VHF LOW NOISE PREAMP KIT
Ramsey Electronics Model No. PR100
Boost up those weak signals without adding in unwanted noises! The PR100 has a three section tuned circuit and a double helical filter to allow only the desired signal to be amplified, while attenuating signals outside the band. A perfect match for any 2 meter receiver!
Extensive filtering for low noise operation, 1dB noise figure! Three section tuned circuit and double helical filter Centered on 145 MHz and is 2.8 MHz wide 16dB Gain Perfect match for any VHF Receiver Powered through antenna feed line, or separately Runs on 12VDC Designed to fit inside of 1 1/2 PVC for quick and easy mounting

PR100 1

RAMSEY TRANSMITTER KITS FM100B Professional FM Stereo Transmitter FM25B Sythesized Stereo FM Transmitter MR6 Model Rocket Tracking Transmitter TV6 Television Transmitter RAMSEY RECEIVER KITS FR1 FM Broadcast Receiver AR1 Aircraft Band Receiver SR2 Shortwave Receiver SC1 Shortwave Converter RAMSEY HOBBY KITS SG7 Personal Speed Radar SS70A Speech Scrambler BS1 Bullshooter Digital Voice Storage Unit AVS10 Automatic Sequential Video Switcher WCT20 Cable Wizard Cable Tracer LABC Lead Acid Battery Charger ECG1 Heart Monitor RAMSEY AMATEUR RADIO KITS HR Series HF All Mode Receivers QRP Series HF CW Transmitters CW700 Micro Memory CW Keyer CPO3 Code Practice Oscillator QRP Power Amplifiers RAMSEY MINI-KITS Many other kits are available for hobby, school, Scouts and just plain FUN. New kits are always under development. Write or call for our free Ramsey catalog. PR100 PREAMP KIT INSTRUCTION MANUAL Ramsey Electronics publication No. MPR100 Revision 1.0 First printing: February, 1995
Ramsey Publication No. MPR100 Manual Price Only: $5.00
KIT ASSEMBLY AND INSTRUCTION MANUAL FOR
TABLE OF CONTENTS Introduction to the PR100.. 4 How it Works.. 4 Schematic... 5 Parts Layout.. 6 Strategy.. 7 Assembly Steps.. 8 Alignment.. 11 Installation... 12 Troubleshooting.. 13 Warranty... 14
RAMSEY ELECTRONICS, INC. 590 Fishers Station Drive Victor, New York 14564 Phone (585) 924-4560 Fax (585) 924-4555
INTRODUCTION TO THE PR100 This amplifier is a truly necessary piece of equipment for your 2 meter receive applications. With 16dB of gain, you mount this up on your mast on the antenna to boost those weak signals to a receivable level. This results in clear, unbroken reception, and a more pleasant listening experience. The filtering of the preamplifier is narrow enough only to allow the desired frequency band through, while rejecting all others. This prevents many problems associated with interference such as intermodulation and front end overload. Having such a narrow bandwidth also reduces background noise that would normally be present in wider band amplifiers. Hookup is very simple in that the unit is powered through the same cable that you receive your signals through. It is possible to feed the 12VDC up the coax cable to the preamplifier. No new wires to run and makes for less weatherproofing. The PC board was designed to fit within a 1 1/2 PVC pipe, so a simple enclosure could be created out of one piece of pipe and two endcaps. Glued together it can make for the perfect weatherproof enclosure. HOW IT WORKS There really isnt much to the preamplifier if you look to the schematic at the right. It mostly consists of filtering, and has only one active part, Q1. We will start from the Antenna end of the preamp, and then on to the receiver end. J1 and J2 is where the user can connect two different antennas. Some people recommend that you use two turnstile antennas at right angles to each other for good satellite imaging, if youre using this with a weather satellite receiver. This allows for good coverage of the horizons. Normally you will only use one of these jacks. From these jacks the unfiltered RF passes through C6, into the bandpass tank circuit consisting of inductor L3 and capacitor C8. This tank circuit and the next two are eventually tuned to be centered at 145 MHz. C4 allows some of the RF from the first tank circuit to be allowed into the next, but is very small in capacitance to offer a large reactance (resistance to AC). This high reactance allows the tank circuits to perform their jobs better by giving them a higher Q factor. This means that the spectrum of RF the tank circuits will allow through becomes narrower due to the high Q.

