[MRCA] 4 pin power connectors...foiled yet again!

[Ray Fantini]

If I were you I would use two separate power supplies , one for each radio. One big power supply may be an issue. Something about sags and glitches on the power bus, think I saw something in a book once. But that’s just me and I am not you.
Ray F

-----Original Message-----
From: mrca-bounces at mailman.qth.net [mailto:mrca-bounces at mailman.qth.net] On Behalf Of W2HX
Sent: Thursday, September 13, 2012 3:02 PM
To: mrca at mailman.qth.net
Subject: [MRCA] 4 pin power connectors...foiled yet again!

Arrgghh! 

Last we visited our hero; he learned that there was an old style 4 pin military connector and a new style connector and never the twain shall meet.  Armed with that knowledge, I thought for sure I’d have this licked! No such luck ☹  

I’ve been trying to power two radios using a Harris power supply (RF-5051PS) that has 2 “new style” 4 pin female MW connectors on it.  One radio is a Harris RF-5020 and the other is my RT-1439/PRC-119 connected through the MT-6352.  Up until now, I’ve never had the right cables to connect both radios at the same time. The cable I would need to do this has one male new style connector and one female connector. That would allow me to connect the sincgars radio to the second connector on the Harris supply.  

So in the meantime, I have been forced to use two separate power supplies, one being the Harris to power the Harris RF-5020 radio and another being a Chinese 120VAC to 28VDC power supply. At the output of this one I put on some Anderson power poles (black/yellow).  

To power the Harris radio, I used a cable supplied by Harris having the new style 4 pin male MW connector on one end and an MS series circular on the other that mates directly to the radio…works FB, all is good.  

Separately, I would power up the RT-1439/PRC-119 (through the MT-6352) using a cable I had, CX-4720. This cable has a 4 pin female “new style” connector on one end and 4 wire pigtail on the other end. The cable came with the four wires paralleled down to 2 wires. Two wires soldered together in a pigtail and labeled (+) and two wires soldered together in a pigtail and labeled (-). The labels were “official” yellow things so I believed them.  To these combined wires, I attached two Anderson power poles to connect up to the Chinese power supply.  And the sincgars worked FB.  

Today in the mail arrived some new cables I purchased to allow me to connect the sincgars to the Harris (male 4 pin to female 4 pin). This cable is CX-13303 and boy was I excited to get this all running.  I connected everything up, powered on the harris power supply, flipped the switch on the MT for the sincgars and … nothing. Nothing at all.   How could this not work? How hard could it be to make this all work!?!?!?

So I began checking the cables and connectors. Here is what I found… The Harris power supply pins are:
A and B carry (+)
C and D carry (-)

Then I checked the cable I’d been using to power the sincgars and I discovered:
(+) is connected to B (only, no other pin, why two wires?)
(-) is connected to A (also no other pin, why two wires?)

So clearly you can see why it didn’t work. What the heck?! Can someone tell me, ___is there a standard?___ If so, what is it? Is it the sincgars set up or the Harris power supply set up?  And totally unimportantly, but why parallel 2 wires for each pole on the sincgars connector if only one pin is actually used for each pole?

And to complete the picture, here is the pinout for the cable I bought CX-13303:
A=A
B=B
C=C
D=not connected (?why-strange).

So what should I do? Theoretically, I could rewire one of the CX-13303 cables (and put a huge label on it that it is customized). This could be hard, these are thick, stiff cables and the connectors look impenetrable (I think there is a ring to remove). Alternatively, I could rewire one of the Harris  connectors and likewise, mark it CLEARLY.

Arrghhh! Why can't things as simple as +24V and ground be simple!

73 Eugene W2HX
</RANT> 

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