[time-nuts] HP and other equipment failure

[Luciano Paramithiotti]

About the HP5370 please got o see my solution to:
http://www.timeok.it/files/hp_5370a_temperature_solution.pdf

Luciano
timeok

see : www.timeok.it

On Fri, Jun 14, 2013 at 4:26 PM, Mark C. Stephens <marks at non-stop.com.au>wrote:

> Talking of Cooling HP 5370's, I have a 12V fan Gorilla taped to mine fed
> from a wallwart.
>
> Not elegant, but it has reduced the heat sink temperature dramatically.
>
> Is anyone else concerned about the heat sink temperature on the 5370?
> Has anyone done a fan modification they would care to share?
>
> Also, my 8566A RF section pass transistor heat sink gets awfully warm too,
> does anyone have a sensible solution?
>
>
> -marki
>
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of David Kirkby
> Sent: Friday, 14 June 2013 7:14 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] HP and other equipment failure
>
> On 14 June 2013 05:48, Perry Sandeen <sandeenpa at yahoo.com> wrote:
>
> > There are two long standing truths about electronic equipment.  One
> > you can't have too much filter capacitance.  Two, you can't cool too
> > much.  (Please spare me the  liquid nitrogen or submarine battery
> > comments.)
> >
> > Regards,
> >
> > Perrier
>
> Well, I have to disagree with both comments.
>
> More filter capacitance in a standard linear power supply means the diodes
> take more current for a longer period of time. For any given diode, that
> puts more strain on it. At very high levels of capacitance, the amount of
> stored energy is huge, and can be dangerous. In the event of a fault,
> higher stored energy has the potential to do more damage than lower stored
> energy. Once you have sufficient capacitance, which includes calculating
> the effects of reduced supply voltage, minimum capacitance of device with
> tolerances, and some safety factor, I don't see what more capacitance does
> other than increase costs, weight, and the potential for more damage in the
> event of a fault.
>
> Whilst it is well known that increasing temperature gives rise to shorter
> component lifetimes, more cooling also requires more noise, and so a
> compromise has to be met. I have here an Air Control Industries VBL9
> blower, which I want to sell in fact. That will move about 1000 cfm at 6"
> of water pressure. It happens to take 2.8 kW from the mains, the startup
> current is too large to not blow a normal mains fuse in a plug here in the
> UK, and the noise is enough to get neighbours wondering what the hell it
> is, despite I live in a detached house, some 50 m from the nearest
> property. So while a HP 5370B needs far more cooling than provided, I think
> the VBL9 would certainly provide too much cooling air.
>
> Engineering is always a compromise. HP usually got that balance about
> right, although in some instances, like the 5370B, that is not true. I know
> mine got pretty damm hot, and I'm quite near sea level. I would imagine for
> someone at a high altitude, it would be even worst.
>
> I have to agree with you about the serviceability of older HP equipment
> though. It is much more serviceable than modern equipment.
> However, you would have to go back a long way before finding equipment
> which one could guarantee one could keep going, as most things I'd
> contemplate buying will have a ASIC and/or some other specialist component
> which if it failed would be impossible to get except by taking one from a
> similar piece of equipment.
>
> Dave
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-- 
Luciano
Timeok
visit : www.timeok.it