The Ameritron ALS-600 QSK Mod Is Done

The QSK modification for my recently acquired ALS-600 solid state amplifier is now complete. The instructions for this modification by AD5K are quite good as is the small PCB he can supply anyone wishing to give this alteration a professional look. The mod is a simple one, easily handled by even a beginner electronic kit enthusiast.

AD5K ALS600 mod in placeThe idea behind this improvement is to replace the stock open frame relay (about 10 ms delay) with much faster (3 ms) closed frame relays so as to ensure that the exciter isn't "hot" during that relay delay during TX decay (cue the music!).

I have an appreciation for keeping equipment stock, so it felt weird to remove the old relay, especially the step where you grab the frame itself, held in my a single screw, and rock it back and forth until the screw strips out. Sort of like pulling a stubborn molar. It's not an entirely irreversible step, but might as well be.

PCB with buss wire sticking through
Besides the two 16-pin IC sockets, the two relays, PCB, and a 1N4007 diode, the AD5X kit comes with two short pieces of stiff buss wire, gauge 20 and 28. These wires are cut into 4" lengths and soldered to the contacts in the old relay base according to the diagram in the instructions. The smaller gauge wires are for the DC power and amp bias, while the bigger ones handle the business end of the RF switching.

The original black RF In and RF out wires, which were cut long when removing the old relay are re-attached via this small board. I departed from the instructions in this respect only in that I re-attached those connections before I had the board in final position so that I had more room to maneuver. Then I pushed the board down as far as it would go, soldered the wires and flush cut them.

finished mod close-up
The final package looks neat and the retro look to the PCB could even make you believe this was part of the original machine.

Really, that is all there is to it. It seems to work very FB at 30 WPM (AD5K tested it at 80 WPM). You'd have to listen closely to even hear the relays switching. Unfortunately, I didn't have time to test it in a QSO as our usual afternoon T-Storm rolled in before I got that far, but soon, soon. 73!

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  1. Awesome blog you have here...overall i'm really like it, very useful article, because 2 meter band & 80 meter its my hobby during my off job

  2. This comment has been removed by a blog administrator.


Thanks very much for your comment! 73, Casey