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Sherlock Ohms

Altered Design Hampers Transmitters

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William K.
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Platinum
Re: Unintended consequences from unapproved changes.
William K.   5/21/2013 12:58:34 PM
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I agree that there are indeed potential problems with air cooling, and a application such as you describe would certainly be more complex with an air cooling system that included redundant inlet filtering and blowers. 

But the additional concerns associated with a water cooling system need to be very carefully understood and considered prior to making that choice. The requirements for monitoring and maintenance are not trivial matters by any stretch.

akili
User Rank
Iron
Re: Unintended consequences from unapproved changes.
akili   5/21/2013 11:25:31 AM
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Re "water cooling" I have also worked on big HF transmitters in East Africa.  One particular model had a huge air-cooled triode rated at 50kW RF output.  This required a large noisy fan and we were forever having to shut it down to clear dust from the inside and larger wind-blown debris from the filter screens where the air entered the building.  The dust and dry grass-stems blew around from the savannah.

I agree that water-cooling requires careful design but it does shift a lot of heat very neatly and the final heat-exchangers were large with big quiet fans that didn't clog with debris.

akili
User Rank
Iron
Re: Countryside and Hank
akili   5/21/2013 11:07:58 AM
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"England and America are two nations divided by a common language" sums it up nicely!  This phrase has been attributed to George Bernard Shaw, Oscar Wilde and even Winston Churchill.  It will be a poor day when we can't exchange banter with our trans-Atlantic cousins (but don't mention the war...  ;-) )

And yes, working in East Africa was absolutely magical.  I stayed on at the Earth Station as "Resident Engineer" then changed jobs twice more in order to stay living in Nairobi for seven years. I met my wife there and we now have three children and two grand-children (so far) so maybe it was a good decision to stay on.  I now live in Yorkshire, England, close to "Bronte Country" and whilst I love the mystery of the wild moorlands under dark grey skies, I often long for the climate of Nairobi.  Hot sunny days and cool nights throughout the year - perfect for a place only just south of the equator.  Happy days!

William K.
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Platinum
Unintended consequences from unapproved changes.
William K.   5/18/2013 1:47:45 PM
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One more example here about how making changes without an adequate understanding of why something was done in a specific way the first time. Definitely some good detective work, though. It would appear that nobody did an FMEA on the modified cooling system, or they would have caught the problem with the bolts.

I have never been very comfortable with water cooling of high voltage tubes, no matter what claims are made about it being entirely safe and problem free. It seems to me that needing constant monitoring is a problem of its own. 

Critic
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Platinum
War
Critic   5/17/2013 5:01:38 PM
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We won the war.

Critic
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Platinum
Countryside and Hank
Critic   5/17/2013 5:01:11 PM
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Beautiful countryside in the area of the subject satellite earth station!  I wish I had a job working in such an area.

Why is it that people from the UK like to use terms that no one else in the world understands?  I didn't know what a "Hank Bush" is until I looked it up.  For those (probably most people outside of the UK) who don't know, it's a sheet metal nut, probably of the self-clinching type.  In the US, we call these PEM nuts, or just sheet-metal nuts.  OK, OK, I admit it, we have our own terms for things, too.  People from the UK are fun to make fun of.

akili
User Rank
Iron
The appeal of field work
akili   5/15/2013 6:10:29 AM
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On reflection, I think I was happiest in this phase of my career while installing the new generations of equipment.  Each station was unique and threw up its own set of problems.  I stayed on in East Africa while the rest of the team moved on to the next projects which by then had settled on a final design with a lot of the over-engineered stuff pared out.

Despite the economies of scale of building a further five identical stations the company didn't find it worth-while to continue in the business.  The earth-station builders from the USA had more muscle and the Japanese offered complete turn-key packages including finance deals.  This latter fact made the Japanese very successful with "third-world" countries for obvious reasons, which is why so many of the second dishes at our original stations were supplied by Japanese companies.

Regarding the Blue Lagoon it is clearly marked "S" and "E" on the original article.

deejayh
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Silver
Google Earth Coordinates
deejayh   5/10/2013 9:58:32 AM
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My Google Earth assumes that locations are entered using North and West as the defualt.  I can only assume that a machine running Google Earth in other locations may defualt differently. If you are looking for the "Bllue Lagoon" mentioned in this article and your program defaults to N and W enter 1°0'59.01" S, 36°29'51.03" E

warren@fourward.com
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Platinum
Re: Another puzzle solved in the field
warren@fourward.com   5/9/2013 2:18:42 PM
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I spent many years in the field troubleshooting problems that weren't forseen.  But that is half the job of a field service engineer.  We never were cut out for assembly line work.

I have seen similiar problems in electro-optics.  A screw is inserted so that the end of the screw protrudes into the optical path, or the antenna path is disrupted by building being built while yours was under construction only to have it block your path.

I find this water problem one of those mysteries not often uncovered until the end of life of the device where a proper autopsy could be done.  Those are the worst, unless it was you who warned them...

naperlou
User Rank
Blogger
Another puzzle solved in the field
naperlou   5/7/2013 9:44:00 AM
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Rob, I love these engineering detective stories from the field.  I have always been on the design side, so I rarely see these situations.  The sins of the designers are always visited on the field engineer. 

I could tell you were British very early on in the article when you refered to "kit".  I worked with a manager in the UK who would talk about "...nice bits of kit...".

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