I actually never have lived in a  place with a lot of noise. It's funny, 
when I first was a ham, I was living with my parents, in the woods pretty 
much with over a hundred feet between houses, well over 100 feet and all 
woods behind me. Next place, in a neighboring town I was in an apartment in 
the center of town, surrounded in a factory, houses, other businesses, a 
place that converts vans to wheel chair vans and works on them, still never 
had any noise for what ever reason and there you could about reach out and 
touch the neighbors. Now I'm in a trailer park and we're not much further 
away form each other I have a light off and on buzz here that my noise 
blanker takes out and other than that, again very quiet. 2 meters I have 
noise but I couldn't care less about that and even that is rare. I don't 
know why I'm that lucky. I spent 2 months with my in-laws at one point, 
there, I had a +40 noise level from 160 through 70 CM, I could get on GMRS, 
and 900 MHz from there, that was about it and no filtering remotely helped 
that but that was an area with all businesses and apartments above them once 
in a while.
----- Original Message ----- 
From: "eric oyen" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, February 01, 2014 7:00 PM
Subject: Re: Low Pass Filter


> the funny thing is that low pass filters operate bi-directionally. If =
> your radio produces harmonics that interfere above its normal operating =
> range, then mix down products from sources above HF would also cause =
> interference on HF. THese mix down products are often caused by =
> interactions within the first stage of the IF in your radio. SO, using a =
> filter eliminates a lot of that from getting to your radio (thus =
> reducing or eliminating the problem).
>
> I have an FM radio station transmitter site less than 3 miles from me =
> producing several thousand watts. without the filter, I hear what sounds =
> like FM modulated signals in a couple of bands. I put the filter in =
> place, and those signals disappeared. THere are other sources (such as a =
> wireless Access point, LAN switches and cable modems'DSL modems that =
> produce signals that can show up in HF directly. Filtering these is a =
> bit harder. I am having to use ferrite beads on the power leads and also =
> on the LAN cables to try and minimize some of these issues. I have only =
> been partially successful. I still get a lot of birdies in the 10 meter =
> band (around 28.5). I am going to acquire a portable shortwave receiver =
> and try to track these signals to their source and see what I can do to =
> remove them.
>
> -eric
>