All you have to do is move PBT down a little bit to hear the low frequencies
better. This will not change the transmit carrier offset.
Carl Moreschi N4PY
Franklinton, North Carolina
n4py@earthlink.net
----- Original Message -----
From: "Thomas Jednacz" <tjednacz@ieee.org>
To: "Barry N1EU" <n1eu@yahoo.com>; <tentec@contesting.com>
Cc: "Peter AA7E Finch" <aa7e@juno.com>
Sent: Wednesday, January 15, 2003 9:05 PM
Subject: RE: [TenTec] Re Microphones--one more thing (long)
> Hello all:
>
> Sorry to jump in and spoil your fun. DO NOT change the carrier offset. You
> will then be transmitting on both upper and lower sideband!! Filter rigs
are
> set at 300 Hz cut off so the filter slope will will get you -30 dB on the
> other sideband. If you change the offset the filter will not have a steep
> enough slope to drop the other sideband to the required level. Filter rigs
> are not adaptable to less than 300 Hz audio without creating problems. I
> have looked at the fellows on 178 and find that they are using up to 40 dB
> boost (over normal audio levels) at 100 Hz and driving the audio and or
A/D
> converter in the DSP chip crazy. They say their RF stages are all linear.
> True - BUT they generate all kinds of junk in the audio stages by driving
> them non-linear and transmit 12 - 15 KC wide signals when they only intend
> to transmitt 4Khz. A full DSP rig (Pegasus/Jupitor, Icom 746 Pro/756Pro,
> Kachina, and of course the new Orion) are the only ones that will properly
> transmit 100Hz to 4 Khz audio and be clean.
>
> Play with equalizers and all the other audio stuff but don't try to make a
> system design do what it is not supposed to do. Do not consider HI-FI/SSB
> with anything but a full DSP radio as above.
>
> When playing with HI-FI/SSB lets understand what we are doing, use good
> engineering practices and have some courtesy in sharing frequencies with
our
> fellow hams.
>
> Tom, W7QF
>
>
> -----Original Message-----
> From: tentec-admin@contesting.com [mailto:tentec-admin@contesting.com]On
> Behalf Of Barry N1EU
> Sent: Wednesday, January 15, 2003 3:29 PM
> To: tentec@contesting.com
> Subject: Re: [TenTec] Re Microphones--one more thing (long)
>
>
> --- Mark Erbaugh <mark@microenh.com> wrote:
> > Could you share with us how you run a response curve
> > and how you determine
> > the needed EQ. I would like to do some analysis work
> > on my GoldLine / W2IHY
> > 8 band Eq / Pegasus setup.
>
> Mark, a full treatment of your question would take a
> long time. I'll make a few comments off the top of my
> head with the disclaimer that there are guys right
> here on this reflector who know more than me. I've
> been hacking at it for a few years though.
>
> The best way to judge mic equalization is with your
> own and other folks' experienced ears. On a
> hifi-capable receiver, listen to a lot of ssb signals
> closely for what you do and don't like about their
> sound. Listen to the guys on 14178 and on the TT net,
> and you'll hear some really good and not-so-good
> sounding audio. By hifi-capable, I mean a minimum of
> 2.8khz bandwith with carrier offset aligned properly
> to extend bass response to below 100hz.
>
> Run your receiver audio (line level) into your
> soundcard and get some recording and spectral analysis
> software. There's some freeware/shareware out there
> (just search around), but currently I'm using CoolEdit
> Pro for recording and SpectraPlus for spectral
> analysis. Record WAV files of those signals that you
> do and don't like. You can open the WAV files in
> SpectraPlus and it will show their response curves
> after running a spectral analysis on them. After
> doing this many times, you can correlate what your
> ears are telling you and what the computer is telling
> you. I'm sure there are lower cost alternatives to
> SpectraPlus, but you'll have to look around.
>
> For setting your own EQ, you can record yourself off a
> second hifi-capable receiver while transmitting
> (choose a phrase with a few sentences and keep using
> it as your standard) and get a good idea of what you
> sound like as well as run a spectral analysis on it.
> Solicit many opinions from others on the air who can
> listen critically as you adjust the audio.
>
> There are a few links on my Web site under "Audio" to
> NU9N, KC4PE, W3OZ, etc. where there's a wealth of
> information and different perspectives on getting the
> equalization correct. There's also a ssb-audio
> reflector on Yahoo Groups.
>
> GL/73,
>
> Barry N1EU
> http://www.albany.net/~bg
>
>
>
>
>
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