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

[Matt Zilmer]

It's a tradeoff.  13 KHz gets you FM capability on TX, but should not
be used for AM.  The 6 KHz filter is adequate for SWL and allows AM
TX.

Personally, I have no need for AM TX, so using the 13 KHz filters (one
in each RX), also allowing regular FM on TX/RX.  This is useful if you
have the K144XV 2m transverter.  The 13 KHz filters work fine for AM
RX.  Because I operate on MARS freqs, the KBPF3 is also a necessary
ingredient and I have one on both receivers.  Same thing for you to
use in SWL work.  Your only limitation is reduced sensitivity around
the 8.2 MHz IF, and TX is hard-locked out from 7.5 to 9.0 MHz.  The K3
RX also won't show the specified sensitivity in between ham bands,
when the KBPF3 is in use.

The KBPF3 doesn't give the front end protection that the bandpass
filters do, but it gives you at least reasonable sensitivity between
the ham banads.

73,
matt W6NIA

On Fri, 13 May 2011 11:06:52 +0100, you wrote:

>Hi,
>
>I read somewhere, some time ago, that there was a plan to introduce variable
>filters to the K3.
>
>Do any such filters exist, either as 3rd party mods or official by
>Elecraft/Inrad? And is there any firmware support for this?
>
>I already have 2*2.7kHz and 2*500Hz in my K3, plus a 2.1kHz in the main
>receiver only, but I would like a wider filter for AM-broadcast SWL and AM
>TX/RX.
>
>Also, I would like to listen to shortwave broadcast stations so I was
>planning to get the KBPF3 and additional filters. As far as I can tell the
>best filter for this would be KFL3B-FM, to capture the wide signals of the
>broadcast stations in the highest possible quality, is that correct or is
>the KFL3A-6K more useful? And can I transmit 6kHz AM with the 13kHz FM
>filter or must I have the 6kHz one as well?
>
>73, Thomas M0TRN
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