So I did some testing today by freezing the AP in the freezer. Heater
warm up varied between 1 minute and 3 minutes. The amps per unit
during the heat up time is .45 amps per AP. We were finding that even
if its warmed up and you unplug it 10 seconds later it will warm up
again and again. After the warm up the AP drops its amps to .2 amps.
We are using 2.1amp psu to feed several APs because we never use more
than that but I think when these heaters get turned on during the
bootup process we exceed it and overload the psu.
This was all ran into Packetflux gear with a SOLA power supply 2.1Amp.
We’re going to split the load so if there’s a power blip where the
backup doesn’t catch it in time all 3 aren’t starting up heaters at
the same time.
Hope this information helps.
-Andy
*From:*Af [mailto:af-boun...@afmug.com] *On Behalf Of *ch...@wbmfg.com
*Sent:* Thursday, January 21, 2016 12:03 PM
*To:* af@afmug.com
*Subject:* Re: [AFMUG] To Cambium With Love - Replace the bad ePMP units.
Or automotive grade.
*From:*Ken Hohhof <mailto:af...@kwisp.com>
*Sent:*Thursday, January 21, 2016 9:15 AM
*To:*af@afmug.com <mailto:af@afmug.com>
*Subject:*Re: [AFMUG] To Cambium With Love - Replace the bad ePMP units.
Or here’s a thought: pay the money for industrial temperature range
parts!
*From:*Adam Moffett <mailto:dmmoff...@gmail.com>
*Sent:*Thursday, January 21, 2016 10:08 AM
*To:*af@afmug.com <mailto:af@afmug.com>
*Subject:*Re: [AFMUG] To Cambium With Love - Replace the bad ePMP units.
They have said there's a resistive heater. I heard it in ePMP
training in Albany and I've seen it stated on this list.
If I remember correctly (I might not), they wanted the CPU to hit a
certain temp before starting up. If it was too cold you'd see a delay
in startup of up to 2 minutes while waiting for this heater to bring
the CPU up to temp. I've never actually observed the delay, so I
guess they're talking about Alaska cold, not NY cold.
On 1/21/2016 10:47 AM, Forrest Christian (List Account) wrote:
I looked at the high resolution photos on the FCC site and didn't
see anything obvious. Now I've got the one I have on the bench out
of the case, I still don't see anything obvious heater-wise, but
again I'm not going to pop the shields off the board (requiring
desoldering), to be 100% sure...
On Thu, Jan 21, 2016 at 8:30 AM, Steve D <bigd...@gmail.com
<mailto:bigd...@gmail.com>> wrote:
Just throwing this out there, but don't the epmp's have a small
heater in them that could be turning on when it's cold, drawing
additional power? I recall it was supposed to pre-heat components
to avoid freezeup on first boot but I can't recall if that's the
only time they run or not.
-Steve D
On Thu, Jan 21, 2016 at 1:44 AM, Forrest Christian (List Account)
<li...@packetflux.com <mailto:li...@packetflux.com>> wrote:
I do want to clarify one item:
This is not necessarily related to the cambium DRAM issue. I
don't want to claim that problem, since this isn't the same
thing. This is more of an issue where you have ePMP's which seem
to start having power-related issues. If moving to a 30V brick
makes your problem go away, then the issue I describe below
probably is your issue. If moving to a higher voltage doesn't fix
the issue then this probably doesn't relate to your issue.
Regardless, it is my intent to recommend that my customers move to
48V as soon as I confirm that this seems to fix at least a decent
number of the problems without causing others.
Unfortunately this might be a case of the cold weather aggravating
two separate issues (or for that matter, the cold weather causing
increased current consumption in the ePMP, which then requires a
higher voltage to operate correctly).
-forrest
On Thu, Jan 21, 2016 at 12:43 AM, Forrest Christian (List Account)
<li...@packetflux.com <mailto:li...@packetflux.com>> wrote:
A bit of an update from the PacketFlux side.
