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Keying relay for amps using opto-isolator


Poorly made and bad design. The IC socket for the opto Isolator is a bad way to mount a part. Very sketchy I know from past experience that there will be problems in that socket. Corrosion will always foul the connections on the chip.
Those opto chips can be very temperamental while voltage is applied.
The president of of a company hired me to help him improve the reliability of his equipment that they designed and built from scratch.
The first thing I told him was to get rid of the chip sockets. They were under every single IC on the control board. At first he refused, I asked for permission to build one unit using the best commercial methods. He gave in and the only difference was no chip sockets.
It lasted 5 years and then it was retired for a more current technology oriented system.
 
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Reactions: Shadetree Mechanic and loosecannon
Using an optoisolator between a ham radio's keying jack and the linear's relay socket is a good way to protect newer radios from the high voltages used to key older amplifiers.

But for a carrier operated relay?

His explanation doesn't cut the mustard for me.

Then again if it works, it's a solution. Doesn't matter how elegant I might think that it is.

Or isn't.

A result is a result. If it's as reliable as he claims, more power to him.

73
 
I think it's a polished turd.

I don't see how it's any better than the keying circuit used in cb amps. He says it provides complete isolation between the rf signal and the 12v power supply, but that's never been an issue.

A better product would key the amplifier via a relay connected to the mic jack of the cb set. All of the chattering on ssb would be eliminated. Why that hasn't caught on is beyond me. I thought SSB guys are supposed to be smarter. ;)
 
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loosecannon said:
just found this while looking around on the bay, and it is the first time ive seen an opto isolator used for one of these.

https://www.ebay.com/itm/Keying-Rel...763358?hash=item3407b7769e:g:0dEAAOSwg-tcT1DA

cheers?
jeers?

is this idea used in any existing products i might recognize?
LC
Click to expand...
My first experience working with an opto coupler was with Perkin Elemer. We used this device in the late 1980's as the detector in the protection circuit used in an 8877 RF generator. The LED is driven by the grid and plate shunt resistors. Regardless of how bad the current spike might be in a fault condition, we never had any issue with the HV getting into the low voltage stages and destroying them after this.
 
Shockwave said:
My first experience working with an opto coupler was with Perkin Elemer. We used this device in the late 1980's as the detector in the protection circuit used in an 8877 RF generator. The LED is driven by the grid and plate shunt resistors. Regardless of how bad the current spike might be in a fault condition, we never had any issue with the HV getting into the low voltage stages and destroying them after this.
Click to expand...
Is that the PE unit that Pete Gagny designed?
 
BlowinSmoke said:
Is that the PE unit that Pete Gagny designed?
Click to expand...
I'm not sure who was credited with the design but it's the only one made with the 8877 just before going with the next version that operated on 49 MHz. using the 3CX1200D7. The first version didn't last long because the 49 MHz. frequency provided better results with the Gas Chromatograph Mass Spectrometer the RF generators were used in. Say that five times fast.
 

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