[Elecraft] [K3] Variable filters? And what filter is best for AMbroadcast reception?

[Joe Subich, W4TV]

> The a.m. receive audio passband was 4Khz wide with either filter.
> The  13Khz filter did not provide wider audio as expected in my K3.

Unless your AM filter is significantly wider than the published 6 KHz
or you are using the Sync detector with the IF filter offset for one
sideband, the AM filter can not produce a flat audio response to the
full 4.2 KHz allowed by the DSP with the added analog lowpass filter,

If the AM filter is doing its job (based on the published selectivity 
at: http://www.elecraft.com/K3/K3_8_pole_plots.htm) and the filter is
centered on the carrier frequency, the audio response should be down
by nearly 40 dB at 4 KHz compared to response at 3 KHz.

73,

    ... Joe, W4TV

On 5/13/2011 9:34 AM, Barry N1EU wrote:
>
> Craig D. Smith wrote:
>>
>> For this purpose, the 13 KHz is better as you point out.
>>
> FWIW, I directly compared the 6Khz and 13Khz filters on AM receive in my K3,
> which has the latest dsp updates (includes a 4Khz low pass audio filter).
> The a.m. receive audio passband was 4Khz wide with either filter.  The 13Khz
> filter did not provide wider audio as expected in my K3.
>
> Barry N1EU
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K3-Variable-filters-And-what-filter-is-best-for-AM-broadcast-reception-tp6358819p6359445.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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