Crystal Filter Configuration

The Crystal Filter Configuration dialog helps you to view or set up the crystal roofing filters that you have installed in your K3.

You may set up the crystal filters using the K3 front panel CONFIG menu and use this dialog to verify the results.

You may also choose to set up the crystal filters from this dialog.

Crystal filter setup is described in the Configuration section of the Elecraft K3 Owner's Manual.

The dialog contains five columns of text boxes, check boxes, and radio buttons. Each of the columns represent one of the five crystal filter positions on the main RF and sub receiver boards.

Note: Filter 1 is rightmost when viewed from the front of the K3.

Filter Bandwidth

The first row of text boxes is used to describe the filter bandwidth, in kiloHertz (kHz). For example, if your K3 has a 2.70 kHz filter installed in filter position 1, enter "2.70" into the Bandwidth text box for Filter 1. If your K3 has a 500 Hz filter in filter position 4, enter ".50" into the Bandwidth text box for Filter 4. You may type the bandwidth into the text box, or click and hold the up and down arrows just to the right of the text box to change the value. Bandwidth is expressed in increments of .05 kHz (50 Hz) between 0.00 and 13.00 kiloHertz. 0.00 is used to indicate that no filter is installed.

Frequency Offset

Enter the filter's center frequency offset, in kiloHertz. This frequency offset information accompanies a five pole filter. The offset value is expressed in increments of .01 kHz (10 Hz) between -1.28 and +.25 kiloHertz. Five pole filters normally have a negative offset. Eight pole filters normally have an offset of 0.00.

Loss Compensation (Gain)

Narrow crystal filters tend to have more passband loss than wide filters. You can compensate for this effect by specifying an amount of added gain to use for each filter in receive mode. Enter the desired gain "boost", in decibels, for each filter. You may specify a value between 0 and 8 dB.

Here are the "starting point" loss compensation values that Elecraft recommends. You may wish to further adjust the values for your particular filters.

Receive Filter Enables (Per-Mode)

There are six rows of check boxes to indicate which filters are to be enabled per mode. You should enable both narrow and wide filters for use in USB and LSB, since they may be used during copy of DATA, SSB, or AM signals.

Transmit Filter Selection (Per-Mode)

There are four rows of radio buttons labeled Tx CW, Tx SSB, Tx AM, and Tx FM, that indicate which transmit filter is used for each mode.

Choose a 2.70 or 2.80 kHz filter for CW and SSB.

The filter you choose for SSB is used for USB, LSB, and DATA modes.

If available, select a 6.00 kHz filter for AM and a 13.00 kHz filter for FM.

The filter you choose for Tx AM is also used for ESSB.

Main and Sub Receiver

The Main/Sub Receiver buttons are disabled if you have changed but not yet "Applied" any of the settings on the current page. See Apply or Cancel below.

OK

You may make changes to the filter settings using the text boxes, check boxes, and radio buttons on the dialog. These changes are stored in the K3 when you click OK or Apply. OK closes the dialog, Apply does not.

Cancel

Click "Cancel" to close the dialog without changing any of the K3's filter settings. Unapplied changes are abandoned.

Apply

This button is enabled when the filter settings in the dialog differ from the settings in the K3. If you change a filter setting on the dialog, the Apply button becomes enabled to indicate that there are unapplied changes pending. Click "Apply" to store the updated filter settings in the K3. Click "Cancel" if you don't want the changes stored in the K3.

The radio buttons used to navigate between the Main and Sub Receiver are disabled if there are unapplied changes pending. Click Apply to store the current page's changes into the K3 or Cancel to abandon pending changes and reopen the dialog to navigate to the Sub Receiver.

OK closes the dialog, Apply does not.