Can't get audio to pass thru DB25 on PM1500

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tskilbride
Posts: 24
Joined: Mon Jun 14, 2010 11:50 pm

Can't get audio to pass thru DB25 on PM1500

Post by tskilbride »

I'm using a Maxtrac as a receiver and a PM1500 as a transmitter. I can get the PM1500 to key up upon proper PL tone being received on the Maxtrac but it will not pass the audio. I'm using pin 11 on the maxtrac for the RX audio out and have feed it into pins 7 and 15 on the PM1500 without any luck. I also grounded the audio to pin 10 with a 2.2uf 50v capacitor inline on the PM1500. Also inline with the audio is a 5k potentiometer.

Tim
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HLA
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Joined: Mon Jul 11, 2005 8:15 pm
What radios do you own?: HT1550's, X9000's, CDM1550's

Re: Can't get audio to pass thru DB25 on PM1500

Post by HLA »

there should be a drop down box in the 1500 cps that will let you set it as a tx radio and it will show you what pins are doing what
HLA
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tskilbride
Posts: 24
Joined: Mon Jun 14, 2010 11:50 pm

Re: Can't get audio to pass thru DB25 on PM1500

Post by tskilbride »

HLA wrote:there should be a drop down box in the 1500 cps that will let you set it as a tx radio and it will show you what pins are doing what
Thanks. I will take a look around.

TIm
Jim202
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Joined: Sun Sep 09, 2001 4:00 pm

Re: Can't get audio to pass thru DB25 on PM1500

Post by Jim202 »

I am not sure you have the pin connections correct for your application. I have used the following with good success.

TXAH = 8

TXAL = 11

RXFLT audio = 9

GND = 10

You need to use a coupling cap in series with pin 8 to keep from shorting out the DC bias and also killing your TX audio. There are a couple of areas in the software you need to be aware of. In the radio wide selection, there is a "TX audio per mode" or something like that. Going from memory as I don't have the radio and software in front of me. In that window, about the middle of the page is the external mic gain. This is normally defaulted to AGC. If you need more gain, then uncheck the AGC and adjust the gain setting on the right side. It defaults to zero. It will go from a -12 to a +12.

Also in the GENERAL tab, at the bottom you will see an external TX audio input selection. If you get no TX audio from the external input, then select the other of the 2 selections. One will work and the other will give no audio.

On the RXFLT audio out of the radio, this is a fixed, squelched audio. It also has a DC bias on it so a coupling cap is in order. I have used a 1.0 uf cap with good results. The le4vel I think is in the order of about 300 millivolts.

Good luck on your endevors.

Jim


tskilbride wrote:I'm using a Maxtrac as a receiver and a PM1500 as a transmitter. I can get the PM1500 to key up upon proper PL tone being received on the Maxtrac but it will not pass the audio. I'm using pin 11 on the maxtrac for the RX audio out and have feed it into pins 7 and 15 on the PM1500 without any luck. I also grounded the audio to pin 10 with a 2.2uf 50v capacitor inline on the PM1500. Also inline with the audio is a 5k potentiometer.

Tim
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