Category: amateur radio

Amateur Radio and Workin’ The Birds

You can view the follow up posts in the Satellites area of my blog.

I originally wrote this piece for Core Concept Podcast. While I hope to resurrect the podcast, I needed to gather my thoughts on what I know as I work towards my goal of making contacts via the ham birds. I decided to attempt contact via the birds after the ARRL Field Day 2015.

Please know that this is not a complete, working guide to making contacts via Ham Radio enabled satellites. These are my notes on the subject, a goal which I’ve been unable to complete yet. I needed to make notes of what I’ve found and learned so far. I figured that I may as well make them public for all to see in the hopes that someone will find them useful.

Equipment

Antenna

The equipment needed is pretty simple. Youtube has videos showing people making contact with an HT turned sideways. However, contact is made easier with a yagi antenna which focuses where your radio transmissions will be sent or received. I elected to purchase an Arrow Antenna but plans for tape measure yagis and beam yagis that you could make are available online. Ham birds usually have a 2m uplink frequency and a 70cm downlink frequency. Sometimes its inverted however, so you would want to make sure that your yagis tuned for both.

Radio(s)

It is often advised to use a second radio so hear whether or not you are coming through the satellite. Otherwise, enabling dual watch on your baofeng should be sufficient. So I can know if I’m making it through, I ordered a Baofeng BF-F8HP to use. Having a second radio will also give me a backup unit for my shack. Another advantage is that the BF-F8HP transmits with 8 watts of power instead of the 4 watts the Baofeng UV5R has, so the F8HP should expand my range, if even for just a touch.

Documentation

Another thing that is noted it it would be worth recording your session so that you can make sure you have copied your QSOs correctly. I will use my laptop and my Blue Snowball microphone to achieve this.

Prepping to Make Contact

Finding Satellites to Contact

If you’re using a baofeng HT, you’re limited to FM birds only. KD0HKD has a great page listing a number of birds equiped with FM repeaters. However, most of his documentation links for the satellites have gone dead, lost to the passage of time on the internet. That’s okay, because some of Amsat’s own links are no better.

I was advised to pick two satellites to work on a regular basis. I was going to try to work SO-50 and the ISS but, alas, the ISS Fan club reports the FM repeater has been down for quite awhile now. So, I’ll stick with trying to work SO-50 and wait for when Fox-1A is operational.

Getting your gridsquare

To make contacts via a satellite, you’ll need to know where to point your yagi. Your gridsquare will give satellite tracking software the ability to determine where a satellite will rise in relation to your location. Also, when doing an exchange over a satellite, one of the pieces of information you’ll need to trade is your gridsquare.

You can calculate your grid square using the awesome Grid Square Calculator from Levine Central which allows you to enter your call sign to calculate your grid square representing your location on the globe. QRZ.com provides one as well, but it is more complicated to use.

Your elevation can be a little hard to find, but the wikipedia page had the elevation for my home town so I used that (and suggest you do to). Satellite trackers need this information as well.

Finding Satellites

There are a few different ways to this. You can use one or more of the following three resources:

  1. The Amsat Satellite Tracker. Very confusing, will only give a list of passes and headings. Will only show the passes for a single satellite. Shows pass times in UTC, so you will have to convert them to your local time zone or it will be useless.
  2. Heavens Above android app. Has a nice “live sky” plotting ability. I don’t think it was designed with Ham radio enthusiasts in mind. Can pull your location from GPS.
  3. GPredict. Probably the best option in my opinion. Not very user friendly, but provides a wealth of information once you understand how the program flows. And there is actual documentation (so far).

On both the AmSat Satellite tracker and GPredict you will need enter your grid square, elevation. I think GPredict is the best option currently.

This is the point where I haven’t been able to translate technical knowledge into physical experience. So everything is abit fuzzy from here on out.

Go outside, and using either a lensatic or baseplate compass figure out the points on the horizon where the satellite will come up, the mid point of its travel, and the point on the horizon where it will descend. Remember to account for magnetic declination.

Connect your radios to the arrow antenna and open the squelch on your receiving unit. Coordinating with the times and azimuth points that GPredict provides, trace the path of the satellite. When you cross the broadcast path of your chosen satellite the static will fade from your reception. You may also hear the call signs and gridsquares of other sat users.

If you can’t find your satellite, Amsat has a status page that other hams can report if they have been able to use a satellite. It may be worth checking and seeing if others have heard from the bird recently.

