Hi Conor! Back in the 60s, I used to listen to medium wave DX on car radios and an old, old radio console from the 1930s. On the old radio, I leaked some IF from the plate to the grid by connecting a wire to the plate and snaking it around to the grid cap, then tying it off inside the plastic sleeve of a clip lead clip, and insulating it from the clip itself. I attached the clip to a screw that stuck out of the IF transformer, and I would swing the assembly around so that it moved the insulated wire around near the grid cap of the IF amp tube. This variable coupling produced an adjustable Q-multiplier effect, and I could get sharper selectivity for digging out the weak signals. I also built a noise clipper and attached it to the detector, and that helped hold the static crashes down.
The old radio could tune longwave, but I never heard anything much down there but navigation beacons, except one time I heard a strong carrier come on, and a record played, and then the carrier went off. I assume it was an old, old wireless phonograph that someone had in my neighborhood. It sounded too good to be coming from a parasitic oscillation in a record player, although that is a possibility. The fun started when I tuned around shortwave, and started hearing amateur radio people running AM. Hey, I could do that... Bacon, WA3WDR
