[Elecraft] Filtering

Fri Mar 1 00:45:01 2002

Mark;
Measurements I have done on the K2's Xtal filters indicate that they would
have extremely high rejection at 6 kHz away from the received signal.  They
would certainly be down over 80 dB, and probably over 100 dB.  I have also
checked the oscillator phase noise and it is good enough that it does not
degrade the SSB filter response.  The problem is not likely in the K2 unless
there is a flaw in the radio.

However, on the transmit side, the FCC only requires that spurious signals
be down by 40 dB.  I would expect that most transmitters 6 kHz away from
their transmission frequency will be down more than that.  Suppose the
transmitter has spurious signals down 60 dB at a 6 kHz offset.  If your
S9+20 signal follows standard S-units, the spurious signal 6 kHz away will
be copied at an S2 level.  There is one well known Texas station that runs
at least a kW whose spurious output I can hear 50 kHz from his transmission
frequency.

-John
 KI6WX

----- Original Message -----
From: "Mark Rozmilowski" <[email protected]>

> Does anybody know why when you tune K2  away (6 kHz for example)  from
strong signal 59 +20db and
> there are many of those on SSB  you can still  hear high freq. "noise"
from that station.
> Is it because filter doesn't attenuate enough or signal is going around
the filter.
> I would like to eliminate this problem but not by adding audio filtering.
This should be eliminated
> at its origin.
> I think that there is similar problem on CW but I have to do more
experiments.
>
> Thanks and 73! Mark WQ7X
> K2 SN#2507
>
>
> _______________________________________________
> Elecraft mailing list: [email protected]
> You must be a list member to post to the list.
> Postings must be plain text (no HTML or attachments).
> See: http://mailman.qth.net/mailman/listinfo/elecraft
> Elecraft Web Page: http://www.elecraft.com
>