Lightning Protection Recommendations

Polyphaser!
Thats what we use at all base site / repeater locations.
http://www.protectiongroup.com/PolyPhaser
Edit: heres a direct link to what youd want
http://www.protectiongroup.com/Surge/RF-Lightning-Protection/Frequency/1-5-to-400-MHz-lightning-protection

Indeed the polyphaser is a great choice....if your using a coax like for the TH and it's external ATU.

But for a common 15.219 system which has no coax..it would have to be installed between the TX output and loading coil input.

They do work though!

RFB

Just to note...

Various manufacturers make such devices for this purpose, but they function only when the voltage on the protected conductor exceeds a certain, relatively high threshold voltage referenced to a very good "earth ground."

Such high voltage is present on such a conductor only for a very short time (milliseconds), during a lightning strike nearby.

Otherwise that conductor ~behaves as if that lightning protection device was not there.

So, if such a protective device is installed in the path from the r-f ground (chassis) connection of a Part 15 transmitter through any long, conducting path leading to a ground rod (or similar), that protective device will NOT de-couple such a path from radiation during normal operation of that transmit system.

This may be of concern to those who want to comply with FCC §15.219(b).

Polyphaser it is then 🙂

Which products should I be looking at from them? Big catalog.

Looking for a PL259 or standard coax product from them for upper side of AM band.

RFB wrote: But for a common 15.219 system which has no coax..it would have to be installed between the TX output and loading coil input.

Don't some Part 15 AM transmitters already include a gas discharge, transient protection device just upstream of their r-f output connector, and after their internal loading coil?

Just curious. then, as to why RFB suggests that an outboard device such as the "polyphaser" installed downstream of that connector is a great choice.

Mr Rich wrote:

"Don't some Part 15 AM transmitters already include a gas discharge, transient protection device just upstream of their r-f output connector, and after their internal loading coil?

"Just curious. then, as to why RFB suggests that an outboard device such as the "polyphaser" installed downstream of that connector is a great choice."

I think it's obvious Mr. RFB was talking about transmitters lacking the gas discharge device, which would be the majority of transmitters.

Just prior to that post member rich wrote:

"So, if such a protective device is installed in the path from the r-f ground (chassis) connection of a Part 15 transmitter through any long, conducting path leading to a ground rod (or similar), that protective device will NOT de-couple such a path from radiation during normal operation of that transmit system.

"This may be of concern to those who want to comply with FCC §15.219(b)."

You can get back to your enforcement check point in a minute, but I happened to read over on another site that you have owned a part 15 FM transmitter that was subjected to a compliance field test and found to be obedient.

It would be interesting for the audience here to learn of that experience, and a description of the model involved.

The main goal of lightning protection is to keep the dangerous voltages and currents associated with a strike outside of buildings and not necessarily to protect the outdoor equipment.

For my ham antennas I ground the coax shield at the point of entry to the house main electrical ground stake and only connect to my radios when they are in use.

For my part 15 AM outdoor unit, the circuit ground lead is also grounded to the ground stake at the point of entry. At the transmitter there is a gas discharge tube connecting the antenna lead before the loading coil to the buried radial system and to a bare wire in the soil.

Years ago there was a direct strike to a tree located 12 feet from the house and the building ground stake and some phones and modems were taken out but the radio equipment had no damage. There hasn't been a nearby strike since I installed the AM system so it remains to be seen what will happen with this.

ETA: You could connect one of these from each lead going to the outdoor transmitter (audio and power)to the ground lead and to the building ground at the point of entry.

Member blare wrote: I think it's obvious Mr. RFB was talking about transmitters lacking the gas discharge device, which would be the majority of transmitters.

"Mr. RFB" has shown himself quite able to present his point of view by himself.

However I believe that at least two of the three most-popular AM broadcast band transmitters now FCC-certified for unlicensed use include that internal gas-discharge device for lightning protection.

So that is most of them, unless other knowledge is presented.

As far as the "duh" remark is concerned, psychology studies have determined that rudeness tends to be answered in kind.

