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[aprssig] Re: APRS Standard Connectors?

Neil Johnson Neil.Johnson at erudicon.com
Thu Dec 1 01:47:21 UTC 2005

Be careful about feeding power through the DB-9 connectors.

I had a radio that provided +12V on it's accessory connector. I fed it 
through my TT3 to power my GPS.

I was programming the TT3 using the radio to power it. When I went to 
plug back in the cable that went to the GPS, I blew a fuse in the radio.

I had managed to short two pins on the male DB-9 with the outer shield 
of the female DB-9 connector. I know I should have powered everything 
off before reconnecting the GPS, but it would have happened sooner or 
later since the TT3 case doesn't have room to put screws and nuts on the 
DB-9 connectors and the GPS cable falls off a lot.

Unfortunately, the fuse is soldered to a PCB inside the radio, so I will 
have to find the right part and re-solder it. Fortunately it didn't fry 
the GPS. I haven't had time to test the TT3, but I worried it is fried too.

I guess I wouldn't recommend the DB-9 as a standard connector.

Neil Johnson

Chris Kantarjiev wrote:
> Standard connectors? To what? From what?
> There doesn't seem to be any hope of a standard connector set at the
> radio end; I've given up on that. When I modify an old radio to 
> bring connections out, I use the Kantronics DB-9 'standard'. 
> That's very convenient because the OpenTracker/TinyTrak world
> has adopted it. Put the cap/resistor network for your HT's PTT in
> the DB-9 shell so you can eventually connect another radio to
> the device without having to restore the missing resistor.
> At the GPS end, I use a DB9 again. The OT/TT folks put +12V on pin
> 4.  I needed +5, didn't want the chance of misconnecting and didn't
> want to count on putting a regulator in the device's shell, so I
> put +5V on pin 8. I declare that the new APRS standard. :-) 
> For random power connections, I use PowerPoles. But Anderson doesn't
> really supply a very good solution for chassis mounting them, which
> still boggles my mind. (You can get pairs, or quads, but a single
> connection requires a whole lot of fiddling to do well with the
> little retainer plates.) Not to mention that they're not particularly
> robust or dustproof. I liked the Molex 'standard' power connector
> better.
> The coaxial power connectors are fairly horrible if you need 
> more than 1A; some of them are rated at 0.5A. That's not
> very much power (not even enough to transmit 5W). Someone already
> mentioned the problem with shorting during connect/disconnect.
> The great thing about standards is that there are so many to 
> choose from.
> 73 de chris K6DBG
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