Relay Failure

[Naysayer]

I've never had any brand of these small relays fail, today was the first time.
It failed days after it was installed and the only usage was testing. Never left bench.
It was one of 4, I purchased on eBay from China. I had a 6v version of same relay and I installed it temp basis.
I know the 6v relay was genuine only time will tell if the remaining 3 fail or not. Changing pcb mounted relays is time consuming.

 

[sp5it]

Use relay sockets.
What failed? Coil or contacts?
Mike

 

[Naysayer]

This is what I found inside.
The failure was it would not do anything when coil powered.
It worked last night but today when I tested prior to taking to roof, it would not activate. Rated at 8A
Can see color diff btwn the 2. The dark one I know is genuine. Light colored 1 I got from PRC

 

[sp5it]

Why diodes are bridged with wire?

 

[Shockwave]

It's been my experience that these relays have a very low tolerance for heat while being soldered into the PC board. A little too much heat and it will melt the contact pin and shift it out of alignment enough to where it either does not make connection or makes one with a little extra resistance, causing heat which will eventually cause the contact to fail. They tend to test out perfectly on an ohmmeter, until after they've been soldered in. Very convenient...

 

[Shockwave]

Use relay sockets.
What failed? Coil or contacts?
Mike

It sounds like you have already found out that cheap versions of this relay work fine, right up until you try to solder their pins directly into a PC board.

 

[nomadradio]

We routinely clip away the unused pins from a DIP socket to match the hole pattern in the pc board. The socket serves to limit the heat stress on the pcb foils if the new relay fails down the line. The adhesive that holds the copper foil to the laminate will tolerate a finite number of heat cycles. Haven't had infant-mortality issues with DIP relays yet. Probably only a matter of time.

73

 

[Naysayer]

It was only 1 bad relay and never had a bad relay coil problem ever, that I can remember. My estimation of the total number of relays I purchased over my lifetime is somewhere 40-ish. Yet I learned something else about the factory relays mounted on the Preamp board. Specifically, the factory relay-pinout on the preamp board has the center pin(s) as common while the standard config that I usually see (like the Schracks or Omrons) has the end pin(s) common. So yeah, I had to remove the relay replacement I mounted (picture) before checking the pinouts. Mistakes happen and it's why I'm only an amateur but able to admit my error.

 

[unit_399]

I have also purchased many (similar) PCB relays, but never through Ebay. I use Amazon, because if there are problems, they refund or replace, no questions asked.

I buy 50 at a time and haven't had a failure yet. Only problem I had was that one brand wouldn't fit in the standard perf board hole spacing.

- J.J. 399

 

[Naysayer]

I neglected to note that the 2:1 antenna relay board works good. Far better than the large latching relay I was using. SWR nearly flat. I do not like that a relay coil stays energized all the time during use. Latching was a failsafe as 1 antenna would always be connected even when power was interrupted. Yet, so far no problems.

 

[Naysayer]

I abandoned the mast-mount preamp effort. The swr bump wasn't worth the small gain on Receive and signal noise. Plus, it would have been another set of relay contacts exposed to elements despite being inside plastic case. The affects from condensation during the few years the old relay was mounted was apparent.

So now I have an unused wire/pair going to mast-mount box. Pondering potential benefit a simple auto 12v bulb for heat inside case. Sounds trivial or downright silly but I'm near Ocean and NYC Winter's cause ice. Stupid idea? Easier to add the bulb than remove the wire. Or I could just leave it alone.

Speaking of removing excess wire: Now that my antenna ground is sorted out (Surge Protector outside), does that mean there is no need for a heavy ground wire running to radio control point? I can remove it?

neil, NYC