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P6046: Difference between revisions
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The ''Tektronix P6046'' is a differential probe and amplifier. | The ''Tektronix P6046'' is a differential probe and amplifier. | ||
It | It was initially intended for use with a [[1A5]] and attaches through a special multi-pin connector. | ||
A separate amplifier was available as an option to use the probe on a 50 Ohm input scope | |||
set at 10 mV/Div. | |||
With a 1A5, it has a 45 MHz bandwidth. The raw bandwidth of the probe and amplifier is 100 MHz. | With a 1A5, it 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 1X or 10X attenuation probe dependent on a signal | |||
voltage on pin D of the connector. When used with the amplifier, 10X mode is used in the | |||
200, 100, and 50 mV/DIV settings and 1X mode for 20, 10, 5, 2, and 1 mV/DIV. | |||
==Operation== | |||
Ground the probe! Seriously. Sticker the probe "Ground Me!" 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. I also recommend stickering the probe amplifier with the | |||
ATTEN BAL setup proceedure from section 2-6 of the manual. | |||
==Repair Issues== | |||
Pay attention to the maintenance section of the manual about the operation of | |||
the P6046 outside it's 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. | |||
The matching criteria should be Idss. | |||
==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 1X to 10X mode. | |||
==Manuals== | ==Manuals== | ||