The RF passes through two more tank circuits consisting of L4 and C9 in the second, and C12 and L5 in the third. Every time the RF goes through an additional tank circuit, the bandpass bandwidth of the RF is narrower. The narrower the bandwidth is before the active component of Q1, the better. The narrow bandpass allows Q1 to devote its amplification to just the desired signals. This means that it doesnt amplify nearly as much noise, and wont amplify signals outside of the bandpass area. Q1 amplifies the RF up to a respectable level, where it is sent out to FL1, the dual helical filter. With steep cutoff frequencies and low loss, FL1 has very good bandpass characteristics for our preamp. This filter is essentially a series of tank circuits that have very high Q, and is designed with a specific frequency band in mind. It is tuned by the user to be centered at 145 MHz with the two coils inside. L2, L1, and C1 allows the DC fed through the coax line to pass on to Q1 to power it, while rejecting the RF so that the unit does not self oscillate. C3 blocks the DC from coming into the filters, but allows the RF down to the cable.

PARTS LAYOUT DIAGRAM

PARTS LIST CAPACITORS 2 2.2pF ceramic capacitors (marked 2.2) (C4, C5) 1 10pF ceramic capacitor (marked 10) (C7) 3 8.2pF ceramic capacitors (marked 8.2) (C8, C9, C10) 1 22pF ceramic capacitor (marked 22) (C6) 1 100pF ceramic capacitor (marked 100, or 101) (C2) 1.001uF ceramic capacitor (marked.001, or 102) (C3) 1.01uF ceramic capacitor (marked.01, 103, or 10n) (C1) FIXED RESISTORS ohm resistor (brown-black-brown) (R1) ohm resistor (brown-grey-black) (R3) ohm resistors (orange-black-brown) (R4, R5) 1 47K ohm resistor (yellow-violet-orange) (R2) SEMICONDUCTORS 1 2SC2498 or 2570 NPN UHF transistor (Q1) INDUCTORS AND FILTERS 3 359-7787 Variable inductors (metallic cans with slug) (L3,L4,L5) 2 2.2uH inductors (green body with red-red-gold stripes) (L1, L2) section helical filter, 145 MHz (Large metallic can with two adjustments) (FL1) CONTROLS, HARDWARE & MISCELLANEOUS 1 Type-F connector (J3) 1 PC Board
RAMSEY "LEARN-AS-YOU-BUILD ASSEMBLY STRATEGY" We'll start building on the left side and work our way across, installing the lower components up to the taller sized components. This will make our placing and soldering of components easy. Be sure to read through all of the steps, and check the boxes as you go to be sure you didn't miss any important steps. Before you connect up the kit in a hurry to see results, check all diodes, ICs, and capacitors for proper orientation. Also check the board for any possible solder shorts or cold solder joints. All of these mistakes could have detrimental effects on your kit - not to mention your ego! Kit building tips: Use a good soldering technique - let your soldering iron tip gently heat the traces to which you are soldering, heating both wires and pads simultaneously. Apply the solder on the iron and the pad when the pad is hot enough to melt the solder. The finished joint should look like a drop of water on paper, somewhat soaked in. Mount all parts on the top side of the board. This is the side that has no traces or pads on it. Part orientation - All parts in the kit are mounted at 90 degree angles to each other, meaning that all parts are either parallel or perpendicular to the board. Part installation - when parts are installed, the part is placed flat to the board, and the leads are bent on the backside of the board to prevent the part from falling out before soldering. The part is then soldered securely to the board, and the remaining lead length is then clipped off. Since this is an RF project, make sure that lead lengths are as short as possible, coming only second to neatness. In ALL PC board assembly steps, our word "INSTALL" 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. Trim or "nip" all excess wire lengths extending beyond each solder connection, taking care that wire trimmings do not become lodged in solder connections. PR100 7
ASSEMBLY INSTRUCTIONS: 1. Orient the PC board as in the Parts Layout Diagram. We will start with the left hand side of the board, then go to the right. 2. Install C6, the 22pF ceramic capacitor (marked 22). 3. Install C8, a 8.2pF ceramic capacitor (marked 8.2). 4. Install C4, a 2.2pF ceramic capacitor (marked 2.2). 5. Install C9, a 8.2pF ceramic capacitor (marked 8.2). 6. Install C5, another 2.2pF ceramic capacitor (marked 2.2). 7. Install C10, yet another 8.2pF ceramic capacitor (marked 8.2). 8. Install L3, one of the metallic, square shaped inductors (marked 3597787) Make sure the holes line up with the pins before soldering. 9. Install L4, another one of the inductors (marked 359-7787) 10. Install L5, the last of the tunable inductors (marked 359-7787). 11. Install C7, a 10pF ceramic capacitor (marked 10). 12. Install Q1, the 2SC2498 NPN UHF transistor. This transistor has excellent low noise characteristics, and can amplify signals into the microwave region! Note that the pin out of this transistor is different than that of a switching transistor, so mount it in the orientation as shown in the Parts Layout Diagram. Make sure and use the correct holes for mounting! 13. Install R2, a 47K ohm resistor (yellow-violet-orange). Note that it is a stand up part. Keep the leads as short as possible, as well as neat! 14. Install R1, a 100 ohm resistor (brown-black-brown). This is also a stand up resistor as well. Bend your leads as shown in the diagram. 15. Install C2, a 100pF ceramic capacitor (marked 100 or 101). 16. Install L1, one of the 2.2uH coils (green body, red-red-gold stripes). 17. Install R4, a 300 ohm resistor (orange-black-brown). Notice that this is a lay down part.
18. Install C1, a.01uF ceramic capacitor (marked 103,.01, or 10n). 19. Install L2, another 2.2uH inductor (green body, red-red-gold stripes). 20. Install R3, a 18 ohm resistor (brown-grey-black). 21. Install C3, a.001uF capacitor (marked 102, or.001). 22. Install R5, a 300 ohm resistor (orange-black-brown). 23. Install FL1, the two section helical filter. Make sure and mount it firmly to the board, and that all leads are soldered correctly. At this point we will check all solder joints for possible cold joints or even worse, solder bridges. Make sure everything looks neat and clean before continuing, since the better it looks, the easier it is to find problems. 24. If you have the appropriate F-connectors, install J3, otherwise leave this part out so that you can solder your connecting cable straight to the PC board. Congratulations! You have completed assembly of your PR100. Before continuing on to install your new preamp, check all of your solder joints thoroughly, as well as part orientation. You definitely dont want to seal this into a weatherproof container before you verify if it works or not!

