Probably not at FM frequencies. Most meters will not work at those
frequencies.
Old radioshack cheap meters would measure the old CB radio frequencies on
their AC setting.
You can give it a try. First just separate the leads like they are a dipole
antenna and walk around to see if they are picking up the transmitted
antenna.
-----Original Message-----
From: Matt Hoppes
Sent: Wednesday, April 24, 2019 10:36 AM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] Fwd: CAT5. FM. And Rain
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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