| Author |
Message |
    
Snowman709
| | Posted on Thursday, May 08, 2003 - 1:30 am: | 
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i have a road runner roger beep and i was tring to wire it in a project box i made the box has different mic sokects in it so i could use different mics on my galaxy 44 and i wired the roger beep to the 4 pin socket and it worked when it was suppose to but it was like it was over modulating and squeling when i had the talk back off what can i do to stop it !!! could i wire it to the main cord that all my mic sockets go to and it work also the same as i got it wired to one !!! |
2600
| | Posted on Tuesday, May 13, 2003 - 12:00 am: |
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Hi Matt,
You pretty well have to use a metal enclosure to shield the beep board and the audio wiring. Same reason they wrap a grounded shield around the audio wire in the mike cord. Keeps nearby stuff from leaking onto the audio wiring. Using an external DC power supply provides and extra "back door" that RF can leak into and bleed the audio circuits. A battery inside the metal box takes care of this problem, but won't last long using a Road Runner beep. The relay is the real power hog, and will run the battery down before long. A Galaxy 44 doesn't really need the relay. It should be possible to remove the relay and hook the mike cord's transmit wire up without the relay, since that radio uses only pins 1, 2 and 3.
The Road Runner beep board I'm looking at right now has a small glass diode on the circuit board between the relay and the two pins marked "T" and "R" on the diagram. The diode has a black band painted on the end facing the edge of the circuit board. The OTHER end of the diode has no black band painted on it. THIS end of the diode is the hole where your "T" connection, hooked to the transmit (pin 3) wire leading to the radio will go. Remove the relay and the little glass diode. The hole where the BLANK (no band) end of the diode used to be gets the transmit wire to the radio soldered to it. The board will still key the radio, and should run from a 9-Volt battery at least as long as a power mike would.
If you look at the inside of the mike socket on a radio, you will see small capacitors and choke coils between the mike socket and the radio's audio circuits. The external beep will need similar parts attached to its mike socket, to filter any RF that may leak into the box through the mike socket. Likewise, the output cable that leads to the radio has to be filtered the same way where it exits the metal box.
Bear in mind that even after using a metal box, a battery and filtering capacitors/choke coils, it may behave ONLY when running barefoot. An amplifier will often "bleed" a power mike causing it to squeal or buzz. Likewise, external gadgets hooked to your mike audio are likely to have the same kind of trouble when running power.
Sounds like a lot more trouble than just putting it inside the radio.
73 |
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