What a priori rudeness are we talking about? The continual and non-stop flapping in our faces of the rules when the entire under-current and title of this website contains the part 15 rules in the collective unconscious.

In other words -- the part 15 rules go without saying.

An enforcement stance is reminiscent of one time in Germany that seems to be arising in the Homeland even in small hobby websites.

Now what about your FM transmitter?

@radio8z:

"ETA: You could connect one of these from each lead going to the outdoor transmitter (audio and power)to the ground lead and to the building ground at the point of entry."

Any idea of how those should be installed inline? Should I just cut my wire (in this case ideally CAT5) and install them literally in line?

Any gotchas or problems doing that @radio8z?

Good looking recommendation and the price is impossible to beat at 85 cents each.

"Don't some Part 15 AM transmitters already include a gas discharge, transient protection device just upstream of their r-f output connector, and after their internal loading coil?"

Are you actually trying to contribute to this thread with that or....

"Just curious. then, as to why RFB suggests that an outboard device such as the "polyphaser" installed downstream of that connector is a great choice."

....just trying to hijack another thread with useless counter points?

But to balance out your point that throws this whole thing off track, it was someone else who suggested the polyphaser. I merely agreed with their suggestion to the point that it is a good device to use...for some of those transmitters which do not have a gas discharge transient protection device, and there are plenty of such devices which do not have that.

"However I believe that at least two of the three most-popular AM broadcast band transmitters now FCC-certified for unlicensed use include that internal gas-discharge device for lightning protection."

Does that mean every single unit out there because of two out of three popular ones?

"So that is most of them, unless other knowledge is presented."

How so? How is two out of three units sporting discharge protection mean that it is "most"? Do you have other knowledge the rest of us is unaware of that supports that statement..say a record of who uses what, where and what is inside their units?

I think someone needs to discover there is a much wider real world and the abundance of choice that exists.

Tip...Google is your friend. It can be anyone's friend irregardless.

RFB

"I think it's obvious Mr. RFB was talking about transmitters lacking the gas discharge device, which would be the majority of transmitters."

Yep. Thank you Carl. I am quite positive most quickly picked up on that and that I did not have to connect the dots.

"Mr. RFB" has shown himself quite able to present his point of view by himself."

Sure can. So please do not try to inject my point of view with divide and conquer or misleading and redirecting irrelevancy. I can speak for myself..and I believe I just have...twice.

Now..back to the subject. Please don't hijack threads. Shame I have to be the one telling you that and not the appropriate ones here.

RFB

Getting back to the OP's question and this thread's intended direction after it being diverted with irrelevant, space wasting commentary, here is another neat little suggestion for lightning protection.

It follows the same principle as the big AM towers do, except much smaller scale.

One method that big AM broadcast towers use is what is called "Ball Arc Gaps", which are spaced very close to each other. One spark ball is electrically connected to the radiating tower, and the other is electrically connected to a ground rod or rods. These arc balls are spaced accordingly in relation to the transmit power level present on the tower so as to prevent arc-over from the high level RF energy, but close enough to do their thing during a lightning strike. Excellent reference to this can be found HERE in PDF format.

And THIS is a third installment PDF written by Barry Mishkind, includes two photos. One photo of the arc ball system and another photo of a different method used for lightning discharge.

You can scale that down and use a small engine spark plug. Attach a small L bracket to the radiator at it's base. Screw in the spark plug so that the "spark" end, or tiny gap end faces the radiator. Then connect the other end, which normally connects to the ignition cable, with a 6 AWG or larger solid copper wire and run that to a ground rod. Tap the spark plug gap so that it is about 0.15 using a common spark plug gap tool which can be obtained at any auto parts store. This neat little add on to your 15.219 antenna can also help with static build up on the radiator and discharge it through the spark plug.

Wala a scaled down ball arc gap system!

RFB

"Any idea of how those should be installed inline? Should I just cut my wire (in this case ideally CAT5) and install them literally in line?"

They would be connected by electrically connecting one end of those to each wire, and the other end to ground.

RFB