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Thread: ASTRO Spectra to Dispatch Console

  1. #1
    psteele35 No Longer Registered

    Question ASTRO Spectra to Dispatch Console

    I'm looking for information on connecting a Motorola (high power) ASTRO Spectra to our dispatch console at work. We are running an IPC (formerly Orbacom) dispatch console. Currently we have a Kenwood TK-790 interfaced via a CPI Tone Terminal Panel. We want to replace the Kenwood with an ASTRO Spectra. Any help would be great!

    Thanks in advance.

  2. #2
    Astro Spectra's Avatar
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    I've done this with the W3 remote mount Astro Spectra.

    I removed the W3 HHC mic from the original cable harness that connects to the LHS P5 connector and plugged it directly into the centre J6 connector on the Astro Spectra drawer and wired a new DB25P cable to have +12 on the IGN pin 3 and of course tied the EMER pin 13 to DIG GND pin 8. That way you can remove the HHC if you want and the radio will power up on whatever the last mode it was set to. The overall cable screen went to DIG GND pin 18 and the DB25 shell.

    For receive audio use DET audio on pin 9 with the screen to ANA GND pin 10. The DET audio might be a little low for the console, see how you go. You might need a small 600 ohm line amp to boost the hi-Z low level signal to 600 ohms and -10 dBm or whatever your console needs.

    For the COR I pulled the command board and jumpered the audio IC (special Motorola pin out version of the TDA7256) enable pin 10 (pin 1 is on the LHS of the IC) to J5 pin 16. This gives you a COR output, +12V on idle and gnd on receive. The idea for this came from Pyramid Communications and I think it’s better than trying to look at the DC voltage on the speaker leads.

    If you want a monitor speaker it hooks to pins 25 and 24.

    The transmit audio goes to MIC HI pin 12, screen to MIC LO pin 11, and PTT to pin 1. Again the overall cable screen went to DIG GND pin 18 and the DB25 shell.

    You will need to drop the 600 ohm console audio down with via pad to get acceptable TX level for the Spectra, a 1k pot should do it.

    Job done.
    Last edited by Astro Spectra; Mar 03, 2013 at 11:20 PM.
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  3. #3
    psteele35 No Longer Registered


    Sounds like a good job for our radio shop. I was hoping that I could get everything I needed from the 25 pin plug without modification to the radio. It is a W4 head by the way. We want to keep the control head so we can edit the scan list on the fly. But the radio for 99.9% of its life would basically be a scanner... We have 3 dispatchers (including myself) that are hams and we use that radio for some 2 meter repeaters. That's about the only transmitting that radio would do.

  4. #4
    Will No Longer Registered


    You can use the second DB25 connector to get RX audio, PTT and MIC.