Over at the RADIO_TIMETRAVELLER blog there are some excellent articles about connecting loop antennas to Tecsun or similar portables. This ought to be my next step after tinkering with the larger ferrites. I need to study the SI labs data sheets for these radios again to see if it is possible to add a loop to the shortwave antenna connection, for use on the Tropical Bands . The SW input doesn't have a varicap tuner so it would probably require an additional variable capacitor to tune manually.
Shortwave listening and technology musings mainly using a selection of portable radios from the trailing edge of technology. You may find the odd SDR starts to creep in too.