[time-nuts] Anyone (ideally in the UK) got a spare rotary knob for the 5370B TI counter?

EB4APL eb4apl at gmail.com
Sat Dec 31 08:03:12 EST 2016


I'm not totally sure about the limits, but I have read several times 
that in the UK the nominal supply voltage is 230 V +10%/−6% to 
accommodate the fact that most supplies are in fact still 240 V. The 
context was that a lot of test equipment failed when operated at around 
250 V and many input capacitors (particularly the ones inside a know 
brand IEC socket - filter) caught fire.

Wikipedia says that several areas in UK still have 250 V because this 
value is withing the current limits.

I think that the governing document is British Standard BS 7697: Nominal 
voltages for low voltage public electricity supply systems — 
(Implementation of HD 472 S1).


Ignacio, EB4APL

El 31/12/2016 a las 11:25, Dr. David Kirkby (Kirkby Microwave Ltd) escribió:
> On 31 Dec 2016 02:03, "Bob Stewart" <bob at evoria.net> wrote:
>> If you can touch the heat sink for 2 seconds, you're made of sterner
> stuff than I am!  They run very hot.  It's a good idea to get a GPIB
> extender so your GPIB cable can clear the heat sink.  Somebody, can't
> remember who, worked up a nice looking conversion to a pair of switching
> supplies.
> SMPSs tend to be less clean than a linear supply. I would be somewhat
> reluctant to take that route on test equipment. But I will search for the
> conversion.
> I have a 13 A variac sitting around that's not been used in the last 25
> years. I think as a short term measure I will drop the voltage to a few
> bits of the equipment with linear power supplies. The spectrum analyzer has
> linear supplies and puts out a lot of heat.  As someone else said,  a 20 V
> transformer would work. Adding the variac will take me 5 minutes to do,
> which has an advantage over anything I need to build.
> I will also log the mains voltage over a period of a few weeks and see if
> it high enough to ask the electricity supply company to do something about
> it.  I do know someone that measured his voltage and found it was outside
> the legal limits. He advised the electricity supplier,  they agreed,  but
> said that they were not going to do anything about it.  He wired his whole
> house on an auto transformer.  I would be speaking to my Membrr of
> Parliament (MP) if it was outside the legal limits. I don't know what legal
> limits exist in the UK for voltage,  but I can find out.
> It is unusual in the UK for a domestic property to have a phase supply, but
> mine does.  I don't know whether any one phase is consistently lower than
> any other. If so phases could be switched.  But given my close promptly to
> the 11 kV transformer,  I doubt it.
> I know at one point I had a dispute with the electricity supply company as
> the 415 V overhead power lines used to be regularly hit by farm vehicles
> down a private road where my property is. This would pull the cables away
> from my house and make a mess of the house. The electricity supplier would
> always repair the damage,  but after this happened a few times I
> complained. I was initially told they would do nothing as it is not a road.
> But I discovered that the cables needed to be a minimum height if there was
> vehicular access. So whether the electricity supplier considered it a road
> or not was irrelevant.  Eventually they extended a pole and raised the
> cables up, which appears to have solved the problem.  Whether I can
> convince them to move the transformer taps is another matter.  I suspect
> that it might be hard if my supply is consistently high, but not outside
> the legal limits.
> Dave
> _______________________________________________

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