station grounding - who's right?

in another thread the hot topic was what TX performs better than the other but the topic of grounding kept coming up. what's legal? what's not? the opinions where everywhere, some of which didnt make any sense.

so here's what i found... the fcc says we must not exceed 3m total length of antenna and ground connection.

so with that in mind we all know of at least one manufacturer using the lightning protection ground loophole yet others are afraid to use it? why?

i did a little research and radial lightning protection systems are industry (and goverment) accepted as can be seen by the following citations. the second being NOAA docs on protecting buildings from lightning.

the logic seems to be a capacitively coupled radial grounding system is more efficient than a ground rod at dispersing a strike. they also cite that its better to use thin wide copper ribbon than thick standard wire due to surface area. there is also mention of lightning protection radials in the NFPA code book.

so there's no reason i cant put my TX in a box at the top of a mast, ground that mast for lightning protection and connect my equipment ground lead to my lightning protection "system". being thourough in my fear of lightning i employ both rods and radials as does NOAA.

yep, its a fine line as we all know whats incidently happening. it is one that you can explain and show citations of it being a commonly accepted form of lightning protection until someone comes up with wireless lightning protection. it's no different really than putting up your TX on the roof of a building and making use the ground lug on the power cord.


radio8z's picture

This topic became so contentious a few years ago that any mention of grounding was banned from this site.  This illustrates that there are many opinions on this by many people all of whom insist that they are right.

You are going to have to gather information and form your own conclusion.

I have done so and my opinion is just opinion.  If one considers why the FCC would limit the total length of the antenna, transmission line, and ground lead then one can conclude that it is because these radiate a signal.  The power radiated depends on the current amplitude and the length of the current carrying conductor.  The current is essentially limited by the power limit and the length limit sets the maximum length of radiating conductors.

Any conductor connecting the transmitter circuit ground to the earth will have a RF current and will radiate, a fact that I have confirmed experimentally using a loop antenna as a pickup.  If the FCC's intent is to restrict the length of radiating conductors then any electrical connection from the transmitter circuit ground to the earth will be included in the 3 meter limit, be it a wire, a mast, a building girder, etc..

This is the information from which I have drawn my conclusion and it is offered here for consideration.



RichPowers's picture

Radio8z's conclusions make perfect sense in respect to the part15 rules. It is indeed an obviously correct interpretation by all accounts.

That said, it has also proved obvious that numerous inspectioning agents have noted installs not meeting the specific requirements and let it slide..  It's a very flakey situation, ain't it?

Rich Powers Part15, Take 2..

Carl Blare's picture

The comments made in this thread have so far centered on what has been called a "ground lead" which is any wire from the bottom of a transmitter to earth-ground.

My fuss is that I believe the term "ground lead" is not true... the correct description should be "negative leg of a medium wave dipole" with the antenna above the transmitter being the positive leg.

But it IS non-compliant regardless of the name because it radiates no matter what it's called.

I'm thinking about buying time on national television to get the word out.

Carl Blare

RichPowers's picture

"But it IS non-compliant regardless of the name because it radiates no matter what it's called."

Carl, somehow you sound like Bill Clinton... But that depends on what your definition of "is" is.

Rich Powers Part15, Take 2..

Carl Blare's picture

What you say is interesting.

We all have an opinion about what a ground-lead is.

Is should probably be spelled "iz".

Carl Blare

Thelegacy's picture

 Carl and I were discussing on TeamSpeak at the Alp be meeting that Carl and I were discussing on TeamSpeak at the Alp be meeting that if you took a piece of coax and you had a 10-foot piece of metal for the hot side and then you took the shield and connected it to a 10-foot piece of metal and had it on the lower side you would have a dipole. To make it legal you would have to cut those two sides in  half so you would have 5 feet up and 5 feet down. It would equal 3 meters and it would be ian AM dipole.


 so I wonder what the so I wonder what the effectiveness of an AM dipole would be? Just have a 5-foot piece of metal for the hot and a 5-foot piece hanging down your transmitter.


Now that range master transmitter we saw on YouTube if that thing was getting out as far as it did Sitting on the top of a roof that thing is pretty interesting.


 it is it is only my opinion but if you're near a radio Market that is huge I think they're going to be stricter on you then if you're out and about a little bit.

Progressive Rock (Album Rock, Deep Tracks), Classic Rock

More Power for Hobby Broadcasters

ke4mcl's picture

you know in reading this thread i just realized another item of abuse and user misrepresentation... the audio feeds to the tx.

going back to the TX on the pole. the small TX's i have seen all have the audio input ground at same potential as the rest of the ground connections on the board. i need to get the audio from the "studio" to the TX dont i? ok. what's the sheild on my audio feed doing? aha.. yep..

there's so many loopholes i think your best bet is just be nice to the guy if he ever shows up, keep your antenna and TX legal, have plausible explanation for your lightning protection.

i'm in the process of relocating my part15 AM to the center of the yard and going with the lightning protection radials.

radio8z's picture

If, as is common in most transmitters, the power ground is common with the circuit ground then the audio and power ground lines can also radiate.  This may or may not be a problem for an inspector but it is something to consider.

