Thursday, February 14, 2013

The RF board..

Now comes the fun. Take it slowly and carefully here and I recommend scrubbing RF board with alcohol and/or flux so the solder will lay down nice and smoothly with the slightest application of the iron. The traces here are huge patches of silvered copper and it's easy to build up mountains of unwanted solder and a bitch to wick the excess away. Also, the check-out/adjustment procedure requires soldering components temporarily onto these pads and then removing them. Inattention might lead to a mountainous mess.

Word to the wise. If you look closely, you can see where I was incautious with the solder on the back plane board and had to steel wool the excess away.

Also, there comes that moment of truth when you have to solder the RF board to the back plane board. Same caveat here: do not go crazy. "A little dab'll do ya."

Back plane, RF, and control board in place with transformer mounted.

Same; obverse view.

Yet more of the same from a different angle.

Here's the RF board with the components mounted

Yet more of same. See comments in this post about trim coil.

Sidelong view of RF board with mounted components

K6WHP luxuriates in his mighty efforts.

The whole magilla.

Lou provides you with the wire to wind the trimmer coil. He also provides some pre-wound springs. Here's my advice: use the springs. You will never wind a coil as neat as those springs. Also, about five or six turns should do the deed for the checkout.

Sidebar war story: I LOVE winding toroids and coils. They are probably the sexiest component in any kit. A long time ago, Doug DeMaw, W1FB, founded Oak Hills Research and they produced the OHR-100A and the OHR-500. The latter had a shit-pot full of toroids (about 20 or 30) in them and Dick Witske (who bought OHR from Doug DeMaw) apologized profusely to me when I bought the kit from him. But I told him I was on the verge of buying another one on the basis of the number of toroids.

Sure wish I kept that radio. It was all transistor; not an NE602 or LM384 in sight and quiet as the tomb. You'd tune across 40 meters in the evening with nary a hiss or crash until you came across a pure. clean CW signal. When I built mine and first turned it on, I thought the front end was dead until WB6JDH straightened me out.

-72-

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