[Elecraft] K2 AM-receive, FINE RIT, and selectivity

[Wayne Burdick]

Ron D'Eau Claire wrote:

> So what's the downside of using the K2 for AM reception? Selectivity!!
> The K2 is designed for optimum selectivity for voice. The OPT1 filter is
> only a smidgen over 2,000 Hz wide! That's pretty narrow for anything but
> voice, and it constricts even the voice a bit. Of course, it gains the
> ability to dig signals out of the noise better that way, but you can't
> get the sort of fidelity a wider IF filter would provide.

Quite true, Ron. It should be possible to roll your own wider 4.9 MHz I.F. filter, though
we haven't tried this yet. You could mount it to the right side panel of the K2 and run
RG174 to/from the SSB adapter, using two small switches or relays at either end to do the
selection. In either case a control could be mounted on the right side panel to switch
between wide and narrow broadcast bandwidths. Some experimentation would be required to
ensure that the ultimate attenuation of the KSB2's SSB filter was not compromised by the
added circuitry.

One other thing I thought I'd mention is FINE RIT, which is available in any revision of
the K2 firmware from 2.01 up. You can use this to fine-tune AM broadcast stations, with
step sizes of as low as 1 Hz depending on the band.

73,
Wayne
N6KR