Elecraft KSB2 User Manual

Page 20

Filter Setup

Connect the K2's internal frequency counter probe to TP2 (BFO).

Select 40 meters, LSB mode, and filter FL1. (It's important to always do filter setup on 17 m or

below to avoid confusion due to the K2's sideband inversion above 17 m. The settings apply to all bands.)

Set up your filters exactly as shown in Table 3 (below), using CAL FIL. Both the filters (FL1-4) and

BFOs (BF1-4) must be set up for each operating mode. The BFO settings are given as actual frequencies
(4912-4917 kHz) rather than as BFO control values (0-255). As described earlier, the

D IS P L A Y

button is

used in CAL FIL to setup the BFO frequencies. You may not be able to set the frequencies to exactly those
shown, but try to get as close as possible. The 10 Hz digit may flicker, which is normal.

Read all of pages 21 and 22 carefully to become familiar with SSB operation.

Set POWER for 5 watts and select LSB mode. Monitor your transmitted voice signal in another

receiver, or contact a nearby station and have them listen critically. Then, as explained on page 22 (SSB
Transmit BFO Optimization), adjust the LSB BF1 value for best transmitted signal quality.

Switch to USB mode and adjust the USB BF1 value for best transmitted signal quality.

Optional: For receive-mode BFO fine-tuning (BF2-BF4) you can use an audio spectrum analysis

program such as Spectrogram, which runs on PC-compatible computers. This is described on our web site.

Table 3. Suggested Filter and BFO Settings.

(Also see notes below.)

Mode

FL1

BF1 t

(note 1)

FL2

BF2

FL3

BF3

FL4

BF4

4913.6

4913.1

4913.0

CW Rev.

OP1

(note 2)

4916.0

0.70

4914.3

0.40

4914.3

0.20

4914.2

LSB

( _________ )

From Page 10

4913.5

4913.0

4912.7

USB

OP1

( _________ )

From Page 10

OP1

4916.1

1.80

4915.5

OFF or

0.70

(note 3)

4914.7

Table 3 Notes
1. The LSB and USB BFO settings are derived from the filter crystal frequency (see page 10) to ensure

good SSB transmit performance. The lower-case t after BF1 is a reminder that these BFO settings
are always used on transmit, regardless of which filter you select for receive.

2. FL1 on CW is set for OP1 since the SSB filter is ideal for casual CW tuning. The remaining CW

filters provide narrower bandwidths, and are centered at approximately 600 Hz.

3. FL4 on LSB/USB is shown set to OFF, which means it will not be accessible with the

X F IL

button.

(Any filter can be turned off except for FL1.) To use this filter for PSK-31 or other data modes, set
FL4 to 0.70 or narrower. The BF4 settings shown provide a center frequency of about 1000 Hz.