As a wireless installer with a little RF knowledge, I can tell you *nothing* is a bigger piece of crap than anything Netgear sells. I'd also guess this WISP also loses a lot of gear based on what you've mentioned so far. I'd have to suggest to them the following:
A> Cisco makes nice switches on the cheap (most WISP POPs don't use more
than a 100mbit switch anyways, you can get a Cisco Catalyst 2924 for under
$50 off ebay, and it's a much higher quality switch with a good power supply
that won't spew RF noise)
B> Shielded cat5/5e/6 bonded to Mot R56 standards. This will further
eliminate RF spew while greatly reducing lightning failures.
Personally, I'm a big fan of running DC over coax (I use super-cheap RG59,
bonded to R56 standards) and *FIBER* for the data. DC is easy to protect
(MOVs and poly-fuses are your friends), Ethernet is much harder. Fiber is
awesome, easy and cheap. Lightning doesn't affect it, which is a huge
bonus. Ethernet<->Fiber transceivers can be had for pennies on the dollar
these days, especially if you only need 10 or 100mbit.
Their noise source may also be the power supply feeding the system.
Assuming they're not using a PoE-capable switch, they most likely have a
'power injector' inline, connected to some sort of power supply. I've
discovered most cheap-o ('Mean Well' is a personal favorite) 'project' brick
power supplies have somewhat dirty output. The long Ethernet run either
increase the noise or work as a much better antenna. 0.1uF capacitors and
ferrites in the correct places can greatly reduce this (or using better
quality power supplies).
Now. the strobe problem you're describing sounds like a potential horrible
electrical problem at the site. In my experience an FM rig shouldn't be
greatly affected by a strobe. It also shouldn't be causing a
problem/reaction with the WISP gear (it may be causing damage to it!) so I'd
definitely find out what is going is going on with the strobe.
Good luck!
Jacob Suter
From: [email protected]
[mailto:[email protected]] On Behalf Of Jim Russell
Sent: Saturday, April 25, 2009 8:53 PM
To: [email protected]
Subject: Re: [Repeater-Builder] Computer noise in 2M Repeater
Thanks for the input from all of you. I went to the tower site this
afternoon to give another look at the problem. The noise has gotten worst.
Our receiver is greatly desensed. The only equipment on site is the site
owner's UHF repeater, our two meter repeater and the Internet equipment. The
site owners equipment doesn't seem to be affected. The strobe lamp puts a
buzz in our receiver each time it fires. I noticed one of the green lamps
on the Netgear switch get brighter when the strobe fires. I'm sure the
Internet equipment is affected by that. The two meter is our primary
machine used in our storm watch activities. I tried to contact the Internet
company today with no answer. Will try again Monday. Again thanks for the
information.
Jim WK5Y
----- Original Message -----
From: Eric Lemmon <mailto:[email protected]>
To: [email protected]
Sent: Saturday, April 25, 2009 9:15 AM
Subject: RE: [Repeater-Builder] Computer noise in 2M Repeater
Jim,
This situation happens all too often, and it usually occurs because cheap
equipment is used (plastic boxes to contain the amplifier, unshielded cable,
no ferrites, ineffective grounding. etc.) to keep the installation costs
down. This is a misguided approach, because repeated visits to fix a
leakage problem will always cost a lot more than a first-class system would
have cost. Sound familiar?
Another possible factor is that *some* wireless installers are primarily IT
(Information Technology) folks who have relatively little experience with
the RF environment at a repeater site. I have met a few of these clueless
guys, whose eye glaze over when I talk about an interfering carrier from a
CPU crystal or intermodulation. They're used to installing APs and bridges
in office buildings, and don't see anything different about tie-wrapping a
more powerful box to a tower that supports many other services, except
perhaps using some electrical tape and silicone goop to waterproof the
connectors. Don't laugh- it happens!
So, to answer your question, immediately contact the wireless system owner
and advise him that his system is interfering with yours, and it must be
fixed promptly. Don't quote the FCC rules quite yet. If the polite
approach does not get results, contact the site owner. Above all, do not
just sit and wring your hands. The wireless owner must comply with Part 15
rules, but he must be told if there is a problem.
73, Eric Lemmon WB6FLY
-----Original Message-----
From: [email protected]
<mailto:Repeater-Builder%40yahoogroups.com>
[mailto:[email protected]
<mailto:Repeater-Builder%40yahoogroups.com> ] On Behalf Of Jim Russell
Sent: Friday, April 24, 2009 7:20 PM
To: [email protected]
<mailto:Repeater-Builder%40yahoogroups.com>
Subject: [Repeater-Builder] Computer noise in 2M Repeater
Does anyone have any suggestions on how to eliminate noise generated by a
Wireless
Internet System. The owner of the tower where our club has our 145.370 MHz
repeater
has rented space to a group who have mounted a wireless Internet "relay" on
the tower.
The system is simple, it consist of a Netgear switch, a Microwave dish and a
smallYagi.
There is approx. 300 feet of Cat 5 wire going up and 300 feet coming down
the tower.
Their antennas are mounted within a few feet of ours on the top of the 260
ft. tower.
We unplugged the netgear switch and the noise cleared, we disconnected our
antenna and the noise goes away. The noise rides on the repeater receiver
squelch tail.
We do use a PL tone or we wouldn't be able to use our repeater at all
Jim WK5Y
<<image001.jpg>>
<<image002.jpg>>
