A REMOTE STEERABLE RECEIVING ARRAY FOR 1.8 MHz GREG SMITH ZL3IX

REASON FOR THE PROJECT

• TO STUDY SKEWING ON LONG PATHS.

• TO AID THE RECEPTION OF WEAK DX SIGNALS.

REMOTE STATION BLOCK DIAGRAM Signal Combiner 160m Rx 438 MHz Tx 433 MHz Rx Controller Telemetry Solar Power Supply Duplexer

ANTENNA DESIGN REQUIREMENTS.

• BEAM WIDTH NOT EXCEEDING 60 DEGREES.

• MUST BE STEERABLE TO COVER ALL COMPASS POINTS • MUST FIT INTO A REASONABLE SIZE, eg 1 HECTARE

THE BEVERAGE ANTENNA

• Long low wire about 2-3m off ground • Needs to be about 2 wavelengths long.

F

ARRAY OF BEVERAGES NEEDS 330m X 330m OR ABOUT 10 Ha

BROADSIDE ENDFIRE ARRAY

BroadSide EndFire ARRAY (ref W8JI www.w8ji.com) 100 m 21 m

100X21m BSEF ARRAY

REQUIRES ABOUT 1 Ha

E/W NW/SE N/S NE/SW

92X38m BSEF ARRAY

ELEMENT CHOICE

• SHORT LOADED VERTICAL • SHORT VERTICAL WITH Hi Z BUFFER.

• SMALL LOOP

FET BUFFER

Ant Element C4 47p C1 270p C2 270p C3 56p R1 100R Q1 J310 L1 90u R2 10k R3 500R R4 Q2 J310 C7 100n C6 100n L2 220u Output 75 ohm T1 C5 100n L3 220u

ANT 1 ANT 2 ANT 3 ANT 4 ANT 5 ANT 6 ANT 7 ANT 8 RL1 N/S RL2 NE/SW RL3 +13.6 V REVERSE 150 150 T1 T2 T3 100n 220u 100n T4 100n 100n 220u RL5 COAX PHASE DELAY 820 15 820 150 T5 T6 ARRAY OUTPUT E/W RL4

SIGNAL COMBINER

SE/NW

From Antenna Bandpass Filter 14.4 MHz TCXO Direct Digital Synth 5.38-5.48 MHz IF Xtal Filter 3.579 MHz IF Amp AGC Xtal Osc Product Detector Audio Amp

CONTROLLER

• 16F876 PIC • WIZ C • DECODES SERIAL CONTROL DATA • PROGRAMS DDS IN Rx • SELECTS CORRECT ELEMENTS FOR REQUIRED DIRECTION

UHF Rx/Tx

• Rx - MODIFIED DEVELOPMENT MODEL TB8100 • 500 mW WHEN “ASLEEP” • Tx - TM8100 PA • CTCSS TONE TO SWITCH ON • LACK OF CARRIER FOR 4 s, OR A DIFFERENT CTCSS TONE, SWITCHES SYSTEM OFF.

• DATA LINK 4800 Bd RAW RS232

POWER SYSTEM

Solar Panel Constant Voltage Controller 45 Ah Lead Acid Battery Load

LOCAL STATION BLOCK DIAGRAM Controller Telemtry Rx Headphone Amp 433 MHz Tx 438 MHz Rx Duplexer

TUNER BLOCK DIAGRAM Shaft Encoder 4x4 Keypad 16F876 Processor LCD Display 4800 Bd Serial Data

THE UHF LINK

TELEMETRY • PARAMETERS - 160m RSSI, UHF RSSI, Batt Volts, Solar Volts.

• SUPERIMPOSED ON AUDIO • 300 Bd FSK, Tones at 1850 and 2150 Hz • Telemetry has HP filter at Tx • Audio has LP filter at Rx

THE TELEMETRY RECEIVER 1850 Hz 2150 Hz Switched Capacitor Filters + 300 BAUD 16F876 PIC 4800 BAUD

PROBLEMS • UNEQUAL ELEMENT PICKUP PREAMP GAIN VARIATIONS

PROBLEMS • UNEQUAL ELEMENT PICKUP PREAMP GAIN VARIATIONS PICKUP FROM COAX BRAID

PROBLEMS •

NOISE FROM COMMON Tx/Rx ANTENNA

HOSE CLAMPS SERIOUS OFFENDERS METAL MOUNTING PLATE PVC TAPE UNDER U BOLTS COAX BRAID • •

FADING ON UHF LINK

AIRCRAFT FLUTTER CAUSES DEEP SIGNAL FADES ON BOTH UP AND DOWN LINKS.

SLOW FADING DUE TO GENERAL TROPOSPHERIC PROPAGATION VARIATIONS

TESTING

W NW SW N REMOTE NE HOME E SE S