Late this afternoon I received a ticket from Tyson in relation to
these issues. In particular, sync from a PacketFlux SyncInjector
dropping off on an ePMP when it's cold. I have spent a bit of
time this evening investigating this issue. The following is a
summary of what I found. It's a bit long-winded so that those
experiencing the problems can understand my current working theory
and help me figure out if this is the case.
WARNING: The following is based on a limited amount of testing
with a single ePMP with no traffic and no clients and on a bench.
This is likely the best case scenario. The field is only going to
be worse.
The setup is as follows:
ePMP 1000 GPS AP, with no GPS hockey puck attached, connected to a
Gigabit Syncinjector (Rev H and Rev I - I have a special one with
a port of each 'type' ;-) ). I am powering the injector with a
variable power supply so I can vary the voltages in. The AP is
connected to the Injector with ~100m of CAT5 cable. The Antenna
connectors have terminators on them, the AP is in transmit mode,
but isn't passing any traffic since there are no clients.
When feeding the injector with 24V, I get about 23V at the AP.
This is pretty consistent with what I would expect in this
situation. The AP seems to work fine, at least on the bench and
without doing any real work. However, as the voltage drops, things
start to get weird:
At around 22V in, (21V at the AP), Sync becomes flaky. This is
consistent on both H and I version ports on the injector.
Sometimes it works, sometimes it doesn't. Note that 22V is the
bottom of the rated voltage inputs for the ePMP.
At around 20.5V in (19.5V at the AP), the radio just turns off. It
won't turn back on until around 22V.
Now here's where some total speculation comes to play. On the
bench, this unit is drawing around 3W. Let's assume that under
load, and when temperatures are cold, this unit draws closer to
6W. This would double the current, and quadruple the voltage drop.
Now, assume 24V in, this puts you at around 20V in at the AP,
which is about the turnoff point. Remember this is on 100m of
wire, and a total speculation about a the power draw of a cold,
under load AP. But the point is valid, regardless of the cause -
if the circuit resistance when combined with the power load causes
a low enough voltage at the AP, weird things will happen. And
since weird things seem to start to happen around 22V, there just
isn't much headroom at 24V.
This explains why things work well at 30V.
For those who are having this problem I'd recommend trying
increasing the voltage into the SyncInjector. The Revision H
injectors can safely handle up to around 56V or so. Assuming all
of the radios on an injector are either ePMP or the newer 450i's,
using 56V into a SyncInjector is perfectly acceptable and the
ePMP's are rated up to 56V as well.
So the summary: Try a 48VDC voltage source instead of 24V and see
what happens.
-forrest
On Wed, Jan 20, 2016 at 11:00 AM, Tyson Burris @ Internet
Communications Inc <t...@franklinisp.net
<mailto:t...@franklinisp.net>> wrote:
Hello Cambium,
At the MidWest-IX launch party last night, several of us
Indiana WISPs compared notes on the ‘cold weather’ problems we
are seeing with ePMPs. It was very interesting to learn we are
experience identical problems across the spectrum.
We all understand this is a DRAM issue with certain units you
have identified. We also understand the firmware RC that has
been made available to fix this short term.
The bottom line is we are very frustrated and grow tired of
dealing with it.
Our concern is simple. If your software fix ‘degrades’ the
performance of the product or triggers other issues, as it has
been suggested, we would prefer a full recall and replacement
program immediately.
If the suggestion that the fix will degrade the product
performance is inaccurate and not cause other issues, I would
like for this to be made public.
Thank you,
*Tyson Burris, President**
**Internet Communications Inc.**
**739 Commerce Dr.**
**Franklin, IN 46131**
***
*317-738-0320 <tel:317-738-0320> Daytime #*
*317-412-1540 <tel:317-412-1540> Cell/Direct #*
*Online: **www.surfici.net <http://www.surfici.net>*
ICI
*What can ICI do for you?*
*Broadband Wireless - PtP/PtMP Solutions - WiMax - Mesh
Wifi/Hotzones - IP Security - Fiber - Tower - Infrastructure.*
**
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