Saturday, August 15, 2009


Whilst I was looking at crystal frequencies for the new qrss-ranges, I came along a very nice combi for a 3 band qrp trx for the bands 80m, 20m and 15m. (Frequencies in MHz)
  • 3,560 = 11,0592 - (15,000/2)
  • 14,060 = 11,0592 + (6,000/2)
  • 21,060 = 11,0592 + (20,000/2)
The division will be done by a flip-flop.

The combination offers the option for a ladder filter at 11,0592. In this case, one could consider, as an experiment at least, a subharmonic b.f.o. using a 5,5MHz ceramic oscillator in combination with a RA3AAE-mixer.

Writing of ceramic resonators, there is one for 6,0MHz. This would enable a nice v.f.o.-range for the 20m band.

When crystals are to be used, one could consider using a super-vxo.

UPDATE: Jan came up with an idea of adding 40m by using the combination
  • 7,037 = 18,096 - 11,059
OK, 7kHz is quite a stretch to pull, possible however, TNX Jan!