[hpsdr] LPU Capacity

[Scott Cowling]

Hi Chris,

The Pennylane PA runs on 12V and should not consume too much from 
that supply. (One source shows Penelope consuming 400mA on the +12V 
rail.) The LPU can supply 2A at 12V for the system, and is not the 
limiting factor (the LPU 5V regulator is the limiting factor).

Note that the PA for Pennylane is designed for 12.0V and NOT for 
13.8V, hence the regulator on LPU to power it (as well as other 12V 
loads, such as Alex relays).

73,
Scotty WA2DFI


At 07:03 2011-12-28 -0800, 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: vk5hse at yahoo.com
> > To: 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
> >
> > 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
> >
> > 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
> >
> > 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
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