[MRCA] Today's noise report

[W2HX]

If you really want to scratch your head, I have a German radio (Siemens) whose meter is calibrated in "Nepers!"
1 Np = 8.685 dB! (just shoot me now)

73 Eugene W2HX

From: mrca-bounces at mailman.qth.net [mailto:mrca-bounces at mailman.qth.net] On Behalf Of Al Klase
Sent: Tuesday, March 18, 2014 3:55 PM
To: mrca at mailman.qth.net
Subject: Re: [MRCA] Today's noise report

Hello Eugene,

While we're on the subject, it's a good idea if we're talking about something like the same thing.

Wikipedia's S-meter article states that by International Amateur Radio Standards S-9 = 50 uV in 50 ohms, and an S-unit is 6 dB.  Here's their table:

[cid:image002.jpg at 01CF42CF.F91218D0]
And from a handy calculator:  http://www.giangrandi.ch/electronics/anttool/decibel.html

1 uV = 0 dBuV = -107 dBm

I've been unhappy with my noise level on 5357 KHz.  It's a constant S-5 on the pencil-drawn sticker around the S-meter on my Transworld TW-100, that I had calibrated with my HP-8640 signal generator.  This agrees with the S-5 reading on my Icom R-9000 and the -96 dBm (11 dBuV) reading on my HP 3586 Selective Level Meter.  I'm only able to do what it do here on 60M because I use a Timewave DSP-59+ audio processor to beat back the noise.  Noise here is mostly white noise, and I've been unable to reduce it.

Your 35 dBuV noise level (-72 dBm) is almost exactly S-9, which likely leaves you pretty deaf.

You've like heard all the fixes.  Get started.


With apologies for the technoweenie freakout, 73,
Al



On 3/18/2014 12:25 PM, W2HX wrote:
I did some calculation to quantify the noise at my qth.  Today the noise as shown on the receiver is a healthy 35 dBuV (receiver's meter is dBuV instead of an "S" meter) which equates roughly to 56 uVrms (microvolts RMS) at the antenna connector.  Better than usual which is a robust 40 dBuV or about 100 uVrms!  So needless to say, no M&S joy today :(

Time to work toward tracking down the source of the noise and getting it eliminated. And in the meantime, I will likely install a receiving H loop.  I've also read good things (believe it or not) about the MFJ-1025 noise canceller. Anyone ever try such a thing?

73 Eugene W2HX





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--

Al Klase - N3FRQ

Jersey City, NJ

http://www.skywaves.ar88.net/


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