PASSIVE AIR BAND MONITOR Ramsey Electronics Model No. ABM1 Imagine monitoring the entire 118 to 136 MHz Aircraft band with no tuning! Then imagine being able to bring your receiver onboard aircraft to hear what’s going on and not having to worry about interference! This monitor give you access to air traffic signals from aircraft and airports . . .
PARTIAL LIST OF AVAILABLE KITS: RAMSEY TRANSMITTER KITS • FM10A, FM25B, FM30, FM Stereo Transmitters • FM100B, FM35 Professional FM Stereo Transmitters • AM1, AM25 AM Broadcast Band Transmitters RAMSEY RECEIVER KITS • FR1 FM Broadcast Receiver • AR2 Digital Aircraft Band Receiver • AR1 Aircraft Band Receiver • SR2 Shortwave Receiver • SC1 Shortwave Converter RAMSEY HOBBY KITS • LBC6K Laser Beam Communicator • SG7 Personal Speed Radar • SS70C Speech Scrambler/Descrambler • DCI1 DTMF Controller • LLS1 Laser L
Ramsey Publication No. ABM1 Manual Price Only $5.00 INSTRUCTION MANUAL FOR PASSIVE AIR BAND MONITOR TABLE OF CONTENTS Introduction .......................................... 4 Circuit Description................................ 4 What You Can Expect to Hear ............ 6 Parts List............................................ 10 Assembly Steps ................................. 12 Schematic .......................................... 14 ABM1 Alignment and Adjustment...... 20 Troubleshooting ................
INTRODUCTION Everyone from aviation enthusiasts to armchair listeners to schoolchildren can enjoy listening to aircraft and airport signals with the ABM1. It’s an Aircraft receiver that does not radiate RF signals so you can take it to the airport and even onboard aircraft without worrying about causing interference. In order for the receiver to be non-interfering, no local oscillators or mixers are used.
2nd Band-pass Filter The 2nd Band-pass filter is a copy of the first. Its job is to further filter the RF signal. It consists of coupling capacitor C8, and filter components M3, C10, L4, C11, C12, and M4. AM Detector The AM detector consists of C13; you guessed it, it’s another coupling capacitor that passes the signal to U2’s non-inverting input while isolating DC. R6 provides the bias for the detector while C17 provides power supply filtering.
Audio Amplifier The Audio amplifier section consists of R11, the On/Off/Volume control. This part turns the power on or off and adjusts the audio level sent to the headphones. C20 couples the audio signal to the Audio Amplifier, U4, while isolating DC. C21 keeps high frequencies out of the amplifier. C22 is a bypass capacitor. C23 sets the gain of the amplifier to approximately 200. C24 filters the power supply. C25 is the output coupling cap. C26 and R12 are used to prevent the amplifier from oscillating.
ATIS, is a repeated broadcast about basic weather information, runways in use, and any special information such as closed taxiways or runways. ASOS/AWOS – Automated Surface Observing System/Automated Weather Observing System This system is similar to ATIS but usually located at un-towered airports. Approach Control & Departure Control These air traffic radar controllers coordinate all flight operations in the vicinity of busy metropolitan airport areas.
routed via computers to the proper company, relieving some of the necessity for routine voice communication. With ACARS, routine items such as departure reports, arrival reports, passenger loads, fuel data, engine performance data and more can be retrieved from the aircraft at automatic intervals. This transmission will sound like a short data burst to the ABM1 user. THOSE FAST-TALKING PILOTS AND CONTROLLERS! Aviation communication is brief but it is clear and full of meaning.
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PARTS LIST CAPACITORS 2 2.2pF ceramic disk capacitor [marked 2.2] (C3, C11) 2 5pF ceramic disk capacitor [marked 5] (C6, C15) 4 68pF ceramic disk capacitor [marked 62] (C2, C4, C10, C12) 8 1nF or 0.001uF ceramic disk capacitor [marked 102] (C1, C5, C8, C9, C13, C14, C16, C21) 4 100nF or 0.
MISCELLANEOUS COMPONENTS AND HARDWARE 1 3.5mm Stereo Jack NOSW [J1] 1 4 inches of 24 gauge Red/black twisted pair 1 Case Top 1 Case Bottom 1 Case Panel 4 Case screws 1 Belt Clip 1 Set of battery contacts 2 Thumbwheel for potentiometers 2 Thumbwheel screws 1 AR3 Rev 1.
ASSEMBLY STEPS In ALL PC board assembly steps, our word "INSTALL" always means to do this: • Insert the part, oriented or "pointed" correctly, into its holes in the PC board. • If helpful, gently BEND the part's wire leads or tabs to hold it into place, with the body of the part snugly against the top side ("component side") of the circuit board. • Solder ALL wires or pins of the part.
on one end of the part; this corresponds to the notch on the IC and shows you which way to place the part. Line up the notches and make sure that all pins are through the board. With no other parts installed (other than surface mount) you can have the part sit flat on your bench and the board will hold U3 in place. That way the part will sit flat on the board. That’s why we’re putting the ICs in first! We typically solder the two corner pins, flip the board over to check placement, then solder the rest.
