SA818 CARRIER BOARD KIT ASSEMBLYVerify that your kit contains the following parts.

Rev2 or higher printed circuit board

Q1, Q2 – 3-020 PNP Transistor (2N4125, 2N2907 can be replacement)

D1 – RED Led

D2 – GREEN Led

R1, R4 – 38K to 47K 1/8 Watt resistor

R2, R3 – 1k 1/8 Watt resistor

R5 – 2K Potentiometer 1/4W

DL – 47 or 50 ohm resistor

C1 – 1uf Ceramic capacitor

(Program pins) 4-pin, 2.54mm male straight header pins

(TP pin) 1-pin, 2.54mm male straight header pin

(3) – 4-40 x ¼” Hex standoff

(6) – 4-40 x 5/32” Pan screws

12” - .015 dia. Kester SN60 Core66 Flux 282 solder

ASSEMBLYRead through this entire document prior to building.

This board should be built from the center out.

Place a piece of scotch tape across the top of the SA818 metal shield extending about ½” on the SA-818 module to assist in aligning and holding of the SA818 module in place prior to soldering.

On each of the rectangle pads there is a small hole ( see Fig. 1). When approximately ½ of the hole is visible in the cutout area on both sides of the SA818 module (See Fig. 2), you are ready to solder.

Solder one pad and recheck that the SA818 is still in the correct alignment position to continue soldering the rest of the pads (13 total). Only apply enough solder to fill the notched fillet area (see Fig. 3 RED ARROW).

DO NOT apply solder above the top portion of the SA818 circuit board pads or a short to the shield may occur. The clearance above each of the SA818 circuit board connection pads to metal shield is less than .02”, (see Fig 3).

Install resistors R1, R2, R3, R4, DL & TP.

Install C1 and 4-pin programming pins.

Note - Use a multimeter set to measure ohms and connect the test leads to the center pin and one of the outer pins on R5. Adjust the potentiometer to a value of 1000 ohms.

Install R5.

Install Leds - Make sure that the longer lead of the led goes in the hole marked +.

Install Q1, Q2 emitter lead goes in the square pad.

Connect wires to holes marked 1 thru 6 at the bottom of the board ( see Fig. 2 )

Lead #1 – +5Vdc @ 500ma capability

Lead #2 - Transmitter PTT

Lead #3 - Receiver audio output

Lead #4 - Transmitter audio input

Lead # 5 – CTCSS Detect output

Lead # 6 – Ground

That completes assembly.

ELECTRICAL TESTINGEquipment needed:

Regulated power supply capable of +5Vdc @ 500ma (min)

Multimeter

Service Monitor - to generate on frequency signal to check receiver and to check transmitter frequency and

deviation. If service monitor is not available, a ht or radio on the desired frequency and

ctcss tone can be used for the test.

Audio or tone generator.

Audio amplifier with speaker.

Apply +5Vdc to lead #1 and power supply negative to Lead #6 Ground.

Check for the following voltages.

Lead #1 – measure current in Receive mode , should be approximately 60-70 ma.

Lead #2 - measure +5 volts

Lead #4 Connect 1000Hz signal @ 10mv.

Lead #3 Connect the audio amplifier/ speaker.

Ground Lead #2, Carrier board Red PTT led will come on and 1000 hz tone will be heard from the Radio/HT speaker or the service monitor’s speaker.

Measure current on Lead #1, should be no more than 770ma on high Tx power and no more than 560ma on low power. Unground Lead#2.

Generate an on frequency signal from the service monitor in to a short piece of wire close by the SA818 radio module.

If a service monitor is not available, key the transmitter (low power) of the on-frequency radio/ht, the Green led on the carrier board will indicate a received signal, audio will be heard from the audio amplifier/speaker and Lead #5 will measure 0 volts when a signal is present and +5Vdc when no signal is present..

If using a radio or HT to transmit to the SA818 module, be careful to not overload the receiver’s front-end and cause possible damage to the receiver.

The receiver has a sensitivity of -124 dbm or better, you want to keep it that way.

If you have questions or concerns, email me at wb6amt@cox.net for a prompt response.

Earl Lizardi – WB6AMT