More on HAM noise and MoCA

I think that I have located all of the sources of RFI in my house. Some are easy to solve, others are not. Here they are:
1 There is a touch lamp in one of the bedrooms that is generating broadband noise. It is easily solved by getting rid of the lamp.
2 There is a television in the living room that is causing noise that extends from 3.4 mHz all the way up to 9.8 mHz.
3 The most vexing is the fact that I have a service called “whole house DVR” that allows us to watch recorded shows in any room of the house. It does this by using a system called “multimedia over coax,” abbreviated as MoCA. Since there are three of these cable boxes in the house, any time two of the three boxes are powered up, they begin to communicate over the house’s cable lines. This is why it was so hard to track down. I am going to have to call the tech support for the cable company and see if they can help me out with calming down this noise.

HAM issues

I am having a problem with my HAM bands. There is quite a bit of RFI coming from my house. To begin with, there is a lot of noise on all bands below 30 meters. I managed to isolate that, it is coming from the LCD television in the living room. When the TV is turned off, the noise is gone. This means that I can only work the 40 and 80 meter bands when no one in the house is watching TV in the living room. I can live with that.
In the 20m band, it is showing up as an S8 on the signal meter most of the time, and this hash covers up all but the strongest stations. Here is the pattern:
–  turning off the circuit breakers to everything but the shack, it disappears and I get an S0-1.
– turning off one breaker at a time doesn’t get rid of it.
– Turning on all of the breakers doesn’t always make it return.
– When it DOES return, it starts at S3, and builds to an S8 over about a 30 second period
– The limits of the hash are from 10.6 MHz through 15.4 MHz.

This is driving me crazy. I think it is more than one piece of equipment.

Horizontal Loop

To end my posting about my HAM radio project, I finished up my installation of lightning protection this weekend, and spent the day yesterday installing my antenna. I have been experimenting with different antenna designs for the past few months. For this round, I bought myself a 500 foot spool of 14 gauge black THHN wire to make my antenna for $43 from Home Depot. I measured out 275 feet of wire, and ran it around the outer edge of the roof. I used hooks on the eaves to attach my insulating anchors, which are just short loops of parachute cord. I cut off the end, and this left me with a 260 foot antenna in a rectangular shape, about 10 feet off the ground. It is nearly invisible from the street.
I soldered the ends to a 20 foot section of 450 ohm ladder line, and attached the other end to a 4:1 balun. Antenna complete.
Do the math by dividing the number 1005 by the total footage of the antenna (260) and you get the resonant frequency of the antenna, 3.865 mHz. That means that I have an antenna that will resonate right in the center of the phone section of the 80 meter band. In theory, I have an 80 meter full wave horizontal loop. The problem here is that these antennas are supposed to be placed 30-40 feet above the ground. So we moved on to testing.
Receiving was greatly improved. Swapping back and forth between my old and new antennas, the difference was amazing. Frequencies that sounded dead with the old antenna had faint but readable signals. Signals that used to be audible but unreadable were crystal clear. I got a 3-4 S meter improvement in all bands.
Transmitting is amazing. The antenna works so well that I have disconnected my auto tuner. Hooked directly from the balun to the receiver, I get a 1:1 SWR in the 160, 80, 40, 30, 20, 17, 15, 12, 10, and 6 meter bands. That’s right: EVERY amateur band from 160 meters all the way up to the 6 meter band. Within 10 minutes of starting, I had made contact with the Hatteras Lighthouse 600 miles from my house.
For anyone that is a HAM operator, I would recommend trying this antenna.

On EMP and lightning protection

One of the things that we as preppers have to be prepared to deal with is a loss of communications. One of the ways that I have dealt with this is through HAM radio. There were some questions about my HAM radio setup and EMP protection when I posted about it last year. Now that I am back in my house, I have more options for making my radio systems a bit more hardened to EMP. Being that I live in the center of Florida, the lightning capitol of the world, this is a wise idea.
Some facts:

(If I am mistaken on any of this, there are some readers who are more knowledgeable than I, and they can feel free to correct me in comments.)
Lightning is an electromagnetic pulse that is pretty powerful, delivering an average of 18,000 amps to whatever it strikes. A lightning strike typically contains 2-5 pulses of electricity. The first pulse is called the leader, and it breaks down the resistance of the air as it heats it to 50,000 degrees F, changing it into a plasma state. This leader channel allows 3-4 more pulses to follow at 50 millisecond intervals. This is the reason why lightning seems to flicker.
The rapid rise of power with each pulse generates radio frequency energy at frequencies ranging from 20 kHz to 15 mHz. Unfortunately, this is the area where much HAM equipment operates, and it is thus vulnerable.
Where I live, we have an average of over 90 thunderstorm days a year. In my area, a 50 foot radio antenna will be struck an average of twice per year. This is why I have upgraded my EMP protection.


