2 watts 3 band qrp cw transceiver - 7/10/14 MHz
This radio is very similar like monoband version but it has been extended with a filter unit.
The filter unit contains three bandfilter which can be switched by latch type relays.
The first mixer and BFO are built around an NE612 gilbert cell IC. The IF amplifier is an MC1350P.
I left the variable bandwidth crystal filter from the previous design.
The final PA transistor is the 2SC1969. It delivers about 2 watts to 50 ohm.
I tried to keep low the current consumption therefore I changed the AD9850 dds to AD9834 low power dds ic.
The AD9834 running at 50 MHz so the maximum usable frequency of the transceiver is about 21 MHz.
Obviously, it depends on the choosed IF frequency as well.
I sell this machine to a ham who made thousands SOTA qso in the field.
Control and DDS unit