Ramsey Electronics PM10DC Manual

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Ramsey Electronics Model No.
Ever need to tune up RF equipment, but didn't have the money
for expensive watt meters and spectrum analyzers? Want to be
able to measure low-level signals and high-level signals without
changing slugs and flipping switches? This versatile piece of
test equipment should be standard on every RF experimenter's
bench. Hundreds of uses!
Accurately tune and match your antenna for maximum
performance!
Can accurately measure signals from –29dBm to +47dBm; that's
<2 microwatts to 50 Watts!
Auto-scaling display shows forward power and reverse power in
dBm, watts, peak power, and average power! Also displays
percent of AM modulation!
2x8 Line LCD display shows measurements on a clear and easy to
read display!
Runs from 7-15V AC or DC. Use our AC-1 wall adapter.
Highly accurate (+/-1dB) from 2MHz to 450MHz. Effective from
100kHz to 1GHz, however refer to the sensitivity charts in the
manual for conversions and limitations.
Perfect match for tuning and testing our various transmitters such
as the FM100, FM25, PX1, TX433, AM1, AM25, and the QRP line of
transmitters. Tune your product for maximum efficiency!
See transmission levels down where other meters simply cannot
go!
PM10DC

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Summary of Contents for Ramsey Electronics PM10DC

  • Page 1 Ramsey Electronics Model No. PM10DC Ever need to tune up RF equipment, but didn’t have the money for expensive watt meters and spectrum analyzers? Want to be able to measure low-level signals and high-level signals without changing slugs and flipping switches? This versatile piece of test equipment should be standard on every RF experimenter’s...
  • Page 2 Ramsey Electronics publication No. MPM10DC Revision 1.3a First printing: July 2002 MRW COPYRIGHT 2002 by Ramsey Electronics, Inc. 590 Fishers Station Drive, Victor, New York 14564. All rights reserved. No portion of this publication may be copied or duplicated without the written permission of Ramsey Electronics, Inc.
  • Page 3: Table Of Contents

    Assembly (Main Board) .......16 Schematic Centerfold ......18 Directional Coupler Assembly .....22 Front and Main Board Mounting ..26 Testing ..........27 Using the PM10DC ......30 How to Tune an Antenna ....31-33 Board Layouts, Schematic .....34-35 Troubleshooting ........36 Sensitivity vs. Frequency Chart ...37 Pictures ..........38...
  • Page 4: Introduction

    PM10DC INTRODUCTION Welcome to the PM10DC kit (and if you don’t have the time, the wired and tested version). This is a product that many of you were asking for; a powerful bench-top power meter in our standard kit case. It is based around two AD8307 log detectors which have a 90dB dynamic range for signal strength measurements.
  • Page 5: Theory Of Operation

    PM10DC THEORY OF OPERATION If we’ve done our job you will come away from this theory with a greater un- derstanding of electronics, dBm, and how power is measured from transmit- ters. You may also learn why this power meter has such fantastic range, and you’ll find out why our engineer (me) has such a bad headache after writing...
  • Page 6 PM10DC and the attenuation, we need to subtract 48.6dB from this answer to get actual dB. This comes out to the conversion of 1000 = -21.74dBm! Now that we have our dBm result we have to calculate watts from it when we need to display watts.
  • Page 7 Luckily the processor is fast enough to average 100 samples before up- dating the display, giving you a pretty good idea of average power. Another useful thing the PM10DC does is show percent of AM. Since we can take more than 200 samples between screen updates, we can take all of the samples and look for the maximum level and the minimum level.
  • Page 8: Learn As You Build

    This is a mixed signal project meaning there is digital and RF circuitry all in one unit. As with all RF circuitry, we want to mount the parts AS LOW AS POSSIBLE to the board. A 1/4” lead length on a resistor not mounted close to PM10DC 8...
  • Page 9 In the case of a surface mount component, INSTALL means these steps: • Dab a small amount of solder on one pad on the PC board of the component you wish to install. Usually choose pin 1 of ICs. PM10DC 9...
  • Page 10 PC board. • Apply solder to the rest of the pads. • Apply a touch more solder to the initial pad if needed to make sure there is a good solder joint. PM10DC 10...
  • Page 11 If a problem does occur, the manual will lead you through step by step in the troubleshooting guide until you find the problem and are able to correct it. PM10DC 11...
  • Page 12: Parts List

    RAMSEY PM10DC PARTS LIST Supplies 1N4002 Rectifier Diode (Black body with white stripe marked 4002) (D1) 78L05 Voltage Regulator (TO-92 Case) (VR1) ADS7841PBN 12-Bit 4-channel A2D converter (U2) LMC662 Dual Rail to Rail opamp (U1) Pre-programmed MC68HRC908JK3 (U4) 0.01uF ceramic capacitors (Marked 103) (C1,3,4,6,7,15,25,26) 0.1uF ceramic capacitors (Marked 104) (C2,10,11,18)
  • Page 13 Typically the preci- sion stripe (which is always last) is wider than the rest, kind of like a period. So always start from the end with the narrow stripe. PM10DC 13...
  • Page 14: Assembly (Display)

    3. On the top of the display there are two screw hole tabs. These will get in the way of mounting the PM10DC inside a case. We will need to cut them off after bending them over flat toward the back of the display so they don’t stick up.
  • Page 15 If we attached it now it would be very difficult to install parts on the main board later, especially the power switch. On the next page we will begin working on the main board. PM10DC 15...
  • Page 16: Assembly (Main Board)

