[Milsurplus] Need help with ART-13

[WA5CAB at cs.com]

Bob,

I agree with Meir's comments on getting output (and plate meter dip when 
you get the meter working).  The problem with the PA plate current meter may 
be that it is mis-wired.  The metering circuit in the ATC can be slightly 
difficult to figure out.  The meter shunt is a nominal 500 VDC above ground, at 
the junction of the 500 and 700 volt windings in the dynamotor.  They 
apparently did it tthat way so that the PA Plate Current reading wouldn't include 
the exciter current and probably to simplify (reduce the number of switch 
contacts required) the switching of the High B+ from 1200 to 500 at around 
21000 feet pressure altitude.  And also so the shunt wasn't at 1200 VDC above 
ground most of the time.  If they had put the shunt between the negative 
lead of the 500 volt winding and ground, the meter would always have read total 
B+ current.

In the TCZ (shipboard and ground version of the ATC) when using the AC 
operated rectifier supply, the meter shunt is in the center tap to ground lead 
of the 1250 VDC supply.  They could do it that way because the AC supply has 
independent 500 and 1250 supplies, not a 500 in series with a 700.  I think 
that the 115 VDC operated supply is the same way but haven't checked.

To wire the AC supply such that the transmitter will also still work with a 
dynamotor, the 13.3 ohm meter shunt should be connected between the High HV 
transformer center tap and chassis/ground in the supply.  The filter 
capacitors and bleeder resistor should also be tied to the center tap, not to 
ground.  Pin 2 of U-7/U (and U-9/U if you built a plug-n-play) should go to the 
top of the meter shunt.  Pin 9 should be grounded (only) in the power 
supply.  If you (or anyone) would like a much simplified schematic (all the remote 
control circuitry removed) of the TCZ-1's AC supply, I can email a PDF.  If 
you wire up your AC operated supplies more or less as shown, ignoring the 
filament transformers if you use solid state rectifiers (and assuming no one 
has made changes in the transmitter), it'll work.

In a message dated 3/8/2011 11:27:51 AM Central Standard Time, 
kn4hhptc at yahoo.com writes: 
> I have acquired an ART-13 (ATC model) and am having trouble getting it on 
> the air.
> My power supply provides 26vdc, 400vdc and 1200vdc.  I powered up the 
> transmitter and the battery meter functrion indicates normal.  In tune mode and 
> using manual channel, I see appropraite amount of grid current when the 
> test switch is operated.  When I place the meter switch in the plate 
> position, the meter immediately pegs off scale to the left.  If I operate the test 
> switch, no change in the reading.  My power meter indicates that 
> approximately 30 watts of carrier is present at the transmitter output and the 
> antenna current meter does show  a low value.  No increase in output power no 
> matter where I position the tune and load controls. I am able to adjujst 
> frequency OK. Hopefully, I am overlooking something.  
>  
> I would appreciate any suggestions for troubleshooting.
>  
> Many thanks,.
> Bob, KN4HH

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480