I come to this topic specifically in the context of working with my HRO. I don't have any "favourite" approaches in mind, but I have built up a small collection of ceramic filters, but I realised yesterday that most of them are 3kHz, with just a few 4kHz. I'll need to read the above new posts and think about the significance of some of those.
In terms of using the ceramics filters, I would be happy to implant a transistor or three in to the HRO if that helped impedance matching and/or compensation for the insertion loss. Taking a look on Google a couple of days ago, I came across two features by this old guy radiofun 232 (who has quite a few fans on this forum
https://www.vintage-radio.net/forum/...d.php?t=195411)
I found these two videos on ceramics;
https://www.youtube.com/watch?v=lVE5IM32VcA part 1 &
https://www.youtube.com/watch?v=mTqXWB6RSOA part 2, (
Part 2 is the best) and I think there may be other videos by that guy which are relevant (certainly to us less-experienced guys).
Peter's article does provide a lot of encouragement to take a serious look at ceramics. I was not aware that some had been produced with valves.
B