Author Topic: HP 438A RF power meter fan info needed  (Read 1874 times)

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Offline MarkL

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HP 438A RF power meter fan info needed
« on: March 29, 2015, 06:13:19 am »
I need to get a new fan for an HP 438A power meter and unfortunately the old fan has no model information on it.  It looks like the sticker fell off.  It's made by Papst and is a standard 60mm x 60mm x 25.4mm, 12VDC.  There's a million different fans out there that would fit but I'd like to get one with the right CFM.

Earlier 438A units had a strange fan that had 4 wires with a separate driver module and was probably some kind of brushless DC motor.  And that's the one shown on all the service manuals I could find.  The one I have is NOT that.

If someone has one of these meters, could you pop the cover and read the fan model number?  Or even look it up in a more recent service manual?

Thanks!
 

Offline ManateeMafia

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Re: HP 438A RF power meter fan info needed
« Reply #1 on: March 30, 2015, 01:05:00 pm »
My 438B came in a with a broken mount on the fan and I replaced it with this part http://www.digikey.com/product-detail/en/0/381-2487-ND

It is a little expensive but I am pretty sure I matched it as close to the original as possible.

BTW, my power meter had some capacitors rattling around inside when I got it. I couldn't see a place that was missing them until I realized there was a board sandwiched between the top and bottom pcb's. When I removed them, I found that three of the four wet tantalum capacitors leaked and ate through part of the board and the leads. All four were replaced and the board was cleaned. There is also a lithium battery hidden in there too.
 

Offline MarkL

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Re: HP 438A RF power meter fan info needed
« Reply #2 on: March 31, 2015, 03:21:10 am »
Thanks for the part pointer!

Working backwards from the part number, this fan is used in a lot of HP gear.  I think you got it right.

Interestingly, the part finder at Keysight lists it as obsolete in the equipment that uses it.  After another level of obsolete part number, they have a current part number of 5065-7092 with a picture of an NMB-MAT 2410ML-04W-B60-B00, which is also available from DigiKey as P15633-ND.  Half the price but made in China.  I think I'll stick with the Papst fan.

No sign of any capacitor issues on my boards, but thanks for mentioning it.  The battery is only used to store the front settings, setups, and the last sensor zero/cal for A and B channels.
 

Offline SV1EOR

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Re: HP 438A RF power meter fan info needed
« Reply #3 on: June 02, 2016, 05:50:49 am »
Can You tell me if your models are droing air from out in the power supplay?

I think that it is not right to send the hot air from the power supplay in the pcb partitions...!
 

Offline MarkL

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Re: HP 438A RF power meter fan info needed
« Reply #4 on: June 02, 2016, 11:50:31 am »
Can You tell me if your models are droing air from out in the power supplay?

I think that it is not right to send the hot air from the power supplay in the pcb partitions...!
I have two 438A meters now, and they both suck air in the back and blow it out the sides.

I agree it doesn't seem optimal, but I was consistent about the direction of the fan I replaced, and neither of them appear to have had any work done on them before I bought them.  Based on this, I have to assume that's the intended design.
 


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