IC-7000 Frequency Alignment Question
Fred McKenzie
and counting the transmitted signal. Twenty MHz WWV appears to be about
12 Hz high after the radio has warmed up. I realize this isn't much,
but it is outside the radio's 0.5 ppm specification.
The IC-7000's 24.8064 MHz reference oscillator is used to generate the
synthesizer clock as well as the second and third local oscillators. It
does not appear to have a variable capacitor or inductor for its
adjustment. Instead, it is voltage controlled. Apparently the voltage
is adjusted to correct the frequency, and the value is digitized and
stored in non-volatile memory.
The service manual provides a method of setting the reference
oscillator's 5th harmonic to 124.032000 MHz. It was slightly off, so I
adjusted it. However, the original error did not appear to change.
Has anyone else experienced this discrepancy? Is it possible that the
value given in the service manual is in error?
Fred
K4DII
Fred McKenzie
Fred McKenzie <fm...@aol.com> wrote:
> The service manual provides a method of setting the reference
> oscillator's 5th harmonic to 124.032000 MHz. It was slightly off, so I
> adjusted it. However, the original error did not appear to change.
It turns out that the setting of the oscillator didn't "take". I made
the change and pressed the SET button. However the oscillator frequency
had not changed after exiting the ADJUST mode.
Well, it really did take, but only when in the ADJUST mode! There must
be some other way of changing the reference oscillator frequency when in
normal operation, but I can't find it.
There are a couple other oscillator adjustments that don't appear to
relate to the reference frequency. They appear to require access to the
back of the front panel electronics, which is quite a challenge!
Fred
K4DII