When the manual for a military radio is written the equipment listed for bench test is what was standard issue at the time. To run the same test today you can substitute more modern equipment as long as the newer equipment has equal or better specs.
For serial numbers in the format iijjAnnnn adding 60 to ii is the year made, jj is the week, the letter is the country where made.
for example 1848J02842
- 18 -> Made in 1978
- 48 -> Weeek # of last prodcution change 48
- J -> Made in Japan, or A = America, G = West Germany, U= United Kingdom
- 02842 actual serial number of instrumentThe series prefix doesn't represent the date of manufacture. Instead, it represents the date of the last production change that affects form, fit, or function, or for other modifications such as firmware version changes. We use the series prefix to tie production changes (changes in production documentation) to changes in customer documentation.
Because of the FM capture effect the way receiver sensivity is measured must be different for FM and AM radios. AM radios have no capture effect.
SINAD FM receiver sensivityThis is an acronym for "SIgnal Noise And Distortion". It's defined as:
SINAD = 20 * LOG((RMS Value of Signal, Noise and Distortion)/(RMS Value of Noise & Distortion))
The inclusion of noise and distortion with the signal is the way a distortion analyzer works, i.e. it measures everything then notches out the test tone. The prior signal to noise ratio was difficult to measure because it required a spectrum analyzer to measure the signal all by itself.
I think the values used for SINAD when the HP 300 series analog distortion meters were popular was 10 dB. But these meters used a average reading AC voltage detection method that was in error about 2 dB for non sine signals. With the introduction of the 8903 and other true RMS reading distortion analyzers the spec was changed to 12 dB to produce about the same sensitivity readings as the prior analog instruments. (The 8903 has an internal jumper option to connect an average reading detector if compatibility with the older 300 series instruments is needed).
The common modern definition of receiver sensitivity is the power level that produces a 12 dB SINAD.
The idea is that there are two factors contributing to the received audio signal to noise ratio in an FM receiver. First as the signal strength increases from the noise level the audio output gets quieter (this is even when there is no modulation on the carrier). Second as the signal strength with modulation increases from the noise a 1 kHz tone will get stronger. The difference between the true RMS audio output with the tone modulation on and the true RMS audio output with the tone modulation off is the SINAD.
Distortion AnalyzerOne way to measure this in a single step is to use a SINAD meter or a Total Harmonic Distortion (THD) meter. Both of these methods notch out the 1 kHz tone and can measure both the tone and what's left. The advantage of this method is that you don't need to turn the 1 kHz modulation on and off. This would be very good when testing the SINAD in the field from a transmitter at a remote fixed point.
By using a real SINAD meter like the HP 8903B/E Audio Analyzer the transmitter can be sending a constant 1 kHz tone and the meter will notch out the tone and report the SINAD. This would allow drive testing using GPS in the mobile unit or using a time log to allow plotting SINAD vs. position of the mobile unit. Note for receiver testing the "E" version (no audio gen, just the meter) of the 8903 is about 1/2 the price of the "B" version (internal audio gen).
True RMS VoltmeterAnother way to measure SINAD is to just turn on and off the modulation (note the carrier is left on all the time). This has the advantage that you only need a true RMS voltmeter instead of the SINAD meter or a THD meter like the TS-723 (HP 330 series) distortion Analyzer. I am using this method with the HP/Agilent 8648A signal generator and HP/Agilent 34401A Multimeter under computer control so that a plot can be made of both the plain AF noise output, the 1 kHz tone output, and the SINAD. The problem with this is the requirement to turn on and off the modulation. Easy to do on the bench but more difficult when a mobile unit is driving.
The Distortion Analyzer, THD and SINAD - college experiment that gives the equations and explanation of SINAD
FM Modulation Tutorial -
Receive Audio Frequency ResponseBy using a signal generator like the HP/Agilent 8648A with option 1EP and a voltmeter like the HP/Agilent 34401A a plot of the audio frequency response can be made. It's interesting that the PRC-25 has a peaky response centered at 300 Hz but the PRC-126 has a fairly flat response from 100 to about 9,000 Hz. This is probably because the PRC-126 was designed to support voice encryption over an even wider audio bandwidth and the SPKR audio has been low pass filtered to improve the s/n for clear voice.
This plot was used in a before and after manner when the PRC-25 was upgraded to the PRC-25B to support multiple channel telephony.
Transmit OutputThere are a number of parameters to look at on the transmitted signal:
PowerCan be measured with a power meter like the PRM-34 or similar meters.
