it makes a fairly large difference. I may have to make an audio recording and upload it here (or put it on audio boo). The only downside issue is that I cannot phase out more than one noise source, so I choose the strongest one and let the chips fall where they may on the rest.
-eric
On Feb 2, 2014, at 12:15 PM, richard fiorello wrote:
> Hi;
> Just wondering how high your noise level is before the mfj unit
> and how much of a difference it makes? I have turned off the
> things I suspect would be a problem and it makes no difference.
> Without the preamp the noise is s 5 with the receive preamp on it
> gets far worse. Its just not pleasant to listen to unless
> someone is s 9. Thought a larger external speaker would help but
> no success. richard
> sent from my braille note
>
> ----- Original Message -----
> From: eric oyen <[log in to unmask]
> To: [log in to unmask]
> Date sent: Sat, 1 Feb 2014 18:05:35 -0700
> Subject: Re: Low Pass Filter
>
> well,
> the situation here is a bit close. I have 12.6 Kv lines directly
> behind =
> the hose. THe neighbors have outdoor florescent lights (and
> there are =
> even 2 bug zappers). I have checked and there are at least 14
> wi-Fi =
> access points within 400 feet of me. THe house itself has 2 AP
> devices, =
> about 300 feet of LAN cable, 2 switches and 6 computer systems
> (the room =
> mates have 3 desktop systems). I have 3 laptop machines, 2 of
> which are =
> turned off. Half the lights in here are of the tube variety
> (those =
> stupid cheap made "green lamps"). all of these make some noise.
> As a =
> result, I also have to have an MFJ 2500 series antenna noise =
> cancellation unit in operation here just to remove all the
> electrical =
> noise. THe power lines are the worst of it.
>
> Basically, I am using every trick I can find to reduce or
> eliminate =
> noise before it hits my radio.
>
> -eric
>
> On Feb 1, 2014, at 5:49 PM, John Miller wrote:
>
> I actually never have lived in a place with a lot of noise.
> It's =
> funny,=20
> when I first was a ham, I was living with my parents, in the
> woods =
> pretty=20
> much with over a hundred feet between houses, well over 100 feet
> and =
> all=20
> woods behind me. Next place, in a neighboring town I was in an
> =
> apartment in=20
> the center of town, surrounded in a factory, houses, other
> businesses, =
> a=20
> place that converts vans to wheel chair vans and works on them,
> still =
> never=20
> had any noise for what ever reason and there you could about
> reach out =
> and=20
> touch the neighbors. Now I'm in a trailer park and we're not
> much =
> further=20
> away form each other I have a light off and on buzz here that my
> noise=20=
>
> blanker takes out and other than that, again very quiet. 2
> meters I =
> have=20
> noise but I couldn't care less about that and even that is rare.
> I =
> don't=20
> know why I'm that lucky. I spent 2 months with my in-laws at
> one =
> point,=20
> there, I had a +40 noise level from 160 through 70 CM, I could
> get on =
> GMRS,=20
> and 900 MHz from there, that was about it and no filtering
> remotely =
> helped=20
> that but that was an area with all businesses and apartments
> above =
> them once=20
> in a while.
> ----- Original Message -----=20
> 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
> =20
> =20
> the funny thing is that low pass filters operate
> bi-directionally. If =
> =3D
> your radio produces harmonics that interfere above its normal =
> operating =3D
> range, then mix down products from sources above HF would also
> cause =
> =3D
> interference on HF. THese mix down products are often caused by
> =3D
> interactions within the first stage of the IF in your radio.
> SO, =
> using a =3D
> filter eliminates a lot of that from getting to your radio (thus
> =3D
> reducing or eliminating the problem).
> =20
> I have an FM radio station transmitter site less than 3 miles
> from me =
> =3D
> producing several thousand watts. without the filter, I hear
> what =
> sounds =3D
> like FM modulated signals in a couple of bands. I put the
> filter in =3D=
>
> place, and those signals disappeared. THere are other sources
> (such =
> as a =3D
> wireless Access point, LAN switches and cable modems'DSL modems
> that =
> =3D
> produce signals that can show up in HF directly. Filtering
> these is a =
> =3D
> bit harder. I am having to use ferrite beads on the power leads
> and =
> also =3D
> on the LAN cables to try and minimize some of these issues. I
> have =
> only =3D
> been partially successful. I still get a lot of birdies in the
> 10 =
> meter =3D
> band (around 28.5). I am going to acquire a portable shortwave
> =
> receiver =3D
> and try to track these signals to their source and see what I
> can do =
> to =3D
> remove them.
> =20
> -eric
> =20
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