Sunday, March 14, 2010

PFR3A success (for a change) !!!!!

A few weeks ago, I received the replacement 50 MHz clock oscillator chip from Dan Tayloe N7VE, for my PFR3A. I soldered U11 in; and was disappointed with still no receive signals on 40 Meters. All the voltages were now more or less correct - due to the tolerance of my VOM, they're a bit off from the PFR3A manual; but they were right in the neighborhood.

Due to a very busy work schedule, I have not had time to tinker until yesterday. Starting with the easiest thing, I replaced the 612s, thinking somehow I might have screwed them up. Still nothing - zip, zilch ...... the big donut hole. I really didn't want to mess around replacing already soldered in active components, if I didn't have to. Feeling clueless and out of frustration, I fired off an e-mail to Steve Weber KD1JV, asking him if he thought anything else might have been damaged by U11 being installed incorrectly. He answered me VERY quickly with this reply:

It's not likely anything else is damaged. Make sure you did indeed make good connections to the clock chip, they can be tricky. If you have a scope, you can check to see if your getting the 50 MHz clock signal out of the chip, down in the lower right corner.

Steve

I was going to play around some more; but then, the power went out as I posted earlier. So this afternoon, I went down to see what I could see. First thing I did was to yet again check the solder connections from the clock oscillator with my Ohm meter. From each corner of the chip, I received a gratifying "beep" telling me that I had connectivity. But I figured that "The Designer" must know what he's talking about; so I gave each corner another hit with the heated tip of my iron.

I hooked up the circuit board to my 12V SLA battery; and ran two jumpers from my Inverted L's feed line. I really didn't expect anything; but ..... lo and behold! The sweet tones of a CW signal greeted my ears! And what was even more beautiful and gratifying was when I fired up the K2 to find that the frequency read out for the K2 and the PFR3A were spot on! The only thing that I can guess as to what was happening was that I didn't have a good solder connection at U11; but when I pressed down with my Ohm meter probes, it APPEARED that I did. Doing the actual re-heat (again) finally made a good and very necessary electrical connection.

So right now, I feel like the contented cat that ate the canary. I am doing the happy dance (big time) knowing that A) I haven't wasted the money that I have spent on this kit; and B) that with some help, I was able to overcome this obstacle. From this point, I can continue onward - after I bask in the success for a few moments.

Thanks to Steve Weber KD1JV, Dan Tayloe N7VE and Bob W3BBO for their help, guidance and encouragement!

72 de Larry W2LJ

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