[1000mp] Yaesu RX detoriation trend per ARRL lab

[Zoli Pitman HA1AG]

Hi,

I'm sorry for the delay with my reaction to the tread but had been out of
reading emails for quite some time and got heaps of emails to check.

A week ago Bill W4ZV quoted the results of ARRL lab measurements and there
seems to be a negative trend with Yaesu RX's:

Rig                           IMDDR3           BDR
Yaesu FT-1000MP                 83             119
Yaesu FT-1000MP Mark V          78             106
Yaesu FT-1000MP Field           73             107

I'm keen to find the reason of the difference and with a friend who has both
manuals (for the MP and MkV we compared the RX chains and found that the RF
and 1st and 2nd IF of the MP and the MkV are completely identical. The only
difference is the one less active element in the MkV 3rd (455 kHz) IF -
Q2052, 2SK302GR in the MP is just to set the level before the mixer. The
switching diodes in the MkV seem to be newer types. I have no data of the
Field.

Were there any changes in the measurement methods or tools?

Does anyone have an explanation for the trend, please?

Thanks,

Zoli HA1AG