Gents:
I've had to deal with AM bdcst EMI like this a lot, and one thing I found
was that one bad/cheap phone or (particularly) answering machine or modem
can foul up the lines on all phones in the house. This can sometimes
make an otherwise RFI-tolerant phone go bad. When testing you should
unplug every single phone/device from all lines into the house, and test
them one by one. Probably 80% of the trouble I've encountered has been
related to answering machines and modems. Individual filters on these
items usually has cleaned up the problem throughout the house. The other
20% require scuttling the offending phone altogether.
Even with 30KW of hot-steaming AM literally right next door, most of
these problems can be fixed with filters and cord-chokes. There are some
phones, though, that are just hopeless. If you got it free along with a
Time magazine subscription, donate it to your mother in law (it'll reduce
her time on the phone to the XYL, as a bonus).
Of course, the EMI at higher frequencies may not behave the same. Your
mileage may vary...
I would like to find a reliable manufacturer/model of EMI resistant
cordless phones. I've suggested the Sony 900MHz digitals to a couple
folks, and they haven't come back complaining, but I haven't tested them
myself. This is something the ARRL could do for us! Test a bunch of
this stuff every year or so. I know if I was certain I could just buy
the neighbor a new phone and the problem would go away, I'd buy it in a
hot minute. FWIW, most of my personal ham/neighbor trouble has been
handled by plug-in line filters, including the new Radio Shack item. Try
these first.
73,
Gary
--------------------------------------
- W3AM - Gary Blau -
- w3am@juno.com -
- http://www.w3am.com -
--------------------------------------
On Thu, 29 Oct 1998 10:47:02 -0800 (PST) PD Wintheiser <w0opw@yahoo.com>
writes:
>
> Only 2 days ago I called the telephone company to complain about
>noxious AM interference on my phone(the AM station is so far away I
>don't even know where it is). They suggested I put filters on the
>phone, which I already have. I persisted and they said they would send
>a repairman out the next day but if they did not find a problem I
>would have to pay for the service. She suggested I try other phones
>in the house to see if it was one or all phones. Interestingly, it
>was only the one phone.
> I immediately trashed the phone and replaced it. Diode
>rectification is not a pretty thing to get embarrased over !
> A suggestion: Loan out to the neighbor a phone you know is free of
>Rfi and let them see the difference while you run a test. I see no
>reason to have to buy any neighbor a new phone just because of bad
>diodes.
>
>
>
>
>
>_________________________________________________________
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>
>
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>
>
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