I see the SD5000 is still listed on Calogic's website
http://www.calogic.net/html/dmos.html Is the SD5000
still widely available? The search engines turn up a
lot of data but very few suppliers. Perhaps a ring of
discrete MOSFETs or a fast switch IC like the FST3125
might be a better choice.

73, Ed. EI9GQ.

GM Ed. Certainly a better choice when it comes to conversion loss. I've
built a half dozen SD5000 mixers and although at least one of them managed a
measured +50 dBm Ip3, (G3SBI measured it not me!) I never managed to get the
conversion loss below 9 dB and more often 10. Conversely, the 3125/ family
readily does 4.8 dB conversion loss thanks to the very respectable Rds on.
REALLY simplifies things in the front end department, to at least 30 MHz,
with attention paid to the front end filters, you can get away without an RF
amplifier.

Regards
W4ZCB