I have experienced the same problem with various rigs (Ten Tec's and others)
and I use an external audio filter to mostly eliminate the high frequency
hiss while not hindering the cw signal. I've used the OHR SCAF, Idiom Press
Scaf, various Datong's, and other analog audio filters with good results.
Although they do help, I don't find the external DSP filters to be quite as
good for this purpose. It doesn't fix the root of the problem, but it sure
makes listening to the signals a lot more pleasant. As a side note, I've
found this to also take care of many of the thumps, and other artifacts on
the sidetone sometimes heard during qsk operation.
just my 2 cents....
Tim
NZ8J
----- Original Message -----
From: "n4lq" <n4lq@iglou.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Thursday, May 12, 2005 1:01 PM
Subject: Re: [TenTec] Hissness
> Very good points Don. One thing I've noticed over the years; Most of the
> rigs these days have way to much RF gain, especially on the lower bands.
> On my TS-xxx, I turn off the pre-amp, kick in the attn and lower the
> RFgain and have gain left over. Basically, we can lower the gain until
> the noise just moves the S meter a tad. Signals stronger than that noise
> wil sound fine. Signals weaker than the noise wouldn't be heard anyway
> no matter how high the gain is cranked.
> I have a really cool sound DB meter from Radio Shack that is great for
> making test like you mention. Tonight I'll try to compare my OmniVI with
> the TS-wood and see what happens.
> The Corsairs bug me when using the 250hz filter and headphones. The IF
> hiss is unbearable
> Steve
>
> -----Original Message-----
> From: Don Rasmussen <wb8yqj@yahoo.com>
> To: tentec@contesting.com
> Date: Thu, 12 May 2005 09:26:09 -0700 (PDT)
> Subject: [TenTec] Hissness
>
> > One other thing you may notice when comparing Corsair
> > II to non Ten Tec radios is that although the guys
> > here
> > have done a pretty good job of analyzing where hiss
> > comes from inside the Corsair II, it can be limited
> > substantially by turning down the AF gain in actual
> > operation. The signal still comes through the speaker
> > well even at low AF gain settings.
> >
> > I think this may be due to the AGC employed on the
> > Corsair II, although I also see this effect on the
> > later OMNI's that don't have the AGC employed in the
> > audio stage.
> >
> > Try this. Hook a big speaker to the C2, V, or VI+.
> > Find
> > an S5 or better (cw/Fast agc) signal, then turn up the
> > AF gain until you get a loud satisfying CW note
> > filling the room.
> >
> > Now switch the A/B switch to (example FT890AT with
> > 500hz filter) and turn up the AF gain to maintain the
> > same volume level of the cw note.
> >
> > No matter how strong the signal is on my FT890 (or
> > other typical rigs), if you want to hear a nice loud
> > signal, there is this noise penalty. The backround
> > hash always increases noticably with increases in the
> > AF gain regardless of the signal level. Noisy bands
> > make it worse.
> >
> > At higher AF gain levels and no signal, even with the
> > hiss of the C2, it's very quiet in comparison to the
> > other radio with it's speaker rumbling away. Equalize
> > the AF gain of both radios in no signal conditions and
> > you'll find that when an S5 signal comes along it will
> > probably be at a satisfactory loudness in the C2, and
> > hard to hear at the other rig.
> >
> > The moral to this story is, if you own an IC756Pro and
> > you are proud and happy with it, don't buy and old
> > Corsair II or OMNI, and NEVER put it on an A/B switch
> > to compare 500hz operation. I did, sold the Icom and
> > bought a second Corsair. Now I am stuck with a shack
> > of old radios. And what could be worse? ;-)
> >
> >
> >
> >
> >
> > __________________________________
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> >
>
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