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 instrument
The 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 sensivity
This 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 Analyzer
One 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 Voltmeter
Another 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 Response
By 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 Output
There are a number of parameters to look at on the transmitted signal:Power
Can be measured with a power meter like the PRM-34 or similar meters.Frequency
Can 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 Deviation
Can 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 outputs
The 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.
Analyzers
HP/Agilent 4395A Combination Network, Spectrum, Impedance Analyzer covering 0 to 500 Mhz. Note this includes audio frequencies. HP-IB
What I miss is the range from 500 MHz to about 2.5 GHz. Maybe a front end down converter is called for. If you know of one, let me know.Bridges
Heathkit IB-5281LCR Impedance Bridge HP 4260A ZM71A/U Universal Bridge HP 4332A LCR Meter - analog 3 to 1 M Ohm, 3 pF to 1 uF, 3 uH to 1 H Marconi TF-2700 1 kHz Universal LCR Bridge mega-T TE7 Antenna Noise Bridge M-4 Bridge ZM-11 AC LCR Bridge Counters
DC Power Supplies
| Model |
Watts |
Volts
@
Amps |
| 6030A |
1200 |
200 @ 17 |
| 6031A |
1064 |
20 @ 120 |
| 6032A |
1200 |
60 @ 50 |
| 6033A |
242 |
20 @ 30 |
| 6035A |
1050 |
500 @ 5 |
| 6038A |
240 |
60 @ 10 |
HP 6633ASystem DC Power Supply
| Model |
Out
1 |
Out
2 |
Out
3 |
Out
4 |
| 6621A |
80W LV |
80W LV |
- |
- |
| 6622A |
80W HV |
80W HV |
- |
- |
| 6623A |
40W LV |
80W LV |
40W HV |
- |
| 6624A |
40W LV |
80W LV |
40W HV |
40W HV |
| 6627A |
40W HV |
40W HV |
40W HV |
40W HV |
| Output |
Low
Range |
Hi
Range |
| 80W LV | 7V @ 10A |
20V @ 4A |
| 80W HV | 20V @ 4A |
50V @ 2A |
| 40W LV | 7V @ 5A |
20V @ 2A |
| 40W HV | 20V @ 2A |
50V @ 0.8A |
| Model |
Voltage
(V) |
Currernt
(A) |
| 6632A |
20 |
+/-5 |
| 6633A |
50 |
+/-2 |
| 6634A |
100 |
+/-1 |
| Model |
W |
V @ A |
| E3610A |
30 |
8 @ 3 or 15 @ 2 |
| E3611A |
30 |
20 @ 1.5 or 35 @ 0.85 |
| E3612A | 30 |
60 @ 0.5 or 120 @ 0.25 |
| E3613A | ||
| E3614A | 48 |
8 @ 6 |
| E3615A | 60 |
20 @ 3 |
| E3616A | 60 |
35 @ 1.7 |
| E3617A | 60 |
60 @ 1 |
| E3620A | 50 |
25 @ 1 and 25 @ 1 |
| E3630A |
35 |
6 @ 2.5 and +20 @ 0.5 and -20 @ 0.5 |
| E3631A |
80 |
6 @ 5 and +25 @ 1 and -25 @ 1 |
| E3632A |
120 |
15 @ 7 or 30 @ 4 |
| E3633A |
200 |
8 @ 20 or 20 @ 10 |
| E3634A |
200 |
25 @ 7 or 50 @ 4 |
| E3640A |
30 |
8 @ 3 or 20 @ 1.5 |
| E3641A | 30 |
35 @ 0.8 or 60 @ 0.5 |
| E3642A | 50 |
8 @ 5 or 20 @ 2.5 |
| E3643A | 50 |
35 @ 1.4 or 60 @ 0.8 |
| E3644A | 80 |
8 @ 8 or 20 @ 4 |
| E3645A | 80 |
35 @ 2.2 or 60 @ 1.3 |
| E3646A | 60 |
2X 8 @ 3 or 2X 20 @ 1.5 |
| E3647A | 60 |
2X 35 @ 0.8
or 2X 60 @ 0.5 |
| E3649A | 100 |
2X 35 @ 1.4
or 60 @ 0.8 |
Calibrated using an HP
34401. Very low cost ($27.50).
This 4000 count meter has the ability to work for DC amps
which is the key thing I got it for. The lowest DC Amp range is
4.000 A full scale. To use the range after powr on and waiting a
little for the meter to stablize press the ZERO button. Then
connect to the wire carrying the current.![]() |
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 ohm reisitor. 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. Failed 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. |
| It
turns 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 now good. |
|
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.![]() |
![]() |
![]() |
| Front Panel |
Back
Instructions |
Inside |
GE
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.
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.
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.
This
Electronic Goldmine 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 Collector.
