[Amps] Maximum RF output in practical application: 4-250A

[Joe Isabella]

I have done some experimenting with marginal S/N ratios as well.  Still, it's easier to copy signals with significant content in the 3-4 kHz range than those with only 300-2.5k.  I will be the first to tell you that it is far from a scientific, but the extended silibance definitely added to my comprehension under poor conditions.  I also have done some "playing" with my transmitted audio, and a majority of the time, when I focus my speech energy between 400 and 3500 Hz, I get noticeably better results than if I cut it at 2.5 or 2.6k.  I believe that is because when in "DX" or heavy QRM "Contest-Mode", most use their IF shifts and heavily favor that range.  Basically, I have 3.1k of occupied BW to "shift around in", and I really think that's what makes the difference.  The existance of that slightly extended energy makes it "stand out" at the receiving end.  Tinkering with that here in my shack I have confirmed that under marginal conditions, I can pick out the stations with
 more upper frequency content than those without.  All I can say is that when there is significant noise & QRM, that extra couple hundred Hz of articulation seems to make a difference.

Has anyone else experimented with that?

Joe, N3JI

----- Original Message ----
From: Tom W8JI <w8ji at w8ji.com>
To: Joe Isabella <n3ji at yahoo.com>; "Joe Subich, W4TV" <w4tv at subich.com>; amps at contesting.com
Sent: Monday, July 3, 2006 4:01:29 PM
Subject: Re: [Amps] Maximum RF output in practical application: 4-250A


> On the contrary, Joe.  I can prove humans can tell the 
> difference between certain letters, words, and sounds with 
> 4k of audio that you can't with 2.5k.

That's certainly true with very high S/N ratios on clear 
frequencies, assuming the people have normal hearing and 
speech.

I can prove the best S/N ratio and readability when signal 
levels have less than 20dB S/N ratio occurs when SSB signals 
are between 2 and 3 kHz wide, and that the most effective 
weak signal communications occurs with about 2kHz bandwidth.

73 Tom