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[Yaesu] YC-601 Display Fix (FT-101 Series Digital Display)

To: yaesu@contesting.com
Subject: [Yaesu] YC-601 Display Fix (FT-101 Series Digital Display)
From: certified-electronics@juno.com
Date: Thu, 8 Jan 2004 20:35:34 +0000
List-post: <mailto:yaesu@contesting.com>
If you own a YC-601 digital display
and it will not calibrate properly from the front panel
calibration control you may just have a bad 11.1 Mhz Crystal in your

I now have several of these gems in my shack, having just picked up a
second YC-601
it came with a problem where as it would not calibrate with the radio
when using
the front panel control when turned completely to the right or left.
There was an attempt from the previous owner to jury rig in some
small capacitors into the 11.1 Mhz oscillator in an attempt to trick the
display into reading
the right frequency.  This worked somewhat but strangely enough you could
not get enough
range out of the calibration control to enable both the Upper and Lower
side bands with
a correct display reading. I could get it to work on one side band, but
not the other with the
jury rig. And even though the old 11.1 Mhz crystal was doubling and
giving me a 
22 Mhz mixing frequency to work with, it must have been too far out of
tolerance to
keep the display units internal mixer working within specifications.
After some trouble shooting, I decided I would pull the 11.1 Mhz crystal
out of my working
unit and install it into the inoperative unit.  It work and everything
appears to be for the most
part normal now.
Here's the fix.  A new 11.1 Mhz crystal, part number H0100051
but it's no longer available from Yaesu.  I just got off the phone with
crystal and I will be sending them the one working crystal I have for
their evaluation.
They will come back with the capacity of this crystal and we will have it
for future
reference if anyone should need it.

An interesting thing to note is the differences between a YC-601 and a
While both units appear to look some what the same from that old 
familiar front panel,
but they are really two different animals.  They both use a 1.31072 Mhz
clock oscillator
frequency and the same crystal for the clock
(Now $26 bucks from Yaesu P/n H0100052).
And they both use a 22.2 Mhz frequency in the mixer stages, but other
then that  the two
units are completely different when it comes to the input stages and
mixing stages.
With the YC-601B being a much improved design over that of the YC-601.

Either way you look at it, both the YC-601 and YC-601B are both getting
by comparisons with technology today.  But if you're like me and you
using and restoring the older equipment then it may be time to change
of those crystals to keep your old display unit up and running with
tiptop performance.

73's & Regards
Carol Maher

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