[ICOM] R70 Frequency Error

[Alan Johnson]

Hello:

I've posted this to the Icomclassic group at Yahoo, but am cross-posting it 
here since there seems to be more activity in this group.

I recently picked up a R70 receiver.  It works but the frequency is off when 
I zero-beat signals in USB/LSB.  The displayed frequency is 3 to 3.3 kHz low 
in the MW band, 2.4 kHz low at 5 MHz, 1.7 kHz low at 10 MHz and 0.7 kHz low 
at 15 MHz.  Adjusting the CAL pot shifts the frequency but does not put it 
spot on.

I went through the alignment and found that I could only adjust the 1st LO 
(X1 adjusted by C135) to 61.43 MHz - it should be 61.44 MHz.  The 3rd loop 
lock (adjusted by L14) is correct at 23.40 MHz and the 2nd loop LO 
(adjustment R189 with R190, the CAL control, at center) is OK at 30.72 MHz.

Has anyone seen anything similar with the older Icoms?  Should I try 
replacing X1 first or could the problem be in the display circuitry?  I 
don't think it's a problem with the VCO trimmer caps as I had a R71A that 
did have bad trimmers which caused (as I remember) distortion of the 
received signal rather than a frequency display error.

TIA and 73,
Alan Johnson
N4LUS/7