The first batch went quickly and the last I heard they won’t have any until Mid March / April. I ended up getting an 810S and it works perfectly on my SDS100. The only difference is that the 810S does not have the O-ring for waterproofing. Otherwise the 810 and 820 are identical.
Out of all the after-market antennas available for the SDS100/200, the Remtronix is definitely worth the wait.
I have 3 Remtronix antennas, none of them sma, all the original bnc and have bought them all here for $19.95 while they are $30 elsewhere, and airspy impressed me with very quick shipping. You might want to give them a call and see if they have what you are looking for with sma and O-rings etc. Lots of times they have stock not advertised...ya never know, ya know
Remtronix 800 MHz Antenna (BNC) – Airspy.US
Airspy.us also has the non O-ring version
https://v3.airspy.us/product/ant-810s/
Out of all the after-market antennas available for the SDS100/200, the Remtronix is definitely worth the wait.