[Elecraft] ESSB and the 6 kHz Filter

[Joe Subich, W4TV]

On 1/29/2016 8:40 PM, Bob McGraw K4TAX wrote:
> Using the K3 Utility, in checking the Filter Config list, while I do
> have the 6.0 kHz filter installed, I must select the 2.7 kHz or 2.8 kHz
> for CW and SSB transmit.
 >
 > Then from the CONFIG menu ESSB I can select up to 4.0 kHz bandwidth.

The K3 and K3S use the AM TX filter for ESSB wider than 2.8 KHz.

> Receive BW on AM will go to 5.0 kHz and on SSB 4.0 kHz.

Receive audio bandwidth will never go beyond 4.2 KHz as there is a
fixed, audio lowpass filter following the digital to analog converter.
In any case, the true audio bandwidth is FC +/- BW/2 for all modes.

Even in AM the maximum value for BW is 4.00 (4 KHz) representing
a recovered audio bandwidth of 0 - 4000 Hz or 200 - 4200 Hz. If
FC (shift) is lower than 2.00, the actual bandwidth will be less
than 4 KHz even when BW = 4.00 due to the formula above (FC +/- BW/2).

73,

   ... Joe, W4TV