ALIGNMENT: Alignment is fairly simple if you follow these guidelines. The first step is to back all of the lugs out of L3, L4, and L5 until they reach the top of the cans. FL1 should be ok, and wont need any adjusting. 1. Screw L3 in 8 turns. 2. Screw L4 in 8 turns. 3. Screw L5 in 8 turns.
If you have the equipment and the know-how, you can adjust the coils and the helical filter further. You will need a spectrum analyzer and a frequency generator to run at 145.52 MHz for best alignment. Set the generator to 145.52 Mhz and tune the coils to get the greatest amplitude and the best shape. Check the width of the bandpass to make sure it is centered on 145.52 MHz, and is about 2.8 MHz wide. Sweep through to check the shape of the bandpass, it should be close to flat across the bandpass, if not you will need to tune the helical filter.
PREAMP INSTALLATION This part of the manual assumes that you have a receiver or transceiver (if using a transceiver a TR Switch is needed, like our RFS-1). This preamp operates off a 12 volt DC supply which is connected to a 2.2 H inductor then to the center of the antenna cable near your radio(see diagram on next page). Care has to be taken so that you dont short out any connections. Also a.01F ceramic capacitor must be installed after the radios output and before the connection to the 12 volt supply. This capacitor serves as a DC block while allowing RF to pass through. Installation of the preamp is fairly simple, yet there are a few considerations you will wish to look into before you continue. Any RF preamp should be located as close as possible to the antenna itself for best performance. This is due to the losses involved in the cabling to the antenna. Since a signal can be very weak at the antenna, it can be almost nonexistent after it has gone through a length of cable. A non existent signal doesnt get amplified very well. If you boost the weak signal near the antenna, it can be boosted to a high enough level that it can easily be sent down the length of the cable.
THE PR100 Hookup is simple if you are using coax cable such as RG-58 or better 50 ohm cable. Just run a piece from the jack marked RCVR (J3) on the PR100 to the.01F capacitor just before the radio. Then a short piece is needed to go from the capacitor to the radio. Finally, you need to connect the Preamp to the antenna and you are ready for testing. HOOKUP EXAMPLE Turn on your receiver, you should be able to pick up a weak signal with little difficulty. If you are not receiving anything yet, check your 12 volt DC supply. If you are still having troubles, test for the twelve volts present on the preamp, then check the orientation of the preamp. If both are correct, you may need to check your preamp for proper assembly, or even possibly your cabling for opens. Consult the assembly instructions for some help on these matters.

