The AR1000 does have a tendency to drift in frequency with age. Later sets
do not suffer to the same degree (different xtal manufacturer used) and
quite often an older set once re-aligned will stay reasonably stable.

The main culprit for the drift is the 154.825MHz oscillator but if the main
PLL ref' osc' is not bang on 12.8MHz, aligning just the 154.825 osc' will
cause misalignment in other ranges. At full operating temperature, align the
12,8MHz xtal with CV1 and CV2 (coarse and fine). Both are located on the top
(RF) board at the bottom edge. CV2 is located on the solder side of the
board next to PLL chip TC9181F and CV1 on the component side next to the
12.8MHz xtal. Both of these trimmers are usually near the end of their
range.

The 12.8MHz frequency will have to be measured with an accurate frequency
counter either sniffed directly from the xtal can or at the input to the PLL
IC on pins 2 & 3. If using the latter method, take care not to shift the
frequency by loading these points.

The radio can now be aligned by ear with a suitable signal (I tend to align
the units on NFM on marine band or 2 metres ham band). With a suitable
signal being listened to, align the 154.825MHz oscillator for best
reception. The easiest way to check for correct alignment is by listening to
a low level signal and tuning 5KHz either side of it to check if the
alignment really is centred on the wanted frequency.
The 154.825MHz xtal can be aligned at CV3 (located on the solder side of the
RF board opposite the 154.825 xtal). This will give a small adjustment but
it is generally better to align transformer T10 located next to the xtal
(green core fitted). In both cases, check that the xtal is not operating on
the edge of its range and that it starts up on switch on every time (i.e.;
reception is obtained immediately on switch on).

After alignment, check that the set is on frequency throughout its frequency
range.