[PCR-1000] pcr1k pll synthesizer calibration?

[Brian Winter]

there is somethign called "reference xtal shift" (centre=128) at address
&H04 that sounds as if it might be what you want
see the link to  19nov98.zip on http://planet.gcn.ou.edu/ahern/home/pcr1000/
for better information.

bw

----- Original Message -----
From: <erik-qth@arpa.org>
To: <undisclosed-recipients:>
Sent: Friday, January 31, 2003 11:27 PM
Subject: [PCR-1000] pcr1k pll synthesizer calibration?


> I'm the proud owner of a first-gen pcr1k, serial number around 021xx.  It
> seems to be performing wonderfully, EXCEPT for one thing; the PLL
> synthesizer's frequency reference is 'off' by about 780ppm.  The radio
must
> be tuned about 0.0008% higher to be centered on the actual received
signal.
> Thermal drift doesn't seem to play a role here, as the offset doesn't
change
> between the radio being just turned on, to being on and actively scanning
> for a few hours.
>
> This may not sound like much, but at 900mhz, it's a full 7KHz off from the
> frequency it's "tuned" to, putting the signal completely out of the 6khz
> passband when in NBFM-6khz mode.  at 440mhz, it needs to be tuned 3khz UP
> to be centered on the received signal, and 1khz up on 2M.
>
> On HF, it's not nearly as apparent (or annoying), being only about 200hz
> off near the top of the HF bands.
>
> Since the offset is proportional to the tuned frequency, I'm going to
assume
> that it's the primary pll reference oscillator, and not one of the 2nd/3rd
> stage mixer oscillators.  Is there any way to fine-tune the reference?
Are
> there schematics available so I may find it myself on the board to attempt
> a recalibration?  Are we lucky to have an adjustment for the pll reference
> stored in the EEPROM?  And if so, which bytes are responsible for this
> calibration?
>
> Thanks
> Erik Schorr, KD6AUT
>
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