Herb,
ADSL, which sounds like what you have, has carriers right up to mid
broadcast band or so. The upper frequency carriers that go up above 1 MHz
are the from the modem to your house, while stuff down low is from you back
to the DSLAM.
This makes modems very susceptible to 160 meter signals. Because the
incoming ADSL signal extends right up through AM BC, the modem is ALWAYS
very difficult to filter. You are not trying to remove audio from something
1000 times higher in frequency. You are trying to remove RF from something
weak running at 15-60% your operating frequency!
My NW antenna pattern puts 10dB nearfield increase into the building where
my ADSL modem is!!! Even 200-300 watts shut down my original ADSL modem,
because it lost incoming signal lock.
Normal methods, even things that normally "work great" for out-of-band,
often won't work.
To build a filter, you have to know what you are filtering. I changed to a
2wire brand modem, which has excellent immunity to out-of-band signals. I
also built a notch filter for 160 meters that has a series-resonant circuit
between wires, and parallel tuned traps in series with the modem Telco line.
I adjusted the L/C values and filter configuration here so the filter
actually peaked the higher frequency carriers, and the filter actually
increased my connection speed (I'm well beyond the normal allowable limit of
distance to the DSLAM where ADSL originates).
>From my experience, you are going to waste a lot of time tossing iron or
regular filters at the problem. The key is good modem, like a 2wire modem,
and if that doesn't work, a really sharp roll-off filter.
Tossing iron at the CAT5 cables is OK, but it is not often useful on the
Telco side.
73 Tom
----- Original Message -----
From: "Herb Schoenbohm" <herbs@vitelcom.net>
To: "TopBand List" <topband@contesting.com>
Sent: Monday, July 16, 2012 8:57 PM
Subject: Topband: DSL knocks out when on TopBand
> Fortunately I have a Wi-Max service that is immune from RFI but I
> frequently use a DSL service for remote control with guest ops during
> contests. The DSL is more reliable in so much is I get 1.5 Mbps up and
> down all the time and every time. (The Wi-Max at times gives me CW
> hick-ups and although it works with Icom's RS-BA1 remote this does not
> compare with reliability and flawless remote paddle CW using Remote Rig
> and a Kenwood TS-2000. Remote ops prefer being able to have a real rig
> head in front of them and use a local paddle as well.)
>
> My problem is that when I try to operate on 160 the DSL crashes. I have
> tried many Type 31 3 inch ferrite rings with 20 turns on both the phone
> line and the Cat 5 cable from the Zhone modem but even at 200 watts the
> DSL looses sync. I even have disconnected all phones and faxes but to
> no avail. I'm sure this problem has been around this site for some time
> but I would like any information on what i should try. My telephone
> line enters the shack about 70 feet from a cage fed 85 foot tower and
> the nearby 80 meter 1/4 wave vertical does not cause problems, only the
> 160 meter antenna, and with relatively low power.
> I don't hear any audible IX on the telephone while transmitting which
> leads me to believe my problem is not a simple one to solve. Any
> suggestions on what to try like using CAt 5 cable to the pole instead
> of normal drop wire, RF Chokes, K-Y or K-Com filters, what works best
> with a DSL with 160 meter IX problems. Please let me know.
>
> Thanks,
>
>
> Herb Schoenbohm, KV4FZ
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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