[Collins] You Won't Believe This

[Alan C. Zack]

Have you recently rubbed the glass surface of the meter with a cloth? 
  If so, you may have place a static charge on it.  Attempting to 
clean most meter glass will cause the needle to deflect to someplace 
other than it should, regardless if it is connected to a circuit or 
sitting free, or in your case, with just one lead connected.

David Knepper wrote:

> I own a Collins 20V-3 broadcast transmitter that is at the Collins Radio
> Center.
> 
> The transmitter has been restored and worked perfectly after modifying it to
> 160 meters.
> 
> Now, the plate current meter (0-800 ma.) is reading to the left of "0" with
> only the high voltage lead from the smoothing choke attached!!
> 
> The high voltage meter is showing 4000 volts.  The positive post of this
> meter goes to the positive post of the plate current meter through some
> multiplier resistors.
> 
> That is right, only one lead connected and the meter is reading negative
> current.  I switched this lead to the negative post and the meter still
> deflects downward past zero.
> 
> Disassembled the meter to see if it may have a carbon path through the case
> to ground.  Nothing.  The meter looks "normal."
> 
> When I hook a multimeter to the terminals:  red to positive post and black
> lead to negative post on the meter, the needle deflects upward, which is
> normal for a current meter.
> 
> I am really stumped on this problem.
> 
> If someone told me that a current meter could deflect left of zero with only
> one lead attached, I would have thought that this was some kind of psychic
> phenonomen.
> 
> Could the meter have changed polarity?
> 
> Can anyone tell me what is going on.
> 
> 
> Thanks
> Dave, W3ST
> Publisher of the Collins Journal
> Secretary to the Collins Radio Association
> www.collinsra.com
> Nets:  3805 Khz, Monday/Wednesdays 8 PM EDST
>           14250 Khz Saturday, 12 Noon EDST
> 
> 
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> 

-- 
__________________________________________________________________________ 

Alan Zack
Amateur Radio Station K7ACZ
Las Vegas, Nevada, USA
Quality Engineer, The Boeing Company, Retired
Aviation Chief Warrant Officer, U.S. Coast Guard, Retired
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