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[[Image:Tek P6046 catalog 2.jpg|350px|thumb|right|Tektronix P6046 Differential Probe and 015-0106-00 Amplifier]]
[[Image:Tek P6046 catalog 2.jpg|350px|thumb|right|Tektronix P6046 Differential Probe and 015-0106-00 Amplifier]]
The '''Tektronix P6046''' is a 45/100 MHz differential probe oscilloscope probe.
The '''Tektronix P6046''' is a 100 MHz differential probe oscilloscope probe.
It was initially intended for use with a [[1A5]], to which it attaches through a 9-pin [[Amphenol 165 series connector]].
It was initially intended for use with a [[1A5]], to which it attaches through a 9-pin [[Amphenol 165 series connector]].


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With a 1A5, the P6046 has a 45 MHz bandwidth.  The raw bandwidth of the probe and amplifier is 100 MHz.
With a 1A5, the P6046 has a 45 MHz bandwidth.  The raw bandwidth of the probe and amplifier is 100 MHz.
Note that the probe itself acts as either a 1× or 10× attenuation probe dependent on a signal
Note that the probe itself acts as either a 1× or 10× attenuation probe dependent on a signal voltage on pin D of the connector.   
voltage on pin D of the connector.  When used with the amplifier, 10× mode is used in the
When used with the amplifier, 10× mode is used in the 200, 100, and 50 mV/div settings and 1× mode for 20, 10, 5, 2, and 1 mV/div.
200, 100, and 50 mV/DIV settings and 1× mode for 20, 10, 5, 2, and 1 mV/DIV.


An additional  ×10 attenuator (010-0361-00) can be plugged onto the P6046's inputs.
An additional ×10 attenuator (010-0361-00) can be plugged onto the P6046's inputs.


==Operation==
==Operation==


Ground the probe!  Seriously.  Sticker the probe "Ground Me!"  The two probe tips are
The two probe tips are (in DC mode) directly connected to the gates of a pair of JFETs.  Use the shorting plugs on the tips when not in use.   
(in DC mode) directly connected to the gates of a pair of JFETs.  Use the shorting plugs
on the tips when not in use.  I also recommend stickering the probe amplifier with the
ATTEN BAL setup proceedure from section 2-6 of the manual.


==Repair Issues==
Ground the probe! Seriously.  Sticker the probe "Ground Me!"  I also recommend stickering the probe amplifier with the ATTEN BAL setup procedure from section 2-6 of the manual.
 
Pay attention to the maintenance section of the manual about the operation of
the P6046 outside its housing.  The bottom section of housing ties the circuit
grounds together.  The schematic diagram calls out four different grounds: The cable
(using the three line earth symbol), the front posts (triangle-1), the middle mounting
screw (triangle-2) and the rear posts (triangle-3).  When operating the probe without
the top housing, reattach a front and rear post screw to hold the board down to the
lower housing.  When operating the probe with no housings, tie a front and a rear post
together with a jumper.  The center circuit board mounting screw ground is only used
for the high frequency CMRR adjustments and none of those will work without both
housings in place.
 
The input FETs must be a matched pair.  A possible replacement is the 2N4416A in a metal
TO-72 package with the substrate pin provided as in the factory part 153-0559-00.  It is
pretty expensive; currently (2014) it's about $6 US dollars each.
Another much cheaper replacement is the 2N3819 in a plastic TO-92 package.
The matching criteria should be Idss.
 
If the "DRAIN VOLTS" adjustment step (R125) fails, check and replace R124. It is a 270K,
1/10W carbon composition resistor and it will eventually drift high so the 10.5V drain voltage
can not be reached.  The calibration section is not clear about the settings for this
measurement, but the schematic diagram shows the voltage measured with 200 mV/DIV set
on the amplifier.
 
==Calibration==
 
<blockquote>
The Tektronix P-6046 is excellent, and usually quite inexpensive because nobody knows what it is.
Make sure it works when you buy it, because these probes are extraordinarily tricky to trim up for CMRR after repair.
  -- [[Jim Williams]], ''The Art of Analog Circuit Design''
</blockquote>
 
Newer versions of the probe have plastic plugs that allow access to the following adjustments
 
* R209 - 42 MHz CM balance
* C209 - 18 MHz CM balance (and drain voltage measurement)
* C245 - 50 MHz CM balance
* R155 - Gain
 
The full calibration shield has access to all ten adjustments.  You will need
to make this by drilling holes in a housing.  The full shield is needed to
recalibrate a probe after replacing the input fets.  Some used probes will
be found with an access hole drilled for R235 (GAIN SWITCHING BALANCE) since this
is adjusted to remove the trace shift when the probe switches from 1× to 10× mode.
 
To calibrate the amplifier, first check the power supply voltages.  They are floating.
Do not check with respect to ground!  When adjusting, watch for exposed line voltage
in the power supply, especially the fuse holder.  The power supply must be adjusted
with everything connected together.  Note that you can check the voltages from the
back of the amplifier output board.


==Manuals==
==Manuals==


* [[Media:Tek p6046 fcp march 1968.pdf]]
* [[Media:Tek p6046 fcp march 1968.pdf|P6046 Factory Calibration Procedure, March 1968]]


There are three versions of the manual
There are three versions of the manual:


* [[Media:070-0756-00.pdf|070-0756-00 - (C) 1968]]
* [[Media:070-0756-00.pdf|070-0756-00 - (C) 1968]] − This version assumes you have a [[1A5]] for absolute gain calibration of the probe without the amplifier.
* [[Media:070-7129-00.pdf|070-7129-00 - (C) 1988]]
* [[Media:070-7129-00.pdf|070-7129-00 - (C) 1988]]
* [[Media:070-7129-00.pdf|070-7129-01 - (C) 1992]]
* [[Media:070-7129-00.pdf|070-7129-01 - (C) 1992]]
The 1968 version assumes you have a [[1A5]] for absolute gain calibration of the probe
without the amplifier.


* [http://w140.com/Tektronix_P6046_Instruction_Manual.pdf P6046 Manual (no schematics, PDF)]
* [http://w140.com/Tektronix_P6046_Instruction_Manual.pdf P6046 Manual (no schematics, PDF)]
* [http://w140.com/Tek_P6046_Differential_Probe-Operation_Manual.pdf P6046 Detailed Manual (no schematics, PDF)]
* [http://w140.com/Tek_P6046_Differential_Probe-Operation_Manual.pdf P6046 Detailed Manual (no schematics, PDF)]
* [http://w140.com/P6046_8.5x11.pdf P6046 Voltage and Waveform Information (PDF)]
* [[Media:P6046 Voltage and Waveform Information.pdf|P6046 Voltage and Waveform Information (PDF)]]
* [http://w140.com/P6046_17x11.pdf P6046 Schematics (PDF)]
* [[Media:P6046 Schematics Rev. C June 1977 11x17.pdf|P6046 Schematics Rev. C June 1977 (PDF)]]
* [[Media:Tek p6046 eis signature page.pdf|P6046 Engineering Instrument Specification Signature Page (PDF)]]
* [[Media:Tek p6046 eis signature page.pdf|P6046 Engineering Instrument Specification Signature Page (PDF)]]


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