DSL filters as RFI filters -- don't bother!

[Vic K2VCO]

I've collected a large number of DSL telephone filters from various
installations.  Someone recently suggested that they can be used as ham
RFI filters, since they are supposed to isolate the telephone from the
DSL carrier.  Although the DSL signal is much lower in frequency than
ham signals (I believe 10-100 KHz, correct me if I'm wrong), I thought
it would be worth a try.

I tried four different types of DSL filter and compared them to a KCOM
RFI filter designed for 3-30 MHz.  I transmitted 100w CW on 7 MHz into a
vertical.  With no filters, the keying could clearly be heard.  The KCOM
filter was quite effective, suppressing most of the interference.  The
DSL filters appeared to have no effect.

So much for that idea.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[Mike WA8BXN]

I had quite good results with a DSL filter used with an external Hayes modem
 Without the filter even qrp power levels at times would cause a modem
disconnect, with the filter I can run several hundred watts of AM without a
problem. I suppose it has to do with who or what is listening!
 
73 - Mike WA8BXN
 
 
 
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[Stephen W. Kercel]

I have found KCOM filters very effective at cutting out telehone RFI.
I have found that the KCOM handset filters do interfere with the
proper operation of some cheap telephones. I have not run into any
problems with the KCOM line filters.

73,

Steve
AA4AK
K2 S/N 5383


At 02:34 PM 4/17/2006, Vic K2VCO wrote:

>I've collected a large number of DSL telephone filters from various
>installations.  Someone recently suggested that they can be used as
>ham RFI filters, since they are supposed to isolate the telephone
>from the DSL carrier.  Although the DSL signal is much lower in
>frequency than ham signals (I believe 10-100 KHz, correct me if I'm
>wrong), I thought it would be worth a try.
>
>I tried four different types of DSL filter and compared them to a
>KCOM RFI filter designed for 3-30 MHz.  I transmitted 100w CW on 7
>MHz into a vertical.  With no filters, the keying could clearly be
>heard.  The KCOM filter was quite effective, suppressing most of the
>interference.  The DSL filters appeared to have no effect.
>
>So much for that idea.
>--
>73,
>Vic, K2VCO
>Fresno CA
>http://www.qsl.net/k2vco
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
>http://mailman.qth.net/mailman/listinfo/elecraft
>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com

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[Alexandra Carter]

> My own understanding is that DSL operates in the 1-2 MHz range, read
> it in some manual somewhere..... 73 de Alex NS6Y


> At 02:34 PM 4/17/2006, Vic K2VCO wrote: Although the DSL signal is
> much lower in frequency than ham signals (I believe 10-100 KHz,
> correct me if I'm wrong), I thought it would be worth a try.73,
>> Vic, K2VCO
>> Fresno CA
>> http://www.qsl.net/k2vco

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[Vic K2VCO]

Alexandra Carter wrote:
>> My own understanding is that DSL operates in the 1-2 MHz range, read
>> it in some manual somewhere..... 73 de Alex NS6Y

That wouldn't surprise me.  My DSL modem goes nuts when I operate 80 or
160 meters, and it's got enough ferrite and RF filters on it to sink a
battleship.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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