[Boatanchors] Looking for Documentation on IM-5210 HV Probe

[rbethman@comcast.net]

This one is blue and completely self contained.  The meter is built into the
body, along with an on/off switch in the handle.

An obvious Heathkit design and so noted by the model number.  It works
wholly in a stand-alone mode.

This is why I am seeking out Heathkit documentation

Bob - N0DGN  Craf-T-Bob  (Because I love Hallicrafters!)
Apache(2), Mohawk(2), HT-32A, SX-99, SX-101 mk III, R-390A
EAC, R-390A Collins, DX-60 w/HG-10, BC-610I, BC-939A

----- Original Message ----- 
From: "Barry L. Ornitz" <ornitz@tricon.net>
To: <rbethman@comcast.net>; <boatanchors@mailman.qth.net>
Sent: Monday, June 03, 2002 7:15 PM
Subject: [Boatanchors] Looking for Documentation on IM-5210 HV Probe


> Bob Bethman asked about a Heath high-voltage probe:
> 
> >     This week's latest Hamfest find is a Heathkit IM-5210 High
> Voltage
> > Probe.  I am looking for a copy of the manual.  A PDF or any other
> form of
> > scan would be just fine.
> 
> I have a Heath high voltage probe but I am not sure if it is the same
> model number.
> Like most HV probes, it is red and about a foot long with lots of
> insulation around the handle.
> 
> Inside there is a 1090 Megohm resistor.  The resistor is spring loaded
> to contact the tip, and the bottom of the resistor is held in by
> screwing on the connector which has the cable.  This is an old-style
> Amphenol shielded microphone connector.
> 
> The probe is designed to work with an 11 Megohm VTVM.  These meters
> have an internal impedance of 10 Megohms and have an additional 1 Meg
> resistor in their probe.  The meter is calibrated to handle the 10/11
> voltage reduction.
> 
> When the HV probe is added, the combined resistance of the meter and
> probe is 1100 Megohms.  Thus the probe provides a 100X reduction in
> input voltage to the meter.  The overall insulation and such provides
> typically 30,000 volts on the meter's 300 volt scale.  If your plastic
> probe has been stored properly (few have) you might be able to push
> the voltage up to 50,000 volts.  However, if the plastic is scratched
> or dirty, this will not be possible.  Cleaning the outside plastic
> with soap and water, followed by buffing with Brasso, followed by
> another soap and water cleaning may help here.  Dry thoroughly! That
> surface dirt becomes quite conductive at high voltages.  If the inside
> of the probe has ever gotten wet, you should probably throw the unit
> in the trash for being too dangerous to use.
> 
> Remember these probes are only good for DC.  Think of the probe and
> meter capacitance as an RC low-pass filter.  With that much
> resistance, it does not take much capacitance to cut off even low
> frequencies.
> 
> Probes designed for modern digital meters will have different resistor
> values.  These meters generally have a 1 Meg input resistance on all
> scales over 200 mV.  Here the probe resistance would be 99 Megs.
> However some digital meters have an internal resistance of 10 Megs and
> the high voltage probe would be 990 Megohms.
> 
>         73,  Dr. Barry L. Ornitz     WA4VZQ     ornitz@tricon.net
>