One side of the transformer has center taps that go to the powered pins.
But they don't have anything to do with the ethernet signal. You can think
of it as 4 separate isolation transformers in a common container. Actually
they are discrete transformers wound on toroid cores. One side has the
power feed taps.
-----Original Message-----
From: Matt Hoppes
Sent: Thursday, April 25, 2019 8:00 PM
To: Chuck McCown
Cc: [email protected]
Subject: Re: [AFMUG] Fwd: CAT5. FM. And Rain
But would the gigabit PoE not jump the non powered pins? Or are all pins
“powered”?
On Apr 25, 2019, at 9:35 PM, Chuck McCown <[email protected]> wrote:
Depends on the voltage. The windings have good insulation on them. And
the inductance of the transformer might choke out some of the signal.
-----Original Message----- From: Matt Hoppes
Sent: Thursday, April 25, 2019 7:33 PM
To: Chuck McCown
Subject: Re: [AFMUG] Fwd: CAT5. FM. And Rain
Interesting -- I assume one could test that by throwing a continuity
tester on the pins.
Wouldn't a high voltage FM on the line be enough to jump even an air gap
like that?
On 4/25/19 9:32 PM, Chuck McCown wrote:
Generally the transformer is not connected from one side to the other.
-----Original Message----- From: Matt Hoppes
Sent: Thursday, April 25, 2019 7:26 PM
To: Chuck McCown ; AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] Fwd: CAT5. FM. And Rain
So a PoE injector without being plugged into the wall? I would have
thought the pins were soldered together inside?
On 4/25/19 9:30 AM, Chuck McCown wrote:
Yes, a Poe injector will do that.
Sent from my iPhone
On Apr 24, 2019, at 6:04 PM, Matt Hoppes
<[email protected]> wrote:
Does something like an iso coupler for CAT5 exist? Like where you
could plug the cat five cable into it and he would isolate the cat five
cable coming out of it magnetically so that there was no physical
contact?
On Apr 24, 2019, at 2:51 PM, Bill Prince <[email protected]> wrote:
This was in the days when we had to run a separate cable for timing
(and those signals we single-ended; not differential). The timing
cable ran parallel to the cat 5, and the APs were losing sync
intermittently. The power/ground inside the CMM was going crazy to the
tune of 8-12 volts or something like that.
We added bigger grounds to the power supply and CMM, and when we got
to 4 AWG it actually got worse.
bp
<part15sbs{at}gmail{dot}com>
On 4/24/2019 11:19 AM, Matt Hoppes wrote:
Interesting, so possibly the issue is occurring through the
grounding/electoral system.
On Apr 24, 2019, at 1:47 PM, Bill Prince <[email protected]>
wrote:
It wasn't actually on the cat5, it was on the ground (and indirectly
the power supply). This when we were using the old-style Canopy
timing box (CMM? not sure of the name any more).
We had to ground isolate the scope to prevent it from being infected
as well.
bp
<part15sbs{at}gmail{dot}com>
On 4/24/2019 10:31 AM, Matt Hoppes wrote:
How did you “look at it” on the CAT5?
On Apr 24, 2019, at 1:28 PM, Bill Prince <[email protected]>
wrote:
Back when we were getting interference like this (around 12-13
years ago), the noise was actually intermod from a couple of
nearby high power transmitters. We didn't see it until we were
able to look at it with a high frequency oscilloscope.
It would come and go based on whether both of those transmitters
were operating at the same time.
bp
<part15sbs{at}gmail{dot}com>
On 4/24/2019 9:36 AM, Matt Hoppes wrote:
If I take a volt meter and measure from ground wire/rack to earth
ground. Would I see voltage if the transmitter is getting in at
any significant amount?
On Apr 24, 2019, at 12:25 PM, Robert Andrews
<[email protected]> wrote:
& if the noise is coming from the grounding point?
On 04/24/2019 09:01 AM, [email protected] wrote:
If you let shields float, they are a faraday shield.
If you ground one end of the shields, they are faraday plus
electrostatic shielding.
