# Crystal Filter Configuration

Automates the crystal filter setup described in the Configuration section of the Elecraft K3 Owner's Manual.

Each of the five 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 describes the filter's 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 the arrows to the right 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. Offset information accompanies a five pole filter. The 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.

Elecraft recommends using the initial loss compensation values below. You may wish to further adjust the values for your particular filters.

Part Number | Bandwidth | Gain
--- | --- | ---
KFL3A-200 | 0.20 kHz | 3-4 dB
KFL3A-250 | 0.25 kHz | 3-4 dB
KFL3A-400 | 0.40 kHz | 1-2 dB
KFL3A-500 | 0.50 kHz | 1-2 dB
KFL3A-1.0K | 1.00 kHz | 0 dB
KFL3A-1.8K | 1.80 kHz | 0 dB
KFL3A-2.1K | 2.10 kHz | 0 dB
KFL3A-2.7K | 2.70 kHz | 0 dB
KFL3A-2.8K | 2.80 kHz | 0 dB
KFL3A-6K | 6.00 kHz | 0 dB
KFL3B-FM | 13.00 kHz | 0 dB

#### Receive Filter Enables (Per-Mode)

There are six rows of checkboxes 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. Filters wider than 2.80 kHz may not be enabled for CW receive.

#### 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.

FM transmit always uses the filter in position 1. If you have an FM filter, install it in position 1.

#### Main and Sub Receiver

If you have installed and enabled the KRX3 Second Receiver Option then the sub receiver radio button may be selected to set up its crystal filters.

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

Changes are stored in the K3 when you click OK or Apply. OK closes the dialog, Apply does not.

#### Cancel

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

#### Apply

Stores the updated settings in the K3. Click "Cancel" if you don't want the changes stored. Apply is enabled when changes have been made that have not yet been stored in the K3.

The 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.