[TheOtherCliff]

When these first came out I bought a set of OpLink Air/Ground (but no Revo Mini, I wanted the SMA on the Ground) and found they did not work with any of my other OpLink stuff (bad clone RFM22 chip).  Big change in RSSI, looks like once a "hop cycle".  This culminated in finding the bad RFM22 chips with the large X2.

My question is whether anyone has bought these lately (or ever) and found that they use the good RFM22 chip.

I might consider buying a Revo Mini, but I would like the option to add RF later if I want, and if that RF is always broken I will just stick with regular Revos.

As an aside, I bet we could determine which hop messes up and code an option to skip that.  This would allow mixing good and bad OpLinks.  We might even have an edge case issue (e.g. 0x0000=0xFFFF or a 0x8000 as positive/negative) that could be corrected.  Are there actually 251 (40kHz) channels (0 to and including 250)?  That would mean that at least one hop is completely outside the band or that the two endpoints are on the band edges.  I tried to flag this long ago...

[karla]

hey, let me check what I have in my bin.
Think I have some.
will take some days...

[TheOtherCliff]

Link to picture showing large X2 (bad) and small X2 (good).  So far, that seems a good way to know which is good or bad without testing.
https://forum.librepilot.org/index.php?action=dlattach;topic=4197.0;attach=7316

[karla]

The only OPLM I have around now is an Air-side unit.
Can't remember when I got it but must have been some years ago.

It has a big X = bad.

hope it helps

[TheOtherCliff]

Anyone have an easy scenario to recreate the OpLink "bad RFM22B" issue?  I can get the 46kHz offset, but can't seem to get the repeated 25dB drop (which causes repeated disconnect when that puts it below the noise floor).

Update and note: I found an old post where I had problems at 50mW, but not at 1.6mW.  Longer range at 1.6mW than 50.  I need to retest for that 25dB drop by trying 50mW.

[trust]

I've bought quite a few Oplink Mini Air units sold as pairs with the Ground unit.
So far the only issue I've had is with occasional bad antennas - swapping them for good antennas seems to fix them.

[TheOtherCliff]

Note that bad seems to work well with bad, and good works well with good.  If all you have is the air/ground sets, then we don't know... 

If you are interested, you can check the link a few posts back for some description and pictures about which is which.