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Solid-state relays

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Author Topic: Solid-state relays  (Read 7542 times)
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Posts: 1962

Making AM GREAT Again!

« Reply #25 on: October 13, 2011, 10:46:32 AM »

I like the guys that when they don't speak, you hear nothing...  Silence on Slop, just silenced carrier on AM.

Then the noise gate gets broken with speech and all hell breaks loose, sounds like the blower noise from a 208-10 Collins.

And no, I really don't like it, but it's an interesting effect.

Contributing Member

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Posts: 10062

« Reply #26 on: October 13, 2011, 12:20:51 PM »

The antenna change over relay alone is one of the major offenders.  It really makes quite a loud snap when it engages.

Same here.  I once used a Dow-Key relay, but the Gates burnt it to a solid block of charcoal before I addressed the relay sequencing problem.  So I pulled out this buzzardly pre-WWII antenna change-over relay I picked up at a hamfest probably decades ago, n.o.s., still in the original box.  The coil is 110V, and the thing is constructed like a transformer core.  Engages with a clank, plus the coil buzzes from the a.c.  It worked well, with plenty of margin, but the noise was unbearable.

I fixed it by mounting it inside a hinged wooden box I had on hand, and mounting the whole thing on the wall.  The relay is suspended on springs, and the springs are fixed to the box using rubber grommets. When the door is closed, the buzzing is inaudible, and the "clank" is reduced to a benign "thump" that is barely audible at the operating position.

* Wooden box.JPG (1145.77 KB, 2576x1716 - viewed 178 times.)

* Spring mount.JPG (1153.33 KB, 2576x1716 - viewed 195 times.)

* Relay.JPG (1156.04 KB, 2576x1716 - viewed 193 times.)

Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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This message was typed using the DVORAK keyboard layout.

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Posts: 11152

« Reply #27 on: October 13, 2011, 02:57:51 PM »

why not run it off DC. Most 110VAC relays work well at 28VDC and they don't buzz

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« Reply #28 on: October 17, 2011, 12:55:34 AM »

MOVs have a limited life span and die in two modes leaky or kabooom ...

It is true that MOVs don't last forever. But that's no reason not to use them. :-)

I've installed hundreds of MOVs--large and small--in the past 30+ years. I am absolutely convinced they are worth using.

Last place I worked, I installed MOVs on many solid-state devices that used to regularly fail during a lightning storm. It reduced those failures to zero.

The only time ever I saw MOVs go up in flames ("kaboom" mode) was when the end-user applied 480 volts to a 120 volt circuit -- after he installed the biggest slow-blow fuse he could find. And somehow, the MOV (along with the vaporized circuit board traces) still protected the circuit.

73 Mike 
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Posts: 3489

« Reply #29 on: October 18, 2011, 10:42:12 AM »

There used to be a ham in Freehold NJ who installed MOVs on all his appliances in the house.

House burned down after an MOV set the guts of a TV on fire after an electrical tormenta.

Moral: enclose MOVs.
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