[time-nuts] HP10811 Oscillator Thermal Fuse

[Bob kb8tq]

Hi

Ok, well since I was *asked* to say more :) 

Long ago heavy users of this sort of gear figured out that you wanted to keep the OCXO’s on
all the time. That was the way  to make the gear the most stable. That is the way you
can use your counter / generator / whatever  when you get to work in the morning. A house
standard is not always the way labs are wired. 

Over the years this power on approach ran up against facilities groups that had objectives to reduce
building costs. As the costs went down, their bonus went up. A multitude of reasons thus
were generated as to why it was a “really good idea” to turn everything off at night / at lunch/ 
in odd numbered hours. Most of them were pretty easy to fight. The “fire hazard” one was
a bit harder to address. It became a conversation point in buying gear. 

Conversation points tend to flow into odd specification details. They may or may not show
up in the written specifications. They are there none the less. The fuse in the 10811 is there
because of fire / smoke hazard concerns. Is it provable that there a direct link from the 
customer “concerns” to the fuse? Without full access to every memo and conversation
within HP, it can’t be proven. Based on what people have said over the years, it is the case. 

Ultimately it all came to no good. The energy conservation rules simply took over. Shutting
down everything during off hours became the way a lot of outfits did things. Don’t turn off all
your bench gear and you get a nasty note. I am not aware of full power being dropped during 
off hours. That tends to take out things you really do not want to shut down (fire sensors …). 

I tend to pick on the US government in the context of gear shutdown. They certainly had all 
these issues. The guys from the various labs certainly fought all these battles. The government is
far from the only organization that went through all of this between the late 1960’s and today. 
I’m also not claiming that energy conservation is a bad idea. It comes to mind every month
when I get the electric bill ….

Bob


> On May 11, 2017, at 1:58 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
> 
> 
> kb8tq at n1k.org said:
>> The is related to safety (full time  power on). As it worked out, the fuse
>> did not help them in that respect. The Fed’s still ruled the gear had to be
>> shut off at night. 
> 
> Could you please say more...
> 
> Does that mean unplugging gear with always-on OCXOs?  Or dumping the main 
> power to the lab when the lights are turned off?
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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