If you ground both ends of the shields they do all of that but
they also add magnetic shielding.
However grounding both ends can cause a ground loop.
-----Original Message----- From: Matt Hoppes
Sent: Wednesday, April 24, 2019 9:22 AM
To: AnimalFarm Microwave Users Group ; dave
Subject: Re: [AFMUG] Fwd: CAT5. FM. And Rain
Why do you mean "moved switching closer to the cluster", what
is a
"cluster"?
Are you saying you floated the copper shields at the base of
the tower
and didn't ground them?
On 4/24/19 11:16 AM, dave wrote:
Matt,
I have that T-shirt For sure.. I was on a FM tower that was
only 5kw combined over one 5/8 coax for years.
Started with FSK then Cambium gear.
The things I noticed worse was the type of cable used. The
longest time we had used AL shielded type cable and eventually
relocated our switching near the base of the cluster which
helped for a while but after some time the AL shielding
evaporated and
that type of cabling was barely good enough to get 10baseT out
of it and still had CRCs
We eventually moved to Superior Essex for everything on the
tower and used clips,hangers and grommets to get it off the
tower leg.
Let the copper shields float on the cables and never looked
back.
We have since moved completely off the tower last year but
still didnt have any issues at that time.
What I did notice is that when we did move our switching and
POE closer to the cluster inside a nema enclosure it cleared a
bunch of issues on the cable for a long time.
Dave
On 4/20/19 10:06 AM, Matt Hoppes wrote:
What's also interesting is none of the stuff in the shack has
negotiating issues -- so it doesn't seem to be the switch as
a whole getting swamped, but rather the CAT5 getting swamped
going up the tower.
On 4/20/19 9:58 AM, Chuck McCown wrote:
So moisture + rf = Ethernet interference. Just as
originally stated. No standing waves.
Is your cat5 in liquidtight? Have you played with grounding
& ungrounding the shields? How about taking a garden
sprayer and selectively wetting things?
Sent from my iPhone
Begin forwarded message:
*From:* Matt Hoppes <[email protected]
<mailto:[email protected]>>
*Date:* April 20, 2019 at 7:52:12 AM MDT
*To:* Chuck McCown <[email protected]
<mailto:[email protected]>>
*Subject:* *Re: [AFMUG] CAT5. FM. And Rain*
Yes. Problem goes away.
On Apr 20, 2019, at 09:51, Chuck McCown <[email protected]
<mailto:[email protected]>> wrote:
Have you killed the ref when you are having the problem?
Might not be ref related.
Sent from my iPhone
On Apr 19, 2019, at 7:11 PM, Matt Hoppes
<[email protected]
<mailto:[email protected]>> wrote:
19watts
On 4/19/19 8:58 PM, Chuck McCown wrote:
What is the reflected power when you are having
problems?
Sent from my iPhone
On Apr 19, 2019, at 6:41 PM, Matt Hoppes
<[email protected]
<mailto:[email protected]>> wrote:
My thoughts too. But the reflected power right now is
only 19watts out of 9,000.
On Apr 19, 2019, at 20:14, Chuck McCown
<[email protected] <mailto:[email protected]>> wrote:
My guess is that the FM station has a problem with the
antenna or transmission line. Moisture throws off
impedance somewhere and you have a strong standing
wave on the transmission line. Probably a bad
connector.
Sent from my iPhone
On Apr 19, 2019, at 5:52 PM, Matt Hoppes
<[email protected]
<mailto:[email protected]>> wrote:
Looking to the wisdom of the AF group on this.
I have some equipment on an FM tower. It’s a 9kw
station around 150ft. We are at 250ft with two
sectors and a backhaul. Netonix switch in shelter.
Nothing else on the tower.
Normally all is fine. When it rains or is very
moist out (heavy heavy fog) we start having major
Ethernet negotiation issues. The ports will go from
1Gig to 10F sometimes. Sometimes drop completely.
I’ve got ferrite beads wrapped about 5 times top and
bottom.
Any further words of wisdom on what to try? I
suspect some odd grounding issue. But not sure how to
track it down or isolate it.
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