Has anyone compared the Timewave 599ZX to the NIR-12?
Jim N7US
-----Original Message-----
From: rtty-bounces@contesting.com [mailto:rtty-bounces@contesting.com] On
Behalf Of Jerry Pixton
Sent: Saturday, October 02, 2004 5:00 AM
To: rtty@contesting.com
Subject: RE: external DSP audio filters (was Re: [RTTY] AA5AU ContestNotes
for CQWW RTTY now on-line)
Jeff, et al
Since the JPS NIR-12 filters were not available, last spring I opted for
the MFJ 784B Audio DSP filters which I put in series from my radios,
FT1000mp and IC756proII, to the sound cards. In spite of good filtering in
both radios, the audio filters make a BIG difference. I have the audio
filters set up with a 500 hz and a 250 hz position as well as a twin peaked
position. With the hundreds of stations on 20 meters last week end I could
search in the 250 hz position and generally seperate almost all stations.
The occassional stations that were sitting almost on top of each other, I
just put on the bandmap and moved on unless they were a multi. If they were
50 hz or so apart then the twin peak filter was useful. I would say that
the audio filters made a big improvement in my station.
Jerry, W6IHG
At 06:25 PM 10/1/2004 -0500, Don Hill AA5AU wrote:
>Jeff et al,
>
>The JPS NIR-12 audio filters give me lots of great advantages to no
>filters. The difference between the audio through the filter and with
>the filter turned off is tremendous. Audio straight from the radio
>with no filter, no matter which radio I use, is full of "snap, crackle
>& pop" no matter how quiet the band. I can't stand to listen to that
>at all anymore. I refuse to.
>
>With the filter, the audio is much cleaner with no transient noise, not
>only for
>my ears but also to the demodulators - both MMTTY and the HAL DXP-38.
>
>The NIR-12 (no longer made but I found one on E-Bay) has two outputs -
>one for the headphones which can be adjusted by the volume control on
>the front of the unit and an Audio Out jack with a constant output
>(independent of the volume
>control) that I split two ways to go to the sound card and the HAL unit.
>
>Furthermore, I take audio from the headphones jack on each NIR-12 and
>bring them
>to my Dunestar 2 Radio headphone selector. I can then adjust the audio
>with the
>volume control on each unit for a comfortable level to each side of the
>headphone (left headphone for left radio, right headphone for right
>radio). It
>just seems perfect this way. I can even switch either radio audio off
>with the
>Dunestar switch, but rarely do that.
>
>I doubt very much if the DSP of the NIR-12 units has any degrading
>effect on MMTTY. When callsigns highlight out of nowhere when I can't
>even hear them, I know something must be working. That happened a lot
>of 15 meters this past weekend. No noise, but couldn't hear a signal
>either, but those weak EU stations were still highlighting.
>
>I used to use the NIR-10, but the problem with that unit is that it has
>only two
>outputs - speaker and headphones. And both outputs are tied to the volume
>control on the filter which is not good.
>
>It's unfortunate JPS has gotten out of the Amateur business. Although
>expensive
>in their time, the NIR-12 is a so valuable I cannot think of RTTY
contesting
>without them (time to look for a spare on E-Bay again).
>
>73, Don AA5AU
>
>-----Original Message-----
>From: Jeff Stai WK6I [mailto:wk6i@twistedoak.com]
>Sent: Friday, October 01, 2004 2:08 PM
>To: Don Hill AA5AU; rtty@contesting.com
>Subject: external DSP audio filters (was Re: [RTTY] AA5AU Contest Notes
>for CQWW
>RTTY now on-line)
>
>At 11:30 AM 10/1/2004, Don Hill AA5AU wrote:
> >For anyone interested.
> >
> >http://www.rttycontesting.com/contestnotes/2004_cqww.htm
>
>hi Don - thanks for the writeup! And thanks again for the excellent
>info
>on the
>rest of your site - it really helped me get my first SO2R attempt going
>for this
>contest.
>
>Question: you have talked about using NIR-12 DSP filters in your
>contest
>setup.
>What are you really achieving with those filters? And how?
>
>It seems to me that MMTTY is a DSP filter in concert with a RTTY demod,
>and if you put another DSP in front of it, you may end up losing some
>of MMTTY's effectiveness by removing information that MMTTY could use.
>
>(As far as cleaning things up for my headphones - my ears can suffer,
>as
>long as
>I am getting the best print...:-)
>
>Or are you using it mainly with your external HAL modem?
>
>Or am I missing something? thanks! - jeff wk6i
>
>
>--
>Jeff Stai jds@twistedoak.com
>Twisted Oak Winery http://www.twistedoak.com/
>
>
>
>
>_______________________________________________
>RTTY mailing list
>RTTY@contesting.com http://lists.contesting.com/mailman/listinfo/rtty
------------------------------------------
Dr. Jerry R. Pixton, PIXOS Designs LLC
http://www.pixos.com/designs/RadioTuner/
jpixton@shentel.net
------------------------------------------
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