[time-nuts] HP 5370B dropping mains voltage

[Randy D. Hunt]

On 7/6/2013 2:39 PM, Mark C. Stephens wrote:
> How Does that Work Robert?
> I mean why out of phase?
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Robert Atkinson
> Sent: Sunday, 7 July 2013 12:57 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] HP 5370B dropping mains voltage
>
> Hi Marki,
>
> Dropping the mains voltage is easy. Get a mains to low voltage transformer. Connect the primary across the mains and the secondary in series opposition (out of phase) with the mains supply. Foar example a 100VA 12V transformer will drop your mains to just under 238V with a maximum load of 8A (the current rating of the secondary).
>
>
> HTH,
> Robert G8RPI.
>
>
>
> ________________________________
>   From: Mark C. Stephens <marks at non-stop.com.au>
> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
> Sent: Saturday, 6 July 2013, 13:25
> Subject: Re: [time-nuts] HP 5370B Leds pulsing slowly, buttons selecting normally, PB ...
>   
>
> Hi Nigel,
>
>
> The only screw type electro can find is 29000uf at 10V. it's the same dimensions.
> Should I risk the strain on the rectifiers (another 10Kuf is rather a lot)?
> Without this timer I am dead in the water so I need to do the right thing here...
>
> That's why I posted on the Agilent group too, I need to be sure that I do the right thing!
>
> By the way, the failed electro measures 39uf :)
>
> I reckon, the line voltage here is 250v and the equipment is set for 240V, that extra 10V on the mains is why I am having so much equipment failure.
> Also the Heat sink on the 5370B got so hot I mounted a 5" fan across it to keep it at a respectable temperature.
>
> How can I drop the Mains to 240V, I have a boat load of gear that needs to be powered concurrently.
> (8566A, 8568B, 3585A, 5335A, 5370B, 8901A, etc, powered on together) we are starting to talk some serious current there.
>
>
> -marki
>
>
> -----Original Message-----
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Because, when you wire the secondary in series with the primary out of 
phase, the voltage sum drops.  this is because when thewave in the 
primary is high positive, the wave in the secondary is high negative.  
so a 12 volt transformer will reduce the voltage by 12 volts. If you 
wire them in series, it will add 12 volts.  It is nothing more than an 
auto-transformer.

KI6WAS