M3 Semiconductor Analyzer| The problem was poor solder
joints caused by using a fine tip soldering iron on a PCB with 2 ounce
copper. You MUST use a high wattage soldering iron in order to
heat this PCB. Note you can see that the solder is not shiny, it's dull when inadaquate heat is used. |
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.
(537)Of individual circuit
component or element
Bipolar transistor(768)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
TM 11-6625-1703-24P120/220 OS-246A/USM-281D Oscilloscope Dumont 115/230 OS-189/USM-281A Oscilloscope HP 180+
PL-1186A PL1187AUSM-425 Oscilloscope Tek 465M 115/230 or
24 VDC BattOS-8 Oscilloscope TM 11-1214
TM 11-6625-252-20115 OS-106/USM-117 Oscilloscope TM 11-6625-640-24P
TB 9-6625-342-35Transistor USM-338 Oscilloscope solid state USM-140B Oscilloscope Tek 531? SG1174/U Sig Gen AUL 6201B
TM 11-6625-2952-24Ptube 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
TM 11-6625-278-20P
TM 11-6625-603-40P10 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 11-6625-2952-24P
TM 11-6625-3029-14,-24P
TM 11-6625-3051-12, -24P, -40
TB 9-6625-2094-35
SG-1144 Sig Gen TM 11-6625-2954-14&P
TM 11-6625-2954-24P50 kHz - 80 MHz URM-103 Sig Gen TM 11-6625-586-12,
-12/1, -24P, -458350B
Sweep
Gen
HP 8350B
TB 9-6625-2124-35
USM-207 Digital Counter
TM 11-6625-700-10
-14-1, -25, -24P
CP-772A/U
HP 5245L
TM 11-6625-1682-24P
USM-459 Digital Counter HP 5328
TM 11-6625-2941-14&P
TM 11-6625-2701-35
TB 9-9925-2334-35
AN/USM-323 Sig Gen HP 8640B-323 500 KHz to 512 MHz AM-FM-Pulse TS-403 Sig Gen TM 11-5091
HP 616B1.8 - 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 fsME-440/USM-381
to 15 kVDiff DV VM Fluke 896A
1 kV0-10-100-1000 VDC ME-297/USM-223 Multi Meter 6-PXB1 1.3 V
1-"C"
conved
2 AA + 1 CFET 2.5 V - 5 KV
0.25 - 10 A DC
1K - 10 M Ohm
HP 3478
TM 11-6625-3071-14
ME-77/URM-105C Volt - Ohm TM 11-6625-203-12,
-24P, -352 ea. AA
22.5 V?1 - 1000 V AC/DC
2k - 20 M Ohm
30 Hz-10KHzURM-127(A) Audio Osc TM 11-6625-683-14, -24P
TB 9-6625-1998-35115 solid state 20 Hz to 200 KHz
Audio Osc
HP 202C
TM 11-6625-589-15
DA-43/U Dmy Ld &
Watt Mtr28VDC 0.2 to 20 MHz
2 to 100 WTS-3329/U HP 236A
TM 11-6625-2903-14&PDPM-3 Power Meter 30 to 600 MHz
50 and 150 W rangesME-165/G SWR Meter TM 11-6625-333-15, -24P
TM 11-809-20, -35up to 30 MHz
600 WURM-120A Watt Meter 2 to 1000 MHz
10 to 1000 WDA-75/U/URM-120 Dmy Ld TM 11-6625-446-15 2 to 1000 MHz
10 to 1000 WME-82 Watt Meter M 11-6625-595-34 50-600 MHz
120 WDA-189/GRC Dummy Load 600 to 1850 MHz
40 WDA-727 Dummy Load 30 MHz
800 WZM-4 DC Bridge TM 11-2019
TM 11-6625-249-12P, -34P
TB 9-6625-388-353 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, -34Pbatt tube URM-145 Voltmeter TM 11-6625-524-14 ME-26B/U Multimeter HP 410
TM 11-6625-200-12,
-15, -24P, -35TS-352/U Multimeter TM 11-6625-366-10,
-15, -24PTS-723/A/B/C/D Spectrum Analyzer TM 11-6625-255-14,
-24P, -34P
HP 330x Distortion AnaME-505 Modulation Meter TM 11-6625-3017-14
TF 2300A
ME-525 Modulation Meter TM 11-6625-3059-10
82AD
ME-57 Modulation Meter TM 11-6625-400-20P, -35, -40
TM 11-6625-2629-14&P, -24P
TB 9-6625-2004-35
tube type
USM-44 Sig Gen HP 608 URM-18 Distortion Analyzer HP 333A
TS-4084/G Distortion Analyzer Tek DA 4084 ?
NSN 6625-01-217-0054
TM 11-6625-3152-14
Tek 1502
TDR
TM 9-4935-601-14-3&P 115AC/230AC/12DC
1 to 2,000 feet of line
HP 530x Counter
TB 9-6625-2215-35
LA-387A
HP 5233L Counter
TM 11-6760-242-24P
18681 hits since page created 11 Nov. 2001.