Keypad Board

The Keypad Board contains fifteen momentary contact push button switches that control all functions of the Express Receiver other than Tuning, RF Gain (pre-amp and attenuator) and AF Gain.

Function Keypad
Function Keypad

The fifteen switches implement the following functions:

FUNC – selects functions available in software; including, retrieving Si570 calibration data, S-Meter Calibration, Aux Audio Level Adjust, Manual IF Gain Set, Band Frequency Calibration Offsets, and Read EEPROM Location (Main Display & Control Board PIC18F45K22).

ENTER – Used to select a given Function and enter values for various Functions into memory.

UP & DOWN – Used for band changing in normal Express Receiver operation. Used to move through various Functions in Function Mode, and used to cycle through allowable values in a given Function.

TX LOCK – Currently used as Dial Hold on the Express Receiver. In future will be used to lock Express Transmitter frequency to Express Receiver.

A/B – Used to switch between VFO A and VFO B frequencies. The active VFO is indicated by an asterik as shown below.

A->B – Used to copy VFO A frequency to VFO B.

MEM – Used to bring up the Memory Display, which is the fourth row of the Main Display and Control Board LCD as shown below. Currently ten memories are available in the Express Receiver. The MEM switch is also used to cycle through the ten memories by repeatedly pressing the MEM switch. The Memory Display is turned off approximately 30 seconds after the last Memory Command to avoid cluttering Main Display and Control Board display.

Main LCD with Memory Display active
Main LCD with Memory Display active

A->M – Used to move the VFO A frequency to the selected Memory Location.

M->A – Used to move the contents of the selected Memory Location to VFO A.

IF FLTR – Used to select one of the four IF Filters available in the Express Receiver. Start up default is 2100-Hz.

AGC – Used to select Slow, Fast or Manual IF Gain Control. Start up default is Slow.

MODE – Used to select USB, LSB or CW mode. Start up default for all bands is USB as I work mostly with data modes.

RATE – Used to select 1000-Hz, 100-Hz or 10-Hz for the Main Tuning rate. Start up default is 100-Hz.

MUTE – Used to mute the Express Receiver.

The fifteen momentary contact push button switches are arranged in a 3 x 5 matrix that is polled by the Main Display and Control Board PIC18F to determine if a button press has occured.

Keypad Board Schematic
Keypad Board Schematic

The ExpressPCB .pcb file for the Keypad Board is here: Switch Board_v2

Refer to the RF Band Pass Filter page for information on the connectors J1 and J2.

SW1 through SW15 are Mountain Switch Tactile Switches Mouser PN 101-0621-EV with Blue Caps Mouser PN 101-0216-EV.