A PRACTICAL GUIDE FOR USING THE HP3586A/B/C SELECTIVE LEVEL METER© (Version 2.
TABLE OF CONTENTS CHAPTER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 PAGE Introduction Description of the HP3586 Signal Connections Front Panel Description and Initial Setup Setting and Measuring Frequency Power Level Measurements Using the Selective Mode Voltage Level Measurements Using the Selective Mode Measuring Carrier Signal Strength Tuning SSB Signals Using the Selective Mode Tuning SSB Signals Using the Noise/Demodulation Mode Measuring Audio Noise Using the Wideband Mode Measuring Impulse Noise Mea
1. INTRODUCTION This documents is intended for those having a HP3586 without the operator’s manual or are having trouble understanding the operator’s manual and want to learn how to use this versatile instrument. It should also be of use to those considering purchasing one of these instruments. This document is not intended as a complete operating manual but should help you understand what it does and how to use it.
2. DESCRIPTION OF THE HP3586 2.1 General – For those not familiar with selective level meters they can best be visualized as a receiver having very high selectivity with a detector system capable of accurately measuring low power signal levels from +20dbm down to –100dbm and frequency over a wide range from 200Hz to 32MHz and.
Power dbm = 10 log (Power in watts/.001) Voltage dbv = 20 log (Voltage volts/Vr) or or Power watts = .001 [ anti log ( power dbm/10) ] Voltage volts = Vr [anti log (Voltage volts/20)] Vr = .775 volts for the A and B models: Vr = 1 volts or .775 volts can be selected on the C model. For optimum accuracy the instrument takes measurements over a small part of it’s total –120dbm to +20dbm measuring range by using a range selectable detector circuit.
comparative measurement between different devices or conditions its accuracy can approach the 100db or 10db ranges precision of .1db or .01db, we’ll talk about that in Chapter 16. To maintain accuracy the HP3586 does a 3 second duration automatic calibration, auto cal, when it’s first turned on, every two minutes during operation, if its frequency is changed more than 1MHz, and when a new measuring range width is selected.
3. SIGNAL CONNECTIONS 3.1 General - In this section I’ll describe how to connect a HP3586 for measuring frequency and power level in the selective modes. In the following chapters I’ll also describe any differences for other measurement modes. 3.2 Signal Input and Termination – Never put more than +27dbm or .5 watts total power into the input 50 or 75 ohm connector of a HP3586 when using the internal termination. Never put more than an AC + DC total of +42 volts into an unterminated connector.
4. FRONT PANEL DESCRIPTION AND INITIAL SET UP 4.1 General - Before turning on your HP3586 be sure it’s configured for the right input power, usually 115VAC. Also be sure the filter on its back panel is clean, if not remove it and clean with only soap and water. The filter should be cleaned after every 720 hours of operation. In the following sections and chapter you’ll see capital letters in brackets like [AUTO]. These identify buttons used to control the instrument or enter data.
and carrier buttons are only active in the SSB channel modes. The tone button is only useful for phone line analysis and won’t be used or discussed in this document. 4.4 Status Group - This small status sub panel on the top far right indicates if the instrument is receiving or sending data to a remote computer and weather it’s under local or remote control. If the remote annunciator is on, press [LOCAL]. For our use it should always be in local front panel control mode. 4.
If you press [OFFSET] on this sub panel you’ll first see the offset in the measurement level offset register. If the number you want to enter is close to the present one in the data offset register, you can change the existing number up or down using the arrow keys, [↑] or [↓] and then press one of the db buttons and followed by [MEAS CONT]. 4.8 Frequency/Tune Group - On the lower right side of the front panel is the frequency/tune sub panel.
5. SETTING AND MEASURING FREQUENCY 5.1 General - Now we’re ready to have some fun doing examples of how to use your HP3586. This chapter we’ll show how to use the HP3586 as a VFO by adjusting its frequency and outputting this frequency for controlling an outboard device like an AM transmitter.
If there is other strong signals in the filter’s band pass and the instrument has trouble locking on to the received carrier, select a narrower filter and repeat the above procedure. Unfortunately the HP3586 can’t be easily used as a receiver when controlling a transmitter, see section 16.11 of Chapter 16 for a possible method.