When I designed my transmitter I had a problem maximizing the output power to the antenna.   Essentially, the maximum power happens with a 100 ohm load yet I knew my antenna impedance would be about 30 ohms.  There are networks which can perform an impedance transformation but they also introduce loss.  I decided the best and simplest way to transform the 30 ohm load up to 100 ohms at the transmitter output was to use a small toroid transformer.  This maximized the power available to the antenna with only a few milliwatts of loss but it gave an additional benefit.

The transformer isolates the circuit ground from the RF output ground so RF does not appear on the audio/power ground lines.It also breaks the ground loop which results with a grounded transmitter and grounded power and audio source.

Though the transformer was not intended to stop unwanted radiation and ground loops it was a nice afterthought to realize that it did so. I don't suggest that all transmitters be modified or built this way specifically to stop unwanted radiation  but if someone wants to design their own then this is something to consider if for no other reason than to gain the highest power delivered to the antenna..



RichPowers's picture

"..there's so many loopholes i think your best bet is just to be nice to the guy if he ever shows up.."

That is so so true, and it makes it pratically impossible to have a 100% compliant 15.219 install. It's also crazy that the most plentifully utilized and most established Part 15 certified transmitters in existence Talking Houses that have been around over 40 years have never actually conformed to 15.219 to begin with!

But that's apparently the nature of part 15. It's a crazy thing. But when I hear proclamations of acheiving in excess of five miles with an elivated ungrounded 100mw transmitter, and indicating it's 100% legal -- When even when our licenced 10watt TIS cousins can't acheive that range.. Well, excuse me, but that's total nonsense.

I really don't care what someone is doing with their installs, but when it's nonchalantly expressed that it these incredible ranges are being acheived, and it's all kosher and legal with the rules of part 15 -- That really bugs me, cause it's not right, and it deceives potential newcomers into believing it's true, and jeapordizes the part15 hobby.

Do you realize that it's in the works for the FCC to recrute licensed broadcasters as members of the present formulation of "tiger teams" for combating the pirate problem?.. It's not going to be a matter of the severly understaffed agents being unable to cover all these areas anymore. While the primary focus is for the FM, it's reasonable to conclude some of the excessive range "part 15" AM broadcasters will be swept up in the net as well.

Expressing "legal install" with 5 and 6 mile range (with just a single transmitter) is just setting newcomers up for a fall. It's deceitful.

Rich Powers Part15, Take 2..

Carl Blare's picture

Rich Powers said:  "When I hear proclamations of acheiving in excess of five miles with an elevated ungrounded 100mw transmitter and indicating it's 100% legal ... Well, excuse me, but that's total nonsense."

I got to thinking about this and remember that many people have the easy habit of guessing distance. Some of these reports may be based on estimates out of left field with no real measurement.

Not long ago I had to look up how far a mile actually is... 5,280-feet.

With 2-radials my AMT5000 reaches about 1,000 feet, so I suppose that adding more radials could get up to a mile or slightly more.

If I hadn't looked it up I might make a wild guess that 1,000 feet is "about a mile".

Still, some of the reports of super-distance might be true! It's kind of fun to wonder about it.

Carl Blare

RichPowers's picture

Also, as so frequently pointed out it depends just as much on the receiver.. I don't know but it's my understanding that most AM car and home radio reception don't hold a candle to the ones of yesteryear - and then there's the questions of whether the receiving radio is indoors or outside, the amount of powerlines, buildings, trees, and other signal interferences, and of course the ground conductivity.. humidity even, and any other number of other factors.

5 miles may be possible with all factors in perfection, but it certainly is not commonplace with a legal install.

Rich Powers Part15, Take 2..

jimhenry2000's picture

I certainly agree about the "Radios of Yesteryear".  As a teen in the early 60's and a AM BCB DX'er I would often go outside and fire up my Dad's 1957 Chrysler, or 1947 Chevy convertible to DX.  It was great back then and I logged AM BCB stations all over the country.Not so much nowadays.

Jim Henry HBR Radio 1610, serving Honey Brook, PA. and NW Chester County.

ArtisanRadio's picture

Back then, there wasn't the same level of background noise that there is today.

Never mind the fact that the electronics in modern day cars introduce far more background noise.  You don't even have to turn the car on - just insert the key (if you have one) and listen to the whines etc. that are introduced.  It got so bad on some Fords that they did a recall to reduce some of the noise.  Not on my car, unfortunately (stations that I can listen to with nary a crackle or whistle at home on cheap radios are virtually unlistenable on my Ford Flex).

