[AMPS] Viewstar PT-2000A Manual

Mon, 28 Jul 1997 13:50:28 +0000

> From:          Sam Ferris <ve5sf@sk.sympatico.ca>
> Date:          Mon, 28 Jul 97 13:17:35 +0000

> Would also appreciate information in the short term on what the HV should 
> run in low and high power modes (both under load and in stand-by).  This 
> amp appears not to have been use for several years and the HV sagged a 
> little in stand-by mode within the first 1 hour in standby mode.  Went 
> from 2550 V to 2350 V and stays there now.  Seems to have good output 
> however (.71 A plate current, 1900 V, 800 Watts <-- does this sound about 
> correct).  

I suspect what you have is a case of the METER circuit being 
incorrect, and drifting. It is quite common for defective HV 
multiplier resistors to change value with temperature and humidity.

If your PA doesn't smoke or hum, or you power line voltage isn't 
changing all over the place, you have bad multiplier resistors. 
The HV multiplier resistors  are between the HV line and the HV 
meter.  They can NOT be carbon, or normal metal film types. 

About the time that amp was marketed, there were large quantities of
defective surplus HV multiplier resistors floating around at a bargain
price. Perhaps those resistors were used, or perhaps they used normal
carbon or metal film resistors instead of the very expensive HV type
resistors.

I can't help you with your other questions.

73, Tom W8JI 

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