If you have the wrong reference oscillator selected, it will create
steps that are invalid.. and thus syth unlock..
The ref osc for factory standalone units is based on 12.8 mhz but there
is an optional 10.0 mhz ref osc.. and it can be external or internal.
The PLL steps are calculated from that osc and the desired step size.
You also need to select a channel in the channel switches that is
occupied, it can be from 1-64 and the prom needs to be programmed
accordingly..
Doug
tait700 wrote:
>
> Hi,
>
> Was wondering if anyone had any knowledge or experience of any bugs
> when burning a new Eprom for one of the above units ?
>
> I can compose the new .Bin file correctly using PGM800 Win ( i think )
> and send it to the Eprom burner that is telling me when it is finished
> that it is copied correctly to the chip ( via Verify ) but when the
> chip is installed on the eprom board and fitted to the tx module i
> have no VCO lock = no transmit.
>
> I have tried adjusting the VCO trimmer but cannot get it to lock with
> the new chip installed. I have added one other frequency to the
> original one that was on the original chip ( up exactly 10 mhz ) but
> it will not lock with either the original Channel freq or the new one
> on the new chip.
>
> The original Chip worked fine with the one that was on there and
> comparing the .bin file from this and the new one both look the same
> when opened with PGM800.
>
> I have read the previous posts on this board about creating a new
> eprom but if i have done something wrong i cannot see what it is.
>
> Any info or advice would be much appreciated,
>
> Unit in question is a T881 850 - 930 mhz
>
> Regards,
>
>
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