So, I don't think it's entirely the fault of the radios.

Radioham's picture

seems the best suggestion so far is bake some cookies when the feds arrive and greet them with cold lemonade cookies and a smile because depending who's on duty that day will depend on if you get cited for whatever violation they want to gift...Play it safe and use a Mr microphone :P


Joe the radio dood


AM 1680 KOIW Old Time

wdcx's picture

Says a range of 1 to 2 miles is possible. They never claim what some have as 5 to 6 miles.

Druid Hills Radio AM-1610- Dade City, FL. Unlicensed operation authorized by the Part 15 Department of the FCC. We do not censor free speech and hide public information.

wdcx's picture

Background noise for Part 15 devices was mostly non-existent then.

Druid Hills Radio AM-1610- Dade City, FL. Unlicensed operation authorized by the Part 15 Department of the FCC. We do not censor free speech and hide public information.

Radioham's picture

would anyone like to talk about radials now >>??<<

I still believe hoist that transmitter to the tallest tower and hook an audio line and a power line and use about 60 rf chokes to demonstrate your not trying to allow your cable to radiateJOE THE RADIO DOOD


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Northeast Region

Detroit Office

24897 Hathaway St.

Farmington Hills, MI 48335-1552

October 9, 2014

(Sent via Certified Return Receipt Requested and First Class U.S. Mail)

Steven Cherry

Hamtramck, Michigan


Case Number: EB-FIELDNER-14-00013074

Document Number: W201532360001

The Detroit Office received information that an unlicensed broadcast radio
station on 1610 kHz was allegedly operating in Hamtramck, Michigan.
October 1, 2014, agents from this office confirmed by direction finding
techniques that radio signals on frequency 1610 kHz were emanating from
your residence in Hamtramck, Michigan. The Commission's records show that
no license was issued for operation of a broadcast station on 1610 kHz at
this location in Hamtramck, Michigan.

Radio stations must be licensed by the FCC pursuant to 47 U.S.C. S 301.
The only exception to this licensing requirement is for certain
transmitters using or operating at a power level or mode of operation that
complies with the standards established in Part 15 of the Commission's
rules, 47 C.F.R. SS 15.1 et seq. The field strength of the signal on
frequency 1610 kHz was measured at 30,000 microvolts per meter (uV/m) at
40.7 meters, which exceeded the maximum permitted level of 14.9 uV/m
(24000/1610) at 30 meters established in Section 15.209(a) of the Rules
(See 47 C.F.R. S 15.209(a)). Thus, this station is operating in violation
of 47 U.S.C. S 301.

Another exception for some transmitters operating in the 510 kHz to 1705
kHz band is found in

47 C.F.R. S 15.219. Specifically, Section 15.219(b) of the Rules states
"the total length of the

transmission line, antenna and ground lead (if used) shall not exceed 3
meters" (see 47 C.F.R. S

15.219(b)). The investigation by this office determined that the ground
lead itself was longer than 3 meters, thereby, increasing the total
length of the transmission line, antenna, and ground lead well beyond 3
meters. This installation violated Section 15.219(b) of the Rules.

You are hereby warned that operation of radio transmitting equipment
without a valid radio station authorization constitutes a violation of the
Federal laws cited above and could subject the operator to severe
penalties, including, but not limited to, substantial monetary fines, in
rem arrest action against the offending radio equipment, and criminal
sanctions including imprisonment. (see 47 U.S.C. SS 401, 501, 503 and


You have ten (10) days from the date of this notice to respond with any
evidence that you have authority to operate granted by the FCC. Your
response should be sent to the address in the letterhead and reference the
listed case and document number. Under the Privacy Act of 1974, 5 U.S.C. S
552a(e)(3), we are informing you that the Commission's staff will use all
relevant material information before it to determine what, if any,
enforcement action is required to ensure your compliance with FCC Rules.
This will include any information that you disclose in your reply.

You may contact this office if you have any questions.

James A. Bridgewater

District Director

Detroit Office


Excerpts from the Communications Act of 1934, As Amended

Enforcement Bureau, "Inspection Fact Sheet", March 2005




AM 1680 KOIW Old Time

RichPowers's picture

That's very similar to other AM citations, nothing odd about it. I can only make an assumption since the deatails are vague, but I get no impression at all that it is making reference to the use of ground radials - I think it's logical to conclude that it is an elevated system with a long ground wire running down to the earth

Case in point, TIS systems also are limited by a total legnth requirement, but ground radials are optional (though advised), and not considered as part of the total length of the system.

Rich Powers Part15, Take 2..

Radioham's picture


AM 1680 KOIW Old Time

ArtisanRadio's picture

The reason that the FCC limits the length of antenna systems (including ground lead) is to limit field strength and therefore range, which limits interference.

