[Test-Equipment] TV-7 Calibration

[DW Holtman]

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

----- Original Message ----- 
From: <WA5CAB at cs.com>
To: <test-equipment at mailman.qth.net>
Sent: Thursday, October 11, 2007 10:19 AM
Subject: Re: [Test-Equipment] TV-7 Calibration


> DW,
>
> As a philosophical statement, DVM's waste time when working on boatanchor
> gear.  The natural tendency is to sit there and fool with the adjustment 
> until
> the meter or counter reads exactly what the book says.
>
> However, whether the meter impedance will make any difference to any given
> measurement depends upon the source impedance.  It could make no 
> difference, a
> little difference or a bunch.  For example, the BC-611 maintenance manuals 
> give
> two charts for most test voltage settings, one using a battery operated 
> VTVM
> and one using another meter.  Some of the numbers are the same and some 
> are
> quite different.
>
> But if you want to make sure to set the thing the way it would have
> originally been set, the TS-382(*)/U is 1000 ohms per volt on all AC 
> ranges and
> selectable either 20,000 or 1000 on all DC ranges.  That being the case, 
> if the
> instructions don't tell you which to use, it's probably safe to assume 
> 20.000.  If
> you shunt the meter probes with (20,000 x full-scale range) ohms, the TV-7
> won't know you aren't using a TS-382.  :-)
>
> In a message dated 10/11/2007 11:01:37 AM Central Daylight Time,
> tubestuff at comcast.net writes:
>> Hello,
>>
>> I'm getting ready to go through a TV-7/U, step by step using the Depot
>> manual (TM-11-6625-274-35). The first step, the bias voltage test calls 
>> out a test
>> setup then asks for a reading of 3.0 +_.1 Volts. I'm reading 5.26 Volts.
>>
>> My question is this. The procedure calls for using a TS-352 Multimeter. 
>> The
>> only meters I have are high input impedance DVM and a VTVM. I know that a
>> TS-352 will load the circuit and cause a lower reading. Is there anyway 
>> to make
>> the necessary adjustments using a DVM or a VTVM? Is this a situation 
>> where I
>> will need to get a good quality VOM (Simpson 260 etc) to do the 
>> adjustments?
>> What is the ohms per volt on a TS-352?
>>
>> Thank you in advance for any suggestions.
>>
>
> Robert Downs - Houston
> <http://www.wa5cab.com> (Web Store)
> MVPA 9480
> <wa5cab at cs.com> (Primary email)
> <wa5cab at comcast.net> (Backup email)
>
> ______________________________________________________________
> Test-Equipment mailing list
> Home: http://mailman.qth.net/mailman/listinfo/test-equipment
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:Test-Equipment at mailman.qth.net
>