[TenTec] Century/22 tapping rx freq for digital counter

[VE3XGB]

Hi all,

I've got a digital freq counter and wanted to use it as a digital freq readout on my Century/22 but I can't seem to find a 'source' in the rig.  The circuit diagram shows the mixer as a UPC1037 (?) IC but mine has a MC1496P.

Anyway I found the data sheet for the MC1496P double-balanced mixer and it would seem to suggest that pins 6 and 12 were the output but when on 80m I couldn't find a 3.5XX MHz signal on any pins.  I can see the 10.000 MHz band crystal output and I can see the 6.5 MHz PTO output (difference in the 3.5XX range) but nothing 3.5XXX 

Thanks for any suggestions