Introduction |
The 706 can be a fairly ugly radio if you don't want to shell out mucho bux for an Icom automatic antenna tuner. Although a manual tuner will work, getting the radio to put out a steady signal so you can tune is a bit of a pain. The radio does have a tune button to cause it to put out a 10 watt carrier, but the button won't work unless it recognizes an Icom tuner plugged into the back. Chris, G4FZN, came up with a nice little circuit to solve this problem. |
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Schematic |
706 Tune Control Schematic |
Parts Layout |
In building this, I decided to use Manhattan style construction, a la K8IQY. With Chris' schematic in hand, the first step is laying out the parts and the necessary pads. 706 Tune Control Parts Layout |
Pad Placement |
I did this in a graphics editor that works in layers so it was a simple matter to print out only the pads to trace on to the copperclad. 706 Tune Control Pad Placement |
Marked Up Circuit Board |
The next step is to trace the pad placement onto a piece of copperclad. I simply laid a printout of the pads over the board then poked at each corner of a pad with a permanent marker, allowing the ink to bleed through the paper. Then I could connect the dots to get the pad outlines. Circuit board marked up ready for gluing pads |
Pads Glued |
Now I can glue the pads (cut from copperclad with a Radio Shack nibbler) on to the circuit board and tin them. Circuit board with pads ready for parts |
Finished Board |
Well, after attaching the parts and plugging the little board into the back of the radio it works like a champ. Pressing the tune button causes the radio to emit 10 watts for about 10 seconds - just about enough time to twiddle the knobs on my tuner! Finished Board |
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27 Dec 2004