I don't think that you're going to be able get away with claiming 5 miles of range, while at the same time also claiming you're legal.  The maximum theoretical and practical range (from experience) of a legal (ground-mounted is the only way to be sure) Part 15 AM transmitter is 1-2 miles to a sensitive (likely, car) radio.  And that's for an excellent installation, with either radials or great soil conductivity.  You'll also likely get less range to cheaper, deafer, portable radios.

If you have an elevated install, you can never be sure that something else other than your 3 meter antenna isn't radiating.  If you're getting much more than that 1-2 mile range, then you can be pretty sure that something else IS radiating.

Pretty simple, actually.

Carl Blare's picture

I keep trying to think of ways that station operators could declare such large distances as we have sometimes heard and I thought of another way.

Measuring the diameter of the circle from edge to edge might add up to 3 or 4 miles!

Of course the transmitter is in the center of the circle therefore the measure from the antenna to the outer edge would be 1/2 of the diameter of the entire circle.

In a circle of this size there are many many square feet! What huge number would that be?

Carl Blare

Radioham's picture

he was running a 40 foot tower 

with a ground wire from Hamilton 

Straight down to ground so about 40ft 

ground wire to a ground rod not a radial field etc 

ken said his average was 4-5 Miles 

now he's doing lpfm and quit am 

But he believes he was able get out

so Good by his forty ft ground wire

 And being 40 ft in air ...

joe the radio dood 

1680 am KOIW


AM 1680 KOIW Old Time

jimhenry2000's picture

Carl, One of the reviews I just read on the Procaster web site, the user claimed exactly that, his range claim was double the distance he went to one point of reception.

Jim Henry HBR Radio 1610, serving Honey Brook, PA. and NW Chester County.

RichPowers's picture

The 40ft water tower was only the most extreme violation of KENC, he actually had 3 (or was it 4?) Rangemasters spread throughout the town all broadcastinging at the same time.. another was on the roof of the football stadium, and another somewhere else - there's nothing questionable about doing that, except that everyone of those transmitters involved extreamly long grounds.

As for to your previous comment: "anything other than 3 meters is cited"

 "The 3-meter combined length specified in Section 15.219(b) refers to the length of all radiating elements"

Rich Powers Part15, Take 2..

Carl Blare's picture

The role of "ground" becomes even more awesome when we consider the several ways of having "virtual ground" by ignoring the earth and putting it up in the air.

Two ways exist of raising the "ground" up above the ground.

Elevated radials work and are legal, as we've discussed... legal because if done according to good engineering do not radiate;

The negative half of a dipole antenna establishes a virtual "ground in the air" as no further earth attachnment is required except for lightning safety. Problem is with only 3-meters to work with a dipole antenna in the medium wave band would be no more effective than a 3-meter antenna with no ground at all.

No matter how RF ground is achieved, the 3-meter limitation dooms the results.

Carl Blare

spareparts's picture

"15.219(b)). The investigation by this office determined that the ground lead *itself* was longer than 3 meters..."

So on a site built to meet Motorola R56, with the shelter on top of the tower*,  with the grounding lead between the transmitter and the common ground bar being shorter than 3 meters that's OK?


*A steel fire watch tower.

Carl Blare's picture

I see your point spareparts.

This may be one of those cases where the FCC's own language in their NOV or NOUO does not literally match the wording of the part 15 rules.

It has happened before and always leaves us in a swirl of uncertainty.

Dealing in such small measurements... 3-meters broken up into several parts... I often wonder if the FCC takes it so seriously.

It is likely that they have "room for error" in the way they measure the small bits, and maybe can "adjust" their judgement based on whether they "approve of" the operator and his station.

Carl Blare

Rich's picture

SP wrote in Reply 27: .. So on a site built to meet Motorola R56, with the shelter on top of the tower*,  with the grounding lead between the transmitter and the common ground bar being shorter than 3 meters that's OK?

     *A steel fire watch tower.

The issue here is that an RF ground does not, and cannot exist at the top of a conductor or other metallic structure that extends above the surface of the earth -- even though the base of that conducting structure is buried in the earth, and/or bonded to an elaborate network of buried radial wires or cold water pipes or ground rods.

Therefore connecting a short wire defined as a "ground lead" from an elevated transmitter to the top of those conductors does _not_ provide an r-f ground for the transmit system.

In reality, that short wire PLUS the length of the conductor it connects to all become part of the radiating length with whatever conductor is attached to the antenna output connector of the transmitter.

With apologies to the many readers who have seen this before, below is a simple illustration showing the basics of this type of installation. 

The ~ vertical red lines there show the total length/height of the setup that is a radiating part of the antenna  system.


wdcx's picture

I accept your apology.

Druid Hills Radio AM-1610- Dade City, FL. Unlicensed operation authorized by the Part 15 Department of the FCC. We do not censor free speech and hide public information.