This project is a simple SA602 (like NE602) based RF upconverter, that mixes the VLF and LF bands (0 to 500kHz) with a 10 MHz local oscillator, making it possible to receive 0-500kHz with a standard HF communications receiver or transceiver.
The 0 to 500 kHz range is translated into the frequency range from 10 to 10.5 MHz.
The device can be run from the same DC power supply as the receiver, the input voltage range is 7V to 13.8V.
EDIT: Regarding the input frequency range, of course the input doesn't go to DC, because the input impedance of the SA602 is matched to 50 ohms via a transformer. As transformers need a change in magnetic flux and therefore a change in current/voltage, DC won't make it to the SA602.
I have assembled the rev. A PCBs. The PCBs for this project arrived heremuch sooner than I had anticipated, as it usually takes stuff from outside the EU 4 to 5 weeks because it is significantly delayed by the German customs office.
As soon as I had all the components to assemble the PCBs, I realized that I had forgotten the SMD capacitors for the input low pass filter. Funny how I always manage to forget something on my component orders.
I decided to move on with the assembly anyway. You can see I have put on three monstrosities made from series and parallel combinations of capacitors to get the value I need. As we're talking about low frequencies, I hope that the added lead inductance doesn't screw things up too much.
The PCB fits the case nicely and because I left the soldermask off of the edge on the back of the PCB, the back groundplane makes good contact with the aluminium case, providing more shielding.
Initial tests with the upconverter were sort of successful (the magic smoke stayed in!), but I currently lack a a proper LF loop antenna to receive any stations with it. I did manage to receive some sort of signals though, which could well be RFI generated from an SMPS.
I will post an update as soon as I have a properly working antenna set up. I should be able to at least receive DCF77 and DWD with a somewhat better antenna.