Yes the INRAD mod will open the audio a bit. The stock Tentec filter is
2.4KHz while going to the INRAD at 2.8 KHz is one difference.
Regarding getting audio from the product detector, yes that can be done and
with external audio equipment which will yield a slight improvement in audio
S/N and distortion. Frankly, I'm not sure if one could detect an
improvement in audio S/N as it surely will be masked by atmospheric noise
and etc. As to distortion improvements, well that helps but keep in mind
that it will only be as good as the transmitted signal. In most cases a few
extra watts of audio power on the receiver will help but most of all a good
high quality speaker adds more and at less cost and aggravation.
I use a Paragon on AM. (Oh yes there's still some of us around.) It has a
6.0 KHz filter and there is "no problem" with the audio response from the
radio within the limits of the filter. Frequency response is +/- 2 dB from
75 Hz to a bit over 7.0 KHz with a 85% modulated signal. The AM detector
begins to crap out at over 90% sine wave modulation.
Regarding EQ, I can and do run TX EQ on the Paragon when operating SSB. I
also use a external processor for TX audio. It tends to "warm things" up a
bit acoustically. The audio lineup consists of a RE-20 mike, a Ramco DC-5RA
mike mixer, a Behringer PEQ-2500 equalizer and a Behringer processor which
has a gate/expander, followed by a compressor/limiter and finally a hard
peak limiter.
I tampered with the audio path on a Tentec SP-325 receiver. On AM it is
limited by the filter, the same as SSB. I did notice that one can shift the
carrier point on the filter slope to improve either the high end or the low
end of the spectrum. It will be different for LSB and USB as the slopes of
the filters are not absolutely symmetrical. (This is where DSP comes in to
do a good job on the new radios.)
For what it's worth, the Paragon, the Omni VI+ and the SP-325 have the same
receive audio path.
73
Bob K4TAX
----- Original Message -----
From: "Clark Savage Turner" <csturner@falcon.csc.calpoly.edu>
To: "Michael and Linda March" <lmmarch@visuallink.com>
Cc: <tentec@contesting.com>
Sent: Sunday, March 24, 2002 4:26 PM
Subject: Re: [TenTec] Omni-6+ RX audio / EQ?
> On Sun, 24 Mar 2002, Michael and Linda March wrote:
>
> > Is it possible to widen the receive audio in the Omni-6+ beyond 2.4 kHz?
> > Has anyone added an EQ to the Omni? What type? Thanks and 73, Mike
> > K4QU http://www.qsl.net/k4qu
>
> INRAD has a small mod that helps open the audio from the OMNI VI a bit.
> It does not open wide, but gets better, for sure. Someone recently
> figured out a way to get wide audio from the product detector, I believe,
> but I don't have a reference to that. The simple improvement is the INRAD
> mod with a couple of INRAD 2.8 filters.
>
> Clark
> WA3JPG
>
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