[ICOM] R70 Frequency Error

[VE6JY Don Moman]

I recall several R71's that had a similar issue - they were just on the
extreme lower edge of what was needed to get it spot on for use with the
ESKAB PLAM board.  I don't believe there was anything wrong with the
circuitry, just that the xtal was on the low side of tolerance. Also saw
that with one of the hi-stab options too.

73 Don
VE6JY

----- Original Message ----- 
From: "Alan Johnson" <alanjohnson at gbis.com>
To: <icom at mailman.qth.net>
Sent: Monday, January 17, 2005 02:51
Subject: [ICOM] R70 Frequency Error


> 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
>
>
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