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Picture above is my Lovely wife Karen ( N3IBN ) who says if you can't beat them join them

Clubs: 10-10 - 50585 with VP of 2541, PODXS 070 - 1533,  EPC - 17661

Here is my Sound Card Interface normally it has a cover on it but for pictures I opened it up. I am using a USB Sound card and not my computer sound for the audio source. This makes for a nice neat package and allows me to still use the sound card in my computer for windows sounds.

Total Cost of this project with Box and 13 Pin Din was $15.00 without parts from the parts box project should not cost over $25.00 and it has a True CW Key Port

It is Sound Powered Keying is done Via Right Channel Tone with Fldigi and I have found that the digital mode audio from most modes is more than enough to power the keying circuit. That is where the pots come into play to back down the audio out and audio into the rig.

Note: it works great with JT65 HF and Digi Pan Also works with CwType for True CW Keying and no it does not read CW

Most of the parts are from scrap dial up modems and the USB Sound card was $1.00 on Ebay

Hello let me give you a parts list and description of operation for this interface.

1 - USB Sound Card EBay $1.00

3 - Isolation Transformer 1:1 from Old Dial Up Modems

2 - 1N4148 Diode $1.99 for 100 of these guys EBay

2 - .22mf Capacitors I used .1 in parallel to get .2mf $.10 each

3 - 820K Resistor $.03 each

1 - 2N7000 MOSFET Transistor $.10 each

2 - 20K Potentiometer $.20 each

1 - 13 Pin Din $5.40

1 - Switch SPDT $.50

1 - Phone Jack 3.5mm $.10

1 - Case Radio Shack 270-238 $3.49

2 - Circuit Boards 276-159 $2.50 for both

Scrap Cable etc.

The keying circuit takes audio from right channel and passes through the full wave rectifier and powers the MOSFET for PTT, FSK and CW keying. The Pots adjust the output and input levels. Volume level must be set High on the computer volume control  for the keying circuit to work. I added some 820K resistors in series with the Pots to allow for a wider adjustment range. The Switch is after the FET to put the PTT from Fldigi to Pin 2 on my Kenwood TS-2000 Acc2 Jack for FSK.                                                  

NOTE: This interface has since been modified for a YAESU FT-817ND and works well but I needed to remove the 820K resistors and changed the pots to 20K might work even better with 50K pots for the Yaesu. An old busted computer keyboard supplied the needed cable for the data port on the Yaesu. Also as you can see I added an old speaker that I had sitting around and it gave me the added feature of TX Monitor. One additional Cap was added on the primary of the Isolation Transformer on the Keying circuit, this was added after I was contacted that a fellow ham built the keying circuit for CW use and at high power portable operation he got an RF feedback and it kept the rig keyed. The .001uf cap solved the problem. Here is a big plus for this interface in Linux you do not have to fight the serial port configuration being that it is a VOX type keying as long as the USB sound card is found in Linux it will work for you. I have tested this on non Linux apps in Wine and it still works no issues.

Please Note I am not the orginal designer of the circuit but I have modified the orginal for my needs



Well I had to sell my trusty Yaesu FT-817nd so for the time being I will be without an HF rig so hope to see you on the waterfall soon.




8637730 Last modified: 2018-02-09 17:22:02, 4474 bytes

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QRZ Logbook Summary for - N3GTY
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dedateband mode grid Country op
CM3HVY 2018-02-22 40m FT8 EL82VL22 Cuba Yunarky Vicente Hernández
WB2HJQ 2018-02-22 40m FT8 FN21kq United States KENNETH E KATZMANN
W5DMT 2018-02-22 40m FT8 EM65NS31 United States DAVID M TIPTON
K2CCW 2018-02-22 80m FT8 FM29CP74 United States Brian Bourdon
AI5I 2018-02-22 80m FT8 DM65xr United States WILLIAM JUNOR
DF2KD 2018-02-22 20m FT8 JO30gm Germany Karl Dieter Heinen
EA1DWI 2018-02-21 20m FT8 IN62bi Spain Carlos Reboreda Bernal
IK4RAS 2018-02-21 20m FT8 JN54sj Italy Alessandro Bernardini
K5IUA 2018-02-21 20m FT8 EL29IJ99 United States JOHN D GODWIN
W0AVM 2018-02-21 20m FT8 DN91pd United States Scott A Ericson
G0DLV 2018-02-21 20m FT8 IO70RU55 England Chris P
WB5XX 2018-02-21 20m FT8 EM33pg United States GEORGE G WELLBORN, JR
HA5UK 2018-02-21 20m FT8 JN97om Hungary GYORGY KOVACS
F5PHW 2018-02-21 20m FT8 IN87js France PHILIPPE BERGER
OZ1FHU 2018-02-21 20m FT8 JO55uq Denmark PREBEN LARSEN

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United States Counties Award#732
Granted: 2016-07-19 15:15:03   (N3GTY)

  • 100 Counties Mixed
  • 1000 Counties Mixed
  • 250 Counties Mixed
  • 500 Counties Mixed
DX World Award#381
Granted: 2015-01-23 19:17:50   (N3GTY)

  • 10 Meters Mixed
World Continents Award#1381
Granted: 2015-01-23 19:14:45   (N3GTY)

  • 10 Meters Digital
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  • 12 Meters Mixed
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Grid Squared Award#1258
Granted: 2015-01-23 19:14:44   (N3GTY)

  • 5 Band Digital
  • 10 Meters Digital
    12 Meters Digital
    15 Meters Digital
    17 Meters Digital
    20 Meters Digital
    30 Meters Digital
    40 Meters Digital
    80 Meters Digital
  • 5 Band Mixed
  • 10 Meters Mixed
    12 Meters Mixed
    15 Meters Mixed
    17 Meters Mixed
    20 Meters Mixed
    30 Meters Mixed
    40 Meters Mixed
    80 Meters Mixed
United States Award#277
Granted: 2015-01-23 19:13:41   (N3GTY)

  • 20 Meters Digital
  • Mixed Digital
  • 20 Meters Mixed
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