Wilderness / NorCal 40A - Modification for 30 Meters

The 40A is designed and sold as single band 40 meter CW transceiver, but it is possible to modify it for other bands.

Here are the component changes needed to put the 40A on the 30 meter band. Note that since you are converting to a higher frequency, the existing wire on the toroid inductors can be rewound with fewer turns.

  1. Replace all six crystals, X1 to X6, with 8 MHz crystals. It is desirable to use a matched set of crystals (within 20 Hz), and to use the four closest matched ones for X1 to X4, the receiver IF bandpass filter.
  2. Replace L1 with a 10uH fixed inductor.
  3. Rewind T3 with 21 turns on the primary and 6 turns on the secondary.
  4. Replace C6 with 39 pF capacitor.
  5. Rewind L6 with 24 turns.
  6. Rewind L7 with 13 turns.
  7. Rewind L8 with 14 turns.
  8. Replace C45 and C47 with 270 pF capacitors.
  9. Replace C46 with 560 pF capacitor.

The VFO will stay at 2.1 MHz. You may need to tweak the turns of L9, the VFO inductor, slightly to achieve the desired VFO tuning range of 2.1 to 2.15 MHz.

Note that this is not an authorized Wilderness Radio modification. You do this mod at your own risk. Although the component values listed above worked for me, there is no guarantee that they will work for you.

Other 40A modifications:

KC-1 modifications:

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Page issued May 30, 2007