Notes and links.
down converters (shortwave to medium wave)
HF to CB/AM Broadcast Receive Converter kit, great for QRP!
Vectronics VEC-101k http://www.vectronics.com/Product.php?productid=VEC-101K
40 meters to CB by vk3ye (includes BFO): https://www.youtube.com/watch?v=hCdt0aXj7bc
upconverters
kf7lze roundup of up converters: http://blog.kf7lze.net/2012/09/14/round-up-of-rtlsdr-upconverter-choices/
W9RAN Ranverter Pi: http://www.hayseedhamfest.com/ranverter_sdr_261668310.html
ct1ffu upconverter: http://www.ct1ffu.com/site/?option=com_content&view=article&id=178&Itemid=104
IF converters
455kHz -> AF Converter (DRM): http://users.belgacom.net/hamradio/schemas/DRM_455kHz_to_LF_Converter_FRG-100.htm
Any SDR that will receive 455 KHz (or whatever the IF is) plus a R-Pi would work. The Pi would need to boot automatically into an SDR app with the frequency set to the IF.
455 kHz BFO Kit – Receive ssb and cw on an am receiver!
RADI0KIT-2 DRM SSB RADIO BROADCASTS DECODER KIT / IF CONVERTER.
IQ converters and panadapters
FST3253 is a commonly used chip for Tayloe mixers.
Babel Fish IF SDR Radio 1st IF I /Q software conversion module: http://www.ebay.com/itm/Babel-Fish-IF-SDR-Radio-1st-IF-I-Q-software-conversion-module-/231292143562
A Binaural IQ Receiver by Rick Campbell: http://www.arrl.org/files/file/History/History%20of%20QST%20Volume%201%20-%20Technology/QS03-99-Campbell.pdf
QSD By Ray Ring: http://circuitsalad.com/2013/12/30/my-phasing-receiver-is-a-success/
Thomas Nylund Tayloe detector and SDR http://tuomasnylund.fi/drupal6/content/software-defined-radio
Softrock Lite II 06 mixer: http://www.wb5rvz.com/sdr/sr_lite_ii/06_mix.htm