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PostPosted: Tue Nov 02, 2021 10:18 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 4151
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Just to update you all on this:

Thanks Bojcha. We were successful in getting it to work but even with the volume in Windows an Stereo Tool set as high as possible, coming out from the back L or R jack sockets of the Behringer UMC202HD, using a straight TS to BNC or a TS to RCA Photo (with a Phono to BNC adapter), the max deviation was 50kHz (with an average of somewhere in the 40s), so it was very under-modulated, to the point where one of our car radios wouldn't even lock to the frequency for more than a few seconds and tried to seek. The best solution for the moment seemed to be to use the UMC's headphone out at exactly 50% volume (knob at 12 o'clock) with the MPX volume in Stereo Tool at ~0.70dB. By the way, I dumped the Ubuntu 20.04 idea and just installed Windows 10 21H1.

A Focusrite Scarlett 2i2 2nd Gen was also tested with the same results as the UMC coming out from the rear L or R outputs.

If anyone has any experience with either of these soundcards going to a transmitter, did you use the headphone jack also, or did you manage to get it correctly modulating coming out from one of the rear outs?
First, Soundcard(s) are not problem there, problem is transmitter. It should have MPX level adjustment so rise it up.
Second, 50kHz is not so much under-modulated at all, and locking to station when you seek on receiver has nothing to do with it. That's again up to transmitter or Receiver (bad or picky) or signal reception.
Never use headphone outputs except for headphones.
So, double check in windows (Control panel > Sound) and/or Soundcard software is Master maxed out to max. Search for MPX Level adj on transmitter and rise it up.

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PostPosted: Tue Nov 02, 2021 10:41 pm 
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Joined: Wed Oct 13, 2021 3:30 pm
Posts: 8
Location: Ireland
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First, Soundcard(s) are not problem there, problem is transmitter. It should have MPX level adjustment so rise it up.
Second, 50kHz is not low modulation at all, and locking to station when you seek on receiver has nothing to do with it. That's again up to transmitter or Receiver (bad or picky) or signal reception.
Never use headphone outputs except for headphones.
So, double check in windows (Control panel > Sound) and/or Soundcard software is Master maxed out to max. Search for MPX Level adj on transmitter and rise it up.
You're a stereo godsend, Bojcha. Windows is maxed - that I am 100% sure of. But I didn't think to look for this little flathead adjuster at the back.

Image

It'll be a tight squeeze to adjust it back there in the little cabinet but I'll certainly give it a go next time I'm up there and report back!

I should mention that using the headphone out didn't play well with my OCD when I didn't realize there was an input MPX level adjuster, but it still sounds better on FM than pre-Stereo Tool times at the site.


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PostPosted: Wed Nov 03, 2021 12:24 am 
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Joined: Tue Mar 17, 2009 2:56 pm
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There you go. Just get a very nice screwdriver and start rise level.

So how to easy adjust it.
Set soundcard master to max, Set MPX output in ST to around -3dB, now adjust MPX level on transmitter to around 75kHz. Then you can fine tune level, tilt calibration, etc, from ST.

I usualy do that in a minute and gone from site to remotely tune ST with my MPXTool.

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PostPosted: Thu Nov 04, 2021 5:25 pm 

Joined: Fri Nov 23, 2012 4:34 pm
Posts: 211
Is the transmitter properly configured to input an external MPX signal?

The transmitter manual that I came across seemed to have some useful information in the 'Quick set-up guide'.
For instance, are you sure the MPX loopthrough jumper was set correctly?

By the way, in your posted picture, it looks like the connector is plugged into the transmitter Baseband/MPX output connector?


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PostPosted: Mon Aug 28, 2023 9:23 pm 

Joined: Tue Feb 08, 2022 2:09 pm
Posts: 17
Quote:
There you go. Just get a very nice screwdriver and start rise level.

So how to easy adjust it.
Set soundcard master to max, Set MPX output in ST to around -3dB, now adjust MPX level on transmitter to around 75kHz. Then you can fine tune level, tilt calibration, etc, from ST.

I usualy do that in a minute and gone from site to remotely tune ST with my MPXTool.
Hello, how can I do that? Can you give some example?

For example, how can I set the MPX level of the Transmitter to 75 khz? How can I calibrate the level and tilt afterwards?


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