QSOing on 20m in PSK31 is fun. However, I think there are more options for the PSK-20.
The first thing that came to my mind, adding some switchable local oscillators. The design of the PSK-20 is a 9.0MHz i.f. with a 5.07 l.o. (5.0688MHz crystal). Here comes the idea, one could add some voice channels using cheap crystals:
This however would require to run a microphone preamp with an active low pass filter. The crystal filter of the PSK-20, for obvious reasons, is wider than a sideband filter.
The second idea is focused on the fact that the intermediate frequency is 9.0MHz.
As you may have seen, I was experimenting with a softrock lite on 30m. Those experiments where mainly aimed at the usablility of the softrock lite for 30m QRSS reception.
The softrock uses super-Nyquist, in short, the center frequency is 0.75 times the l.o.-frequency. This makes it comparably easy to use the softrock lite to "look" at a 9.0MHz i.f. with a l.o. crystal of 12.0MHz. This would add SDR and panoramic display to the PSK-20.
But, not only, since there also is a crystal 5.0MHz (or 10.0MHz divided by two):
And finally, one could think of penning down a 5,0688MHz crystal, in order to reach the QRP frequency. All one would need for a CW qso would be a 800Hz sine generator.
- 14.120 = 9.0 + 5.120
- 14.185 = 9.0 + 5.185
- 14.200 = 9.0 + 5.200
- 14.120 = 9.0 + (10.240 / 2)
- 14.350 = 9.0 + (10.700 / 2)
This however would require to run a microphone preamp with an active low pass filter. The crystal filter of the PSK-20, for obvious reasons, is wider than a sideband filter.
The second idea is focused on the fact that the intermediate frequency is 9.0MHz.
As you may have seen, I was experimenting with a softrock lite on 30m. Those experiments where mainly aimed at the usablility of the softrock lite for 30m QRSS reception.
The softrock uses super-Nyquist, in short, the center frequency is 0.75 times the l.o.-frequency. This makes it comparably easy to use the softrock lite to "look" at a 9.0MHz i.f. with a l.o. crystal of 12.0MHz. This would add SDR and panoramic display to the PSK-20.
But, not only, since there also is a crystal 5.0MHz (or 10.0MHz divided by two):
- 14.000 = 9.0 + 5.0
And finally, one could think of penning down a 5,0688MHz crystal, in order to reach the QRP frequency. All one would need for a CW qso would be a 800Hz sine generator.
