I have the RF modulator from a VIC-20 connected via a bunch of adapters to my poppa's old Pye 12G-15 set (yes I know this is overcomplicating everything). RCA male to F-type coax female, coax to a twin prong 75 to 300ohm adapter (https://www.ebay.com.au/itm/402658588970 basically one of these).

I'm not really getting anything out on channel 3 or 4 with any tuning (just static and snow) but I'm also not really sure what I'm doing. I disconnected the two twin prong connectors from their spot as I assume this is connected to the built in antenna (seen here https://www.radiomuseum.org/r/pye_au_12g_15.html# on the back photos) Would appreciate if anyone has the schematics or even advice/guidance on what to check/test?

Welcome to the Forum from Some Geriatric Nerd.

I think you are right about the white wires being connected to the rabbits ears. But you could check with a resistance test for continuity between them. But shouldn't really prevent the set from working if they are connected. But ideally the rabbits ears should not be connected.

Don't know the modulator so someone else will need to comment on that.

Dear Some Generic Nerd.

Loosen the antenna screws on the back of the set and remove the two white leads. One going to the rod aerial, the other to earth.
.Place the two black leads from the mast head balun under the antenna screws.

I have two schematics for this set. 12G-15B, and 12G-15C. Your 8, might be the letter B.

If you un-hide your email, I will send both diagrams to you.

Good luck.

Wayne.

Are you sure the Vic 20 modulator output isn't UHF?

Commodore had a mixed bag of output channels across its range. I've never used a VIC-20 but the C-16 outputted to Ch 0 - 1 and the later version of the C-64 outputted to Ch 36.