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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Tue 06, 2018 10:48 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11547
Location: North of Mpls, Minnesota
Quote:
I have a tower along side the back of my house with its own ground rod separate from the electrical service ground rod. The 2 rods are about 15 feet apart and in clay soil. After reading posts here about electrical code I'm now curious to measure the AC voltage and/or resistance between them. But, all of my antennas on the tower have no electrical connection to the tower. So the only grounding that happens is when I screw the coax on the back of a boatanchor radio that uses a 3 prong power cord. So if there was some differential voltage between the 2 outside grounds I'm pretty safe from it since no coax shield is connecting between them.


Lar H wrote:
forumuser, That's a good installation. It's electrically safe and in compliance with electrical codes.
Regards, Larry

Sorry but that is a very unsafe situation and is NOT in compliance with the National Electrical Codes. All your ground rods have to be connected . Seems everybody has to learn the hard way. I had 50 ft of RG-8 explode, 2 radios destroyed and some other damage. I had a ground rod on the antenna tower which was not connected to the house ground rod. Insurance company would only cover the damage if I agreed to take the tower down. I found another insurance company that would cover me only if I used poly phasers on the installation and it had to be inspected the the electrical inspector.
You can do what you want but don't suggest to others bonding is not necessary, putting your family's lives and home at risk is not worth it.

Dave


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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Tue 06, 2018 10:52 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11547
Location: North of Mpls, Minnesota
Deleted: Double post.


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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Wed 07, 2018 1:23 am 
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Joined: Apr Thu 12, 2007 3:24 am
Posts: 1405
Location: Milwaukee,WI
What exactly happened to trigger your explosion? Was this when you connected up radios and coax for the first time or was it later on when something failed somewhere?


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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Wed 07, 2018 1:39 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11547
Location: North of Mpls, Minnesota
forumuser wrote:
What exactly happened to trigger your explosion? Was this when you connected up radios and coax for the first time or was it later on when something failed somewhere?

It was a lightning strike on my tower.


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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Wed 07, 2018 1:44 am 
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Joined: Apr Thu 12, 2007 3:24 am
Posts: 1405
Location: Milwaukee,WI
So are you saying if your rods were connected things would have been better? I would think its hard to know for sure when it comes to lightning strike's power. Or just that insurance hassles would have been less?


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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Wed 07, 2018 2:46 am 
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Joined: May Sun 13, 2012 8:12 pm
Posts: 10478
Location: Central PA 16801
Lar H wrote:
Steve, Nice long wire. Sounds like it works quite well. I read through all your postings you pointed to and just had a couple questions:

1. Is your ling wire terminated in any way?
2. How high is it? I know you said it started at your roof eve.
3. Did you try it without your large ground field and with just a small one next to your home instead?

Regards, Larry


1. no, but i buil this box that connected between the radio and the antenna at the radio as seen below. it was my static bleeder box.

2. 50-60 feet or so

3. when the ground field was eliminated, both long wave and medium wave (regular AM / USA Broadcast Band) signals were cut in half or more and noise increased incredibly.

if you want a good copy of the circuit as shown below, pm me with your personal email address.

put "static box" in the subj line so i don't kick it out.

steve


Attachments:
Antenna Static Box Small.jpg
Antenna Static Box Small.jpg [ 17.03 KiB | Viewed 622 times ]

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I am not responsible for any damage, injury, or death from any content / advice in this thread.
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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Wed 07, 2018 4:03 pm 
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Joined: Dec Mon 18, 2017 12:19 am
Posts: 63
Location: Jefferson, WI 53549
Chas wrote:
creinemann hasn't responded in a week...



Work get's in the way of fun too much. Thank you all for the advice. I will check the antenna impedance on my radio(s) and am looking into a balun as part of the long wire antenna. Just had a heavy snow yesterday, so, that'll delay stringing it up till it's safe.

Carl

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Carl Reinemann
1953 Dodge M37 &M101 Trailer
WWII Crosley SCR-284
Assorted WWII military radios


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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Wed 07, 2018 8:59 pm 
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Joined: Apr Thu 12, 2007 3:24 am
Posts: 1405
Location: Milwaukee,WI
Sorry for the lame drawing but I figured it would be better than nothing.