TROUBLESHOOTING GUIDE:

<-- To Antenna

To Radio -->

Problem: When I insert this in line, I dont observe any gain in reception. Solution: There are several causes to the problem, but the major one is that the preamp has been assembled incorrectly. Check Q1 for correct installation, then check J3 for 12VDC. If those check out, go through assembly steps again to make sure you have the parts where they belong. Problem: I cant get the @#*%! thing to work, its Ramseys fault! Solution: Read the warranty information on the next page.
+12 VDC @ 50mA or greater

2.2 uH Coil

TO RADIO

TO ANTENNA

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. If you need help, please read through your manual carefully, all information required to properly build and test your kit is contained within the pages! 1. DEFECTIVE PARTS: It's always easy to blame a part for a problem in your kit, however, customer satisfaction is our goal, so in the event that you do have a problem, take note of the following. Before you conclude that a part may be bad, thoroughly check your work. Today's semiconductors and passive components have reached incredibly high reliability levels, and its sad to say that our human construction skills have not! But on rare occasion a sour component can slip through. All our kit parts carry the Ramsey Electronics Warranty that they are free from defects for a full ninety (90) days from the date of purchase. Defective parts will be replaced promptly at our expense. If you suspect any part to be defective, please mail it to our factory for testing and replacement. Please send only the defective part(s), not the entire kit. The part (s) MUST be returned to us in suitable condition for testing. Please be aware that testing can usually determine if the part was truly defective or damaged by assembly or usage. Don't be afraid of telling us that you 'blew-it', we're all human and in most cases, replacement parts are very reasonably priced. 2. MISSING PARTS: Before assuming a part value is incorrect, check the parts listing carefully to see if it is a critical value such as a specific coil or IC, or whether a RANGE of values is suitable (such as "100 to 500 uF"). Often times, common sense will solve a mysterious missing part problem. If you're missing five 10K ohm resistors and received five extra 1K resistors, you can pretty much be assured that the '1K ohm' resistors are actually the 'missing' 10 K parts ("Hum-m-m, I guess the 'red' band really does look orange!") Ramsey Electronics project kits are packed with pride in the USA. If you believe we packed an incorrect part or omitted a part clearly indicated in your assembly manual as supplied with the basic kit by Ramsey, please write or call us with information on the part you need and proof of kit purchase. 3. FACTORY REPAIR OF ASSEMBLED KITS: To qualify for Ramsey Electronics factory repair, kits MUST: 1. NOT be assembled with acid core solder or flux. 2. NOT be modified in any manner. 3. BE returned in fully-assembled form, not partially assembled. PR100 14

