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Author Topic: Grounding station in 2nd story extra room  (Read 3303 times)
WD4ELG
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Posts: 875




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« Reply #15 on: February 04, 2013, 04:18:08 PM »

K8AXW, awesome post!   Grin
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KT4DLB
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Posts: 76




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« Reply #16 on: February 10, 2013, 03:05:46 PM »

This brings up a question on this ground too. I'm trying to start my shack and I'm going to use a MFJ-4601 Feed line thru to run my coax and grounds from radio thru. I had plan on putting a ground rod outside of my window and run the ground to it. Someone told me that I need to run the ground to the electrical ground and that's like on the other side of the house. I do have the three prong receptables that have a ground. What should I do to be right and SAFE?


73 Lamar
KK4NZO
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W9KDX
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« Reply #17 on: February 13, 2013, 02:59:55 PM »

After reading everything I possibly could here and elsewhere on the subject of grounding for lightning and external static, I set up a protocol where I disconnect the radio, amp etc. from any AC as well as the coax (at the entry plate)from the antennas at the end of every session.  

I have all the proper outside grounding and it is a bit more work but I sleep very well through all our summer storms.  Lightning may still impact my house, but nothing will touch my equipment.
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Sam
W9KDX
K8AXW
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« Reply #18 on: February 13, 2013, 06:15:50 PM »

NZO:  I'll probably get shot out of the saddle on this post but the way I see it your have a good plan.  As for the connection to the house electrical system ground, the three pronged plugs will have to do.  

I have the same situation in my shack.  The entrance panel is on the other side of the house and it would be a major problem to run a ground strap around my house to these service ground rods.  Not only that it would look like hell to boot.

KDX has adopted a protocol, as he puts it, that is right on the money as far as I'm concerned.  

I have a stainless steel box outside and about 6ft away from the house.  All of my antenna leadins terminate in this box.  When I finish operating in the summer, I disconnect the shack leadins, pull them out of the box and hang them in a housing away from the junction box.

My major pieces have heavy strap (RG-8 shield) that connect to a copper plate on the back of the desk which in turn goes through a very heavy copper wire to a ground rod outside the house.

I also have a master knife switch (old style AC disconnect) that isolates the gear from the AC power.

That's all I can do and if lightning gets to the gear, so be it!  I feel at some point enough is enough.
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KD8TGK
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« Reply #19 on: February 13, 2013, 06:39:25 PM »

Here's an interesting point, no-body mentioned a ground tuner. It is my personal understanding ( please be aware this my be flawed ) that if u have an excessively long ground lead it will radiate RF at various freq's. Reasoning for this: although it may be a sufficient D.C. safety ground it makes a poor R.F. ground due to length. Has anybody used the mfj-931 artificial ground, basically a LC circuit consisting of a tapped inductor and variable capacitor or home brew equivalent. The purpose of the LC circuit is to add/remove inductance/capacitance there by changing the actual "seen" impedance of the ground conductor to allow the r.f to flow to ground, ( in theory, im always confused by this point ) , which I believe helps to push any RFI to ground, and I also believe that it may be turning the ground lead into a counterpoise. I really dont know, Like I said I'm hardly an expert here and if anyone could clarify the use and or purpose of a artificial ground/ground tuner please do so. I only mentioned it because I have seen the advert's and home-brew versions, and if there was no purpose or point to making said ground tuner or if they did not work, I do not believe hams would home-brew meaningless equipment, As far as commercial companies go, they love to sell u meaningless junk, in the hopes that it breaks and you feel compelled to replace it! 73's KD8TGK
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K5LXP
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« Reply #20 on: February 14, 2013, 06:29:10 AM »

Here's an interesting point, no-body mentioned a ground tuner.

Because it wasn't in the scope of the ground question you posted about.

Quote
if u have an excessively long ground lead it will radiate RF

What about a "ground tuner" would change that? 

Quote
the actual "seen" impedance of the ground conductor to allow the r.f to flow to ground,

Here's the kicker - just because you drive a rod into the ground doesn't mean you have an infinite "RF sink", where all energy that arrives there just goes away.  Dirt is a pretty poor conductor and RF has skin effect, making the available area for RF to dissipate even less.  So even if you created a perfectly tuned transmission line to your "ground" it would still suck as an "RF ground".

Then, we have to consider just why you have, and would want all this RF to be dissipated rather than radiated.  You're hell bent on turning everything into heat.  If you have so much "RF in the shack" you have an *antenna* problem, not a "ground" problem.

Quote
if there was no purpose or point to making said ground tuner or if they did not work, I do not believe hams would home-brew meaningless equipment,

It's a very niche application and frankly, a solution seeking an appropriate problem.  You're going to find very few instances where a "ground tuner" is effectively used.


Mark K5LXP
Albuquerque, NM
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VU2NAN
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Posts: 248




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« Reply #21 on: February 14, 2013, 10:04:43 AM »

Hi OM Bill,

The main purpose of the main-supply-earth (third pin) is only to blow the fuse in the event of a live chassis fault.

Protection against static build-up / lightning strike is another matter altogether.
As a SWL in the mid-1970s, the antenna I used with a Philips transistor portable receiver was a long wire at a height of about 50 feet. One summer afternoon, the receiver front end blew right after a loud crackle of static was heard.

Then again, my first tube homebrew CW rig had a 3-pin mains supply plug. The antenna was a straight dipole 50 feet high. Operating on a summer afternoon, I received a jolt through my Junker CW Key and survived to hear the crash of thunder from a nearby lightning strike. I immediately yanked out the twin-line feeder and threw it on the floor (upper floor of my 2 storey house). After a few moments I was surprised to see the arc from the banana plugs to the cement floor.

Those days, in our sparsely populated area, my antenna was way above other surrounding structures. The static build-up on a 2m ¼ λ ground plane antenna would cause a whine in my 2m receiver, as it dissipated through the front end coil to ground.

Today, the conditions are totally different with my 2 storey house surrounded by high rises, cell phone towers and other structures with lightning arrestors. Problems of static build-up and lightning are a distant memory. I have not heard that static whine for years, even though I still use that ¼ λ ground plane antenna.

And I only have the mains supply earth (third pin)!

Of course, if you live in the country, the lightning arrestor at the feeder entry-point with a separate earth bonded to the mains-supply-earth is a must.

While on the subject of bonding – a friend’s shack and attached bath had a separate safety earth, not bonded to the house mains earth. His 2m antenna was mounted on a metal mast which was also separately earthed. For some reason the shack earth was open and the hot water heater also developed a ground fault. The path of the fault current was through the floating earth wire, his 2m rig, the coax feeder braid, antenna mast and finally to ground resulting in a coax cable fire.

73,

Nandu.
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