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   Home   Help Search  
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Author Topic: Newcomer Help  (Read 12098 times)
K4DPK
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« on: June 22, 2000, 01:19:56 AM »

Based on your description, and the fact that you're accustomed to essentially interference-free FM, I'd say you're hearing your first heterodynes.  When two carriers appear in close proximity, a tone will be produced that has a pitch equal to the difference in the frequencies of the two signals.  Such tones are called heterodynes.  Notch filters are used to "notch" these tones out, reducing them in amplitude so they are not so bothersome.  These aren't generally heard on FM because of the capture effect.  Welcome to HF.
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KF6RNU
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« Reply #1 on: June 19, 2000, 04:08:24 PM »

I've been licensed for about 2 years now, but I'm still new to the HF thing. I have a Yaesu FT-100 going to an old CB antenna (temporarily, for receive only). While tuning through the HF bands, I'm receiving noises which I can only describe as a high pitched 'eeeee'. Is this normal? If so, what are these noises? Why are they there? As I mentioned, I'm new at all of this, I apoligize if I sound a bit too new :-) Thanks.



Scott
KF6RNU
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N2MG
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« Reply #2 on: June 19, 2000, 04:19:57 PM »

As a start:
Are you running any other electronic devices nearby? TVs, computers, monitors, etc., all produce crud. Turn everything off and see if the noise goes away.  If your neighbors are close (like in an apartment building) their stuff might interfere, too.  You might also move the antenna around (not normally very easy) and hunt the source(s) down.

Good luck,
Mike
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KC8OPV
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« Reply #3 on: June 21, 2000, 01:04:36 PM »

Another source of noise that I've noticed is light dimmers.  I have a halogen light (which has a dimmer) in the living room that I have to turn off because it creates major noise on HF.
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WB6BYU
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Posts: 17064




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« Reply #4 on: June 21, 2000, 07:45:01 PM »

There are a lot of different sorts of digital signals on the bands these
days.  Many of them sound like more of a "beedle-eedle-eedle"
or a "brap brap" more than a continuous tone, but you could be
hearing one of them.  Are there any particular frequencies where you
are picking up these signals?  Do you hear them all across the ham
band?  Are they interfering with your reception of ham signals?
Are the signals of overpowering strength, or about the same levels
as other received signals?  Are they continuous, or do they turn on
and off at intervals?

There certainly are other sources of interference around the house,
such as TV sets and fax machines.  But there are also other users of
the HF spectrum, and other modes in the ham bands as well.  It is
difficult to tell which you may be hearing from the information you gave.

Good luck!

 - Dale WB6BYU
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KB3ERM
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« Reply #5 on: June 20, 2000, 01:05:04 PM »

I agree with Mike, other electronic devices are usually guilty of producing noise. I have an Icom 706MKIIG. Before my upgrade I only used 2M FM, no noise there:-) Then I upgraded to General, and then to Extra... I noticed noise on the HF bands, just as you described! Turned out it was my computer.. I installed chokes, moved the CPU, moved the monitor... I was able to decrease the noise but not eliminate it. So, what is the solution?? For me it was turning OFF the computer and using my paper log book when I operate HF..
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KF6RNU
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« Reply #6 on: June 20, 2000, 01:17:29 PM »

Thanks for the help. I tried turning off the computer (which is located right next to the radio). That didn't seem to fix the problem. There are many computers here though, and some RF every now and then. I'll have to look into chokes. Thanks again.


Scott
KF6RNU
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