[Johnson] Johnson Viking II Meter Shunt Question

[Gary Schafer]

Hi again Scott,

I don't know if the manual gives the resistance of the shunt or not. I think
it is nichrome wire in that little coil and I think it is crimped
connections to it as it is hard to solder to. The crimps become loose. It's
been awhile since I looked.

The best way to check is to put a known ma meter in series with the circuit
and see how far off your meter is. It is hard to measure low values of
resistance accurately with an ohm meter.

73
Gary  K4FMX

> -----Original Message-----
> From: johnson-bounces at mailman.qth.net [mailto:johnson-
> bounces at mailman.qth.net] On Behalf Of Freeberg, Scott (STP)
> Sent: Friday, July 20, 2007 9:16 AM
> To: johnson at mailman.qth.net
> Subject: [Johnson] Johnson Viking II Meter Shunt Question
> 
> Greetings!  I got the modulator running in the Viking II.  It is
> definately the Ranger modulator circuit in there.  The resting modulator
> cathode current is reading 200 ma instead of the 80 ma per the manual.
> 
> Gary  K4FMX suggested I check the meter shunts and said they have a
> reputation for changing values.  I found the meter shunt for the modulator
> cathode current.  I was expecting a low value precision resistor but found
> a piece of insulated wire with a funky bend in it.  It matches the one in
> the manual photo.  I'm assuming it's some kind of special wire with a high
> resistance.
> 
> What is the shunt resistance supposed to be?  I'm guessing it wants to be
> 0.5 ohms or 1 ohm.
> 
> Thanks.  73, SCott WA9WFA
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