6. POWER LEVEL MEASUREMENTS USING THE SELECTIVE MODE 6.1 General - The most basic function of the HP3586 is to measure the power of signals on telephone lines using its selective measuring mode. This useful feature can also be used to do on the air measuring of radio signal strength or on the bench measuring output of electronic circuits such as oscillators and amplifiers.
and a reading on the LED level display, we need to accurately set the filter center frequency. Press [COUNTER] just under the LED frequency display. Now set the instrument’s frequency register to this frequency by pressing [CNTR→FREQ] followed by [MEAS CONT]. Last select the 20Hz filter to eliminate as much noise as possible from the level measurement. To see the difference in precision for the different ranges, press [100db] under the range label on the measurement/entry sub panel.
7. VOLTAGE LEVEL MEASUREMENTS USING THE SELECTIVE MODE 7.1 General - The HP3586 can only output level measurements in db’s referenced to a power like one miliwatt, one picowatt, or a voltage level like .775 volt on all models and a 1 volt input on the C version. But remember that every level reading is only in db referenced to a power or voltage level. If you’re not familiar with this comparative nonlinear system of measurement, take a look at Appendix A for a better understanding.
8. MEASURING CARRIER SIGNAL STRENGTH 8.1 General - In this chapter we’ll do an example showing the use of the carrier mode in the A and B versions. This mode is not available in the C version but this example can be performed with a C version by using the low distortion selective mode by using the procedure described in chapter 7. If you saved the C models configuration in chapter 7, press [RECALL] followed by entering 1 on the entry sub panel keyboard.
9. TUNING SSB SIGNALS USING THE SELECTIVE MODE 9.1 General - This Chapter will describe the only method of tuning SSB signals on the HP3586C. The next chapter will describe a much easier method used only in the A and B versions. Even if you have an A or B versions with the SSB channel tuning and measurement features, reading this section and understanding its example will give you a better understanding of how your HP3586 works. 9.
The difference is caused by the different way telephone and radio people denote SSB cannel frequency. When comparing a SSB radio frequency with a HP3586 frequency on LSB the HP3586 will have a fixed negative offset from the receiver’s whose value depends on the filter that is selected in the HP3586. On USB the HP3586’s frequency offset will be positive by the same filter offset.
10. TUNING A SSB SIGNAL USING THE NOISE/DEMODULATION MODE 10.1 General – The A and B versions of the HP-3586 have SSB channel modes that speed the setup of the instrument for reception and measuring of SSB signals. Unfortunately the C version doesn’t have these modes but can still be configured to tune SSB signals using the method I described previously in Chapter 9. The noise/demodulation mode was designed for measuring noise and copying SSB signals on telephone channels.
11. MEASURING AUDIO NOISE USING THE WIDEBAND MODE 11.1 General – All versions HP3586 can be used to measure total power input over their entire frequency range of 200Hz to 32MHz by placing them into the wideband measuring mode. This mode is useful for rapidly measuring a signal whose frequency isn’t important or is determined by tuned circuits like in an IF stage as a digital wide band power or voltage meter.
12. MEASURING IMPULSE NOISE 12.1 General – During our wideband noise example we noticed some level changes indicating possible shot noise from some IC’s, a common problem with many inexpensive consumer solid state IC chips. In this chapter we will use the impulse measuring mode to test the shot noise from these chips and illustrate the use of this measuring mode.
13. MEASURING AUDIO HARMONIC DISTORTION 13.1 General – In this chapter we will show how to measure harmonics of a sinusoidal signal. This is an extremely valuable feature removing the necessity of having an audio distortion analyzer if you already have a HP3586. In a later chapter we’ll demonstrate using the HP3586 to measure harmonic distortion at radio frequencies.
13.4 Measuring Harmonic Levels – With the amplifier still putting 2.5 watts at 1000Hz into the 75 ohm dummy load resistor, enter a frequency of 2000Hz using the HP3586’s keyboard to change it’s measuring frequency to 2KHz. You should see a lower than 0dbm reading on the level display. If you have trouble finding it go to a wider filter and then back to the 20Hz filter after tuning it in. Let’s say it’s – 24db but we are not really sure that maybe the signal generator’s frequency has not shifted a few Hz.
14. PASSIVE AND ACTIVE NETWORK ANALYSIS 14.1 General – In this chapter we’ll demonstrate the ability of the HP3586 to be used for network analysis. The HP3586 has the ability to accurately measure relative power and voltage levels over a wide range of frequency and also output a signal at the frequency it’s tuned to. It can do the work of many instruments in one package. We’ll start by taking measurements on a passive band pass filter covering the 160 meter amateur radio band, 1.
power to stay around an input power of 0 dbm to our HP3686 to stay well within its accurate measuring range of +20dbm to –100dbm. The best way to do this and since we are dealing with low power, is to insert a 20db 50 ohm attenuator pad between the 150 ohm resistor and the amplifier’s input. We remove the amplifier and insert the attenuator between the resistors in place of the amplifier. We now repeat the normalization procedure of section 14.
15. MEASURING A TRANSMITTER’S SPURIOUS EMISSIONS 15.1 General – One consideration when working on older or homebrew transmitters is maintaining low spurious emissions. These should be as low as possible, usually down–30db or more from the transmitter’s carriers or maximum output level. The HP3586 has an excellent capability for searching for and measuring spurious emissions, as the following examples will show.
Next change to the noise/demodulation mode under SSB channel on the measurement/mode sub panel. And be sure the [CARRIER] button is on below the frequency display and select USB. Now tune to you’re transmitter frequency, turn up the volume on the audio sub panel and listening to the audio using headphones and speak into the microphone hooked to your AM transmitter. You should hear your USB audio clearly.
16. SELECTION OF MEASUREMENT MODES AND OTHER CONSIDERATIONS 16.1 General – In this last chapter I’ll discuss the advantages and disadvantages of the different measuring modes used in our examples and some other measurement accuracy considerations along with additional applications. Many measurements can be done in more than one of the measurement modes. Usually when in doubt select the low distortion selective measuring mode for best general purpose use.
center of its filter’s band pass like in the other modes if the [CARRIER] button under the frequency display has its light on. Its performance should be similar to the low distortion but it selects the instrument’s widest filter. Its important to realize when using this mode that the instrument’s tracking oscillator’s output signal is always at the RF frequency of the center of the instrument’s filter band pass and offset from the display frequency.
16.9 Other Accuracy Considerations –Always use averaging if a level measurement is rapidly changing its level like when measuring a radio carrier subjected to selective fading or SSB signals. This will give representative average readings over a two second periods and make it easier on your eyes by preventing racking of the display levels. As discussed earlier, using the 10db measuring range will yield the greatest precision of .01db were the 100db range would have a lower precision of .1db.
APPENDIX A UNDERSTANDING THE DECIBEL RATIO MEASURING SYSTEM The HP3586 will only outputs level measurement in the nonlinear logarithmic system of decibels. This system is widely used to express levels of power in electronic and acoustic measurements because it has the advantage of emphasizing only changes that are significant.
As and example again lets say we have +6 dbm, we divide 6 by 10 to get .6 and using our calculator get the anti log as 3.98 on my HP 25 calculator, which is nearly 4, and multiply it by our reference of one mw and have 4 mw of power equal to +6dbm. If it were –6dbm the ratio would be negative, -.6, and the anti log would be .25, which is .25 mw since PR is in miliwatts.
When working with voltage the formula is a little different from the power formula: Voltage ratio in dbv = 20 log (V/VR) Where V = the level in volts and VR is the reference in volts. Our HP3586 uses .775 volts as a reference where: dbV.775 = 20 log (V/.775) Where VR is now .775 volts and V is still in volts.
APPENDIX B HP3586 ERROR CODES During initial power up and following auto cal cycles, the follow error codes could appear on one of the LED displays indicating a failure to calibrate and or an instrument failure. Some error codes could also indicate improper entries or operation of the instrument. Below is a list of these codes to help you in determining the problem and a solution: The format for all non-calibration error messages is Err N=1 N or E N.
APPENDIX C SCHEMATICS FOR USEFUL HP3586 ACCESSORIES Print these Adobe PDF files from the following files you received with this text file for the contents of this appendix and insert them behind this page: C1-C2.PDF Fig C1– Hi Z ONE TO ONE ISOLATIONS AMPS Fig C2 – DC ISOLATED 50 OHM TERMINATION BOX C3.PDF Fig C3 – AMP FOR HP3586 Fo OUTPUT TO A BC-610 OR A VIKING 2 I would like to thank David Jennings, WJ6W, for the excellent job of drawing these figures in Auto Cad.
