[Test-Equipment] Fw: Tektronix 465 question

[ab6mt]

Thank you to all those who have responded.  I'll try to answer all questions
here.

Probe:  Tek P6130.  Have two of them, both seem to work fine.  Have a HP
1740A Scope which is in working condition and have verified probes on that
device.  Have also tried other probes, with same results.  Probes are
trimmed to display correct square waves.

A fresh D battery measures 1.625 volts using a digital multimeter.
Strangely, both channels on the 465 display exactly the same measurements.

1.625 VDC battery       0.5 v scale        nearly 5 divisions   both
channels
300 mv calibration         .1 v scale         4.4 divisions           both
channels
1 volt cal (on HP)            .5 v scale         nearly 3 divisions  both
channels

All voltages read correctly when using the P6130 probes connected to the HP
1740A.

I did remove the cover, and made rough measurements to see if a simple
problem could be found in any one stage.  Unfortunately, measurements seemed
all over the place, and will have to repeat and carefully document readings.
One possiblity at this point may be power supply problems, although quick DC
voltage checks seemed ok.

The previous owner stated that initially, one channel in the scope exibited
the gain problem, but the other channel worked correctly.  The second
channel then reportedly soon failed also, whatever that means.

A front panel vertical gain trimmer could not be found.  Red knobs do not
seem to have any push-trim capability from what is apparent inside.  Perhaps
I have overlooked something.

Thanks again, and any additional comments very welcome!

73 de Bill, AB6MT
ab6mt at sonic.net


----- Original Message ----- 
From: Dale H. Cook
To: Bill Smith ; test-equipment at mailman.qth.net
Sent: Sunday, August 21, 2005 6:59 AM
Subject: Re: [Test-Equipment] Fw: Tektronix 465 question


At 12:50 AM 8/21/2005, Bill Smith wrote:

>Have just acquired a 465 oscilloscope in beautiful condition.  However,
both
>channels are out of calibration and read about 150% high when connected to
>the calibration bar.

Bill -

Are you using the original Tek probes?

Dale H. Cook, Chief Engineer, Centennial Broadcasting, Roanoke/Lynchburg,
VA - WZZI / WZZU / WLNI / WBWR
http://members.cox.net/dalehcook/starcity.shtml


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