[Johnson] (no subject)

[Rodger]

Hi John,

The shunt of interest is a .202 ohm from the centertap of the HV 
transformer secondary to ground, R-56.  In most Valiants this is a very 
short piece of nichrome resistance wire and it has to be the proper 
length after tinning and it rarely is the proper length.  I replaced 
this in both of my Valiants with precision resistors from Mouser.

How are you determining your transmitter meter is reading incorrectly?  
The best bet is to break the connection where HV is fed to the final at 
the point where C-46 connects to L-12 and insert a DMM or VOM in series 
with the plate feed to measure the actual current and compare it to your 
plate meter reading.  This point will be up to 800 volts above ground so 
make sure that your meter is rated for this type of voltage and observe 
proper operator safety!

Although you can make an educated guess that the plate meter is wrong if 
the output is low based upon indicated current there may be other issues 
other than an incorrect plate meter reading such as: inaccurate 
wattmeter used to measure output, incorrect final operating conditions, 
failure of one or more of the coarse loading caps, bad final tube(s), 
etc.  So it is best to make sure of the actual current draw if possible 
before condemning the shunt.

While you are inside your Valiant, also check the wiring from the LV 
transformer which provides filament voltage for the 866A rectifiers.  In 
the early Valiants standard hookup wire is used and the insulation is 
not sufficient for the HV that also appears on this wiring.  The end 
result is arcing and shorting to ground which can take out both the low 
and high voltage transformers.  If the wiring is not heavily insulated 
then you should add shrink tubing to provide additional protection.  Of 
course, if the 866A rectifiers have been replaced with solid state units 
then you can disconnect and insulate the filament leads at the 866A sockets.

Also, if you have not already replaced the dropping resistor to the VR 
tube in the VFO now would be a good time to do that before it creates 
additional damage.

Good luck with your Valiant and let me know if I can be of further help.

73, Rodger WQ9EJohnPerz at aol.com wrote:
> Hello all, 
> Suspect I have a problem with a meter reading high on my Valiant.Some 
> research says to check the meter shunt resistance.looked at the schematic on Bama but 
> do not recognize it. Some guidance please......
> Thank you, John WA2FNS
>
>
>
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