[Elecraft] Width of AM filter

[VE3NFK]

I hope I am not stepping on any toes - but I found someone who had designed a 13Khz +/- filter with some toroids and caps - incl variables to adjust and built two and they work great in main KRX3 -
just confirmed again they give nice fidelity on AM  - and I can hear the 6khz filter click in when I reduce BW to 3...  low cost - fair bit of labour :-)

73 John VE3NFK


Jerry,

The WIDTH control sets the final audio bandwidth, which is limited to 5 
kHz in AM mode. But in AM mode, the crystal filter bandwidth needed is 
2x the audio bandwidth, or 10 kHz in this case, because it has to pass 
both sidebands. To obtain this full bandwidth, you'd have to have the 
13 kHz FM filter installed. The AM filter is only 6 kHz wide (an 
industry standard), and if that's the widest filter you have, you're 
actually getting only a little over 3 kHz of audio bandwidth even if 
you set the WIDTH control to max (5 kHz).

73,
Wayne
N6KR

On Mar 26, 2009, at 11:23 AM, Gerard Jendraszkiewicz wrote:

> Hello,
>
> I have K3 with KFLA-6K. I can only adjust the width to 5.0 using the
> width knob on the K3. I use AM to listen to the AM BCB and some SW. I
> remember getting a wider width in the past ?? Any suggestions ?
>
> Thanks
> Jerry, KE9I
>
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