FrequencyCan be measured with a filed test meter like the PRM-34 or a modern spectrum analyzer like the Agilent 4395A. When the transmit output frequency is not known the spectrum analyzer is a great tool to find the frequency.
FM DeviationCan be measured with a deviation meter like the ME-505 or ME-525 but can also be measured directly on the Agilent 4395A or other spectrum analyzer. The HP 8901 Modulation Analyzer is a modern version of the ME-505/525.
Harmonic and Spurious outputsThe spectrum analyzer makes this an easy test but it could also be done using a receiver, but finding spurious outputs with a receiver is very tedious unless a computer can do a spectrum sweep.
This paragraph is for equipment that I either have now or have used. Since I do LabVIEW programming, instruments with IEEE-488() and/or RS-232 so that they can be computer controlled are a plus for me. You can get a lot more out of an instrument when a computer is in control vs. manual operation.
DC Power Supplies
||Volts @ Amps
||60 @ 50
||20 @ 30
||500 @ 5
||60 @ 10
|80W LV||7V @ 10A
||20V @ 4A
|80W HV||20V @ 4A
||50V @ 2A
|40W LV||7V @ 5A
||20V @ 2A
|40W HV||20V @ 2A
|This was purchased very
used to replace the HP E3631A Triple Output Digital Power
Supply. The problem with the E3631A is that after a
power failure it defaults to all three outputs at zero
The 6236A uses front panel knobs to set the voltage and so comes up from a power failure at the set voltages (+5, +12 and -12 in this case).
Note: There are only two voltage adjust knobs. One for the 0-6 Volt supply and the other controls both polarities of the 0-20 Volt outputs. But there are seperate metering switch positions for each of the three supplies.
|when connected to the
Thunderbolt GPS receiver,
both the +12 and -12 were at zero and the 5V was low.
C33 s.b. 490 uF @ 85V tests at 54 Ohms ESR & 0.53 uF so is bad. When removed it tests as an open. It's across the +7.5V rail, maybe why the +5 output has limited range.
Since this supply also poweres the op amps and reference voltages it may be the only problem. Caps on order 21 Feb 2011.
|HP 6236A C33 Date Code
7626L i.e. it's 35 years old
The vent (hole in center on right) is intact, i.e. it has not blown.
Test open for DC and capacitance.
||V @ A|
||8 @ 3 or
15 @ 2
||20 @ 1.5
35 @ 0.85
||60 @ 0.5
120 @ 0.25
||8 @ 6
||20 @ 3
||35 @ 1.7
This is my most used power supply.
||60 @ 1
||25 @ 1
25 @ 1
||6 @ 2.5
+20 @ 0.5 and
-20 @ 0.5
Not suitable for long term use.
It resets when the power fails.
||6 @ 5 and
+25 @ 1 and
-25 @ 1
||15 @ 7 or
30 @ 4
||8 @ 20 or
20 @ 10
||25 @ 7 or
50 @ 4
||8 @ 3 or
20 @ 1.5
||35 @ 0.8
60 @ 0.5
||8 @ 5 or
20 @ 2.5
||35 @ 1.4
60 @ 0.8
||8 @ 8 or
20 @ 4
||35 @ 2.2
60 @ 1.3
||2X 8 @ 3
2X 20 @ 1.5
||2X 35 @
2X 60 @ 0.5
||2X 35 @
60 @ 0.8
Mesa Power Systems Model 10199 Power Supply Aircraft
My hope was that this would contain a 400 Hz 3-phase supply, but instead it has a number of DC power supplies.
Note aircraft "14 Volts" is exactly the same a ground vehicle "12 Volts" just as aircraft "28 Volts" is the same as ground vehicle "24 Volts".
These power supplies are set for the upper end of the range for each voltage (12V = 10 to 15 and 24V = 20 to 30).
28 (30V ?)
I'm going to remove each supply and use No. 2 and 4 by connecting "12 Volt" Power pole connectors. Note "12 Volts" means 10 to 15 Volts so these are perfect.
No. 1 will have a "24 Volt" power pole connector added. No. 3 will go on the shelf.
Front panel only has circuit breaker and pilot lamp
Top View with numbers for each power supply
Topward 33010D 0-30V, 0-10A.
Switching Mode Power Supply Modules
On eBay you can buy ready made printed circuit boards with a SMPS circuit.
Note: a SMPS can be thought of as a transformer for DC.
