[Amps] Rectifier equilization?

[Carl]

> >The problem with MOV's is they have a narrow current range where they
>>are most efficient and either side of that the internal resistance and
> heat
>>goes up.
>>
>>Carl
>>KM1H
>>
> Please could you expand on that, Carl? MOVs are non-conducting unless
> they are actually limiting a surge, so I'm not sure how internal
> resistance, heat and "efficiency" (in the normal engineering sense of
> that word) come into it.


My error, I had them confused with the GE surge suppressors many use and 
have trouble with, the CL-90 for instance.
 MOV is a GE registered trademark BTW.


>
>> They also have a finite life.
>
> MOVs are sacrificial components. Their mission in life is to 'take a
> bullet' from line surges to protect other, more valuable components
> downstream. But their working life is closely related to the total
> amount of energy they have absorbed... and as well as damage due to
> large surges, there is also damage from long-term exposure to the much
> larger numbers of small surges.



Already well covered in the literature.


>
> In a normal shack PA, the working life of an MOV can be greatly extended
> by placing the MOV on the downstream side of the main power switch, so
> it isn't exposed to any surges unless the amp is in use.



IMO placing them after the switch is the normal way of installing them. The 
other option is as part of an external line filter/Spike suppressor which is 
popular with the receiving end but those have proven to be prone to failure 
resulting in smoke when least expected.


> Also don't forget the benefits of a mains filter. As well as filtering
> high-frequency impulses coming backward out of the power supply, the
> filter will reflect most of the high-frequency components of any
> incoming surges.
>
> 73 from Ian GM3SEK

Ive been using HB line filters for decades on everything from home 
electronics, vintage radios scattered around the house, vintage and modern 
ham gear including amps, test equipment, etc. It started when I built a very 
competitive contest station in the 80's and wanted to keep family and 
neighbors out of my hair. It grew once consumer electronics became a scourge 
and I became obsessed with a clean AC line as well as what was coming in on 
feedlines and control cables.

Large full house MOV's are installed in the mains box right after the 200A 
breaker.

Carl
KM1H