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Author Topic: Wiring Ranger 5450Dx for digital  (Read 670 times)
TTOMAS59
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« on: September 10, 2012, 01:03:31 PM »


I am wiring a mic connector to use a Ranger 6 meter radio for digital modes. According to the diagram the mic has a dpdt switch. When the mic is keyed (PTT) the TX pin is shorted to ground and the RX pin is disconnected from ground. However if this were so the Rx would not work with the mic disconnected from the radio. It clearly does.

Seems to me just grounding TX key should be enough for PTT but I thought I would get advice first so I don't break the radio. Thanks for any assistance.

 Tim
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AC5UP
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Posts: 3955




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« Reply #1 on: September 10, 2012, 01:48:59 PM »

On most electronically switched transceivers (Translation: PIN diodes or similar, no relay) the mic is wired so the PTT is normally closed on the RX contact. Squeeze the mic and it switches from RX enable to TX enable, or at least that's the way I think of it. In a legacy rig with a T/R relay the PTT keys the relay which in turn does whatever is required to transition from RX to TX. You are correct in that most diode switched radios will not operate without the mic as neither RX nor TX will be enabled without it. I've worked on CB's that needed a jumper on the mic connector before the RX would open up.

Notice that I say "most" as I haven't worked with "all" and we both know there's an oddball in every crowd........

If the radio 'clunks' like a relay when keyed it's a safe bet that grounding the TX line is all you need do. If not, you could play it safe with a small 5 volt "TTL" relay that fits a 14 pin DIP socket. They're cheap, easy to find, and draw very little current so it doesn't take much of a transistor to key it. If you're going to build up an interface box between your TNC / Computer and the radio there should be enough room for the relay plus 5 vdc to make it play. The added relay will affect the T/R turnaround time very slightly but I'd think not enough to matter.
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TTOMAS59
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« Reply #2 on: September 10, 2012, 05:09:48 PM »

AC5UP,

Thanks for your response. I created the post since Ranger did not respond to my inquiries.
They finally did this evening and said the RX is switched over automatically and the TX pin to ground is all that is needed.  Thanks again.

Tim
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