Radio Check: Repeaters & Range Testing

As I discussed in my previous article, I successfully installed a much larger antenna for my HAM radio base station, but due to my schedule I wasn't able to really flex my HAM muscles outside of a few basic tests: the SWR for the new antenna was good, and I was able to connect to a few repeaters slightly outside of the range of my old mono-pole mobile antenna. So, this week I hopped on Chirp and went about testing the full power of the upgraded station. 

Using Chirp, a programing application for radios and scanners, I downloaded lists of repeaters within 25, 50, and 75 miles of my location in northeast Ohio. Chirp is a great resource for HAMs and radio enthusiasts, as it allows users to download lists of frequencies from a variety of sources which are updated daily and filter based on your preferences. I used the query source from RepeaterBook, a listing of all known HAM repeaters in the United States and abroad, and pulled in all the repeater frequencies for the 2 meter and 70 centimeter bands on which I'd be transmitting. Chirp provided a list of more than 100 repeaters within listening range of my station, their sub-audible tones and general information about their locations. I began going down the list, which stretched across most of northeast Ohio on into Pennsylvania, and made radio checks for each repeater, to see if I could get a "hit" or hear a response. The image above shows a sampling of repeaters I  hit while testing. The range of my station alone, without the additional boost of a repeater's relayed transmission, is more than 50 miles, so I was quite happy with the result.

If you've already read my previous articles, you'll know that repeaters are automated transceivers HAMs use as relay points. They use a "duplex" receiver and transmitter to listen for transmissions on one frequency then beam them out on another, often across a much farther range than what the original transmission would otherwise carry. Because repeaters are always in the same location, and often have courtesy tones, or beacons, which let listeners know their transmission has been heard, they make ideal testing frequencies, rather than using a person-to-person "simplex" frequency where another person must be present to hear and respond to a radio test. Transmitting to a repeater also increases the chances that another HAM operator will hear your radio check and respond with feedback about their location and how well they heard you, which is really exciting! 

The task however, like a lot of work in radio and signal testing, is a long and somewhat tedious process. For one, while RepeaterBook strives to keep their record as up-to-date as possible, some frequencies are bound to be out-of-date, repeaters may only be re-transmitting at certain times, and others may not have a tone or beacon which will clearly confirm that you've hit it. In may ways, the testing process is like walking blindfolded, until you find something. But, finding something is quite rewarding when it happens. It's always great to hear the "beep", Morse code beacon, or recording from a newly discovered repeater and recording a new active frequency in your log. Below is an example of a repeater response from W3LIF near New Castle, Pennsylvania. 

Sometimes I stumbled across a conversation, or a full-blown "net" which is kind of like a HAM radio call-in show, with people who check-in and talk at scheduled times each day. Sometimes, the same group of people will keep in touch via nets regularly for many years. One net I stumbled across while testing had 47 HAM operators check-in on one night, so the HAM community in northeast Ohio is alive and well.  

But, by far the most rewarding experience, is connecting one-on-one with other people. In my first week of testing I connected with a handful of individuals, from Wadsworth to Youngstown (Home of the YSU Penguins), who heard my transmissions and responded to my radio checks. Not only is it great to make a new contact, it's good to know that your transmission was heard loud-and-clear by a real person in a certain location. Most of the time the other HAM operator is happy to spend a few minutes providing feedback on your signal. For example, they can let you know if your signal is clear or garbled, to give you an idea of whether you can transmit with low, medium or high power to reach a certain location clearly. My particular radio can transmit at 50 watts, which at full power, uses a considerable amount of energy and can even make the radio and antenna hot to the touch, or even interfere with other devices near the transceiver -like a Bluetooth stereo. (FYI: a ferrite choke will limit interference like this even at high power outputs. That's the answer to question G4C08 on the General License exam question pool, by the way).

There are a lot of factors that can impact signal propagation, including the transmitter location, the location of the receiving antenna -whether it's high atop a hill, tower, or city sky-scraper, etc.- physical barriers -such as hills, mountains, etc.- and the availability of a receiving counter party, human or otherwise, to confirm receipt of your message. But, in one week of testing, I've been heard as far as 54 miles out, without the help of any signal boost from a repeater's output transmission. With the help of the repeaters on my own signal's frontier range, I estimate I can probably be heard clearly on the 2M and 70CM bands around 100 miles in all directions, covering an area of over 28 thousand square miles across parts of Ohio, Pennsylvania, West Virginia and even southern Ontario. 

I will continue to test that frontier and see just how far I can potentially transmit beyond that boundary. I did hit a repeater in Lisbon, Ohio roughly 35 miles southeast of my location using only low power, which suggests my range could be even greater than the images I've included here. 

I'll stick to my 2M and 70CM band with the antenna I have for now, and continue to make to contacts in northeast Ohio and surrounding areas. However, as I continue to invest in the hobby, many more challenges await such as transmitting to orbiting satellites, or even the International Space Station -both can be done with my current equipment and technician's license. And, as I get even more advanced, I can even try using a shortwave antenna on the 20M band, which can basically transmit world-wide!