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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