4. BE accompanied by the proper repair fee. No repair will be undertaken until we have received the MINIMUM repair fee (1/2 hour labor) of $25.00, or authorization to charge it to your credit card account. 5. INCLUDE a description of the problem and legible return address. DO NOT send a separate letter; include all correspondence with the unit. Please do not include your own hardware such as non-Ramsey cabinets, knobs, cables, external battery packs and the like. Ramsey Electronics, Inc., reserves the right to refuse repair on ANY item in which we find excessive problems or damage due to construction methods. To assist customers in such situations, Ramsey Electronics, Inc., reserves the right to solve their needs on a case-by-case basis. The repair is $50.00 per hour, regardless of the cost of the kit. Please understand that our technicians are not volunteers and that set-up, testing, diagnosis, repair and repacking and paperwork can take nearly an hour of paid employee time on even a simple kit. Of course, if we find that a part was defective in manufacture, there will be no charge to repair your kit (But please realize that our technicians know the difference between a defective part and parts burned out or damaged through improper use or assembly). 4. REFUNDS: You are given ten (10) days to examine our products. If you are not satisfied, you may return your unassembled kit with all the parts and instructions and proof of purchase to the factory for a full refund. The return package should be packed securely. Insurance is recommended. Please do not cause needless delays; read all information carefully.
VHF LOW NOISE PREAMPLIFIER Quick Reference Page Guide How it Works.. 4 Schematic.. 5 Parts Layout.. 6 Strategy.. 7 Assembly Steps.. 8 Troubleshooting.. 13 Warranty... 14
REQUIRED TOOLS Soldering Iron Ramsey WLC100 Thin Rosin Core Solder Ramsey RTS12 Needle Nose Pliers Ramsey MPP4 or RTS05 Small Diagonal Cutters Ramsey RTS04 <OR> Technicians Tool Kit TK405 ADDITIONAL SUGGESTED ITEMS Holder for PC Board/Parts Ramsey HH3 Desoldering Braid Ramsey RTS08 Digital Multimeter Ramsey M133
ESTIMATED ASSEMBLY TIME Beginner. 1.0 hrs Intermediate. 30 min Advanced. 20 min
RAMSEY ELECTRONICS, INC. Manual 590 Fisher Station Drive Price Only: $5.00 Victor, New York 14564 Ramsey Publication No. MPR100 Phone (585) 924-4560 PR100 Assembly and Instruction manual for: 16 Fax (585) 924-4555 RAMSEY MODEL NO. PR100 www.ramseykits.com VHF Low Noise Preamplifier Kit

High gain - 20 dB Broadband coverage. Excellent review in Feb. 90, 73 Magazine. Two stage feedback design ensures stable operation. Runs on 12-15 VDC @ 15 mA. Complete with applications and hook-up instructions.

BROADBAND RF PREAMP

100 KHz - 1.3 GHz
Perk up that old receiver! Great for scanners, TV sets, frequency counters, shortwave sets, anywhere a stable 20 dB gain is needed!

Kit No. SA7

SA7 INTRODUCTION:
A "preamplifier" gives an initial boost, measured in decibels, to the level of a signal before it is processed by tuned circuits, filters, amplifiers, mixers, detectors or other circuit stages. Preamps may be designed for either RF or audio use and may be either tuned or broadbanded. The SA7 is indeed a "general purpose" RF pre-amplifier. While we realize that most users understand the term "broadband", we understand that some of you would appreciate some clarification. In short, "broadband" means you can use the SA7 to boost the RF level of any signal from the AM broadcast band through VHF and UHF FM and TV bands all the way into the 1300 MHz microwave spectrum. This is possible because the SA7 does not limit or restrict the RF input by means of tuned circuits or filters. Therefore, ALL signals reaching the input are amplified equally. This amplifier differs from the Ramsey PR-10, 20 and 40 models for 144 MHz, 220 and 440 MHz respectively, in that those models include hi-Q tuned circuits to "pre-select" the desired frequency range, restricting the strength of other signals, out of band. A "pre-selector" is a pre-amplifier with a tuned input. We'll show you how to use the SA7 as the heart of such a pre-selector configuration, either fixed or tunable, if that is the practical application which is of most interest to you. So,"broadband" is a mixture of good news and bad news, though it's mostly good news if you understand what such a circuit can and cannot do. Because it boosts all signals equally, its successful operation relies on the input tuned-circuit selectivity of the receiver whose performance you wish to boost. If the receiver does not have much ability to reject unwanted signals, such signals will be boosted just as much as the desired signal.
PARTS SUPPLIED WITH SA7 KIT
Capacitors 1 2.2 pF capacitor [axial style, green body with red bands] (C6) 1 4.7 or 5 pF disc capacitor (C1) 3.01 uF disc [marked.01 or 103 or 10 nF] (C2,3,5) 1 4.7 to 10 uF electrolytic capacitor (C4) Resistors ohm SMT (surface mount technology)"chip" resistor (R6) ohm [green-brown-black] (R2) ohm [brown-black-brown] (R1,R5) ohm [yellow-violet-brown] (R3) 1 1K ohm [brown-black-red] (R4) Special Components, Semiconductors: 1 SA7 printed circuit board 1.04 uH coil [4 turns pre-wound] (L1) 2 2SC2498 or 2SC2570A microwave bipolar transistor (Q1,Q2)
REQUIRED, NOT SUPPLIED 8-15 VDC power source your choice of power on-off switching RF input and output connectors (your choice of type) enclosure of your choice, if SA7 is not mounted inside receiver or counter, etc. SA7 layout
SA7 PRE-AMP ASSEMBLY PROCEDURE
Soldering 15 parts to a PC board is not a big job, but good performance of the SA7 requires attention to keeping all leads as short and neat as possible. The order of the parts installation is not critical for this and other small kits, so the purpose of following the suggested order of assembly is just to make it as easy as possible for you to get the right parts in the right holes. By the time you build your fourth or fifth SA7 for your neighbors old shortwave set or your aunt's FM radio, you'll be an honorary member of the Ramsey factory assembly line! In working with a small PC board such as the SA7, a miniature vise plus a magnifier may prove very helpful.
STEP-BY-STEP PC BOARD ASSEMBLY:

In all steps below, the word install means to insert the component, oriented correctly, into the right holes, solder all wires and cut or nip away excess wire flush with the solder connection. 1. Install R1, 100 ohms (brown-black-brown). 2. Install R2, 51 ohms (green-brown-black). 3. Install C1, 4.7 or 5 pF. 4. Install C2,.01 uF (marked.01 or 103 or 10 nF).
5. Install C5,.01 uF. Notice that C5 lines up with the DC voltage supply points on the PC board. If you have your red (+) and black (-) supply wires ready, they could be installed now while correct polarity is on your mind. 6. Install R4, 1K ohms (brown-black-red). Note that this resistor is installed vertically, with the resistor body closest to Q1. 7. Install C4, the one electrolytic capacitor. Make sure polarity is correct. 8. Install R5, 100 ohm (brown-black-brown). 9. Install Q1 and Q2, 2SC2498 or 2SC2570A. Both transistors are identical. Press both into their respective PC board holes, now made very obvious by the installation of the previous parts. Orient the flat sides as shown on the PC board illustration. Press both in firmly with finger pressure so that a minimum amount of wire leads are exposed above the PC board. Bend the inserted leads in opposing directions just enough to hold each transistor in place. In soldering, do not be afraid to apply enough heat to make good, solid connections. 10. Install L1, the small pre-wound coil. 11. Install C3,.01 uF. 12. Install R3, 470 ohms (yellow-violet-brown).
Installation of C6 and R6. The style of these components might be new to you, but don't be concerned. We'll get them in right. Having installed all the conventional resistors according to color code, note that the remaining resistor-like part is marked with 6 bands; the first two at one end should both be red. This is the 2.2 pF axial capacitor. Install it between Q1 and R3, taking care that the capacitor body is as close as possible to the PC board. 13. C6, 2.2 pF capacitor installed. Resistor R6 is, for many of us, Ramsey Electronics' mandatory crash-course in SMT("Surface Mount Technology") components. It is used in the emitter-to-ground lead of Q2 instead of an ordinary resistor to minimize the possibility of self-oscillation. After you install it correctly, consider yourself a step beyond the 1995 edition of the ARRL Handbook, which simply shows how many SMT parts can gather on a dime and states that the "how to" is beyond the scope of the book! Tools recommended for installing R6: Tweezers Magnifier Low-wattage, very clean and well-tinned soldering tip.
Procedure for installing SMT R6: 1. Unpack from cardboard protective holder and study how R6 is made, using the magnifier if necessary. 2. Notice that both ends are metallic - these are the soldering points. 3. Lightly pre-tin the PC board trace points where R6 is to be positioned. Do not make too heavy a solder build up. 4. Holding R6 in position with tweezers, touch one end and the PC trace with the soldering tip. The solder should flow nicely. Remove the iron and allow the joint to cool while holding R6 in place. 5. Repeat for the other end of R6. 14. R6 properly installed.

Substitution of a small 47 ohm conventional resistor may work out in some applications but it is not recommended. If you somehow destroy R6 on your first try, a request and SASE to the Ramsey factory will get you another. Wiring of your SA7 pre-amp PC board is now complete. It's time to work out the DC voltage supply and inputoutput connections.

