Boonton 3440 Service Manual

Interesting Electronic Schematics and Circuits - Novotill

http://members.shaw.ca/novotill/RfProbeSensorMvUw/index.htm

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 relevant 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 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 CF		1/4W CC	Low noise double
				100 ohm		330 ohm	shielded cable
		+	|<|	5%	#	10%	> out -
				/\/\/----		/\/\/-----------		Amphenol 80-MC2M
	1n5F	|	diode		|		2
		|		1n0F	---			CNA-type Male
	600V?	|			---|		S	Cable End Plug
<	||	|		Cer				Probe output to
		#		Cer	#--------------------		> GND
	chip	|			|			differential
		|	diode	1n0F	------			chopper type
		|					1	amplifier
		|	|>|	/\/\/	|	/\/\/		and shaper
		+---			#----		> out +
				5%		10%
				100 ohm		330 ohm
				1/8W CF		1/4W CC

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 |	Measured at	| Ir	| Vr	|
+-------	+-------	+		+-------	+-------	+
| 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 chip 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 I've autopsied it a few times? Just kidding.

Later revisions of the probe use 1K0 resistors at the output, and the 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.

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Interesting Electronic Schematics and Circuits - Novotill

http://members.shaw.ca/novotill/RfProbeSensorMvUw/index.htm

				1/8W CF		1/4W CC	Low noise double
				68 ohm		1K0 ohm	shielded cable
		+	|<|	5%	#	5%	> out -
				/\/\/----		/\/\/-----------		Amphenol 80-MC2M
	1n5F	|	diode		|		2
		|		1n0F	---			CNA-type Male
	600V?	|			---|		s	Cable End Plug
<	||	|		Cer				Probe output to
		#		Cer	#--------------------		> GND
	chip	|			|			differential
		|	diode	1n0F	------			chopper type
		|					1	amplifier
		|	|>|	/\/\/	|	/\/\/		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 soldered 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 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 -
	/\/\/----			/\/\/----		/\/\/-----------		Amphenol 80-PC2F
|		|	diode*	1n5F	|		2
|	750pF	|			---			CNA Female Chassis
^		|		chip	---		S	Mount Receptacle
| |	||	|		Cer	|
<-------		#		Cer	#--------------------		> GND	Sensor output to
| |	chip	|			|
v		|	diode*	chip	---			probe cable and
|		|		1n5F	---		1	microwatt meter
|	/\/\/	|	|>|	/\/\/	|	/\/\/
+----		#---			#----		> out +
	0.2%?			5%?		5%
	100 ohm			160 ohm		220 ohm
	1/8W RF			1/8W RF		1/8W CC

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	|	Measured at	| Ir	| Vr	|
+-------	+-------	+		+-------	+-------	+
| 10uA	?	mV |	20 degrees	| 10uA	?	V |
| 100uA	?	mV |	Celsius	| 1uA	?	V |
| 1mA	?	mV |		| 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 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.

		1/8W CC		1/4W MF	Low noise double
	BL 10	130 ohm		332 ohm	shielded cable
+		5%	#	1%	> 5	(Out-)
	---|<|----	/\/\/----		----/\/\/-----------
|	diode	Cer	|			5 Pin
|
|		1n0F ---	|			Male Plug
|	+				> 4	(Heat+)
22nF |

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5/6/2009 8:21 AM