10. The side tone will now announce “CO” A low pitched tone will be heard in the headphones.
Local Oscillator frequency trim:
This is used to trim the LO frequency to exactly match the center response of the IF crystal filter. This will ensure the best
sensitivity of the receiver. This adjustment is made with the help of an Oscilloscope. An audio spectrum analyzer program
running on your PC would also work. A program of this type is located on the CD. If one isn’t available, skip to step 5 and
peak the BFO trimmer by ear. You can solder a short wire to TP2 and one of the headphone jack pins to hang a clip lead
onto.
1. Connect a ‘Scope to TP2 (pin 1 of U3) ( 2V / div, 1 ms / div sweep)
2. Preset the BFO trimmer cap (CT1) by giving it about a ¼ turn.
3. You should hear a pretty loud tone in the headphones.
4. Repetitively click the Tune Down switch to step the LO frequency through the pass band of the filter. Note when the signal
at TP2 starts to decrease. Now start clicking the Tune Up switch and keep track of how many steps it takes before the
signal starts to decrease again. This tells you how wide the filter is. (Each click (step) tunes about 10 Hz.) Divide the
number of clicks by 2, then re-tune with the Tune Down switch that number of steps. The LO frequency will now be set to
the center of the pass band of the filter.
5. Move the input to the Scope to one of the headphone jack pins.
6. Adjust the green BFO trimmer cap, CT1, and peak the audio signal at the headphone jack. This centers the beat note in
the audio band pass filter.
7. Click the MENU button again to finish the calibration. The rig will reset and restart.
If the above calibrations worked, you know everything but the transmitter and filter boards are working properly. You can now
go onto the testing and adjusting the band filters. Otherwise, go to the trouble shooting guide on page and track the reason
the rig isn’t working down.
Band filter test and adjustment:
Turn the power to the rig off and insert a band module. Temporarily connect an antenna jack to the antenna pad and
ground on the main board, using short wires or coax. If possible, use regulated 9.0 volt supply or “AA” battery pack with new
batteries.
1. Connect an antenna or signal generator to the antenna input.
2. Power up the rig. Peak the Rx input trimmer caps for best signal or peak band noise.
3. Turn rig off.
4. Disconnect the antenna and connect a power meter and dummy load.
5. Insert a straight key or paddle into the paddle jack. If using a paddle, hold the DASH paddle closed when turning the rig
on, and hold closed until you hear the band annunciation. After that, the DOT paddle will work like a straight key.
6. Turn power back on. Key the rig and note power output. With a 9.0 V supply, power output should be 2 watts or more.
With a 12.0 V supply, power out should be between 4 and 5 watts out.
7. If power output is off significantly, check capacitor values in the filter and number of turns on the coils. Make sure your
using a watt meter which is accurate at these power levels.
8. Power output can be adjusted by changing the spacing between the turns on LF1 and LF2. LF1 generally has the most
effect. Assuming the coils were wound with the wire more or less evenly spaced, you will find most of the coils need to
have at least some of the turns moved closer together to archive at least 2.5 watts out. The 17 and 15 meter bands are
most sensitive to these adjustments and will definitely need to be tweaked to achieve the desired power output.
9. You can remove and insert the filter board with power to the rig on, though moving the coils to the top of the board makes
things easier. Ideally, you should shoot for about 2.5 watts out on all bands, using a 9.0 V supply and no more that 4.5
watts with a 12.0 volt supply.
If you've gotten this far, Congratulations! Everything seems to be working and you can mount the rig into a tin and start
operating.
Mounting the board into an Altoids tin:
Although other enclosures for the rig are possible, especially if ultra light weight is a goal, the board was designed to fit into
the ubiquitous Altoids tin. The hinged lid of the tin makes it easy to get inside and change band filter modules. Don't worry
about it not being rugged enough. I have carried my rig for literally 100's and 100's of miles along the Appalachian Trail,
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