[Test-Equipment] TV-7 Calibration

[DW Holtman]

Eric,

Not sure why I thought I was measuring AC, but now have things sort of under 
control. The bias adjustment went fine, the plate 150 was fine, next I tried 
the screen grid, it was way low, around 96 volts instead of 130 Volts. Next 
I did something I should have done before I started and checked the two 
tubes. The 83 was not an 83, it was a 5Z3. The 5Z3 tested bad on my Hickok 
600A, it lit up the short light. I ordered a 4 pin socket and will solid 
state the 83 when it gets here and start the process over.

Thank you for taking the time to help me out, sometimes (frequently) I can 
really use it.

Best,
DW Holtman

----- Original Message ----- 
From: "Eric Lemmon" <wb6fly at verizon.net>
To: "'Discussion of Electronic Test Equipment'" 
<test-equipment at mailman.qth.net>
Sent: Thursday, October 11, 2007 9:22 PM
Subject: RE: [Test-Equipment] TV-7 Calibration


>I beg to differ; the bias voltage is DC, not AC.  But, I am curious- why 
>did
> you think it was AC?
>
> I have the Army TM 11-6625-366-10 for the TS-352 meter, and it shows that
> the meter has both 1,000 ohms/volt and 20,000 ohms/volt ranges for DC.
>
> I have a TV-7A/U tube tester, and I have all of the Army TMs that cover 
> it.
> Please take careful note that the testing procedure and the expected
> voltages vary among the various TV-7 models.  Also, be aware that the
> calibration procedure must be performed in a specified sequence; you 
> cannot
> just jump to the bias adjustment without completing some prior steps.  Be
> careful that you perform all of the preoperational switch and control
> settings before taking any readings.
>
> The total resistance across the screen and bias power supply is a little
> over 4,000 ohms, which is not particularly high impedance.  It was pretty
> standard practice to use the 20,000 ohms/volt setting, which is what a
> Simpson 260 or an Air Force PSM-6A meter provides.  Figure 38 on page 48
> shows the meter settings for voltage measurements.
>
> 73, Eric Lemmon WB6FLY
>
>
> -----Original Message-----
> From: test-equipment-bounces at mailman.qth.net
> [mailto:test-equipment-bounces at mailman.qth.net] On Behalf Of DW Holtman
> Sent: Thursday, October 11, 2007 9:47 AM
> To: Discussion of Electronic Test Equipment
> Subject: Re: [Test-Equipment] TV-7 Calibration
>
> Robert,
>
> Great information. I should have specified, the voltage in question is AC
> volts, not DC Volts. Any idea if what the imput inpedance might be for a
> TS-352 type of VOM in the AC ranges?
>
> Thank you,
> DW Holtman
>
>
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