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1、The old Boonton RF Millivoltmeter or Boonton RF Microwattmeter or Ballantine Labs RF Millivoltmeter you bought on eBay likely came without an RF probe or RF Power Sensor. The probe and sensor is not well documented in the service manual so here is the probe schematic and sensor schematic with releva

2、nt info. Feel free to share this info or to post it on your own web site. HOME Boonton 952001 RF Probe - 10KHz to 1.2GHz with 1.5pF loading Below is the schematic diagram of my probe serial number 10091. Please see the last section of this web page for more info about the special diodes, and do emai

3、l me with your successes and failures. Please also help me identify the mysterious factory selected diodes as to manufacturer and part number. 1/8W CF 1/4W CC Low noise double 100 ohm 330 ohm shielded cable 5% 10% +-| out - | | 2 Amphenol 80-MC2M 1n5F | diode - CNA-type Male 600V? | 1n0F - Cable End

5、to expose the following characteristics: +-+-+ +-+-+ | If | Vf | | Ir | Vr | +-+-+ Measured at +-+-+ | 10uA 140mV | 20 degrees | 10uA 41.5V | | 100uA 210mV | Celsius | 1uA 15.5V | | 1mA 320mV | | 100nA 0.4V | +-+ +-+ Pictured below are some of the innards I pulled out of the probe. Notice the thin c

6、hip capacitor soldered between he two diodes and the probe tip header. The secretive diodes have no markings. No I did not destroy my probe, but would you like to buy it on eBay now that Ive autopsied it a few times? Just kidding. Later revisions of the probe use 1K0 resistors at the output, and the

7、 resistors at the diodes are selected during manufacturing to match individual diode characteristics. The resistor values and picture for probe serial number 16364 shown below are courtesy of Ray M. Interesting Electronic Schematics and Circuits - Novotillhttp:/members.shaw.ca/novotill/RfProbeSensor

9、 | diode - amplifier | | 1 and shaper +-|-/-#-/- out + 5% 5% 33 ohm 1K0 ohm 1/8W CF 1/4W CC Boonton 51013 ( aka 4E ) RF Power Sensor - 100KHz to 18GHz with built in 50 ohm termination Below is the schematic diagram of my sensor serial number 51013. The thin rectangular 750pF chip capacitor is solder

10、ed directly to the N connector center post, between the two red termination resistors. The white 160 ohm RF resistors are soldered directly in series with each diode. The termination is adjustable by loosening the screws and rotating the brass disks. Please see the last section of this web page for

11、more info about the special diodes, and do email me with your successes and failures. Please also help me identify the mysterious factory selected diodes as to manufacturer and part number. 1/8W RF 1/8W RF 1/8W CC Low noise double 100 ohm 160 ohm 220 ohm shielded cable 0.2%? 5%? 5% +-/-#-| out - | |

13、marked diodes are almost certainly Low Barrier Silicon Schottky Detector Diodes. I have measured the original diodes to expose the following characteristics: +-+-+ +-+-+ | If | Vf | | Ir | Vr | +-+-+ Measured at +-+-+ | 10uA ? mV | 20 degrees | 10uA ? V | | 100uA ? mV | Celsius | 1uA ? V | | 1mA ? m

14、V | | 100nA ? V | +-+ +-+ Ballantine Labs 3440A Standard RF Probe - 10KHz to 1.2GHz with 2.5pF loading Below is schematic diagram of the probe circuit. Please see the last section of this web page for more info about the special diodes, and do email me with your successes and failures. Please also h

15、elp me identify the mystery diodes as to manufacturer and part number. Note that the 2N4921 power transistor simply heats the diodes at a constant temperature in order to prevent drift. 1/8W CC 1/4W MF Low noise double 130 ohm 332 ohm shielded cable BL 10 5% 1% +-| 5 (Out-) | diode | | Cer - 5 Pin |

16、 1n0F - Male Plug | | 22nF | +- 4 (Heat+) Interesting Electronic Schematics and Circuits - Novotillhttp:/members.shaw.ca/novotill/RfProbeSensorMvUw/index.htm 2 of 45/6/2009 8:21 AM RadioFans.CN 收音机爱好者资料库 600V? | | 2N4921 | | +-| | -|-# |-| 3,Shell | +- 2 (Heat-) differential | | chopper type | 1n0F

17、 - amplifier | Cer - and shaper | diode | +-|-/-#-/- 1 (Out+) BL 10 5% 1% 130 ohm 332 ohm 1/8W CC 1/4W MF The unmarked diodes are almost certainly Low Barrier Silicon Schottky Detector Diodes. I have measured the original diodes to expose the following characteristics: +-+-+ +-+-+ | If | Vf | | Ir |

19、s web page for more info about the special diodes, and do email me with your successes and failures. Please also help me identify the mystery diodes as to manufacturer and part number. Note that the 2N4921 power transistor simply heats the diodes at a constant temperature in order to prevent drift.

