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| Modifications by Bill W4HBK |
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| Written by Hans Summers | ||||||||
| Monday, 03 January 2011 17:46 | ||||||||
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Click the thumbnails for the full size photos. Bill W4HBK writes: "The QRP Labs MEPT is one of the sweetest little rigs I've ever used. Here's how I finished it up and made a few mods to tailor it to my particular needs.
"The external keyer is QRS by ON7YN which I use because it has a very accurate and stable timing control which is required for image stacking using Rot'N'Stack. The AT13 keyer timing is subject to drift with temperature. The program's output is via the serial or parallel computer port either one of which will key the rig the same as the AT13. You can see the red wire which runs from pin 3 of the AT13 in the upper left of pic 2 to the keyer jack input at the lower right. To restore the keyer I just pull the wire out of pin 3 and re-insert the AT13. "I'm also using a 9V ps which has increased the output power to 280 mW, compared to 60 mW when using 4 AA cells. The AT13 is designed for 5 v and QRP Labs cautions that anything over 6 V may kill it. Since I pulled the chip that's not a problem. At 9V the 2N7000 is barely warm to the touch, due in part to the little heat sink thingy. When going to a higher voltage be sure to follow the adjustment instructions carefully..I've read a few emails about burned out 2N7000's." |
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| Last Updated on Monday, 03 January 2011 18:02 |



