[Elecraft] Filters

[Joe Subich, W4TV]

> I would like to update some things especially the roofing filters
> first so the question I would like to ask is Has anybody upgraded
> from the 2.7 five pole filter to the 2.8 eight pole filter?

You will not notice any difference going from the 2.8 KHz to 2.7 KHz
filters.  The ultimate bandwidth is determined by the DSP in the
second (15 KHz) IF and the roofing filter skirts don't make much
difference once they're down 30 - 40 dB.

If you're into serious SSB contesting you may want to add either
the 2.1 KHz or 1.8 KHz roofing filter for that additional protection
from strong adjacent channel signals but in most cases the adjacent
channel garbage is often transmitter IMD (splatter) that is actually
"on channel" and can't be rejected by any filtering.

 > also could I use the fm filter for use in the am position.

Yes, he FM filter (13 KHz) can be used for both AM transmit and
receive.  Note: even with the 13 KHz filter, the widest receive
bandwidth will be 4.2 KHz - not 6+ KHz - as the receiver audio
chain includes a sharp 4.25 KHz low pass "brick wall" audio filter
to limit artifacts from the digital to analog converter.

73,

    ... Joe, W4TV


On 1/30/2017 8:21 PM, mtruss wrote:
> I have purchased a used  K3, serial number 3000 or so, it has been sent back
> to Elecraft for updates etc  and returned to me working great so far. I
> would like to update some things especially the roofing filters first so the
> question I would like to ask is  Has anybody upgraded from the 2.7 five pole
> filter to the 2.8 eight pole filter? I understand the 8 pole is a wider
> filter with 3 more filtering  crystals , does it make any difference in
> received audio? also could I use the fm filter for use in the am position.
> Any other suggestions would be appreciated.
> Thanks
> Mike  W8FLT
>
>
>
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