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Thread: Astro Spectra audio and PTT problems

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    Default Astro Spectra audio and PTT problems

    Hi there all,

    I have recently bought a 110W VHF Astro Spectra radio. From the serial number, I have figured out that it was manufactured in the first quarter of 1996. So it is a very very old kind of Astro radio. It has the 512k Vocon board. Its HOST firmware is amR05.04 and the DSP version is I04.02.11 (VSELP).
    When I first turned on the radio and tried to use it, I have noticed some very strange popping coming from the loudspeaker. I have somewhere read that all of the Spectra radios had capacitor problems and they could leak after some years, causing heavy damages to the radio itself.
    I opened the radio's housing and a very stinky smell came out....yepp....leaking caps! In the RF PA unit, the leaking was so serious, it damaged the PCB panel itself. I could replace all the SMD capacitors and repair the damaged PCB in the RF PA unit. I have also replaced the caps in the W9 control head.
    Now the radio works fine, I can program in, it receives well and transmitts as well. It can do maximum up to 167 Watts on a dummy load. Nice little radio. But the popping in the audio didn't disappear in 100%. It is not so loud, it is very hard to recognize the popping, I have to listen very carefully. I can only hear it when I turn the volume down, below level 3 or 2.

    Is it possible that the leaking capacitors have somehow damaged the audio PA IC, but it still works?

    And I wanted to attach an external desktop mike to the radio using the front panel D25 connectors. There is a 'MIC HI', a 'GND' and a 'PTT' pin on the connectors. I have properly soldered a mike onto it, but when I pushed the PTT, nothing happened.

    Is it possible to attach an external mike to the radio? I don't want to connect it to the control head because I don't have a spare Mic connector.


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    I moved your post to the ASTRO forum.

    Leaky caps in the Spectra is always a bad situation. Sometimes the caps can be replaced and the problem is fixed. But if the caps have caused board damage, you will have permanent problems and will likely require a new command board. (You can find them in the Q-split ASTRO Spectras for cheap)

    You can attach a mic to the radio. I would get a mic. Here's one for $18 from Lau, in China. Trusted seller.

    http://www.ebay.com/itm/USED-OEM-Mot...item2eaebe607f

    Others are selling mics for as cheap as $5.99, but they do not ship outside of USA because they're lazy.

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    Thank you very much for the mic link I'll take a look on it, but I want to connect the mic to the front of the radio, not to the control head. Because my control head is on the shelf near the radio and I want to use the mike at the other end of the room, independently from the W9 head.

    The caps only made some damage at the RF PA Stage. In the radio's command board, there was no leaking. I have replaced the caps there for sure.


    PS:

    I also have an analog VHF 45W Spectra which acts really strange. I have replaced all the caps but it has the popping sound in the audio and the audio volume is very low and the modulation of the mic is very very low to. Is it an audio PA damage?

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    Quote Originally Posted by HA5BRG View Post
    Thank you very much for the mic link I'll take a look on it, but I want to connect the mic to the front of the radio, not to the control head. Because my control head is on the shelf near the radio and I want to use the mike at the other end of the room, independently from the W9 head.
    Try plugging into the Key-load (KVL) port on the front of the radio brick. It should work. I worked on a W9 a few years back and I think I was able to use the KVL port with a 1080A mic. Give it a try.

    I also have an analog VHF 45W Spectra which acts really strange. I have replaced all the caps but it has the popping sound in the audio and the audio volume is very low and the modulation of the mic is very very low to. Is it an audio PA damage?
    Some yahoo probably grounded out one of the speaker leads. Can't do that in the Spectra. The audio PA is likely blown or damaged. Can't say for sure, as I'm not working on your radio, but that would be real good start -- especially if you say the caps have already been replaced.

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    I can't put anything into the KVL slot, because I don't have a spectra type microphone connector. That is the most reason I want to connect the mike into the front panel D25 connector. So that's not possible?

    I'll bring the radio to one of my friends who has the lab equipment to repair two way radios. Maybe we can find the problem of the audio stage too.

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    Quote Originally Posted by HA5BRG View Post
    I can't put anything into the KVL slot, because I don't have a spectra type microphone connector. That is the most reason I want to connect the mike into the front panel D25 connector. So that's not possible?

    I'll bring the radio to one of my friends who has the lab equipment to repair two way radios. Maybe we can find the problem of the audio stage too.
    You said you have a 110W ASTRO Spectra.

    The HIGH POWER BRICK, has a keyload port on the brick. It should be in the upper-left corner (going on memory here..), on the same side of the radio as those DB-25 connectors.

    The KVL port should be covered by a rubber cover. Again, going on memory here. I don't have a high power ASTRO Spectra in front of me.

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    See the KVL/mic port? To the right of the power connector.
    Attached Images Attached Images

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    Yes I can see the KVL connector, near the power connector, on the right side of it. I have the same connector on my radio at home, but the KVL cable is a straight one and the spectra type microphone connector is "L" shaped. But as I told you I don't have any kind of connector what fits into the KVL or mic socket, so I can't connect my microphone. That's the second reason why I want to use the front panel D-SUB25 connectors. Is it possible or not? Because there is a PTT and GND pin....but it doesn't respont when I connect them. When I short these pins on the back of the W9 head, the radio transmitts normally.

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    Oh and something else:

    I have successfully repaired the popping audio sound coming from my analog Spectra. It was a faulty ceramic SMD capacitor in the microphone amplifier line. A simple oscilloscope and a volt-meter could solve the problem

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    No offense, but stop being a ham. Invest the $15 and buy yourself a mic for the radio, instead of spending hours and hours trying to figure out the DB25 connector and talk about it on the a forum all day.

    A mic is $15. It will solve your problems.

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    There are some jumpers on different interconnect boards that may affect ptt, but most of those schematics are Motorola secrets because they have a keyload port on them.

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    I have modified the jumpers on the command board to enable the PTT line and the MIC HI line on the front panel D25 connector. With a digital multimeter, I have successfully figured out that there is a physical connection between the front panel D25 and the command board inside the radio. But tha radio still won't transmit when 1 connect the D25's pin 1 to pin 18 or the radio chassis.

    One of my friends' Astro Spectra can do that. It is the same trunk mount 110W configuration.

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    Check for jumpers on the CH interface board. Some mid power units need a jumper moved for the ptt input to work.

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    Here comes the interesting part: I have already did that