Monday, December 26, 2011

Re: [HamBrewers] Required- Noise reduction circuits for speaker

 

Hi Raj,
 
No Problem and Thanks for the tips. I will have a look at the website and come back with queries, in the meantime Yan suggested an Audio LP filter whose details are available at http://lpistor.chez-alice.fr/filtrebf.htm and I found one at http://newenglandqrp.org/nescaf   . Let me know your thoughts on these.
 
73's
Nitin [VU3TYG]

 

From: Raj <vu2zap@gmail.com>
To: HamBrewers@yahoogroups.com
Sent: Monday, 26 December 2011 6:32 PM
Subject: Re: [HamBrewers] Required- Noise reduction circuits for speaker

 
Nitin, sorry for the late reply. From my experience of making loudspeaker crossovers, I think you can make a good filter easily. It will be better than a R/C filter with a better roll off and almost no loss in the passband.

http://www.apicsllc.com/apics/Misc/filter2.html

Use non polarised capacitors.. back to back electrolytics will work at low power or better still use mettalised polyester.
For the inductors, wind on a large diameter former (1") with 20 gauge or less. You can better results with a coil wound on ferrite.

Usually values I remember winding is in 1mH range and 1-10uF caps.

You can use a high pass and a low pass in series to get a band pass configuration. This addition to the shack is not rig specific!

I use a LC high pass in all my shack mics. I roll off below 600 Hz, gives me an edge in a pileup.

(Members note that small PCB inductors will not work here, they will be lossy and fail quickly!)

Cheers
Raj, vu2zap

>Has anyone got any simple noise cancelling circuits either dsp or otherwise which would remove the high tones on ssb reception, this includes the background radio noise. I understand that there was an article in the QST November 2011 issue.
>
>73's
>Nitin [VU3TYG]



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