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Install C4, 68pF ceramic disk capacitor (marked 68). RF AMPLIFIER Install C5, 1nF ceramic disk capacitor (marked 102). Install C6, 5pF ceramic disk capacitor (marked 5 or 4.7). C6 is put in on a 45 degree angle. This is done to keep the foil run as short as possible as part of good, standard RF (Radio Frequency) practice. Excess lead length adds unwanted inductance in RF circuits. U1 is already installed. Install R1, 470 ohm resistor (yellow-violet-brown).
U2 is already installed. Install C17, 100nF ceramic disk capacitor (marked 104). Install R6, 560 ohm resistor (green-blue-brown). This is our 3rd and last lay-down resistor. SQUELCH CIRCUIT Install C19, 1uF electrolytic capacitor. Electrolytic caps have a polarity and must be installed correctly in order to work . . .
Install R3, 100k ohm resistor (brown-black-yellow). This part is located at the notched end of U4. Install R5, 1k ohm resistor (brown -black-red). This part is located in the corner of the board that does not have anything mounted yet. Install R4, 10k ohm potentiometer (marked B10K). The three potentiometer contact leads (middle leads) may need to be bent slightly to fit in the holes. This was done intentionally to keep the part in the board while soldering.
Find the two battery clips. Look carefully at the two clips; the one with the narrower contact is the (+) clip and to be attached to the Red wire. The wider contact is the (-) clip and is to be attached to the Black wire. Feed the Red wire though the appropriate clip from the battery contact side (not the side that clips into the case). Solder the Red wire into place. Repeat the process for the black wire and appropriate clip.
ABM1 ALIGNMENT AND ADJUSTMENT TUNING THE ABM1 The ABM1 does not require any frequency tuning. It will receive the entire Aircraft Band at one time with the audio volume level being greatest for the strongest signals. The ABM1 is a total band monitor so you will hear any signal generated in that band. Since this is a total band receiver the bandpass filters have been specially designed to be wideband. The aircraft band is located between the FM broadcast band and one of the Pager bands.
ABM1 TROUBLESHOOTING While we had hoped that it wouldn’t come to this, if you are having trouble with your receiver, here are a few suggestions. By far the most common sources of problems are misplaced parts or poor solder connections. It’s always best to take a break before searching for bad connections. A good way of checking component placement is to double check the assembly steps going backwards from the last steps to the first.
No Signals can be heard Check MAR-1SM (U1): Check the input pin for 2.5 Volts DC +/- 10 %. This is the pin with the dot. Check the output pin for 4.7 Volts DC +/- 10 %. This is the pin across from the dot. Check the 1st Band-pass Filter, 2nd Band-pass Filter and the AM Detector circuits for solder bridges, misplaced components, polarity of components, and orientation of components. Check U2’s supply Voltage at U1 pin 6 or 7; it should be 4.
CONCLUSION If you enjoyed this Ramsey product, there are plenty more to choose from in our catalog - write or call today! We sincerely hope that you will enjoy the use of this Ramsey product. As always, we have tried to compose our manual in the easiest, most “user friendly” format possible. As our customers, we value your opinions, comments, and additions that you would like to see in future publications. Please submit comments or ideas to: Ramsey Electronics Inc. Attn.
ABM1 SPECIFICATIONS Frequency of Operation: Receiver Type: IF Frequencies: Receiver Sensitivity: Antenna Input Jack (Headphones): Audio Output Jack: Audio Output Power: Power Supply Requirements: Current Draw: Circuit Board Dimensions: Case Dimensions: Weight completed (with 9V battery) 118 to 136 MHz Patented Passive Detector None Less than 2uV for detectable audio 3.5mm Stereo Jack 3.5mm Stereo Jack Approx. 700 mW into 8 - 24 ohms 9 Volt Battery 50 mA Maximum 20 mA typical 2.25 inches X 2.80 in (57.
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The Ramsey Kit Warranty Please read carefully BEFORE calling or writing in about your kit. Most problems can be solved without contacting the factory. Notice that this is not a "fine print" warranty. We want you to understand your rights and ours too! All Ramsey kits will work if assembled properly. The very fact that your kit includes this new manual is your assurance that a team of knowledgeable people have field-tested several "copies" of this kit straight from the Ramsey Inventory.
TABLE OF CONTENTS Introduction ..........................................4 Circuit Description ................................4 Parts List ........................................... 10 Assembly Steps ................................ 12 Schematic ......................................... 14 ABM1 Specifications ......................... 24 Parts Layout Diagram ....................... 25 Warranty............................................ 27 RAMSEY ELECTRONICS, INC.
