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Author Topic: How do I reduce sound card drive  (Read 1945 times)
N5LRZ
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Posts: 0




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« on: November 13, 2007, 03:08:04 PM »

without losing all power output....

I have a little problem/big problem with digital pictures.  Perhaps you gentlemen can help.

Background...

A P3 computer running XP pro, adequate but not great memory and a 10 K storage.

Software Easy pal-lite

Key Interface, home made simple interface off the easy pal web site.

Yaesu HF/VHF/UHF radio--that mobile base rig.

Audio input to the radio from the computer and the PTT (both) via the mic plug in the front of the radio.  

Audio from the radio to the compuer sound card via jumper from the Headphone Jack to the conmputer.

PROBLEM....

Cannot achieve any lock on signals that I transmit.  Not even on the local level.

To get proper tune of the soundcard I have to reduce all soundcard volume output to zero AND reduce ssb mic gain to zero.  I get great picture on the tune indicator  (3 crisp bars and my call in the waterfall).  BUT ZERO output from the radio/nada/nothing.  ANY mic gain at all results in an instant sound card overdrive.  ANY soound card output above zero relults in instant overdrive.  ANY thoughts on how to reduce soundcard drive and maintain power output?

I was thinking of installing interface on the sound drive to the radio from the soundcard using a couple of 10 K varable resistors in parallel to tweak the audio input to the radio to reduce the ALC/overdrive.  Thoughts?Huh


PS

The radio is built into/embeded in an enclosed part of the radio desk having very adequate venilation.  The only access to audio input and output is the mic input and the headset jack in the front of the radio.  Access to the rear connections will require redesign of the radio desk and I would much not rather do that if at all necessary.

Seeking alternative options.
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NA4IT
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Posts: 196


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« Reply #1 on: November 13, 2007, 05:01:32 PM »

Turn off the rig's compression. If that doesn't do it, make sure you have some type of attenuation in the TX audio lines. Sound card out put can be too hot for radio input, especially into the mic amp.

Scott NA4IT
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N8UZE
Member

Posts: 1524




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« Reply #2 on: November 14, 2007, 09:30:03 AM »

Sounds like you need some attenuation in the line from the computer out to the radio in.  There are diagrams available for free on the internet showing simple networks (3 resistors) that you can build.  If you still have problems, you may be getting feedback.  Then you may need an isolator in the line.

Try the attenutation first though.  I don't know anyone who has been able to set up digital without doing so.
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AA4PB
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Posts: 15066




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« Reply #3 on: November 14, 2007, 04:36:23 PM »

It also might be RF getting into the sound card cables. Put on the dummy load to do your initial testing.
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Bob  AA4PB
Garrisonville, VA
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