[Boatanchors] VTVM QUESTION

[Morris Dillingham]

One problem I had with my Heath V7A was the aging phenolic in the 1/4 =
inch
phone jack.  It was preventing any calibration on the 5 volt scale and =
much
leakage on the high scale positions of the range switch.  Replacing it =
with
a new one cured the problem for a while.  Then the phenolic in the wafer
switch added it's influence by throwing off the high range measurements.
Don't spray the phenolic switch with contact cleaner.  It will swell but =
not
work so swell.  The 1 meg resistor in the DC probe is a requirement for =
most
of the VTVMs.  Supposedly it helps prevent loading of RF circuits by =
being
at the end of the cable and not in the VTVM.

       73 de KI4IUA
         Morris=20






-----Original Message-----
From: boatanchors-bounces at mailman.qth.net
[mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of k0dan
Sent: Saturday, February 04, 2006 2:02 PM
To: Ron Hunsicker; Dave Brown
Cc: boatanchors at mailman.qth.net
Subject: Re: [Boatanchors] VTVM QUESTION

Thanks Ron...

Someone else mentioned the 1 meg resistor, which I'm gonna try. I think
there may be another problem in the meter and I'm also gonna replace a =
few
of the caps and see if I can calibrate it. It's a pretty simple circuit =
but
something just doesn't feel right with the way the meter is operating so
far.

Thanks and 73

Dan
K0DAN
----- Original Message -----
From: "Ron Hunsicker" <ronhunsi at ptd.net>
To: "Dave Brown" <tractorb at ihug.co.nz>
Cc: <boatanchors at mailman.qth.net>
Sent: Saturday, February 04, 2006 5:04 AM
Subject: Re: [Boatanchors] VTVM QUESTION


> I have an RCA Senior Voltohmist WV-98A.  It came with a WG-299C probe.
> The parts list for the probe lists a 1 meg resistor, but no diode.  =
Two
> other probes are also listed, WG-299B and WG-299A, and both only have =
a
> 1 meg resistor.
>
> The 1 meg resistor is "in circuit" in the DC position (versus the
> AC/Ohms position).
>
> --
> Ron Hunsicker
> 1238 Cleveland Avenue
> Wyomissing, PA   19610-2102
>
>
> _______________________________________________
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> ** List Administrator - Duane Fischer, W8DBF/W9WZE **
> ** For Assistance: dfischer at usol.com **
> $$ For vintage radio info, see the HCI web site $$
> http://www.w9wze.org
>
>


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