Not exatly homebrewed, just a quirky use of existing gear (an AOR AR-3000).

I was looking for NDB's in the UK, and accidentally hit the wrong buttons,
easy to do on an AR-3000... I heard what sounded like an unusually clear, low
level voice, very different to normal long wave AM, and realised I'd
accidentally set to wide FM and was hearing Radio 4, many tens of KHz above
where it would be in AM mode. After exploring a bit I found that I could
detune the R4 long wave broadcast on 198 KHz to between 160 and 180 KHz and
WFM would give a sound so much closer to R4's FM broadcast that I decided to
post about it and see what comment results. The sound has a cleaner and lower
noise floor. It has a wider AF spectrum. It is clean with a barely
perceptible high frequency background sound. Obviously it's not FM at 93.7
MHz, but it's a damn good imitation, better than MW AM, far better than the
normal sound this same 128 KHz AM signal normally makes. Tonally it's
actually beautiful, it reminds me of the sound FM broadcast used to make on
an old valve radio.

Given how effective this is, I'm wondering why it's not done as standard. My
guess is that it may cause a selective exclusion of many signals, making the
strongest signals win hugely at the expense of all the others in the entire
band. But it's a clear win if I want to hear the strongest (and in UK, there
is only R4 on long wave so it makes sense). Should do wonders for the sound
of TMS cricket commentary tomorrow...