[TenTec] Model 260 PSU problem

[Dr. Gerald N. Johnson]

On Sat, 2006-12-02 at 12:48 +0000, Steve Hunt wrote:
> Jerry,
>  
> Just to report that the PSU is now repaired and working well. I'll
> keep an eye on the Diode Bridge case temperature for a few days to
> check the heat-sinking is OK.
>  
> Yes, I drilled a new hole midway between the TO-3 mounting holes, and
> a corresponding one in the bottom of the case. I could have used one
> of the existing TO-3 holes, but I felt it was better to have the new
> bridge sitting centrally in the heat sink. I was careful to "deburr"
> the new holes so that bridge "sat" flush on the sink, and the sink sat
> flush against the case.
>  
> The PSU is now very much quieter. Hardly surprising when you think
> that the transformer was supplying nothing on one half-cycle, and lots
> of current on the other half-cycle!!

For sure. The half wave rectifier puts unbalanced DC in the transformer
and that biases the core so it's certainly running much further into
saturation that it was designed for. And being a 50/60 Hz (I hope)
design the 50 Hz gets it more into saturation that it would on 60 Hz.
The magnetostriction from going into saturation should have had it
buzzing loudly.

>  
> 73,
> Steve G3TXQ

-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer