when I was a young SWL, I has build my first direct conversional
receiver (pict. 1) It was
too wonderful for me because he is very simple, just a three transistors
are in receiver's circuit and a few any details. I powered this RX by 9 volts battery
of pocket broadcast receiver. I has not a good antenna and I used
a piece of wire in my room. For the first testing construction
I did not made a PCB and build this RX as "space" style
on a piece of printed board. It was a 80m band version. Results
was shocked me at once!
Before I used for SWL old broadcast receiver
by 6 valves with home-made local oscillator. Having heard an ether on my new DC
RX and at once forgot about the old lamp receiver. The sound was
clear, sensitivity very high and I has heard a lot of DXs during
some evenings and nights. After my first fun I has developed
PCB and rebuild the RX for the box of printed boards also.
to this 80m variant receivers under the similar circuit on
40 and 20 m bands are also were constructed. The results
were obtained also excellent.
My next step with Direct Convertional was when I get a
HAM license. I began to experiment the receiver in hope to transform
it into the transceiver. First of all I have decided to submit
a VFO signal to the antenna through a keyed amplifier stage (pict.2). It worked well. There was even a frequency
shift by transmission
about 1 kHz
that enabled to hear stations without additional RIT. But, taking
into account, that VFO works on frequency twice below, than the
received frequency, power of a transmitting signal in the antenna
was rather small, just few decimals of milliwatts. I has
just a few nearest QSOs with this QRPp on 80m band only. It is
impossible to use this circuit on 40 or 20m bands because the
friequency shift is too large (5 to 10 kHz) and your signals will
be outside from a signals of your correspondents.