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Message |
k8vf_mark@centurytel.net
Guest
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 Posted:
Sat Aug 20, 2005 12:20 am Post subject:
modem losing sync |
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Has anyone who has DSL AND is a Ham radio Operator had success with any
DSL modem regarding immunity from r.f. overloading, especially from a
160 meter transmitter.
I lose sync with 5 watts output. All shielded, including phone line,
all cables, r.f. filters, chokes on transmitter leads, etc.
Looking for an r.f. proof modem.
Currently using Netopia 3300(3341) series Cayman device on Centurytel.
Thanks for the Help.
k8vf |
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Ken Abrams
Guest
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| Posted:
Sat Aug 20, 2005 4:20 pm Post subject:
Re: modem losing sync |
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<k8vf_mark@centurytel.net> wrote
| Quote: | Has anyone who has DSL AND is a Ham radio Operator had success with any
DSL modem regarding immunity from r.f. overloading, especially from a
160 meter transmitter.
I lose sync with 5 watts output. All shielded, including phone line,
all cables, r.f. filters, chokes on transmitter leads, etc.
Looking for an r.f. proof modem.
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I can't help with a modem recommendation but over the years I have seen
cases where trying to shield phone wires actually increases the RF pickup. |
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John P. Dearing
Guest
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| Posted:
Sun Aug 21, 2005 12:20 am Post subject:
Re: modem losing sync |
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k8vf_mark@centurytel.net wrote:
| Quote: | Has anyone who has DSL AND is a Ham radio Operator had success with any
DSL modem regarding immunity from r.f. overloading, especially from a
160 meter transmitter.
I lose sync with 5 watts output. All shielded, including phone line,
all cables, r.f. filters, chokes on transmitter leads, etc.
|
The problem is the fact that the 160 Meter band (1.8 - 2.0 MHz) is using
frequencies pretty close to the spectrum that DSL uses. It's going to be
*very* difficult to keep the two from interfering with each other.
My suggestion would be to try and keep the modem and transmitter as far
apart as possible.
I would also suggest that you install a whole house filter (sometimes
called a splitter) at the Telephone NID. Then run a short home run to
the DSL modem, keeping the modem as far away from the transmitter as
possible.
What you're trying to do is introduce as much separation as possible
between the DSL modem and the RF signal. The filter keeps any RF that is
getting coupled into your house phone wiring from interfering with your
DSL signal.
Do a Google search for DSL Splitter and you should have plenty of sources.
Good luck, but I really think you're in for some trouble with that 160
Meter signal. 8-(
John
--
John Dearing
A+, Network+, Server+ |
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Capt. James. T. Kirk
Guest
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| Posted:
Mon Aug 29, 2005 7:11 am Post subject:
Re: modem losing sync (with 160 meter Ham) |
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John P. Dearing wrote:
| Quote: | k8vf_mark@centurytel.net wrote:
Has anyone who has DSL AND is a Ham radio Operator had success with any
DSL modem regarding immunity from r.f. overloading, especially from a
160 meter transmitter.
I lose sync with 5 watts output. All shielded, including phone line,
all cables, r.f. filters, chokes on transmitter leads, etc.
I would also suggest that you install a whole house filter (sometimes
called a splitter) at the Telephone NID. Then run a short home run to
the DSL modem, keeping the modem as far away from the transmitter as
possible.
|
I highly recommend a outdoor DSL filter to be located at the demarcation
point (where your house line meets your phone co. line in a box).
Then route shielded wiring (don't forget to ground its shielding) from
the outdoor DSL filter to where your modem is located. This limits the
pickup length to just between your modem and the grounded phone jack
junction box.
Keep your antenna away from this setup.
Works for me. |
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David Schwartz
Guest
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| Posted:
Mon Aug 29, 2005 8:20 am Post subject:
Re: modem losing sync (with 160 meter Ham) |
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"Capt. James. T. Kirk" <james.t.kirk@enterprise.federation.int> wrote in
message news:99uQe.45$Lh.22@newssvr25.news.prodigy.net...
| Quote: | Then route shielded wiring (don't forget to ground its shielding) from
the outdoor DSL filter to where your modem is located. This limits the
pickup length to just between your modem and the grounded phone jack
junction box.
|
I would try it both with the shield grounded and with the shield
unconnected. I have definitely seen cases where grounding the shielding
makes things *much* worse, though I suspect it's largely because the ground
is poor.
DS |
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John P. Dearing
Guest
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| Posted:
Tue Aug 30, 2005 4:12 am Post subject:
Re: modem losing sync (with 160 meter Ham) |
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David Schwartz wrote:
| Quote: | "Capt. James. T. Kirk" <james.t.kirk@enterprise.federation.int> wrote in
message news:99uQe.45$Lh.22@newssvr25.news.prodigy.net...
Then route shielded wiring (don't forget to ground its shielding) from
the outdoor DSL filter to where your modem is located. This limits the
pickup length to just between your modem and the grounded phone jack
junction box.
I would try it both with the shield grounded and with the shield
unconnected. I have definitely seen cases where grounding the shielding
makes things *much* worse, though I suspect it's largely because the ground
is poor.
|
If you *do* decide to ground the shield, only ground *one* end.
Preferrably the end at the NID which should already be grounded and
bonded. You only ground one end to avoid "ground loops" where each end
of the ground is at a slightly different electrical potential causing
current to flow in the ground conductor. In addition to be unsafe, it
also greatly reduces the effectiveness of the ground.
Let us know how you make out!!
John
--
John P. Dearing
A+, Network+, Server+
To reply: Just drop "YOURPANTS" in my address! 8-) |
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k8vf_mark@centurytel.net
Guest
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| Posted:
Thu Sep 15, 2005 8:20 am Post subject:
Re: modem losing sync (with 160 meter Ham) |
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OK, I got someone at Centurytel to listen.
Tech brought me a Westel modem to try instead of the Net(less)opia I
was using.
IMMEDIATELY, I could run 85 watts on 160 meters.
Installed splitter at demarc and ran shielded twisted pair home run to
DSL modem(55 feet away).
Grounded all unused pairs in regular phone circuits through splitter
box.
Now using 500 watts with no issues.
Thanks to all for your advice.
BTW, tech came back to check on my progress and said he was surprised
modem change helped at all. He had given me the DSL splitter and was
real helpful. He saw that I was all shielded and graounded and choked
at his initial visit so he must have figured I wasn't totally
inept.....this was a pleasant experience, all in all.
best regards,
Mark
K8VF |
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