Additional resources


Fixing Over-modulation in a Cheap Throat Mic

I purchased this throat mic back in April. When I hooked it up to the UV5R, it was reported that I was over-modulating the mic. In layman’s terms, the mic was so sensitive that it was picking up my voice so well it was “overdriving,” or clipping the audio. You can see a fair example at the beginning of this youtube video:

So how to deal with the over-modulation in mics? If you have your Technician’s license, you know that this is one of the questions on the Amateur Radio Technician’s test. The answer is to move the mic further away from your mouth. But throat mics use a piezo element which translates vibration into an electrical signal. So, to work, they have to be touching the source of the vibration.

The solution is to dampen the vibration. One way to handle this is to rotate the throat mic about your neck so its not directly setting over your voice box. But, in my case, it wasn’t enough. To much low end in my voice, I suspect. In the end, the solution I employed was to put some theraband between the cup wall and the piezo element in the cup.

Theraband is basically rubber banding. Removed from sunlight, it doesn’t break down like a regular rubber band will do – an excellent quality for our intended use. Jorge Sprave uses it for his ridiculous launchers. I had some left over from a previous infatuation. If you don’t have theraband, you can use foam sheeting. I actually wanted to use the foam sheeting, much like this amazon product, but all I had was theraband. The idea was to reduce the amount of vibrations that the mic can “feel” by adsorbing some of the vibrations produced by speaking.

In the photo of the throat mic, the piezo element is located in that left hand cup. You can take it apart by removing the two Philips head screws on the inside of the band and gently pulling the cups apart. Then cut a piece or theraband or foam sheeting into a circle (a nickle is about the right size) and place it in the cup in between the piezo element and the inner wall that will be contacting your throat. Put the cups back together and then screw the screws back in. Be careful – the cheap plastic strips easily. I ended up needing to use some black electrician’s tape to hold mine together because I managed to strip out the screw holes and then lose one of the screws. I actually only needed a single piece of theraband to bring the mic into a usable range.

I used it to check into the local repeater net earlier, and heard no complaint. I’ll have to check with the fellow that pointed it out, but if I’m still over-modulating I’ll just place another coin sized piece of theraband between the cup and the piezo element. This is probably my favorite mic system to use. The acoustic tube makes for discreet listening and the mic needs to be directly on the sound source so it won’t pick up background noises.


Welcome To Ham Radio

So, I qualified for my amateur radio license in November. I was asked the other night about how to go about acquiring one for yourself. My response was pretty simple:

Studying at http://hamstudy.org , paying $15 to take the test at a club, $35 for the baofeng + $10 for a Nagoya na-701.

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But I thought in addition to fleshing out some links, I would give some other things that I’ve learned in the few month I’ve had my license.

Studying for your test at hamstudy.org is great. It’s not the eye stabber that most ham test sites are. But you will learn the questions and answers. You’ll need to read outside of that to learn how to actually ham. Thankfully, almost everyone in the community I’ve met is willing to teach you what you need to know and to give advice. Its called elmering. Not everyone will elmer you, but everyone is pretty welcoming and will through a bone to you if they can.

Hardware

  1. Programming Cable. You definitely want the programming cable. The baofeng is notoriously hard to program. There’s guides online, but this make everything super simple, especially when you pair it with chirp.
  2. SWR Meter. Strictly optional … unless you want to build antennas. I’m not sure how accurate it is, but I get great signal reports on the baofeng after tuning my antenna with it.

Online Resources

  1. Chirp. Its great. It can also be used to backup your radio presets (which I do).
  2. Repeater Book. Repeater book is a great way to learn about the repeaters in your area. Using a repeater is a great way to expand the range of your hand held.

Etiquette

Or, what I wish I could have been told to start
How do I get into a conversation? The correct way is to wait for a pause or break in the conversation, then key and state your call sign.
NATO Phonetics: Please learn them. Please use them. Yes, Kangaroo Dingo Nine Fluffy Chuckie Oppenhiem works, but when you have to revert to phonetics, its probably because the signal isn’t as strong as it could be. As an operator, you’re expecting certain patterns. By using the correct Kilo Delta Nine Foxtrot Charlie Oscar, we’re hearing a pattern we know and thus we can match it better.
Making sure you identify every ten minutes: I purchased this sand timer from Amazon. Flip it the second time, and identify a bit through that second flip.

Antennas!

The antenna is arguably the most important part of your rig. The antenna that comes with the UV5R is crap. That’s why I said to switch for the nagoya. But I also want to throw out the antenna I’m currently using – a 1/4 Wave ground plane. My local ham club is on the 2cm band, so I made and tuned this antenna for the 2cm band. It works great, and under the right conditions I’ve made a 54 mile reach with the 4 watts from my baofeng.

Community

Another thing you can do is reach out for advice through the internet. ##hamradio on freenode is a good place to hang out. Another good amateur radio community online is /r/amateurradio.

That’s all I can think of for now. I’ll post a follow up as I learn more.