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Ham Radio

Success with the SS-40TX

[Today: rest day]

Success!

Short version:  I cleaned up my mess and the thing works as expected.

Long version:

I built the thing; I had a couple of glitches along the way.  But I was pretty sure I had it put together correctly, in the general sense.  The last step was to tune it up and aim for 5 watts of output.  The directions specified how to set the no-drive bias current.  And, as you recall, my bias current was some out of whack number.

So I looked it over and I pondered the schematic and I tried to take measurements.

Eventually I broke down and sent a few emails out.

It frequently is the case that I’ll find some elementary problem after hitting “send”.  This time it took a bit longer.

I actually had “tuned” it up such that I got it on the air and had a few QSO’s during the November Sweepstakes CW contest.

But then I got an email back from the kit designer.  He confirmed the numbers in the directions and that my out-of-whack reading was not within the expected range of good values.  He suggested I take pictures of my board, front and back, and send them to him.  I proceeded to take a video, which I will attach at the end of this post.

I find the shiny soldery side to be very hard to see.  In looking it over, I finally decided there was one place that I had forgotten to solder and another place where the solder looked a little lax.

The place I had forgotten to solder was on the right-hand leg of diode D5.  In the video at the :27 mark you can see right through the hole.  It’s not supposed to be that way.

I touched up both of those two places, went back to my measuring setup, and I measured the zero-drive idle current at 92 mA, very close to the published value of 95 mA.  Following the rest of the directions, I soon had the thing putting out well over 5 watts.  I set it at 5.14, or some such number; as close to 5 watts as I could get.

It’s a win!

Now I need to go back to all of my question email places and be embarrassed about having missed soldering in a component!

Link to the video