    16. Install R20, a 1K ohm resistor (brown-black-red). 17. Install C25, a 0.01uF ceramic capacitor (Marked 103). 18. Install C18, a 0.1uF ceramic capacitor (Marked 104). 19. Install R11, a 47K ohm resistor (yellow-violet-orange). Note this resistor is installed in a stand-up position. PM10DC 16...
  • Page 17 Plastic egg cartons will have too much static since they are Styrofoam so don’t use those. Sort out all of your components and note that we give you extra, because we know a few will fly PM10DC 17...
  • Page 18: Schematic Centerfold

    PM10DC 18...
  • Page 19 PM10DC 19...
  • Page 20 51. Install R22, a 1K ohm SMT resistor (Marked 102). 52. Install R23, a 47K ohm SMT resistor (Marked 473). 53. Install R13, a 50K ohm potentiometer. (Orange top marked 503). 54. Install R19, another 50K ohm potentiometer. (Orange top marked 503). PM10DC 20...
  • Page 21 56. Install J7, the 2.1mm power jack. 57. Install J4, one of the BNC connectors. Make sure it is flush and square before soldering. Also solder the mounting pins for added stability. 58. Install J3, the other board mounted BNC connector. PM10DC 21...
  • Page 22: Directional Coupler Assembly

    4. To make it easier to wind the second half without messing up the first half, use a small piece of scotch tape to hold the windings in place, mak- ing sure to tape down the ends so they don’t dangle and get in the way. PM10DC 22...
  • Page 23 8. Place one of the bus wires you bent in the first step into each hole, and then hold down to the position on the main board into which this will be installed. Verify that the bus wires will solder OK to the main board without PM10DC 23...
  • Page 24 1/2” of un-tinned wire before entering the core. This is to prevent the wires from shorting when we cross them over in the next steps. 11. Take the magnet wire exiting one side of the core, and cross it over to PM10DC 24...
  • Page 25 15. Solder the bus wires down to the main board’s provided pads using your tweezers or needle nose pliers to press down on the bus wire while soldering to keep it from springing up. PM10DC 25...
  • Page 26: Front And Main Board Mounting

    5. Make sure all of the provided pads are joined. 6. Check your work for shorts! It is fairly easy to correct these problems so you may as well do that now. PM10DC 26...
  • Page 27: Testing

    Yes, this can pick up microwaves, but not very effectively. Plug in the power to your PM10DC. We will adjust the display contrast so we can actually see something. Using a small screwdriver adjust R4 until you see something.
  • Page 28 Since the base line does vary slightly from unit to unit, it will give your PM10DC a +-2dB accu- racy. If you can calibrate with a known signal level, you will achieve a better than +-1dB accuracy.
  • Page 29 At this point calibration should be complete, and as accurate as possible. Consider a well matched reading as when “F:” and “R:” are within a few per- cent of each other. PM10DC 29...
  • Page 30: Using The Pm10Dc

    It can tell you forward power, reflected power, VSWR, peak power, av- erage power, AM percent and more. The PM10DC is used in-line with your antenna or load, and can tell you a variety of things about your quality of transmission. Once you begin using this,...
  • Page 31: How To Tune An Antenna

    HOW TO TUNE AN ANTENNA An efficient antenna is a well matched antenna! The PM10DC allows you to easily match your antenna to your transmitter. Connect the PM10DC between your transmitter and antenna and set the display to the VSWR mode. You will see VSWR indicated which is indicative of the quality of the antenna match.
  • Page 32 On very low power transmissions like micro-power broadcasting, the additional 2.5% of energy not wasted may bring someone who was in the fringe area into a more acceptable clean trans- mission range. PM10DC 32...
  • Page 33 17.4 1.81 0.078 23.7 1.17 1.32 17.2 1.91 0.083 24.9 1.25 1.33 2.02 0.087 1.61 1.34 16.8 2.13 0.092 1.93 1.35 16.53 2.23 0.096 40.6 2.27 1.36 16.3 2.33 0.101 44.4 2.56 1.37 16.1 2.44 0.106 50.8 3.08 PM10DC 33...
  • Page 34: Board Layouts, Schematic

    MAIN AND DISPLAY BOARD LAYOUT PM10DC 34...
  • Page 35 PM10DC 35...
  • Page 36: Troubleshooting

    We are here to help, and reduce your frustration as much as possible. It usually is something simple. Oh, please count to ten before calling taking some deep breaths first… These DO work, I promise! PM10DC 36...
  • Page 37 FINAL ASSEMBLY PICTURES PM10DC 37...
  • Page 38: Sensitivity Vs. Frequency Chart

    Level set at 0dBm on HP 8647A 250kHz to 1000MHz signal generator Serial #: 3349A03018 Measurements on final board layout, August 20, 2001 Results may vary according to assembly of DC1 PM10DC Calibrated at 50MHz, no extensive “tweaking” performed. PM10DC 38...
  • Page 39: Warranty

    '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.
  • Page 40 PM10DC ADVANCED POWER METER Introduction ..........4 Theory of Operation ......5 Learn as you build .........8 Parts List ..........12 Assembly ..........14 Schematic Centerfold ......18 Using the PM10DC ......30 Antennas and VSWR ......31 Troubleshooting ........36 Warranty ..........37 REQUIRED TOOLS • Soldering Iron Ramsey WLC100 •...

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