Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
ESD Prevention Equipment ?




 
The AM Forum
September 20, 2017, 07:07:51 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: 1 [2]   Go Down
  Print  
Author Topic: ESD Prevention Equipment ?  (Read 5122 times)
0 Members and 1 Guest are viewing this topic.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 7499


"Let's go sailing, Tommy!" - Yaz


« Reply #25 on: January 14, 2011, 02:07:39 PM »

Very good additional info, Bob, thanks!

I like the step by step instructions.   No, I don't have a hygrometer, but will take a look on the web for a cheap one. This is relative humidity that you commonly see displayed by those meters hung on the wall, right?

Yep, the worst part about ESD is a partially damaged part and it then becoming intermitant or bad later on. That's all I need with this surface mount SDR stuff... :-)

T
Logged

“Remember, remember, this is now, and now, and now. Live it, feel it, cling to it. I want to become acutely aware of all I’ve taken for granted.”  -  Sylvia Plath

A Night in Tunisia:  https://www.youtube.com/watch?v=baMsQeQpUvw
W1RKW
Contributing
Member
*
Offline Offline

Posts: 4033



« Reply #26 on: January 14, 2011, 02:23:37 PM »

Yes, on the hygrometer/relative humidity meter.  Yes, like what's on one of those fancy barometers.  I have a couple of them, both electronic.  They're pretty close to each other, maybe off by 10% compared to the other but good indicators of what the humidifiers are doing. I suspect that if you're getting static from Yaz your humidity is low, probably in the 15% to 20% area even with the pot of water on the coal stove. But if you can get your humidity up to say about 35%, I think you'll be good and knock down any hint of static discharge.  That doesn't mean you've squelched it completely, just reduced it to an imperceptible level.  Yaz will be more happy too!

I try to maintain 35 to 40% relative humidity during this time because it makes it more comfortable in the living area and it protects not only electronic stuff somewhat but the wood in the house, especially the guitars. No zaps on door knobs either.  Liz complains occasionally of being chilled because I keep the temp around 65 to 67 but having a higher humidity makes it seem warmer in the space without having to jack up the thermostat.
Logged

Bob
W1RKW
Home of GORT. A buddy of mine named the 813 rig GORT.
His fear was when I turned it on for the first time life on earth would come to a stand still.
W1VD
Contributing
Member
*
Offline Offline

Posts: 401



« Reply #27 on: January 14, 2011, 03:42:39 PM »

A couple lessons learned over 30 years ago when low noise GaAsFET transistors were difficult to get in quantity and were still very expensive ...

Don't trust the soldering iron ground through the power cord. We used (and still do) Weller TC-202 soldering stations and add an extra ground wire between the base of the soldering station and a threaded stud installed in place of the wall outlet cover screw.

The connection between the replaceable tip and the 'barrel' that secures it can deteriorate and go open over time. It became SOP, once a week, to remove the tip and clean the areas where the two pieces meet ... as well as replacing tips before they became old and cruddy.

We built dedicated meters to measure the resistance between the tip and ground. The 'tip receptor' of the meter was located close to the cleaning sponge for frequent 'no hassle' ground verification.

Untold numbers of GaAsFET transistors have been spared an early demise  Smiley   
Logged

'Tnx Fer the Dope OM'.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 7499


"Let's go sailing, Tommy!" - Yaz


« Reply #28 on: January 14, 2011, 03:49:18 PM »

Funny that you would mention that, Jay.   When I tested my soldering iron tip-to-ground continuity, it was open!  I couldn't understand what was wrong cuz it was a metal to metal contact from the coller to the tip. But as you said, after pulling it apart and cleaning it, the connection returned FB.

I'm thinking of adding a wire that gets wrapped around the tip base and shunts this mechanical connection - or something like that.  Your idea of an on-the-fly tip resistance tester is clever too.

T

Logged

“Remember, remember, this is now, and now, and now. Live it, feel it, cling to it. I want to become acutely aware of all I’ve taken for granted.”  -  Sylvia Plath

A Night in Tunisia:  https://www.youtube.com/watch?v=baMsQeQpUvw
KA2QFX
Member

Offline Offline

Posts: 239

Mark


« Reply #29 on: January 15, 2011, 12:14:01 AM »

All good advice.  

Here's another little tip.
In a home shop environment I found that even with ESD safety devices in use their are often places where voltages can develop; synthetic clothing, plastic anything, carpets, tool boxes...  So in addition to the usual precautions before I start handling or working on sensitive stuff I liberally spray my floor, desk chair etcetera with "Static Guard". You know the stuff to keep your skirt from sticking to your panty hose.  Wink

It doesn't conduct per se but it does a lot to deionze the area and keep all the local surface potentials to a minimum.  I swear it's saved me a few times when doing service work in an environment that I couldn't control.  Especially if you drop something outside of your ESD comfort zone and have to pick it up.
Logged
K1JJ
Contributing
Member
*
Offline Offline

Posts: 7499


"Let's go sailing, Tommy!" - Yaz


« Reply #30 on: January 15, 2011, 11:21:46 AM »

Interesting on the panty hose spray, Mark. I'll check - I think the Huzman left a can of it around here somewhere the last he was here.... Grin

I was walking around the coal stove yesterday and was conscious of the little zaps I was getting off the rug. It certainly is a dry environment out there and I will be sure to run the humidifier with the door closed in the shack/work area.

