Only as background information:

there was an obsolete standard in my country (possibly others) that the IF
should be 473 kHz. Theoretically there may exist receivers using this
ones. It is true the IF circuits are shielded but I don't know what
happens if the IF comes the input circuitry of the rig. That remark also
o. k. with 27 MHz but maybe there is some designing differences between
the original project and the new one.

Imre

And another question: as the original depilator was described as a $3,500
device, maybe it emits not sinusoidal but some another curve? Or it is
meaningless?



On Tue, 16 Jun 1998, Paul B. Webster VK2BZC wrote:

> Dr. Imre Bartfai wrote:
>
> > The remark for 1 MHz due to bci is o. k. but 460kHz is also close
> > enough to the common intermediate frequency of the most AM receivers
> > to cause also harmful interferences. 1,9 MHz would be a better
> > solution I guess.
>
>   I'm not totally sure, but I doubt 1.9 MHz is appropriate.  There are
> certain defined "ISM" (Industrial; Scientific; Medical) frequency
> allocations and one of them is around 460KHz; perhaps 465 or 470.
> 500KHz is by the way a *distress* frequency, lest anyone should idly
> make that suggestion!
>
>   The fact that the ISM frequency is in close proximity to the standard
> 455KHz IF frequency is not accidental; a proper radio is supposed to be
> designed *not* to receive this frequency, (procedure called "shielding")
> but the intention is that stray 455KHz *from* radios will fall in a band
> where it cannot interfere with any other service.  I know that sounds a
> bit fuzzy, but that's how it works!  Other ISM bands include the 27 MHz
> "CB" band.
>
>   Cheers,
>         Paul B.
>
>