Articles for Amateur Radio Newsletters aimed at new hams
 written by Gerry Crenshaw, WD4BIS, Rowlett, Texas

 

 

NHP #13: R.A.C.E.S. Standard DC Connectors: Are they Good Enough?

Is the connector as used by R.A.C.E.S. and as recommended by the ARRL field service really good enough for today's higher-powered radios.?

There has been some continued discussion around the repeater and on the nets lately on the R.A.C.E.S. standard connector. This connector is the .093 pin, 2 circuit connector. Dose it have enough current carrying capacity.

The answer to this is "Yes". Please bear in mind when a manufacture makes a part and offers it to the public, he tends to be a bit conservative in his ratings. The connector from AMP and Molex is actually rated in several catalogs (Mouser, Digikey, Waldom) as 12 amps per circuit. Yet when you purchase this connector from Radio Shack in the blister pack, the rating is listed at 8 amps. This leads us to questions: is it the same part, and what is its rating?

Yes, it is the same part. Radio Shack does not manufacture them, but buys in bulk quantity and re-packs them for retail, small quantity sale. The Molex and AMP logos, can be found on the parts if you look with a magnifying glass. As to the mystery on the ratings, Radio Shack being a distributor and being somewhat conservative again, de-rates the part to 8 amps to limit returns.

What is the Amp Rating on this connector?

Tests done by myself and test data provided by N5TIM from his company's testing lab yielded some surprising results on this connector. Testing at 20 amps was normal, no problems with capacity or voltage drop. Testing at 50 amps was surprising: even after 100 connect/disconnect cycles, the connector carried the current and showed only 100 milivolts drop.

Failure modes in this Connector

This same connector was used in a power distribution panel for telecommunications equipment and we had reports of high failure rate on it. When the connectors were sent in for Failed parts evaluation the results again were surprising.

This was a "field install" part (meaning that the connectors were added in the field after the installer had cut the wires to length and dressed it in to the rack harness). Every failed connector we found was not a connector failure, but a failure to do a good crimp on the pin. In cases where the installer crimped and soldered the pin, not one failure that could be attributed to the connector (installer-caused reversed-polarity problems were not the connectors fault)

There are other questions about this connector such as wire gauge, strain relief and and insulation I would like to cover in another article, but I do hope that this relieves fears that this connector is not good enough for high powered mobile insulation.

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Copyright 2005 Gerald Crenshaw WD4BIS. All rights are reserved.

Permission in advance is granted to those who use this for non-profit Amateur Radio club newsletters as long as it is used unmodified including this copyright notice and that notice is given to the author via email (wd4bis@arrl.net). In addition, please forward a copy of any newsletter this appears in to: Gerry Crenshaw WD4BIS, c/o GARC, 1027B W. Austin St, Garland, TX, 75040

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