[Yaesu] Problem aligning the shift/width on the IF unit of an FT-ONE

[Rob Atkinson]

why don't you just experiment by sticking an extra 50 ohms fixed resistor in
series with the variable one and see what happens?  Maybe that will give you
enough range to get to 19.7475 MHz

Rob
K5UJ

On Tue, Jun 7, 2011 at 12:48 PM, David Kirkby <david.kirkby at onetel.net>wrote:

> Hi,
> I've got an FT-ONE (S/N 080046, which appears to be one of the later ones).
>
> I've had reports the TX and RX frequencies differ, so I decided to
> align it. One does not have to search the web hard to find that the
> FT-ONE's tend to go out of alignment a lot.
>
> Not one of the PLL oscillators (20.000 MHz +/- 100 Hz, 48.615 MHz +/-
> 500 Hz and 54.280 MHz +/- 100 Hz) were correct - all were outside the
> specification. But it was easy to bring them back on - how long they
> stay correct is another matter.
>
> But aligning the IF unit was more problematic. The first thing
> mentioned in the technical manual is to adjust the Width and Shift. It
> says to put the rig in USB, put the width and shift controls in the
> centre, and adjust TC9001 for 19.7475 MHz on a counter. The problem is
> there is no TC9001. Looking in the technical manual I see there were
> two versions of the IF unit. It looks like mine is the later one. They
> differ in that the one I have has a variable resistor to set the
> frequency, not the variable capacitor mentioned in the alignment
> section.
>
> There are two problems.
>
> 1) The alignment section does not say how to align the version with a
> resistor.
> 2) Assuming one is supposed to set the resistor such that the
> frequency is the same as on the earlier IF boards, then I can't do
> this. No matter where I put that trimmer, I can't get the oscillator
> to oscillate at 19.7475 MHz. The closest I can get is about 350 Hz
> below that, which is outside the specification, as its supposed to be
> set to +/- 100 Hz.
>
> I'm wondering if the frequency this should be set to on the newer IF
> boards is not 19.7475 MHz. Or perhaps my crystal has aged too much,
> and it can't be put on frequency.
>
> I've not looked at the circuit in any detail, but I assume the new IF
> board uses a varicap diode to do the adjustment.
>
> I expect I could get this to oscillate at 19.7475 MHz by changing a
> resistor, capacitor, varicap or as a last resort the crystal. But I'm
> unsure if that's needed, since the only alignment instructions I have
> are for the older IF board.
>
> I note one of the reviews on eham by N8NN on Oct 6, 2006 11:06  says:
>
> "Within the first three months of ownership Yaesu recalled my FT-ONE
> to correct the IF Shift/Width function that was not properly aligned
> at the factory."
>
> I don't know if "not aligned at the factory" was really a case of
> Yaesu realizing it would not stay aligned.
>
> Is there any known mod which will bring this oscillator onto
> frequency? Or should the new IF board be aligned differently (that
> seems unlikely I must admit).
>
> Dave, G8WRB
> ______________________________________________________________
> Yaesu mailing list
> Home: http://mailman.qth.net/mailman/listinfo/yaesu
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Yaesu at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>