After a little more research I see its also a requirement that every line of coax needs to be connected to a grounding block outside. That means the 5 coax cables from my tower will be grounded together at this block and then this block will have a 10 foot long wire running to the tower ground rod. Then of course the tower ground rod will get connected to the house power ground rod 15 ft away. Now, the other ends of the 5 coax cables will be connected to radios with chassis that are grounded again to the electrical system with 3 prong cords. Sounds like I'll be creating 5 ground loops between the 5 radios and the outside grounding block. Add to that the hassle of having to cut all 5 cables to install a total of 10 connectors and 5 couplers. Arg. What about antennas with ladder line instead of coax? Can't ground the ladder line.

P.S. I would also loose my totally isolated from ground antennas which comes in handy when connecting to tube radios with only 2 prong cords or absent-mindedly connecting to a transformerless radio.


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GROUNDLOOPS.jpg
GROUNDLOOPS.jpg [ 51.14 KiB | Viewed 587 times ]
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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Wed 07, 2018 10:15 pm 
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Joined: Sep Thu 01, 2016 3:56 am
Posts: 191
Location: San Jose, Ca.
My apologies to all. I was wrong about the grounding requirements for a tower in the NEC. Dave is right. Thanks for posting the correct info. It needs to be bonded to the main electrical ground for the home with a #6 AWG or larger as part of the lightning protection design. Lighting arresters are also required.

Regards, Larry


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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Thu 08, 2018 4:59 am 
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Joined: Feb Sun 17, 2008 11:36 pm
Posts: 1928
Location: Dayton, Ohio
When this was discussed once before, I believe it was Curt Reed brought up the safety and insurance codes that, as I recall, forbade grounds other than the power safety ground at the circuit panel.

Until recently, the gas pipe to my furnace was fed by steel pipe and went through the earth ground all over the neighborhood. The furnace blower motor got its ground by way of the A.C. power line. Seems like a contradiction, I don't remember if a tower was mentioned in the original discussion.

The BC-348, as I recall, has a "high impedance" antenna input. I can't lay hands on my manual at this moment to see if it is mentioned there.

Charlie


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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Fri 09, 2018 2:55 am 
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Joined: Oct Tue 11, 2016 4:41 am
Posts: 113
Location: USA
Quote:
Sorry but that is a very unsafe situation and is NOT in compliance with the National Electrical Codes.


Does the NEC specifically cover SWL and amateur radio towers, antennas, and grounding? If so, does it specifically require that such stations be connected to mains ground?


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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Fri 09, 2018 10:16 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11547
Location: North of Mpls, Minnesota
https://www.seapac.org/documents/semina ... 0Radio.pdf

Dave


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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Sat 10, 2018 5:24 am 
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Joined: Oct Tue 11, 2016 4:41 am
Posts: 113
Location: USA
Dave,

Thanks for posting the link. Some of what is discussed in that presentation seems like good ideas. Others seem unnecessarily burdensome. At least a couple, like mandatory wire size for antennas and minimum distance of an RF radiator from a structure go well beyond the scope of electrical safety, in my opinion.

Brad K4RT


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 Post subject: Re: Longwire antenna and Radio Receiver Grounding questions
PostPosted: Mar Sat 10, 2018 6:42 am 
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Joined: Sep Thu 01, 2016 3:56 am
Posts: 191
Location: San Jose, Ca.
The SeaPac document looks like a good one, but keep in mind that it's based on the 2011 NEC. That is not good or bad as different states 'adopt' different levels of the NEC at different times. Take a look at this map maintained by the NFPA:

https://www.nfpa.org/NEC/NEC-adoption-a ... ption-maps

The following link will 'down load' a good document (about 10 MB) by Mike Holt (he teaches NEC classes) on the Article 810 part of the 2014 NEC about transmitting and receiving antenna grounding (this is applicable to SWL's and ham's). The relevant part is at the end:

www.mikeholt.com/download.php?file=PDF/ ... 014NEC.pdf

Regards, Larry


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