[Radio Wrangler]

Ah, there is only a variable capacitor resonating the mixer transformer primary and no serious filtering ahead of the mixer to reduce out-of-band signals. There's nothing to stop them tenderising the FET RF amplifier, it's completely broadband.

It's a straight forward small direct-conversion receiver, designed around parts likely to be in a junk box. Inevitably there are limitations. If you run into overload problems, using a receiver type ATU ought to help.

In the 1980s, the Jandek stand at a lot of radio rallies had one of their little DC receivers running and people were rather surprised at how good this sort of receiver sounded.

There is no sideband selection, you hear whatever lies above your LO superimposed with whatever lies below, so it can get some frequency-inverted and offset audio appearing in a congested band. Find signals in clear areas and it'll be great.

It is possible to make a DC receiver select sidebands, it has to have two signal paths with two mixers running from LOs which are 90 degree phase shifted. The trouble is in doing 90 degree phase shifting for the audio, the phase shift has to be accurate not only across the audio band you want to hear, but across the full audio range the audio section can pass. Some SDRs use this technique, but pass their two audio paths into a stereo soundcard for the software to do the phase shift with a Hilbert-transformed digital filter pair.

So this little DC receiver is the tip of an iceberg!

David