This Digital Interface Connects Between Your Collins HF
Transceiver and a Computer.
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| Based on a circuit offered in
www.DigiPan.com, it has been
redesigned to provide a universal radio/computer interface, and to meet
the specific needs of a Collins KWM-2. The Rx audio out circuit is
designed for a 500/600 ohm Line Out feed, which most radios do not give.
If your radio only provides speaker impedance, use the circuit values in
the original design. [C1 may require 3.3mfd electrolytic if radio uses
common PTT & mike audio line]. (See DigiPan circuit for details). A
potentiometer in the Tx audio portion, allows a gain set independent of
your transceiver Mike gain, allowing the Mike gain to be set constantly at
what is used for Voice. Relay K1 (instead of an optocoupler), is used for
universal transceiver PTT control, including tube type older rigs that
often use -70 volts, which would overwhelm an optocoupler (K1 load
contacts will handle up to 500 ma). Since the KWM-2 brings all necessary
connections to the rear via RCA phono jacks, I elected to use them on the
interface, with RCA/RCA phono cables for interconnects. Please note the
input common is isolated completely from the output common. Also, the
middle (Ring) connection on the 3.5mm stereo plugs to the Computer Sound
Card are NOT used, only the tip connection (left audio). |
enclosure (LMB Crown Royle series) ... 537-CR-321
serial cable & plug ............................... 172-0910
T1,T2 .................................................. 42TL016
K1 ...................................................... 655-JWD-107-5 (DIP 5/6 VDC SPST-NO)
D1 ...................................................... 1N34 Germanium diode
(Mouser minimum resister order is 10 each,
currently $0.08 each, otherwise, Mouser has no minimum order)...
560 ohm ........ 270-560-RC (10)
4.7 K ............ 270-4.7K-RC (10)
22K .............. 270-22K-RC (10)
10K pot ........ 31VJ401-F
Knob ............ 450-1170
C1 = 0.01mfd, disk ceramic ................... 140-50V5-103Z-RC
[3.3 mfd electrolytic ( if needed)............... 647-UVP1HS3R3HDD ] |
A printed circuit board has been made available for this project from
FAR Circuits. It is a double sided board so that you can solder
the DB9 connector and the pot, directly to the board. Cost is around $7.50
ea. Many thanks go to Fred, KF9GX of FAR Circuits for his time and
interest in making this p.c.b. available. Take a look at the FAR Circuits web
site at www.farcircuits.net
then email Fred at FAR Circuits
snail mail to:
Fred KF9GX
FAR Circuits
18N640 Field Ct.
Dundee, Il. 60118
tel: 847-836-9148 fax and phone.
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| Other notes: Resistors may be 1/8w, or better. Use
shielded cables for the sound card feeds, AND, for the audio connects to
your transceiver. Use a metal enclosure, it will be in a high RF
environment. Use rubber grommets if cables pass through the case. Check
each 3.5mm audio cable for color coding, they are NOT uniform. [Roland
Burgan, KB8XI - Nov/2006 ].
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