If you look at the voltage x current at the input it's about the same as a voltage x current at the output.
While in operation the output power as a fraction of the input power (efficiency) is typically in the mid 90% range.
DSN2596 based on LM2596
40/4 VDC input, 35/1.3 VDC adjustable output step down only.
|When trying to test a Weston 594 Photonic
cell no current could be measured, but it did have
voltage output. Also voltage across a shunt 100
The self test on the Fluke 87 is to probe in Ohms mode between V-Ohm-diode connector and the mAuA connector where you should see 1 k Ohm.
Also the fuse check is to remove test leads, select V= or V~ plug a test lead into uAmA - meter should click if fuse is good. Failed
Plug test lead into A - meter clicks if fuse is good. Passed
The yellow component is NOT blown, it's a spark gap.
|The fuse that's standing
up is open
Also the yellow part OK.
out the 1k resistor from the bottom of the mA/uA jack
that gets shorted by the range switch when in the mA
range is not part of the analog circuitry but rather
part of the digital monitoring of where the test leads
are plugged in. So it was reinstalled along with
the adjacent four pin DIP bridge diode and a wire
soldered across the blown fuse terminals. After
reassembly not only are the mA and uA ranges working but
also the back light now works. There must have
been a bad connection (see What
Goes Wrong) between some of the parts that's
|Heathkit IT-10 Transistor-Diode Tester -
simple way to ID diode and transistor polarity and get a
rough idea of beta. The IT-27 may be the same tester
with different color paint.
This tester is very simple and seems to be very reliable.
You get some idea of relative beta.
Transistor & FET Tester
Uses a couple of "D" batteries and a 100 uA meter movement to test Beta, gm, and a number of leakage currents.
Needed some contact cleaner in the switches and pots (was used by a heavy smoker). The 166 Ohm cal resistor is supposed to be taped to the inside of the front panel (it's used for setting the pot on the PCB, but if not you can make one by connecting two 100 ohm resistors in series then connecting that 200 ohm resistor in parallel with a 1000 ohm resistor.
Transistor Manual "Safe
and Simple Transistor Tester'. Made this
for work when we were buying Ge microwave transistors
and characterizing them ourselves rather than pay TI a
lot extra to sort them. The 150 Ohm cal resistor
is built in on S4 so to do the full scale cal just press
BATT TEST and S3.
You can get numbers for beta, and a number of leakage currents.
TS-1836C/U - Military in and out of circuit tester
also tests FETs and diodes. Uses self rectification
of square wave input to generate a DC output when xixtor
is in a common base configuration.
So far not very useful.
|TL-120 - rechargable battery powered tester, automatic detection of NPN or PNP, no setttings or meters, just LEDs for PNP, NPN & Fail LEDs. NSN 6625-00-367-9323 patent 3870953 In-Circuit Electronic Component Tester 324/72.5; 324/537 made by Testline. Uses a single probe that has three plunger type pointed tips so you can contact all three transistor PCB pads with one hand. Handy probe and quick check.|
tester uses a 555 oscillator driving a Flip Flop
to act as a DPDT switch reversing the polarity to a common
emitter configuration. By noting which of two LEDs
turns on you can tell the polarity of a transistor.
But you need to which terminals are the Emitter, Base and
Not too useful.
The schematic diagram for this kit should win an award for the most convoluted, upside down and twisted schematic
possible for such a simple circuit.
This is the most advanced unit for the price. Although there are a number of things I'd do to improve it.
There are three test leads, each of which is fed using a series resistor that's selectable (100k, 10k, 1k or 100 Ohms) and that resistor can be connected to either +5 or ground. There's a DC voltmeter on each lead. So by driving the leads two at a time and subtracting voltages you can find the voltage across the DUT. Also since the voltmeters are after the series resistors you can also find the current at each lead.
I'm having a problem with calibration. It may be that I've just got some high resistance mux chips (M3 is sending 3 more chips at no charge, good support). It turns out that if there's solder flux left on the board it can allow leakage to the high impedance voltmeter inputs. Radio Shack no longer carries flux cleaner, so it's not available in my small town. Isopopropal alcohol did not work. But acetone did work.
The neat thing about it is that it not only figures out which lead is which for transistors, FETs, etc. but it also shows some variable parameters like Vbe, HFE, whether it's a PNP or NPN, or N-JFET or P-JFET, etc. The display cycles automatically which may be good for an experienced user, but I'd rather have a "next" button to make writing down the answers easier.
