[time-nuts] Replacement fan in SR620

Charles Steinmetz csteinmetz at yandex.com
Sun Feb 2 15:34:47 EST 2014

Magnus wrote:

>These days I would assume that heat-pipes would be used to move heat 
>to a large external heat-sink. It's fairly cheap these days.

I have looked into heat pipes for several projects, and in the end 
have never used them.  The main problem is that almost every solution 
is customized.  No trouble if you make PC motherboards or 
consumer-grade stereo amplifiers 50,000 at a time.  But most 
instruments are made in quantities of 5,000 or fewer, and it takes 
many years to make (sell) even that number.  With production numbers 
that low, the bean counters want the design and tooling costs 
amortized over the first year's production -- maybe only 100-500 
units -- which can raise the retail price by a factor of 2-10.  At 
least that's what I've found.

Also, most heat-pipe systems are gravity-fed, so if someone turns 
your product on its side they can burn it down.  (I almost always 
operate my "portable" spectrum analyzer (HP8591E) standing on its 
rear feet with the screen pointing up.  I can foresee someone with 
limited bench space setting an SR620 on its side.)

Best regards,


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