POWER BOOSTER AMPLIFIER Ramsey Electronics Model No. LPA1 Looking to boost the output of a small transmitter or signal generator? Look no further. Our general purpose broadband power amplifier is ideal for the test bench as well as any ham radio applications. Get up to 1 watt RF power output! • State of the art “MMIC” amplifier technology ensures great quality amplification.
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Ramsey Publication No. MLPA1 Price $5.00 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR LPA1 POWER BOOSTER AMPLIFIER TABLE OF CONTENTS Introduction to the LPA1 ................... 4 How It Works .................................... 4 LPA1 Parts List ................................. 7 Schematic Diagram .......................... 8 Parts Layout Diagram ....................... 9 Feedback Circuit Considerations .... 10 LPA1 Assembly Instructions ............ 11 Setup and Testing ...........................
Welcome to the LPA Power Booster Amplifier Thank you for purchasing the LPA1 Power Booster Amplifier. The LPA -1 is a state of the art amplifier for almost any low power transmitter. With a frequency range from 100Khz to almost 1Ghz, it is no wonder that it is so versatile. And with an incredible gain of up to 38.5dB (7079 times the input power) at 10 Mhz, you can finally be heard over all of the noise and interference on many bands.
There are three other parts of this circuit. One simply turns on and supplies power to the circuit. The second, supplies power to the MAV3 amplifier. The third biases Q2 for proper operation. Ramsey “Learn-as-you-build” Power Booster Assembly Strategy Since the LPA1 runs at very high frequencies, it is extremely important that you follow the instructions provided. Incorrectly installed components, excessively long component leads, and bad solder joints may mean that your kit won’t work.
Double sided component soldering instructions: You’ll notice that the circuit board contains plating on both sides of the board, with a large ground “plane” area on the component side of the circuit board. In order to electrically connect this topside ground plane to the bottom side ground connections, it will be necessary to solder some connections on both the top and bottom sides of the circuit board. These topside connections will be clearly pointed out when necessary in the assembly instructions.
RAMSEY LPA1 Power Booster Amplifier Parts List SEMICONDUCTORS ❒ 1 MAR3 RF amplifier [Small, black, round on one side] (U1) ❒ 1 PNP transistor [marked 221334] (Q1) ❒ 1 MRF581 NPN power transistor [Small, black, round and marked “581”] (Q2) ❒ 1 Red LED (D1) CAPACITORS ❒ 8 .01uF disc capacitor [marked .01 or 103 or 10nF] (C1,2,4,5,6,7,8,9) ❒ 1 10uF electrolytic (C3) INDUCTORS ❒ 1 VK200 inductor [black ferrite core and bare wire to wind through it] (L1) ❒ 1 5.
LPA1 • 8
LPA1 PARTS LAYOUT DIAGRAM LPA1 • 9
Feedback Circuit: Your Ramsey LPA1 Power Booster Amplifier has been designed to give you great amplification over a wide range of frequencies. Included in the design of the circuit is a feedback loop consisting of the parts R8 and C5. You must decide whether or not to include the feedback circuit into your kit. According to the table below, with the feedback circuit in place, you may experience a lower gain at frequencies up to 500Mhz.
Now we will begin building our kit. There are just a few more things to know before we put the first components in. For each part, our word “Install” always means these steps. 1 2 3 4 Pick the correct value to start with. Insert it into the correct PC board location. Orient it correctly, following the PC board drawing and the written directions for all parts - especially when there’s a right way and a wrong way to solder it in.
❒ 4. Install J1, the power jack. This is a black plastic jack. Solder the connection on the back of the jack to the bottom side of the board. Now, solder the other connection to both the bottom and the top sides. ❒ 5. Install S1, the main switch. The switch is black, with a white button coming out of it. Solder all six pins. First we are going to install the power circuit. This circuit, containing R5, C3 and D1 light up the LED when the switch is on.
Now that we have completed the power circuits, we will move on to the biasing circuit. This circuit holds the transistor output voltages in the desired range. ❒ 13. Install C1, .01uF capacitor [marked .01 or 103 or 10nF]. Make sure that you crack or peel off the insulation on the legs of the capacitor. Solder the topside connection closest to the outside of the board (towards the switch side) on both the top and bottom sides of the board.
❒ 22. Install C9, .01uF capacitor [marked .01 or 103 or 10nF]. The insulation should be stripped from the legs and a topside connection made nearest the edge of the board. Now that you have installed the biasing circuit, we have only a few more parts to put in before we install the amplifiers. This is a good time to look back over your work and look for misplaced parts and bad solder joints. You should take a rest now if you need one. Take a look at the table on page 10.
BOTTOM SIDE OF BOARD SOLDER BEND LEGS THROUGH BOARD AND SOLDER ON BOTH SIDES SOLDER NOTE: BEFORE SOLDERING PART, MAKE SURE THAT THE MARKING IS ORIENTED AS SHOWN IN THE PARTS LAYOUT DIAGRAM! SOLDER COMPONENT SIDE FOIL SIDE SOLDER MAR3 OR Q2 SOLDER solder them directly onto the board. All four leads should now be connected. Again, make sure that the small “M” is closest to L1. This is very important. ❒ 31. Find U1, the MAR3 amplifier.
Setup and testing Now you are ready to set up and test your amplifier. Follow the steps below. If you have any problems, refer to our troubleshooting section. ❒ 1. Plug your kit into a 12V power source with the switch on your LPA1 turned off (click it until it is in the “out” position). You should not see the LED light up. ❒ 2. Turn on the switch. The LED should light up and stay on. ❒ 3. Turn on a (preferably portable) receiver to the same frequency as the transmitter.
PROBLEM: The amplified signal is distorted. SOLUTION: Make sure that all of the component leads are as short as possible. Leaving the leads longer than necessary leaves you open for noise. You should also check the gain. You may be overdriving the amplifier. Try lowering the input power or installing the feedback circuit. The amplifier will only be able to deliver a watt of power, so any more will cause your signal to distort. If the gain is still too high, you can install an attenuating circuit like shown.
Conclusion We sincerely hope that you have enjoyed the construction of this Ramsey Kit. As always, we have tried to compose our manual in the easiest, most “user friendly” format that is 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 Attn. Hobby Kit Department 590 Fishers Station Drive Victor, NY 14564 Thanks again, from the folks at Ramsey.
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 manual is your assurance that a team of knowledgeable people have field-tested several "copies" of this kit straight from the Ramsey Inventory.
LPA1 POWER BOOSTER AMPLIFIER Quick Reference Page Guide Introduction to the LPA1 ................... 4 How it works ..................................... 4 LPA1 Parts list .................................. 7 Schematic diagram ........................... 8 Parts Layout diagram ....................... 9 Feedback circuit considerations ....... 10 LPA1 Assembly instructions ............. 11 Setup and testing ............................. 16 Troubleshooting................................
