Hi

Rb's die if you let them get to warm. If it's in a plugin sized enclosure count 
on a pretty good fan.

Bob



On Sep 16, 2010, at 3:57 PM, [email protected] wrote:

> 
> 
> Hi Bob- 
> 
> 
> 
> I don't have the LPRO in a plugin, but I had considered it, and was wondering 
> if any of those that had built one had thermal and/or lock issues. 
> 
> 
> 
> Re the sun in our valley... not this year!  My tomatoes just started really 
> producing and my squash and zucchini still haven't even flowered.  That has 
> NEVER happened to me before.  A very odd year weather-wise! 
> 
> 
> 
> Dave 
> ----- Original Message ----- 
> From: [email protected] 
> To: [email protected] 
> Sent: Thursday, September 16, 2010 8:07:19 AM 
> Subject: Re: [time-nuts] LPRO101 orientation vs lock 
> 
> I assume you mean Tektronix TM5xx or 5xxx modules. 
> 
> I haven't seen an LPRO plugin, but considered doing one for my TM506 rack. My 
> conclusion was that I couldn't get rid of enough heat without cutting custom 
> fins for the LPRO. 
> 
> Recall that the physics package in the LPRO is the biggest source of heat, 
> and looking at the unit with the connector facing you and on the left, the 
> physics package is along the right side toward the rear of the unit. I 
> decided the way to mount the LPRO if I had to go vertical was with the 
> physics package closest to the top, to minimize the components that got 
> baked. (I welcome recalibration of this opinion from more knowledgeable 
> sources!) 
> 
> If I could cut fins for the new "top" edge, as well as a good plate for the 
> bottom, and some fans, i might be able to get rid of enough heat to make it 
> work. I considered mounting the LPRO to the rear of the module connectors, in 
> the area containing the linear power supply components. 
> 
> I reconsidered on recalling admonishments in the LPRO docs and on this list 
> that cesiums do not like magnetic fields! Mounting the unit next to large 
> power transformers wouldn't seem to be suck a good idea... 
> 
> You might have better luck running it in a TM5006 rack, as they have much 
> better cooling and airflow (a reason to get rid of that 506 and pick up a 
> 5006!). 
> 
> I've had good results with my LPRO mounted on a half inch plate of T6061 
> aluminum and an old AMD heatsink+fan mounted above the physics package, held 
> in place with arctic silver heat transfer compound and spring-loaded wire 
> clips going to the plate. I've been meaning to run noise studies to see if 
> the fan causes any problems (vis a vis mag fields). 
> 
> Since I expect to be using the LPRO only occasionally, I've been trying to 
> talk my son into making me a steampunk-themed case, something like rosewood 
> with brass corners and detailing... 
> 
> Cheers and 73 -- Bob K6RTM in sunny silicon valley 
> 
> 
> On Sep 16, 2010, at 2:51 AM, [email protected] wrote: 
> 
>> I got one of the ebay LPRO-101s about 6 months ago and played with it for a 
>> while, but had problems maintaining a lock. First of all, it has a heat sink 
>> bolted to the bottom that is just a little larger than the LPRO itself, 
>> including being about 1.25" thick( 1" fins). Typical frequency when locked 
>> is 10,000,000.007 on a 5360A clocked by a Z3801A. 
>> 
>> 
>> Both then and now, it takes about 45 seconds to lock from cold, and will 
>> stay locked for about 45 minutes. I found that in the position with the heat 
>> sink on the bottom will stay locked the longest (up to a few days), but then 
>> it becomes intermittent. Other positions will lock for a while, but bottom 
>> down always works the longest. 
>> 
>> 
>> For those of you who employed these in TM5xx or similar plugins, did you 
>> have lock issues? Is my unit just old? 
>> 
>> 
>> Dave 
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> 
> 
> 
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