USING YOUR SA7 PRE-AMP

The very best way to find out what your SA7 can do, and also cannot do, is to set one up right from the beginning with the input and output connections most practical for your uses. If you are building it with no specific or "dedicated" use in mind, we suggest that you setup its connections to serve as a sort of quickconnect test instrument. Try it out in a variety of situations. A small metal mini-box with convenient input and output connectors makes a dandy little amp to use around the shop. It is ideal for perking up your frequency counter, shortwave rig or wireless FM transmitter. Having the amplifier in a rugged box with connectors permanently attached allows easy hook-up to all sorts of equipment.
THE RAMSEY PR2: ULTIMATE BROADBAND PRE-AMP
After you find out how practical a well-built SA7 can be, you will be quite impressed with the higher gain plus the convenient AC power supply, BNC I/O connectors and LED "on-off" indicator of the Ramsey PR2. The PR2 uses an advanced microwave MMIC for signal-to-noise figures that are typically 27 db (over 4 "S-units") gain, and only 2-3 db of noise. The PR2 also features a high power output compression point of 18 dBm almost 100 milliwatts!
FINAL NOTES ABOUT BROADBAND PRE-AMPS
Yes, the Ramsey SA7 or PR2 RF pre-amp will give that promised boost to the signal strength of that distant FM broadcast station that your wife, sister or dad wants to tune in without so much static. However, if there is a strong local station 20 KHz up or down the band, remember that station is entitled to the same amount of boost! The result may be that the radio will try harder to "lock" on to the frequency of the stronger station, wiping out the very station you want to boost. In such cases, a highly directional gain antenna, with a good line-of-sight view of the broadcasting station, needs to be the first improvement, using the pre-amp for a further boost. When using a broadband preamp with a frequency counter to check the performance of an RF oscillator, remember that neither the preamp or counter have any control over the quality of the oscillator's frequency output. If the next harmonic of the RF source looks better to the counter-preamp combo, that is exactly what you will see and count! Finally, be aware that adding a preamp to a poorly designed VHF or UHF receiver used in busy RF environments will result in very noticeable boosting of out-of-band images and heterodynes.

BROADBAND "ACTIVE ANTENNA"
For situations where a short or indoor receiving antenna is needed, the SA7 preamp will give considerably improved performance even if the antenna is little more than a collapsible whip or short length of wire. For a well-engineered active antenna kit for both HF and VHF, at a breakthrough low price, take a look at our new Model AA7 Active Antenna, which features on-board battery supply, adjustable gain control, heavy-duty whip, HF-VHF mode switching, and jack for using external antenna.

ADDING A TUNED RF INPUT:

The SA7 is designed to give a high RF boost to all that it "hears" - from a few hundred Hz into the GHz region. If you want a preamp that can be "choosy" about what comes from the output, you need to add a tuneable L/C network or filter to the input or output or both. Even though the ARRL Handbook was not much help on soldering SMT components, it's loaded with circuit examples which will show you clearly how to use the SA7's tried and true amplification stages with coils and variable capacitors to accomplish the goals of many different projects. Have fun with your SA7 pre-amp!

Adding a tuned RF input

SA7 ANT Freq. = 1 6.28 LxC
WARNING: Under no circumstances should transmitter power be applied to the SA7. Although this seems common-sense, most receivers are in transceiver configuration and one slip of the mike key will blast your little SA7 to La-La Land.

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. If you need help, please read through your manual carefully. All information required to properly build and test your kit is contained within the pages! 1. DEFECTIVE PARTS: It's always easy to blame a part for a problem in your kit, Before you conclude that a part may be bad, thoroughly check your work. Today's semiconductors and passive components have reached incredibly high reliability levels, and its sad to say that our human construction skills have not! But on rare occasions a sour component can slip through. All our kit parts carry the Ramsey Electronics Warranty that they are free from defects for a full ninety (90) days from the date of purchase. Defective parts will be replaced promptly at our expense. If you suspect any part to be defective, please mail it to our factory for testing and replacement. Please send only the defective part(s), not the entire kit. The part(s) MUST be returned to us in suitable condition for testing. Please be aware that testing can usually determine if the part was truly defective or damaged by assembly or usage. Don't be afraid of telling us that you 'blew it', we're all human and in most cases, replacement parts are very reasonably priced. 2. MISSING PARTS: Before assuming a part value is incorrect, check the parts listing carefully to see if it is a critical value such as a specific coil or IC, or whether a RANGE of values is suitable (such as "100 to 500 uF"). Often times, common sense will solve a mysterious missing part problem. If you're missing five 10K ohm resistors and received five extra 1K resistors, you can pretty much be assured that the '1K ohm' resistors are actually the 'missing' 10 K parts ("Hum-m-m, I guess the 'red' band really does look orange!")

