Heathkit C3 Condensor Checker – 25 Volt Mod

As noted in my previous post, the 25 volt scale for the leakage test function of the Heathkit C3 Condensor Checker provided a voltage that was considerably higher than 25 volts.  It was closer to 50 volts.  This seems to be a design flaw, or a documentation flaw, as I don’t know which side of the team dropped the ball.  I chose to treat it as a design flaw, since the documentation and the front panel screen printing indicated that it should be a 25 volt scale.

25 Volt Mod in place

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Tektronix 2465A Oscilloscope Repair – Part 13

Dynamic Centering, DC Balance and X-Y Phase Differential

I got in a hurry and forgot to get photos of this procedure.  But all went as described in the manual.

Dynamic_Centering.PDF

All Done!

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Tektronix 2465A Oscilloscope Repair – Part 12

CAL07 – Readout Centering and Gain

CAL07.PDF

We are near the end of the poor man’s calibration of the 2465A Oscilloscope.

CAL07 adjust the position of the Readout characters on the screen.  They are simply moved with two controls (R2918 and R2931) to place them just inside of the graticule area of the screen.

CAL07 – Readout Centering and Gain

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Tektronix 2465A Oscilloscope Repair – Part 11

CAL 06 – Vertical Transient Response

Now comes the most difficult part of the calibration – The Vertical Transient Response.

The goal of this procedure is to end up with a scope that is relatively flat across its bandwidth.  It uses a very fast rise time pulse to make the adjustment, and I just do not have one available. When I first checked the bandwidth, it fell off drastically at 8 Mhz, and was nearly unusable at 350 Mhz.  There were several significant dips and peaks as I swept the input sine wave from 1 Mhz to 350 Mhz, and I hoped that these would be corrected when I finished.

Steps a – c start up the procedure.

CAL06 – Start

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Tektronix 2465A Oscilloscope Repair – Part 10

CAL 05 – Hours ON and PWR ON/OFF Cycles

This routine simply allowed me to set the Hours and Power cycles to whatever number I wanted.

CAL05 – Start

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