[NJARC] Megohms in primary?

[antqradio at juno.com]

I would think 5 Mohms is pretty close to infinity.  Leakage current
calculates to about 25 microamps at 120 volts RMS input.  You must be
using a DVM which can read very large resistances easily.  An analog
meter like a Simson 260 would barely measure the 5 megs but might measure
the leakage current.  I don't remember if the 50uA scale is DC only or
not.
I agree with Rob about the moisture and baking it to drive it out.  At 95
pounds, no easy task.  Obviously a good summer outdoors project but with
fall well under way?  You could let the transformer do the work by
putting a reasonable load on it and allow self heating to do the job. 
Variac anyone?
Regards,
Jim

On Thu, 11 Nov 2004 12:17:59 -0500 StephenTetorka at cs.com writes:
> Hi all:
> 
> I'm starting my checkout of the W2PLY AM/CW rig with the 95 pound 
> power supply.
> 
> With no power supplied, when using a VTVM from either primary lead 
> to ground of the main power transformer, I get a reading of 15 
> megohms with the SPST in the primary in the OFF position.
> I get 5 meghoms in the ON position - which completes one primary leg 
> circuit allowing the 115 VAC to primary.
> 
> Naturally, I'd expect infinity on this open circuit.
> 
> Not much there: terminal screws on the back chassis; hvy AWG to the 
> switch, a lamp indicator in parallel on the primary amd the xmfr 
> bolted to the chassis.
> 
> I would guess that some insulation somewhere has 'gone old'.
> 
> Your generous comments and suggestions most welcomed.
> 
> Regards,
> Steve
> WA2TAK