Does anyone know how to tweak the gain on the MRTI audio input path on an MTR2000? The manual indicated that it shares the local mic audio path, but I can't figure out how to adjust either.
Thanks!
Adjusting MRTI path gain on MTR2000
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Thanks Will.
I'm afraid that I had to walk away from this one for a while, (After disovering that an entire corner of my house needed an emergency rebuild
)
First things first: I'm not actually running a MRTI here. I'm using the MRTI port to return audio from a CDM750 via an i750r (for MDC generation)
Here are some things that I have thought about / considered / discovered on this one, so far:
1) The repeater is running narrow band, with companding enabled (it has to be enabled on the repeater because the link channel is wide-band). I don't know if the companding is throwing off the audio. The field radios, running through a Zetron 38 on the aux. audio path, sound great with the companding, and have plenty of level.
2) I am using pin 1 on the J7 MRTI connector to return the audio, and pin 2 for PTT in.
3) I metered pin 1 on J7, and found a +2.2VDC voltage on pin 1. Time for a blocking capacitor?
4) I'm seeing .2V P-P out of the CDM750on pin 11, when fed with 1KHZ tone at 60% deviation. Is this a normal level?
5) I currently have the i750r set for unity gain. If I crank it up to +12dB, I start to get some (but not enough) level, but the audio sounds like
, and seems to overload and drop out with actual TX audio instead of tone.
6) Being a good little audio type, and worthy of my HumHead handle, I only have one signal ground going to the MTR. Does the MRTI connector require a separate ground for any reason?
I think my next step will be a blocking capacitor on the audio line, but I am wide open to suggestions, thoughts, and input.
Thanks!!
I'm afraid that I had to walk away from this one for a while, (After disovering that an entire corner of my house needed an emergency rebuild
)First things first: I'm not actually running a MRTI here. I'm using the MRTI port to return audio from a CDM750 via an i750r (for MDC generation)
Here are some things that I have thought about / considered / discovered on this one, so far:
1) The repeater is running narrow band, with companding enabled (it has to be enabled on the repeater because the link channel is wide-band). I don't know if the companding is throwing off the audio. The field radios, running through a Zetron 38 on the aux. audio path, sound great with the companding, and have plenty of level.
2) I am using pin 1 on the J7 MRTI connector to return the audio, and pin 2 for PTT in.
3) I metered pin 1 on J7, and found a +2.2VDC voltage on pin 1. Time for a blocking capacitor?
4) I'm seeing .2V P-P out of the CDM750on pin 11, when fed with 1KHZ tone at 60% deviation. Is this a normal level?
5) I currently have the i750r set for unity gain. If I crank it up to +12dB, I start to get some (but not enough) level, but the audio sounds like
, and seems to overload and drop out with actual TX audio instead of tone.6) Being a good little audio type, and worthy of my HumHead handle, I only have one signal ground going to the MTR. Does the MRTI connector require a separate ground for any reason?
I think my next step will be a blocking capacitor on the audio line, but I am wide open to suggestions, thoughts, and input.
Thanks!!