[hpsdr] Problems Calibrating Pennylane and with LPU, Could Use Some Help

[Bob G Mahrenholz]

Mark:

Thanks for your help. I had seen the Errata Sheet but the problems was so old that
I figured they were fixed by now. I found the manufacturer's datasheet on the ones
listed on the Bill of Materials and I assume that is what we got. They are made by
Bourns and sold by Mouser. The data sheet is at:

   http://www.bourns.com/data/global/pdfs/mfmsmf.pdf

The Bill of Materials lists F2 and F3 as MF-MSMF110/16-2. The 110 in the part number
means the fuse will hold at up to 1.10 amps. Kind of small for a 2A fuse. The 16 is
the voltage rating and the -2 is the packaging (tape). There should be a four character
ID on the fuse. The first two characters should be 11 for the 110. The second two
characters are the date code.

I jumpered F2 and F3 out like you did. I may try and replace them with a larger fuse
later.

Thanks again for your help.

73,
Bob



-----Original Message-----
>From: Mark Leone <midnightjava at verizon.net>
>Sent: Nov 28, 2011 10:43 PM
>To: hpsdr at lists.openhpsdr.org
>Subject: Re: [hpsdr] Problems Calibrating Pennylane and with LPU, Could Use Some  Help
>
>***** High Performance Software Defined Radio Discussion List *****
>
>On 11/28/2011 10:04 PM, Bob Mahrenholz wrote:
>>
>> However, if I hold the output at 500mW for too long, I hear a "poof" 
>> from Pandora and everything goes dead!  All the red lights
>> go out and the program stops. If I turn my power supply off and back 
>> on again, things seem to recover. I suspect maybe a fuse
>> blowing because of excessive current drain but the total Pandora 
>> current drain including the fan only measures 1.670 amps. LPU
>> has 2 amp fuses in both its 12 and 5-volt outputs.
>
>Bob,
>
>I just built Atlas and LPU and installed Mercury, PennyLane, and Metis. 
>Even with just Metis and Mercury, the system powered off 10 min or so 
>after starting, just as you describe. I took this to be a manifestation 
>of what is described in the LPU Errata document. The text says that 
>fuses F2 and F3 are rated for 1A but draw slightly more. Like you, I 
>noticed that they are labeled as 2A, so I thought the original problem 
>was fixed in a later production run.
>
>But given that the problem is exactly as described in the errata 
>document, and that the regulators have built in over-current protection, 
>I went ahead and strapped out F2 and F3 as recommended. I also wondered 
>if I installed the fuses in the right places. Searching online I 
>couldn't find any description of SMT fuse markings that jived with what 
>I saw on the parts supplied; but since F2 and F3 have the same value, 
>and F4 is a different value, I assumed that the two fuses with the same 
>markings were F2 and F3.
>
>My system has been running with F2 and F3 strapped out for about 16 
>hours now, with Just Metis and Mercury; but there's no smoke, fire, 
>excessive heat, crackling noises, or any other adverse indications; and 
>the signals are being processed just as expected.
>
>-Mark K4XML
>
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