[Icom] Why does the IC-751 change frequencies when you change modes?

[Gary Jacek]

My 745 does the same thing.

I have Roberto Nardo's replacement memory board which I understand
also contains the firmware for operating the radio.

I wonder if this could be tweaked so that the 745/751 etc behave like
the newer Icoms?



"George, W5YR" wrote:

> Not sure, but I think the 765 was the first Icom to NOT do this. I know
> that the 761 did, and my little 730 does - to my great disgust - but the
> 765 and now the 756PRO act like they should.
>
> I have no idea why the original setup was made that way, but time and
> experience has proved that it was not the best idea in the world.
>
> 73/72/oo, George W5YR - the Yellow Rose of Texas
> Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
> Amateur Radio W5YR, in the 56th year and it just keeps getting better!
> QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
> Icom IC-756PRO #02121  Kachina 505 DSP  #91900556  Icom IC-765 #02437
>
> Chris wrote:
> >
> > Does anyone know why the Icom folks coded the uP in the IC-751, R-71
> > ect. to change frequencies when the mode was changed? I thought it might
> > be to keep the center frequency of a signal in the receiver passband on
> > mode change but it doesn't seem to do that. I made a change in the
> > firmware of our UX-14PX board to monitor a mode change and reset the
> > frequency to what it was before the mode change occured, that is, when
> > you changes modes the frequency of operation stays put, and the result
> > seems very satisfactory. But, I wonder why it wasn't done this way in
> > the first place? Let me know if you have an insight on this.
> ----
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