Ramsey Electronics project kits are packed with pride in the USA. If you believe we packed an incorrect part or omitted a part clearly indicated in your assembly manual as supplied with the basic kit by Ramsey, please write or call us with information on the part you need and proof of kit purchase 3. FACTORY REPAIR OF ASSEMBLED KITS: To qualify for Ramsey Electronics factory repair, kits MUST: 1. NOT be assembled with acid core solder or flux. 2. NOT be modified in any manner. 3. BE returned in fully-assembled form, not partially assembled. 4. BE accompanied by the proper repair fee. No repair will be undertaken until we have received the MINIMUM repair fee (1/2 hour labor) of $18.00, or authorization to charge it to your credit card account. 5. INCLUDE a description of the problem and legible return address. DO NOT send a separate letter; include all correspondence with the unit. Please do not include your own hardware such as non-Ramsey cabinets, knobs, cables, external battery packs and the like. Ramsey Electronics, Inc., reserves the right to refuse repair on ANY item in which we find excessive problems or damage due to construction methods. To assist customers in such situations, Ramsey Electronics, Inc., reserves the right to solve their needs on a case-by-case basis. The repair is $36.00 per hour, regardless of the cost of the kit. Please understand that our technicians are not volunteers and that set-up, testing, diagnosis, repair and repacking and paperwork can take nearly an hour of paid employee time on even a simple kit. Of course, if we find that a part was defective in manufacture, there will be no charge to repair your kit (But please realize that our technicians know the difference between a defective part and parts burned out or damaged through improper use or assembly). 4. REFUNDS: You are given ten (10) days to examine our products. If you are not satisfied, you may return your unassembled kit with all the parts and instructions and proof of purchase to the factory for a full refund. The return package should be packed securely. Insurance is recommended. Please do not cause needless delays, read all information carefully.

RAMSEY TRANSMITTER KITS FM10A FM Stereo Transmitter TV6 Television Transmitter RAMSEY RECEIVER KITS FR1 FM Broadcast Receiver AR1 Aircraft Band Receiver SR2 Shortwave Receiver AA7 Active Antenna SC1 Shortwave Converter RAMSEY HOBBY KITS SG7 Personal Speed Radar SS70A Speech Scrambler SP1 Speakerphone MD3 Microwave Motion Detector PH14 Peak Hold Meter TG1 DTMF Tone Grabber RAMSEY AMATEUR RADIO KITS DDF1 Doppler Direction Finder HR Series HF All Mode Receivers QRP Series HF CW Transmitters CW7 CW Keyer CPO3 Code Practice Oscillator QRP Power Amplifiers
TOTAL SOLDER POINTS 37 ESTIMATED ASSEMBLY TIME Beginner.. 1.1 hrs Intermediate. 0.6 hrs Advanced. 0.5 hrs
REQUIRED TOOLS Soldering Iron Ramsey WLC100 Thin Rosin Core Solder Ramsey RTS12 Needle Nose Pliers Ramsey MPP4 or RTS05 Small Diagonal Cutters Ramsey RTS04 <OR> Technicians Tool Kit TK405
ADDITIONAL SUGGESTED ITEMS Holder for PC Board/Parts Ramsey HH3 Desoldering Braid Ramsey RTS08 Digital Multimeter Ramsey M133
RAMSEY MINI-KITS Many other kits are available for hobby, school, Scouts and just plain FUN. New kits are always under development. Write or call for our free Ramsey catalog.
Call or write for our full line catalog!
Published by Ramsey Electronics, Inc. Copyright 1994 All rights reserved. Ramsey Electronics, Inc. SAFishers Station Drive Victor, NY 14564 Phone (585) 924-4560 Fax (585) 924-4555