[Elecraft] FM filter - AM transmit with it?

Dave, G4AON elecraft at astromag.co.uk
Thu Jan 1 16:47:27 EST 2009


Gary, this question has been asked before, 24th May 2007. Eric replied 
with the following:

    The short answer is a 'qualified' yes. The wider FM filter can be used
    for AM transmit and receive, since the DSP limits the AM bandwidth, but
    there will be two issues.

    1. On receive you will be subject to AGC blocking (de-sense) from
    nearby
    signals inside the 13 kHz FM filter's bandwidth but outside the
    DSP's AM
    bandwidth. (Typically those over S9+20 to 30.)

    2. On transmit we will not guarantee that there will not be an increase
    in close in spurious signals inside the FM filter bandwidth. Normally
    the AM filter reduces any undesired transmit signals outside of its
    bandwidth.

    So for casual AM listening, or AM transmission on a non-crowded band
    this might be OK. But we recommend the AM filter for any regular AM
    transmit usage.

    73, Eric   WA6HHQ
    Elecraft

------------------------------

For my K3, I am thinking of getting the general coverage addition
KBPF3 and want to get a filter that works well with it so the FM
filter seems like it would be best as regards the European broadcast
setup.

I also would like to be able to transmit on AM but have no filter for
that (I presently have the 2.8, 1.0 and 250 filters installed in it).


Does having the Inrad 725 installed allow transmit on AMor essb? I
don't think it does as on the Elecraft order page it mentions an AM
filter for transmit. I'm just double checking here to make sure
before ordering an extra filter I might not need.

Thanks,
Gary
KA1J


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