Frederf,
Thanks for the clarification. I mentioned latitude because that's the unit the PU-26 accepts as input. After reading the Mi-8 manual on the PU-26 unit (hint ED, please make the Yak manual more complete), it is clear that it corrects for drift due to rotation rather than magnetic declination. Until your reply I was not aware that was a factor. Thanks! Always more to learn. In either case, correcting for drift brings the Yak inline with the L-39.