[hpsdr] LPU Capacity

Steven Doyle steve_doyle at o2.co.uk
Thu Dec 29 02:21:03 PST 2011 

I also use the wide input version picoPSU and I have not detected any spurs 
which I went looking for :)

73s

Steve
G1YLB

-----Original Message----- 
From: n3evl
Sent: Thursday, December 29, 2011 12:21 AM
To: hpsdr at lists.openhpsdr.org
Subject: Re: [hpsdr] LPU Capacity

***** High Performance Software Defined Radio Discussion List *****

Thanks for the clarification on the meaning of the 5VSB.

As far as the picoPSU being a bit RF-noisy, can't say I've noticed any
difference since switching from the LPU, not that I've done any
scientific A-B tests.

73,

Pete, N3EVL


On 12/28/2011 6:08 PM, Scott Cowling wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Pete,
>
> The 5VSB pin is +5 Volt standby power, used to power things like the NIC 
> (for wake on LAN) and the power on-off switching circuitry that has to be 
> always active in the PC. It is not used (or even distributed over the 
> Atlas bus) by any HPSDR boards.
>
> The picoPSU is a good choice, but it is a bit RF-noisy.  The reason that 
> it is so small and runs so cool is that it is a switch-mode power supply 
> (SMPS) as opposed to the LPU, which is a linear power supply.
>
> The 5V regulator on the LPU is rated at 2A continuous, but the pico fuses 
> are not. When you get up towards the maximum rating of the regulator, the 
> fuses will trip (and reset, and trip, and...). This is the reason for the 
> LPU errata suggesting that you remove them from the circuit (short them 
> out).
>
> 73,
> Scotty WA2DFI
>
>
> At 14:04 2011-12-28 -0500, n3evl wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>>
>> A couple of months ago I decided to retire LPU in favor of the 
>> picoPSU-120-WI-25.  This appears to fulfill the current requirements of 
>> the usual suspects + Metis at 1 Gigabit. The picoPSU spec quotes two 
>> figures for 5V:
>>
>> 5V 6A
>> 5VSB 1.5A
>>
>> I have no idea what 5VSB refers to - maybe somebody can shed some light 
>> on this designation?
>>
>> The picoPSU unit is quite small and does not have the tall heatsinks used 
>> with LPU.   It supposedly runs quite a bit cooler but I left the fan in 
>> place figuring some air flow through Pandora can't hurt.
>>
>> Pete, N3EVL
>>
>> On 12/28/2011 10:03 AM, Chris Day wrote:
>>>
>>> ***** High Performance Software Defined Radio Discussion List *****
>>>
>>>
>>>
>>> Thanks, Erich. Replacing the soft fuses with wire has been enough so 
>>> far, but I haven't fired up the transmitter section of Pennylane yet. 
>>> Linear chain will be external, so there will be no extra load from that. 
>>> Meanwhile, playing with Mercury with delightful results.
>>>
>>> Chris Day
>>> AE6VK
>>>
>>>
>>> > Date: Wed, 28 Dec 2011 04:12:10 -0800
>>> > From: <mailto:vk5hse at yahoo.com>vk5hse at yahoo.com
>>> > To: <mailto:hpsdr at lists.openhpsdr.org>hpsdr at lists.openhpsdr.org
>>> > Subject: Re: [hpsdr] LPU Capacity
>>> >
>>> > ***** High Performance Software Defined Radio Discussion List *****
>>> >
>>> > Have cobbled together various reflector postings for my own
>>> reference as well as for others.
>>> >
>>> >
>>> > There was a summary posted to the reflector that is worth reviewing:
>>> >
>>> >
>>> <http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/2011-March/014678.html>http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/2011-March/014678.html
>>> >
>>> > the meaty bits were:
>>> >
>>> > Magister = Ozy
>>> >
>>> >
>>> > power consumption summary:
>>> >
>>> >
>>> >                        12 V         5 v
>>> > OZY               .001  A        .1 A
>>> > PENY             .4 A           .2 A
>>> > MERC            .2  A          .5 A
>>> >
>>> > Metis 100                         .4A
>>> >
>>> > Metis 1000bT                   .75A
>>> >
>>> >
>>> > no-one seems to have stated excalibur power requirements, but it
>>> doesn't appear to be huge
>>> >
>>> >
>>> > add the LPU errata document:
>>> >
>>> >
>>> <http://www.tapr.org/pdf/LPU_Errata.pdf>http://www.tapr.org/pdf/LPU_Errata.pdf
>>> >
>>> > which mentions in errata #2:
>>> >
>>> > "Description of Error:
>>> > Fuses F2 and F3 are underrated for a full system. They are rated
>>> at continuous 1.1A without
>>> > tripping, while an Ozy/Mercury/Penelope system draws typically
>>> 1.3A from the +5V rail.
>>> >
>>> >
>>> > Symptoms:
>>> > An Ozy/Mercury/Penelope system will operate for a short period and
>>> then unexpectedly shut
>>> > down. The time can vary, but is typically around 10 minutes. This
>>> is due to F2 opening and shutting
>>> > down the +5V output. (Note that F2 doesn't actually "open"; it
>>> becomes higher resistance to protect
>>> > the load.) After a power cycle, normal operation resumes.
>>> >
>>> >
>>> > Recommended Corrective Action:
>>> > Short across F2 and F3 with pieces of wire."
>>> >
>>> >
>>> >
>>> > There has also been talk of strapping the 12V feedtrhough for high
>>> power things like a PA
>>> >
>>> >
>>> <http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/2010-July/012616.html>http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/2010-July/012616.html
>>> >
>>> > and some suggestion of shorting the 5V fuse and relying on the
>>> regulator to protect itself +/- modifying R6 the series resistor
>>> >
>>> >
>>> <http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/2010-July/012617.html>http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/2010-July/012617.html
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