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Protection Diodes

TonyV225

W9WDX Amateur Radio Club Member
Apr 18, 2005
5,824
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143
Wisconsin
What is a good all around common diode to use?? I know my 2510 took a 1N4005 and the Cobra 148 took a 1N4003 Will the 1n003 work for all Cobra Uniden Gallaxy RCI ETC???? Or what would you suggest ordering to be safe I am out of them and need to order more along with light bulbs for the radios S meters. I would like to buy everything from one place if I could to combine shipping and making one paymentany ideas would be grateful
 

Uh, your "diodes" link also shows the 6-Amp "6A1" rectifier. It's a far better choice, since reversing the polarity with the RIGHT fuse will still hammer a 1-Amp rated 1N400x rectifier. Even then you'll have a broken radio until the protection diode gets replaced.

We use the 6-Amp rectifier as an upgrade for all slip-seat drivers, as a 'permanent' replacement. Permanent until they reverse the juice with a 20-Amp fuse in line. Even then, the larger diode will at least stay in one piece when it shorts inside. The tiny 1-Amp rectifiers tend to explode when they wrap cig-pack foil around the fuse, or use a 20-Amp borrowed from the cig.lighter circuit.

The 6-Amp rectifier will survive when it blows the correct-size fuse with no damage. Much less aggravation the next time Joe SlipSeat is fumbling in the dark with his gator clips. So long as he has the correct fuse in line, the only damage is to the fuse, and NOT to the radio.

73
 
Nomad makes a good point but if you dont mind replacing the 1 amp it will work fine.They will both protect the radio.
For customers I can see why he uses the heavier diode.
I usually have 1,3 and 6 amp around.Mainly use the 3s and 6s in amplifier power supplies.73
 
Hey Tony,
The rectifiers that start with 1N4000 and go to 1N4007 are all the same 1-Amp rated rectifier, but with progressively higher voltage ratings. Pretty sure the 1N4000 is rated at 50 Volts, the 1N4001 at 100 Volts, on up to the 1N4007 at 1000 Volts.

Since they are all used in a 13.5-Volt circuit, any of those numbers will be interchangeable. What any one model radio has in it will be the one the factory got cheap that month. Since any of those numbers has a high enough voltage rating, the difference between a 1N4001 and a 1N4003 is negligible. They will both work exactly the same. So long as the polarity is correct, they will all stay turned off, no matter what the last digit in the type number.

If the polarity of the radio's power is applied backwards, the diode becomes a short-circuit. The normal 5-Amp (I think) fuse for a 2510 will take a short moment for the element inside to melt. During that short moment, the 1-Amp diode gets several Amps through it, while the fuse element gets around to melting. This overheats the diode inside, and melts the silicon junction that made it a diode in the first place. Now that little black part is a dead short for EITHER polarity, until someone replaces (or clips) it.

Now, when a new fuse is installed, and the polarity turned around right, the new fuse blows, too. That's because the 1-Amp diode committed suicide while doing its job. It prevented reversed-polarity juice from reaching all the expensive stuff in the radio, but died in the moment it took to blow the fuse.

If there's any chance you'll get the polarity backwards again, the larger diode will save you the aggravation of having to disassemble the radio and replace the protection diode again later. Assuming that you DO use the correct fuse, and don't put a 20 or 30 Amp fuse in line.

Sure, the original 1-Amp part WILL protect the radio, but only by getting "blown" itself.

In my situation, I worry that a frustrated slip-seat driver will wrap cig-pack foil around the fuse and explode the little 1-Amp diode, leaving the radio unprotected. The larger 6-Amp part won't do that. If you hook up the radio backwards with a 20-Amp fuse, the 6-Amp diode will overheat and short inside, but it won't explode. Might set his pants leg on fire if the power cord is draped across his lap, though.

73
 
Pant leg on fire LMAO. Ok namad i appreciate your help I knew what the diodes purpose was and how it works I dont have a problem with hooking these up backwards (reversing polarity ) But Theres alot of truck drivers who apparently do. I have a friend that drives for a big company and oh my lord i replaced a few lights for him and reset his radios on frequency along with adjusting audio ETC. well I now have a mountain of radios alot DOA that his coworkers are digging out and throwing at him and believe it or not most of them are polarity reversalsand I went through all my 4003 and 4005 diodes and need more thats why I asked if there was one diode that I could use other than ordering the specific number for each radio .I seen 3 different numbes in the same radio already lmao... I am thinking I will go with the 6 Amp diodes because Im sure these clowns will do it again. Thanks again Nomad you are a tremdous to me always and also thanks to the rest of you your all a huge help as well........Tony
 
oops one more thing I need S meter lights where is a good deal on these i looked at the link above and couldnt find what i wanted. I know cobra has those rubber gromets on there lights and i did find 10 lights for$13.00 plus shipping is this good or can any of you find better?? I want to order by tomorrrow so monday it can be shipped so what im looking for is some 1N4001 diodes to start with and I need 4 1000uf 25v electrolitic capacitors (arial lead) and 10 or more S meter light bulbs for cobra uniden Gallaxy ETC and some whte thermal greese for transistors. As I said I need this stuff this week I have alot to do and Im moving soon and also going back in under the knife due to my illness so I these projects out before then Thanks again folks
 

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