Hi, I just bought myself one of these on eBay, and it's identical to the one pictured elsewhere on this forum except that it still has it's "Ricoh" pin intact.
Tried it on my K7 with Tamron 18-250mm & no auto focus & no aperture indication or control!! So I tried it on my Sigma 90mm Macro lens ("A" setting combined with manual focus & electronic contacts for same). Again no aperture indication or control. So I checked all the electrical contacts for continuity - they were all fine.
So I "Googled" & found a thread on this forum. I also "Googled" and found a description of the PK series of lens mounts on Wiki (here to be exact
https://secure.wikimedia.org/wikipedia/en/wiki/Pentax_K_mount#K_mount). Then I did a detailed comparison of both sides of the converter with the camera mount and the two lens mounts and the picture in Wiki and .... The "the digital information pin" is missing from the Vivitar converter!!!!
I just tried it with my SMC Pentax A 50mm lens & the camera controlled the aperture just fine without the Vivitar converter & not with it!!
For now it's got me beat as neither of the two "A" lenses seem to use the digital information pin !