I spent the weekend driving copper ground rods. 6 of them in all. There are three, 8 foot copper ground rods just outside of the room that I am using as a radio shack. They are in a triangle, and spaced 10 feet apart. They are connected to each other, and to a ground bus inside of the shack ( I used a 3 foot long, 3/4 inch copper pipe), with a 1 inch braided grounding strap. All of the radio equipment, my computer equipment, power supplies, and all other electronics in the shack, are grounded to this bus. The radio tower  is also grounded to another ground rod array. The shield of the antenna cable is grounded at both ends. All of this grounding gives any pulses or stray energy a place to travel that doesn’t include my sensitive electronics.
The antenna feed line is protected with an arc plug. An arc plug is two electrodes hermetically sealed in a gas filled ceramic cylinder.
Acting like a voltage dependent switch, the Arc-Plug can repeatedly
carry large currents to ground for brief periods.

The idea here is to shunt dangerous pulses away from my equipment and harmlessly into the ground.I think this will do it.
The entire project of hardening this equipment cost me a weekend and about $250. As with most of my prepping projects, this one covered likely as well as unlikely threats, and was done for a reasonable cost. My electronics are now safe from the likely event of a lightning strike, and the unlikely event of a man made EMP attack.


High frequency on this HAM set is turning out to be more problematic and frustrating than I counted on. I have had this rig for a week, and still haven’t made my first HF contact. I tried to use a G5RV antenna, but all of the bands seemed dead. Then I figured the problem was that the antenna wasn’t optimal, so I looked for another solution.

I ran a coax to a 1:1 balun, and ran a piece of wire from that to the aluminum downspout outside of my window, and connected it with a sheet metal screw. The spout runs some 35 feet from the ground to the roof, where it connects to about 60 linear feet of horizontal gutter. Now, I receive some stations, but most of the bands are dead most of the time. Last night, I was receiving some traffic on the 18 meter band, but no one could apparently hear me.

So here I sit, trying to figure out what to do next.

I’m moving from this apartment in three weeks, and back into my house. I will have a bit of flexibility there. Maybe I will try to erect my Cushcraft R7 vertical there.

HAM geekery

So I got me a new rig: A Yaesu 897D. I put an autotuner on this thing, and I am using a G5RV jr antenna for the high frequency side. It took about 2 hours to get everything rigged up, and I was slowed down by some rain, so I have only been playing with it for about the past hour. With that said, I got it to tune up on 40, 15, 12, 10, and 6 meters. I am happy with it. Now to see if I can make a few contacts.

(I am getting the HF beacon in Atlanta at 50.065 mHz with it.)

HAM issues

I am studying to upgrade my HAM radio ticket from a Technician class to a General Class. One thing I want to do when I get the new ticket is buy an HF radio. I am wanting to get into the 20 meter band, so I next have to see what sort of antenna I can get in there.

The lot is 77 feet wide, and the house is 52 feet wide. I need to figure out an antenna that will fit nicely and be hidden behind the house, or perhaps something that looks like a TV antenna, so I don’t run the risk of neighbors running to the HOA and complaining.

EMP and prepping

In a comment to yesterday’s post, Robert Hewes asks if my radios are stored in a faraday cage. I assume that he is asking the question because he has heard of EMP, or electromagnetic pulse, and its ability to damage solid state electronics. I will explain why this should not be a concern for most preppers.
EMP works by exposing semiconductor components to voltages high enough to break down the semicondictor. There is nothing magic about EMP, it is simply a powerful radio wave in the microwave spectrum (4-20 GHz) with a wavelength between 1 and 5 centimeters. This pulse is subject to the same physical laws as any other form of electromagnetic energy. The two that you have to keep in mind are the fact that radio waves travel in straight lines, and that their energy dissipates according to the inverse square law.
EM energy traveling in a straight line prevents it from damaging anything beyond the horizon, and the inverse square laws say that energy drops off that the inverse square of the distance. An EM weapon capable of damaging electronics at half a mile would require 250 times as much energy at 60 miles.
To extend the reach of an EM weapon, you must either set it off relatively high in the atmosphere, thus extending the horizon, and you must greatly increase the power. Weapons that cause long range EM effects to semiconductors over great distances require a lot of energy. This is why nuclear weapons produce the powerful pulses that reach long distances, but not many others.
Couple that with the fact that radio equipment is hardened to withstand certain amounts of EM, due to their nature (they are built to receive EM, after all, they ARE radios, it’s kind of what they do), and the problem becomes even more difficult.
In short, I am not worried about it. There are many things that I can prep for, and EMP is not on the radar.

Random Quote of the day

There are more molecules in a glass of water than there are glasses of water in the ocean.

(If you doubt this, consider Avogadro’s number: 6.02 x 10^23. This means that for every 18 grams of water, there are 602 billion billion molecules. A liter of water weighs 1,000 grams, meaning that a 1 liter bottle of water contains  3.31 x 10^25 molecules.

The volume of the Earth’s oceans is about 1.4 x 10^9 cubic kilometers. That works out to 1.4 x 10^21 liters, meaning that there are more than 2,000 times as many molecules in a glass of water than there are glasses of water in the ocean..)

Hope I got all of the math correct.

Geek humor

My grad school class is filled with people who have a wide range of degrees: Pre-med, Chemistry, Cellular and Molecular Biology, and Psychology degrees are common. So I got a laugh when one of the students, complaining that a professor was rather long winded and boring, said: “I could feel my telomeres getting shorter.” Geek humor.