It's great for sorting out grab bags of 3 leaded devices. I'm planning on adding a machined pin IC socket cut down to 3 terminals in addition to some nice E-Z-Hook grabbers to replace the cheezy ones that come with the kit.
DCA - Semiconductor Analyser - looks to be a
very similar to the Me above
Shenzhen DY294 Digital Transistor DC Parameter TesterThis unit runs from 6 VDC, either 4 internal AA cells (although the battery compartment can hold 6 cells, but two positions have no electrical contacts) or using a female plug wall wart.
It can test transistors for: VBR, VCEsat, hFE, Iceo. 3-terminal voltage regulators with 27 Volts input.
Withstanding voltage on electrolytic caps up to 1000+ VDC. This tester has a current limited high voltage supply that is activated when the TEST buttom is pressed (the red LED warning lights when high voltage is present). When measuring the forward voltage drop on a semiconductor at 800 mA or 2 A the external 6 V @ >=2A power supply should be used.
Professional Type Semiconductor AnalyzersI wrote many HP Basic programs to dirve the HP semiconductor analyzer boxes like the 4142 & 4145 DC box and the related LCR meters.
Transistor - L/C ESR Tester
Shown measuring a 470 uF 10 V cap as 482.6 uF &
Also has provision for SMT parts. If the SMT LED
was removed it might also be used to test LEDs?
Comes with short test leads that are connected to screw
Pushing the red button at the lower right displays the
test frequency (which changes with component value
because this tester works be resonating the DUT with a
component that's part of the tester.
May be a knockoff of the AADE L/C Meter.
Note (Up/Down) the White (/HiC), Blue (/HiL) and yellow
(C/L) buttons are latching.
|Fluke 87 (or any DMM with a diode test) can be used
to check for the Base-Emitter and Base-Collector junctions
of a transistor. This is a very powerful method
that's also simple. But it's more time consuming
than more advanced test methods. In diode test mode the
red lead is positive and the test current is 1 ma (this is
a very good way to do this since the Vf of most dioeds is
specified at 1 ma). If a transistor tests as two
forward diodes with the red lead common then the
transisotr is an NPN but of the black lead is common then
it's a PNP.
Most silicon PN junctions have a Vf of about 0.6 volts. Silicon Schottky junctions range over 0.28 to 0.35 depending on the barrier metal. Germanium is more like 0.4 volts.
The 87 is the first piece of test equipment that I use. If you're going to only have one test instrument this is it. The only time it failed me was when checking a lawn sprinkler system and the 87 showed voltage at the valve but the valve was not activating. The Fluke 12 showed no voltage in the "V-check" where the input impedance is 1 k ohm.
Transistor Test Set Related PatentsClass 324/768 Electricity Measuring & Testing/ (537) Of individual circuit component or element Bipolar transistor(768)
2847645 Null Type Transisotr Alpha Measuring Set, Thomas (Bell labs), 12 Aug 1958
2899642 Transistor Test Set, Hussey, 11 Aug, 1959 324/768 - very simple battery powered appha & Ic tester, very much like the Heath IT-10.
2909730 Transistor Gain-Bandwidth Test Circuit, Timm, 20 Oct 1959 324/768 - sweep gen & Scope
3054948 High Frequency Mesurements, Rymaszewski, 18 Sep, 1962 324/629; 324/158.1; 324/615; 324/639; 324/647; 324/650; 333/225
3056924 Null Type Transistor Beta Measuring Set, Thomas (Bell labs), 2 Oct 1962 - prior methods used b=a/(1-a)
3076140 Transistor Test Set, Smith, 29 Jan 1963 - Curve Tracer with stepped base currents
3201690 Wave Transient Time Interval Measuring Circuit with Wave Comparison Function, Embree (Bell labs), 17 Aug 1965 - sub ns
3237104 Pass Fail Transistor Tester for Indicating the combined result of BVceo and Spurious Oscillations, Merkel, 22 Feb 1966 -
3314008 Circuit Empolying Calibrated Variable Impedances for MEasuring Transistor Beta and Beta Cutoff Frequency, Heard, 11 Apr 1967 -
These are instruments that show up in the military radio manuals but that I don't have. Just for info.
