This one follows the design of the DK7IH Cigarette Packet Micro Transceiver. The changes made to the original design are:
– Plug in front end, transmit driver and PA low pass filters
– FET power amplifier (IRF510) rather than bipolar
– Toroid filters for front end, transmit driver and PA low pass filter
– Discrete crystal SSB filter
– Nokia type LCD display
The construction is mostly SMD on the bottom of the board, with leaded parts on the top side of the board. I didn’t make a PCB for this one, it is built on pad per hole prototyping board. Earthing could be a problem, so lots of earth run around the board underneath. It does look rather untidy compared to the previous compact transceivers where a PCB was made. Maybe a PCB later on if it works out ok.
I like the idea of swapping the clock generator outputs to the mixers in software for receive to transmit switching. It certainly simplifies re-use of the mixers for transmit and receive.
So far the receiver is working fine, with a 0.1 uV minimum discernible signal (MDS). Still some work to do on software before the transmitter can be tested. The SSB filter is slightly broader (~ 4kHz wide) than intended although the response shape is good.
The main transceiver and clock generator board is 50mm x 100mm. With some luck it will fit into a 60mm x 120mm x 35mm enclosure. It may end up being a hand held type HF radio if things work out. Of course, it will need a trailing ground if used in this configuration. There also needs to be some access to the plug in band modules on the enclosure.
Mechanics test fit: