TECH NOTES

Using Keyer Paddles with the W9XT Contest Card

Dave Pruett, K8CC

Beginning with NA Version 8, provisions were included to allow a keyer paddle to be connected to the computer’s LPT port to manually send CW. The W9XT Contest Card from Unified Microsystems was originally designed prior to NA8, and therefore did not include paddle capability. Fortunately, this feature can be readily added to the Contest Card. Courtesy of Gary Sutcliffe, W9XT of Unified Microsystems, here’s how to do it. But first, a few words from our sponsor:

CAUTION: Making these modifications could void the FCC Class B certification of the Contest Card. It will be your responsibility to see that proper steps are taken to prevent interference to nearby radios, TVS, etc. If interference occurs, you must stop using this device until you correct the problem. Furthermore, making this modification will void the warranty if, in the opinion of Unified Microsystems, damage occurred because of improper modifications or poor workmanship in making the changes.

Procedure:

1. Add a wire from U11 pin 1 to U11 pin 15.
2. Install a 10K, ¼ watt 5% resistor between U11 pin 16 and U11 pin 10.
3. Install a 10K, ¼ watt 5% resistor between U3 pin 14 and U11 pin 6.
4. Install a wire from J1 (the DB-25 connector) pin 17 to U11 pin 10 (including the resistor added in step 2). The wire end connecting to J1 will need to be soldered to the pin on the solder side of the board. You may wish to route and solder both ends of the wire on the solder side of the board.
5. Install a wire from J1 (the DB-25 connector) pin 18 to U11 pin 6 (including the resistor added in step 3). The wire end connecting to J1 will need to be soldered to the pin on the solder side of the board. You may wish to route and solder both ends of the wire on the solder side of the board
6. Add a wire from U11 pin 9 to U9 pin 9.
7. Add a wire from U11 pin 7 to U9 pin 7.

Note: If you are using the optional RECORD switch (not required with NA), one side may already be connected to pin 5. Both the paddle COMMON and the record switch GROUND wires may be connected to pin 5 if both are used.

Here is a photo of a modified contest card. At the lower right the resistors added in steps 2 and 3 are clearly visible. The wires added in steps 1, 6 & 7 are also located in this area. The long wires added in steps 4 and 5 stretch from the resistors across the bottom to the lower left where these make connection to the pins of the DB-25 connector.

Some K8CC construction tips:

• The Contest Card manual does not include a PC board component layout, but the various ICs can be readily identified by the silk screen on the component side of the board.
• Pin 1 of each IC is marked with a molded in dot on the top of the IC. On the foil side of the board, the PC pad for pin 1 is square while the others are round. When counting pins on the foil side of the board, start at pin 1 and count clockwise.
• Small gauge wire is crucial for making the fine connections required. I use the small wire intended for wire-wrapping prototype boards. BE CAREFUL TO AVOID STRAY CONNECTIONS OR SOLDER BRIDGES.

Paddle connections to the Contest Card are made as follows:

• J1 pin 17 to the DOT contact on your keyer paddle.
• J1 pin 18 to the DASH contact on your keyer paddle.
• J1 pin 5 to the COMMON on your keyer paddle.

For more information on the W9XT Contest Card, visit the Unified Microsystems web page at http://www.QTH.com/w9xt, or e-mail W9XT at ppvvpp@mixcom.com.

DATOM Tech Notes:

• Use of Computer Ports
• Using Keyer Paddles with the W9XT Contest Card
• Understanding Rate Displays in NA
• State QSO Party Tips Using NA
• Using NA with the new WPX Multi-Single rules