Mil Nomenclature Description Commercial Nomenclature Power Const Key Spec(s) AN/USM-281C Oscilloscope Tek 7603N11S
120/220 OS-246A/USM-281D Oscilloscope Dumont 115/230 OS-189/USM-281A Oscilloscope HP 180+
USM-425 Oscilloscope Tek 465M 115/230 or
24 VDC Batt
OS-8 Oscilloscope TM 11-1214
115 OS-106/USM-117 Oscilloscope TM 11-6625-640-24P
Transistor USM-338 Oscilloscope solid state USM-140B Oscilloscope Tek 531? SG1174/U Sig Gen AUL 6201B
tube 3.8 - 7.6 GHz SG-297/URM-103 Sig Gen TB 11-6625-586-12/1 tube 18 - 80 MHz FM SG-376 2 tone IF Sig Gen Transistor 497.5, 498.5, 501.5, or 502.5 KHz SG-823 2 tone Ref Sig Gen 2, 3.6, 4, 14.4, 16, 28.8 MHz /URM-25 Sig Gen TM 11-5551B
10 KHz to 50 MHz AM SG-117/URM-26B Sig Gen 115 4 to 405 MHz AM-CW-Pulse SG-1170/1171 Sig Gen Wavetek 3001
TM 11-6625-3051-12, -24P, -40
SG-1144 Sig Gen P TM 11-6625-2954-14&
50 kHz - 80 MHz URM-103 Sig Gen TM 11-6625-586-12,
-12/1, -24P, -45
USM-207 Digital Counter
-14-1, -25, -24P
USM-459 Digital Counter HP 5328
AN/USM-323 Sig Gen HP 8640B-323 500 KHz to 512 MHz AM-FM-Pulse TS-403 Sig Gen TM 11-5091
1.8 - 4.2 GHz SG-557/TS-621 Sig Gen 3.8-7.5 GHz USM-441 Time Mark Gen Ballantine 6130A 120 TS-1010/UPM-84 Spectrum Analyzer 115 tube 10 MHz to 44.88 GHz ME-180/USM-116 AC-DC Voltmeter 115 tube 20 Hz to 100 MHz
1 to 300 V fs
to 15 kV
Diff DV VM Fluke 896A
0-10-100-1000 VDC ME-297/USM-223 Multi Meter 6-PXB1 1.3 V
2 AA + 1 C
FET 2.5 V - 5 KV
0.25 - 10 A DC
1K - 10 M Ohm
ME-77/URM-105C Volt - Ohm TM 11-6625-203-12,
2 ea. AA
1 - 1000 V AC/DC
2k - 20 M Ohm
URM-127(A) Audio Osc TM 11-6625-683-14, -24P
115 solid state 20 Hz to 200 KHz
DA-43/U Dmy Ld &
28VDC 0.2 to 20 MHz
2 to 100 W
TS-3329/U HP 236A
DPM-3 Power Meter 30 to 600 MHz
50 and 150 W ranges
ME-165/G SWR Meter TM 11-6625-333-15, -24P
TM 11-809-20, -35
up to 30 MHz
URM-120A Watt Meter 2 to 1000 MHz
10 to 1000 W
DA-75/U/URM-120 Dmy Ld TM 11-6625-446-15 2 to 1000 MHz
10 to 1000 W
ME-82 Watt Meter M 11-6625-595-34 50-600 MHz
DA-189/GRC Dummy Load 600 to 1850 MHz
DA-727 Dummy Load 30 MHz
ZM-4 DC Bridge TM 11-2019
TM 11-6625-249-12P, -34P
3 each D no active devices
1 ohm to 1,011 M Ohm ZM-11 AC Bridge Navships 91704A 115 tube TS-505 VTVM TM 11-5511
TM 11-6625-239-12, -34P
batt tube URM-145 Voltmeter TM 11-6625-524-14 ME-26B/U Multimeter HP 410
-15, -24P, -35
TS-352/U Multimeter TM 11-6625-366-10,
TS-723/A/B/C/D Spectrum Analyzer TM 11-6625-255-14,
HP 330x Distortion Ana
ME-505 Modulation Meter TM 11-6625-3017-14
ME-525 Modulation Meter TM 11-6625-3059-10
ME-57 Modulation Meter TM 11-6625-400-20P, -35, -40
TM 11-6625-2629-14&P, -24P
USM-44 Sig Gen HP 608 URM-18 Distortion Analyzer HP 333A
TS-4084/G Distortion Analyzer Tek DA 4084 ?
TM 9-4935-601-14-3&P 115AC/230AC/12DC
1 to 2,000 feet of line
HP 530x Counter
HP 5233L Counter
[an error occurred while processing this directive] page created 11 Nov. 2001.