Antenna Tuner is Too Smart

Automatic antenna tuners are great. Just tune your radio to the frequency you want, flick the TUNE switch, and you quickly get an optimum match between your rig and the antenna. Well, not always. I have an ICOM IC-7000 with an LDG AT-7000 antenna tuner. This is a great little tuner, but it sure tricked me this time.

I wanted to try my rig on the 6 meter band for the first time. So I set up the station and was listening around for signals during this weekend’s VHF contest. There are some CW beacons I had heard before, so I tuned to that part of the band, activate the tuner, and heard nothing. Then I hit the TUNE button again, bypassing the Tuner, and the beacon suddenly appeared! So I hear no signal with the Tuner doing the matching, but I hear the beacon when I bypas the Tuner.

After noticing that the SWR was indeed lower when the Tuner was inline, I realized what was happening, The Tuner has many memories. If it found a “good” match at a frequency, it uses that information to shorten the tuning cycle next time you go to that frequency. The Tuner had apparently found a match that provided a low SWR, but it also resulted in a lossy signal path. The instruction manual showed me that I could go into the Tuner case and push a switch that would force it to retune, even though it thought it had a good match already. So I pushed the button, the relays clacked, and presto, a good match and the beacon reappeared. Guess this button should be on the front panel! Then I worked my first 6 meter station ever.

Mounting passive SMT components

Just getting around to continuing assembly of NUE-PSK modem. Latest work included soldering SMT diodes (very small), electrolytic caps, and chip capacitors. These are all 2-lead packages. I found that the easiest way to mount all of these components was to do the following:

1.Put a drop of solder flux on each pad for the part

2. Put a very small amount of solder on one pad for the device

3. Position the board so you can see both of the pads for the device

4. Place the part, making sure both leads line up with the center of corresponding pads

5. Press down on the part, holding it in place and assuring contact between the leads and pads

6. Reheat the solder on the pad where solder was added (the part should now be holding to the one pad)

7. Add a very small amount of solder to the other pad

8. Press on the part and reheat the solder on the second pad

9. Return to the first pad and reheat briefly to make sure a good connection was achieved.

This sounds like alot of work but is really fairly easy. A good magnifying loop, small solder (.015″ or .020″ diameter), and a small soldering iron tip are indespensible for SMT work.