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Author Topic: 572b's  (Read 8652 times)
N3OQD
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Posts: 104




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« Reply #15 on: August 12, 2010, 08:51:31 AM »

There is a guy named Phil of whom runs the spirit net saturdays through thursdays from 9:30pm to 10:30pm on 3.905 LSB (conditions permitting).  He has an ameritron AL-572. He had trouble with the Chinese (re-branded "Taylor Made") 572b's.  He went ahead and bought a matched set of 4 Svetlana tubes from RF parts and just over two years later (as far as I know) they are still going strong.   In doing this net, he uses his amp much more than the average ham.  Just stop by and give him a holler.   
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N3LCW
Member

Posts: 155




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« Reply #16 on: August 12, 2010, 01:57:18 PM »

The 811H replacement fan URL:

http://www.mouser.com/Search/ProductDetail.aspx?R=8500DPvirtualkey59120000virtualkey5912-8500DP

Just shy of twice the CFM and still relatively quiet.  It is what I use and it has made a noticeable difference.
Plenty of warm air volume exiting the amp now.

Andrew
N3LCW




Question for N3LCW:

Just curious.  Where did you find a fan with twice the CFM? I would like to change the fan in my 3 tube 811; I suspect they are the same. I use mine
mainly on CW and the exhaust air temp seems pretty high on ragchew QSO's.  If you would care to share part number and source, I would be much appreciative.

Thanks,

Jon,  K0ZN
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K4RVN
Member

Posts: 261




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« Reply #17 on: August 12, 2010, 04:23:14 PM »

K0ZN
Here is a link for the Sprite SU2e1 specs. It is 115 volts handles 25 CFM@.123sp max.
 I checked out his fan and the cfm @ .123 sp is zero. the 25 CFM rating is at 0 inches static pressure. Anytime a fan flows air through components such as power supply, cabinet, tube compartment and grilles there is a static pressure drop. Therfore this fan and any fan must be considered based on the cfm delivered at a static pressure drop. I checked out the fan curve for the Mouser fan posted and it will probably deliver somewhere
around 20 to 30 cfm guessing at the pressure  drop through the AL 811 cabinet,etc. Also one must consider that the original 811 replacement fan from MFJ is rated at 28 cfm, 1800 rpm, and 30dBA noise level. Mine is noisy to me. MFJ has no presssure drop listed for their fan so it probably is rated at 0 inches SP which is unrealistic in service. I looked for a fan with all three ratings and found one but it may be too noisy at 32 db.
I modified this post to reflect further information I found during my search.

http://www.comairrotron.com/cgi-bin/acfansearch.pl?VoltList=115v&FreqList=60hz&airflow_val=&airflow_unit=CFM&pressure_val=&pressure_unit=inh2o&diameter_val=&diameter_unit=in&SortBy=sizeup

I am looking for a better quiter fan for my AL811, but want more air than this one.
Just ordered one to try at  http://www.weisd.com/store2/SRCACFAN-7P.php

Frank
« Last Edit: August 13, 2010, 10:15:50 AM by Franklin M. Cloud » Logged
K7ZRZ
Member

Posts: 279




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« Reply #18 on: August 12, 2010, 04:31:57 PM »

Has it been determined that the Svetlana 572b tubes have the same performance characteristics as the Chinese tubes - output, plate dissapation, et al?  And what about the reports I seem to recall about significantly smaller plate cap? I'm using ceramic caps with internal contacts that are difficult to adjust in that manner.

Brian K7ZRZ
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Brian K7ZRZ
K0ZN
Member

Posts: 1862




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« Reply #19 on: August 12, 2010, 05:16:07 PM »


 THANKS for all the info/data on a bigger fan!  MUCH appreciated!  I will jump on that project SOON.

   73,  Jon,  K0ZN
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K7ZRZ
Member

Posts: 279




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« Reply #20 on: August 12, 2010, 06:44:16 PM »

Jon,

The fellow who runs The Heathkit Shop, developed a great circuit board for the Clipperton L fan, which is a 110 v fan slowed by a big resistor. His board shunts the resistor, speeding up the fan significantly. It operates on a timed basis, coming on a bit after key-up, and shuts back down a bit after - the delay depending on how long the transmitter was on.  That board also incorporates a keying interface circuit... that being the way the fan control circuit senses keyup.  I'm sure it could be fitted to just about any amp.

Brian K7ZRZ
« Last Edit: August 12, 2010, 06:46:18 PM by Brian J. Ingoldsby » Logged

Brian K7ZRZ
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