12 volts.
R1 (K ohms) = Vcc/2.
Art used R1 = 4.7K ohm --> Vcc ~ 9 volts DC
R2 = 2 K ohm
You could use Vcc = 12 volts DC, with R1 = 6 K ohms for convenience,
since many shacks have 12 VDC readily available.
Ham Radio1\K3KU.DOX
Voice Keyer Control
K8CC's documentation reads:
NA has the capability to trigger four memories of an outboard voice
keyer through the LPT1 port. The exact implementation of an interface
will
depend on your particular keyer, but the following should be typical:
Q1
LPT1 ---
10K | C|-----------------
memory 1 sw
3 --------/\/\/----------------- |B |
| E|---
--- |
|
Q2 |
--- |
10K | C|---|-------------
memory 2 sw
4 --------/\/\/------------------|B | |
| E|---o
--- |
|
Q3 |
--- |
10K | C|---|-------------
memory 3 sw
5 --------/\/\/----------------- |B | |
| E|---o
--- |
|
Q4 |
--- |
10K | C|---|-------------
memory 4 sw
6 --------/\/\/----------------- |B | |
| E|---o-------------
switch common
---
11 --
|
o------------------------------------------------
case ground
|
25 --
Q1 thru Q4 are four garden-variety NPN transistors
(2N4400, 2N3904, etc.). Further details or ideas are are available from
K8CC. The following keys activate the outboard voice keyer:
F1 Send keyer message 1
F2 Send keyer message 2
F3 Send keyer message 3 (assumed to be the QSL/QRZ
message)
F4 Send keyer message 4
* Log QSO and send keyer message 3 (log/QSL/QRZ process)
To stop the message, you must use the voice keyer controls.
Mike Griffin WE6G also had a nice schematic, powered by a 1.5 volt
battery, published in the March/April 1990 issue of NCJ, page 25.
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