FM Tuner with MPX Output

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piratefm
big in da game.. trust
big in da game.. trust
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Joined: Sun Dec 28, 2014 8:41 pm

FM Tuner with MPX Output

Post by piratefm » Sun Jun 26, 2022 8:36 pm

EDIT

Have since found out you can use an SDR.



Hey guys,

I've got a copy of MPX Tool, it's a bit of software that can monitor FM Modulation, Deviation, and Pilot Tone for calibrating a TX.

However, I know that part of the software needs an FM Tuner with an MPX OUTPUT to work. Anyway, I've looked back on Wayback Machine and they say 'Good consumer tuners, such as the Tivoli Model One, can be modified for MPX output with relative ease'.

....So my question is, can anyone modify an FM Tuner for me with an MPX Output?

Here is the Wayback Machine link:
https://web.archive.org/web/20081226060 ... oring.html

https://web.archive.org/web/20081225025 ... 2c610448af

Hit me up if you can help out or know another way of doing this. :tup

mikroman
who u callin ne guy bruv
who u callin ne guy bruv
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Re: FM Tuner with MPX Output

Post by mikroman » Sun Jun 26, 2022 9:41 pm

most receivers (technics, sony, jvc, yamaha ... hi-fi components) from the 80s, 90s and 00s can be upgraded with mpx output. Download the service manual before buying a used fm tuner.
Look for the MPX path between the IC demodulator and the stereo decoder. Now all you have to do is somehow amplify that weak signal with a decent premap. Preamp with ne5532 can be found quite cheaply on aliexpress (avoid board with mic preamp mark). connect the 5532 board and you are almost ready to connect to the mpx tool.
You also have to adjust the tuner if it is older production (offset null / distortion) because without that you will get wrong results.

The newer generation SDR Sharp has a problem with the MPX plug-in and you will get wrong readings. Hit the 20Hz-60KHz sweep and look at the response via the newer version of SDR Sharp and MPX tool. It won't be flat.

radium98
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Re: FM Tuner with MPX Output

Post by radium98 » Mon Jun 27, 2022 5:15 pm


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