Frank gave me a good suggestion. Whenever he approaches the workbench, he FIRST seeks out the main ground or cabinet and grabs it to discharge himself. When he works on the stuff, when getting into sensitive areas, he leans his arm or some part of his body on the cabinet ground.   That's a good habit to develop.

Well, I learned a lot here in the last day or so and never practiced any of this in the past. I can think of just one time I had a problem with my FT-1000D when I popped a FET while measuring it with a VOM.  I always have my test equipment grounded but it pays to think things out first. For example, when plugging in an external cable or even a board into the backplane, keep the contacts aligned as they go in. Nothing worse than missing the alignment and putting the wrong pins on the wrong places, even with voltages off.  Some circuits hold a charge for a long time.

T
Logged

“Remember, remember, this is now, and now, and now. Live it, feel it, cling to it. I want to become acutely aware of all I’ve taken for granted.”  -  Sylvia Plath

A Night in Tunisia:  https://www.youtube.com/watch?v=baMsQeQpUvw
W1VD
Contributing
Member
*
Offline Offline

Posts: 401



« Reply #31 on: January 15, 2011, 08:31:15 PM »

Couple more lessons learned ...

Best to have all equipment at the bench on one ac circuit. Sounds obvious, but when one runs short of power strip outlets avoid the temptation to run ac from another wall outlet ... especially one that may not be on the same circuit. 'Daisy chaining' another power strip is a better alternative.

It's a good idea to remove dc power to sensitive circuitry before swapping rf cabling - switching from a signal generator to an outside antenna, etc. Once the rf cabling has been changed reapply power to the circuit under test. One may determine later on that this isn't an issue ... but during the initial development phase extra caution is often warranted.       

 
Logged

'Tnx Fer the Dope OM'.
WA1GFZ
Member

Offline Offline

Posts: 11152



« Reply #32 on: January 15, 2011, 08:44:09 PM »

ESD is dealing with high voltage in reverse. ESD case you are the high voltage source and that poor little microcircuit is the guy with his hand in a pocket.
Logged
K1JJ
Contributing
Member
*
Offline Offline

Posts: 7499


"Let's go sailing, Tommy!" - Yaz


« Reply #33 on: January 15, 2011, 08:47:49 PM »

Jay,

How about the risk of switching antennas using a rotary antenna switch?  One time I had the MFJ 259 hooked up to the antenna switch common and blew the switching diodes in it when I switched. Those things can't take any static as you know.

I wonder if the SDR stuff will be at risk when I go from say, delta loops to low dipole, etc?  The FT-1000D seems to have survived it all these years.  I did read somewhere that the Mercury RX had some kind of front end protection limiting voltage to 5V, but not sure.

T
Logged

“Remember, remember, this is now, and now, and now. Live it, feel it, cling to it. I want to become acutely aware of all I’ve taken for granted.”  -  Sylvia Plath

A Night in Tunisia:  https://www.youtube.com/watch?v=baMsQeQpUvw
WA1GFZ
Member

Offline Offline

Posts: 11152



« Reply #34 on: January 15, 2011, 09:06:13 PM »

Tom,
Mercury does have input protection at the antenna. A high speed diode in series with a Zener. Then a second pair reversed. I polled to have the Zeners biased at a bit of current to make it very fast but that would have required a negative supply. HPSDR design guys have been trying to avoid using negative supplies. I suppose for the mobile and portable operators.
I change antennas all the time but do have a 6 dB pad at the input. I have the HPSDR on the KAZ loops.
Logged
W1VD
Contributing
Member
*
Offline Offline

Posts: 401



« Reply #35 on: January 15, 2011, 09:36:54 PM »

Quote
ESD is dealing with high voltage in reverse. ESD case you are the high voltage source and that poor little microcircuit is the guy with his hand in a pocket.

That's good Frank!

T ... Started out with a 3 dB attenuator in front of the Perseus but have since dropped down to 1 dB. Not sure what's inside the 'P' for protection but the relatively low resistance values of a 1 dB attenuator should be sufficient protection ... and it has worked well here over the past couple years. Don't always remember to disconnect antennas in time during lightning season, switch antennas with impunity and run kW transmitters on LF with the antennas mere feet apart. The ADC 'clip light' ocassionally lights indicating a BIG signal is present but so far 'no worries'.

MFJ ... dunno ...       

Logged

'Tnx Fer the Dope OM'.
WA1GFZ
Member

Offline Offline

Posts: 11152



« Reply #36 on: January 16, 2011, 01:03:35 PM »

I saturate my A/D all the time since there is an RF amp. I need the amp when on the loaded loops. I wish Mercury designers made the relay default position the 20 dB pad rather than the RF amplifier. This way there would have been additional protection when power is removed and antenna left connected by mistake.
Logged
Pages: 1 [2]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.077 seconds with 19 queries.