20、1/8W CC 1/8W CF Low noise double 160 ohm 100 ohm shielded cable BL 10 5% 5% +-| 5 (Out-) | diode | | | Cer - Cer - 5 Pin | 1n0F - 1n0F - Male Plug | | | 22nF | +- 4 (Heat+) 600V? | | 2N4921 | | | +-| | | -|-# |-| 3,Shell | +- 2 (Heat-) differential | | | chopper type | Trimpot - 1n0F 1n0F - amplifie

21、r | 200 ohm - Cer Cer - and shaper | diode CF 1/4W | | +-|-/-/ #-/-#- 1 (Out+) BL 10 5% | 1% 56 ohm | | 100 ohm 1/8W CF +-+ 1/8W CF The unmarked diodes are almost certainly Low Barrier Silicon Schottky Detector Diodes. I have measured the original diodes to expose the following characteristics: +-+-

22、+ +-+-+ | If | Vf | | Ir | Vr | +-+-+ Measured at +-+-+ | 10uA ? mV | 20 degrees | 10uA ? V | | 100uA ? mV | Celsius | 1uA ? V | | 1mA ? mV | | 100nA ? V | +-+ +-+ Connecting cable for Sensors and Probes - Shielding arrangement The cable consists of two individually insulated coaxial shielded wires

23、in a twisted pair configuration which is additionally shielded by an outer braid. The two inner shields and the outer braid attach to the connector shell/GND at the meter side, but at the probe/sensor side only the outer braid connects to the housing/GND leaving the inner shields totally unconnected

24、. Be mindful that the cable caries a small DC voltage proportional to the amplitude of the RF signal, and that impedances rise extremely high when measuring microvolt or nanowatt levels, making the cable susceptible to leakage and interference. - - - | | | | - | | | | Signal(+) | | | | | | | | | | |

25、 | v | | Inner Shield | | v +-+-+ | | | | | Probe/ | | | | | Sensor | | | | | Meter | | Inner Shield | | | +-+-# | | | | | | | | | Signal(-) | | | | | | | | | | | | | | - | | | | - | | | | | | v Outer braid & GND v | Square Law Detector Diodes - Details and general information A diode detector conti

26、nues to produces a DC output even when the AC input falls orders of magnitude below the diode junction threshold voltage. This is called square-law region operation and here the DC output voltage is proportional to the square root of the peak AC input voltage. Ordinary PN junction silicon diodes and

27、 ordinary Schottky hot carrier diodes have an extremely high video resistance when biased to mere microvolt levels, making it difficult to separate a meaningful DC output signal from the noise. Such diodes typically also have way too much junction capacitance and this loads down the signal source at

28、 megahertz or higher frequencies. Therefore you must use one of the special types of hot carrier diodes Interesting Electronic Schematics and Circuits - Novotillhttp:/members.shaw.ca/novotill/RfProbeSensorMvUw/index.htm 3 of 45/6/2009 8:21 AM RadioFans.CN 收音机爱好者资料库 listed below, many of which are a

29、lready configured as back to back matched pairs in a single SMD package. In any case you will need to recalibrate your millivoltmeter in order to obtain correct readings with your choice of diodes. 1) Zero Bias Silicon Schottky Detector Diodes. These have a reverse breakdown voltage of only around 3

30、V so they are only good for measuring signals of 1 volt or less, but they work fantastically well in the microvolt and nanowatt ranges, and they exceed the 1.2GHz upper limit original spec of the Boonton probes. HSMS-2852 MZB600 CMS-825x SMS7630 MP20 xx 2) Zero Bias GaAs Schottky Detector Diodes. Th

31、ese have a reverse breakdown voltage around 10V and are good to about 100GHz but they are expensive and a bit hard to find. They also dont come as back to back connected matched pairs within a single package. This is your only option if you want to maintain or exceed the original 18GHz spec of your

32、Boonton power sensor. HSCH-9161 3) Low Barrier Silicon Schottky Detector Diode: These have a reverse breakdown voltage of 7V so you will need to use them if you intend to measure at the upper end of the 3V range on your boonton millivoltmeter. Unfortunately they dont turn on enough to measure well i

33、n the low microvolt and nanowatt ranges. HSMS-2862 BAT62 SMS7621 4) Old Germanium Point Contact Microwave Detector or Mixer Diode: These are obsolete, large, thermally unstable, mechanically fragile, and electrically fragile, but their junction capacitance is low enough that they can be used at UHF

34、and beyond. These too dont turn on enough to measure well in the low microvolt and nanowatt ranges. 1N23 or 1N21 microwave diodes. 5) Common old Germanium Point Contact Detector or Mixer Diode: These are obsolete, thermally unstable, and have high parasitic capacitance, but you can easily find these

35、 in old gear or in old UHF TV tuners. Its the poor mans solution, and definitely at the bottom of the list. 1N34A or 1N48 or OA91 or K3A diodes 6) For more information and application notes regarding detector diodes, just google the phrase shown below. Note that Zero Bias Schottky Detector Diodes in

36、 differential configuration as above make a decent crystal radio detector, but dont ask me about it because I didnt spend much time on it. square-law Schottky detector diode application I do not gaurantee the accuracy or safety of any information herein. HOME Do not experiment with or build any of the above circuits. Interesting Electronic Schematics and Circuits - Novotillhttp:/members.shaw.ca/novotill/RfProbeSensorMvUw/index.htm 4 of 45/6/2009 8:21 AM

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