[Elecraft] K3: Why can't I use my 1.8kHz filter for SSB TX?

[Doug Faunt N6TQS +1-510-655-8604]

Early versions of the firmware did, in fact, allow transmission
through the 2.1kHz filter, and that capability was removed.  I suggest
that speculation is futile, since there are authoritative sources
available.

73, doug

   Date: Tue, 26 Jan 2010 08:41:18 +0000
   From: "David Woolley (E.L)" <forums at david-woolley.me.uk>

   One possibility is that the rig has only been type approval tested in 
   that configuration, so anyone wanting to operate it with a different 
   filter would require a professional RF spectrum analyzer.

   Top posted through policy, not belief.

   Brian Machesney wrote:
   > reflector. The only "authoritative" information I found information was this
   > from July 2008:
   > 
   > "Until further information to the contrary is available from Elecraft, you
   > must select the 2.7 or 2.8 filter for SSB, Data and CW transmit. The AM
   > transmit filter must be 6 kHz and the FM transmit filter must be 13 kHz. Any
   > other settings will result in failure and a ERR TXF (Error TX Filter)
   > message.