2014 Tech study guide: station setup

There were two question changes in this section. Question T4A02 was changed from a question about headphones to a question about using computers in the shack. Question T4A05 was changed from a question about band-reject filters to one about using an SWR meter. I’ve added that question to the appropriate section…Dan

When setting up an amateur radio station, choosing the radio itself is the most important consideration, but you must also choose a wide range of accessories, such as power supplies and microphones. In addition, how you set up the station is important for it to operate efficiently.

One accessory that you’ll definitely need is a power supply to provide the DC voltage and current that your radio needs. A good reason to use a regulated power supply for communications equipment is that it prevents voltage fluctuations from reaching sensitive circuits. (T4A03) When choosing a supply, check the voltage and current ratings of the supply and be sure to choose one capable of supplying a high enough voltage and enough current to power your radio.

If you are going to operate with one of the voice modes, you’ll need a microphone. When considering the microphone connectors on amateur transceivers, note that some connectors include push-to-talk and voltages for powering the microphone. (T4A01)

A computer has become a very common accessory in an amateur radio “shack.” All of these choices are correct when talking about how a computer be used as part of an amateur radio station (T4A02):

  • For logging contacts and contact information
  • For sending and/or receiving CW
  • generating and decoding digital signals

If you plan to operate packet radio, you will need a computer and a terminal controller, or TNC, in addition to the radio. A terminal node controller would be connected between a transceiver and computer in a packet radio station. (T4A06) The TNC converts the ones and zeroes sent by the computer into tones sent over the air.

A more modern way to operate digital modes, such as RTTY or PSK-31, is to use a computer equipped with a sound card. When conducting digital communications using a computer, the sound card provides audio to the microphone input and converts received audio to digital form. (T4A07) The sound card may be connected directly to the radio, but it’s usually better to connect it through a device that isolates the radio from the computer. This prevents ground loops from causing the signal to be noisy.

Audio and power supply cables in a amateur radio station sometimes pick up stray RF. At minimum, this RF can cause the audio to be noisy. At worst, it can cause a radio or accessory to malfunction. To reduce RF current flowing on the shield of an audio cable (or in a power supply cable), you would use a ferrite choke. (T4A09)

Modern radio equipment is very well-designed, and harmonic radiation is rarely a problem these days. Even so, there may be times when it does become a problem, and you’ll have to take steps to attenuate the harmonics. To reduce harmonic emissions, a filter must be installed between the transmitter and the antenna. (T4A04)

Good grounding techniques can help you avoid interference problems. When grounding your equipment, you should connect the various pieces of equipment to a single point, keep leads short, and use a heavy conductor to connect to ground. Flat strap is the type of conductor that is best to use for RF grounding. (T4A08)

If you plan to install a radio in your car and operate mobile, you have a different set of challenges. One is connecting the radio to the car’s power system. Some amateurs connect their radio with a cigarette lighter plug, but this plug is not designed for high currents. Instead, a mobile transceiver’s power negative connection should be made at the battery or engine block ground strap. (T4A11) The positive connection can also be made at the battery or through an unused position of the vehicle’s fuse block.

Another challenge is noise generated by the car itself. One thing that could be happening if another operator reports a variable high-pitched whine on the audio from your mobile transmitter is that noise on the vehicle’s electrical system is being transmitted along with your speech audio. (T4A12)

The alternator is often the culprit.  The alternator is the source of a high-pitched whine that varies with engine speed in a mobile transceiver’s receive audio. (T4A10) Should this be a problem, there are filters that you can install to mitigate the alternator whine. One thing that would reduce ignition interference to a receiver is to turn on the noise blanker. (T4B05)

2014 Tech study guide: digital modes

Three questions in this section were updated. The answer to TD802 was changed from “Automatic Position Reporting System” to “Automatic Packet Reporting System.” T8D05 was changed from a kind of irrelevant question about Techs being able to use data in the 219 to 220 MHz range to one about an application of APRS. T8D11 was changed from a question about the parity bit to one about ARQ transmission….Dan

When hams talk about “digital modes,” we are talking about the ways in which we use a computer in conjunction with a radio to communicate with one another. They all involve sending digital data back and forth to one another. All of these choices are correct (examples of a digital communications method) (T8D01):

  • Packet
  • PSK31
  • MFSK

Packet radio was one of the first digital modes. It is called packet radio because the data to be sent from station to station is separated into a number of packets which are then sent separately by the transmitting station and received and re-assembled by the receiving station. All of these choices are correct when talking about what may be included in a packet transmission (T8D08):

  • A check sum which permits error detection
  • A header which contains the call sign of the station to which the information is being sent
  • Automatic repeat request in case of error

Some amateur radio digital communications systems use  protocols which ensure error-free communications. One such system is called an automatic repeat request, or ARQ, transmission system. An ARQ transmission system is a digital scheme whereby the receiving station detects errors and sends a request to the sending station to retransmit the information. (T8D11)

APRS is one service that uses packet radio. The term APRS means Automatic Packet Reporting System. (T8D02) A Global Positioning System receiver is normally used when sending automatic location reports via amateur radio. (T8D03) Providing real time tactical digital communications in conjunction with a map showing the locations of stations is an application of APRS (Automatic Packet Reporting System). (T8D05)

A popular digital mode on the HF bands is PSK. The abbreviation PSK means Phase Shift Keying. (T8D06) PSK31 is a low-rate data transmission mode. (T8D07)

2014 Tech study guide: SWR and antenna measurements

In the 2010 study guide, this section was part of the section on feedlines and connectors. I think it makes more sense to separate it like I have here. There is one added question in this section T7C13 asks what a dummy load consists of…Dan

Standing wave ratio is a term you’ll often hear when talking about antennas and feedlines. In general terms, standing wave ratio (SWR) is a measure of how well a load is matched to a transmission line. (T7C03) In this context, the “load” is the antenna. When we say that an antenna is matched to a transmission line, we mean that the impedance of the transmission line is equal to the impedance of the antenna.

The reason it is important to have a low SWR in an antenna system that uses coaxial cable feedline is to allow the efficient transfer of power and reduce losses. (T9B01) The bigger the mismatch is between the feedline and the load, the higher the SWR will be, and the more power you will lose in the feedline. Power lost in a feedline is converted into heat. (T7C07) Power converted into heat is not radiated by the antenna, meaning your radiated signal will be weaker.

You can measure the SWR of your antenna system with an SWR meter. You usually connect the SWR meter near the output of your transmitter because it is important to have a low SWR at that point. A directional wattmeter is an instrument other than an SWR meter that you could use to determine if a feedline and antenna are properly matched. (T7C08)

1 to 1 is the reading on an SWR meter indicates a perfect impedance match between the antenna and the feedline. (T7C04) 2 to 1 is the approximate SWR value above which the protection circuits in most solid-state transmitters begin to reduce transmitter power. (T7C05) An SWR reading of 4:1 means that there is an impedance mismatch. (T7C06)

One way to ensure that the impedance of the antenna system matches the output impedance of transmitter is to use an antenna tuner. An antenna tuner matches the antenna system impedance to the transceiver’s output impedance. (T9B04)

In addition to the SWR meter and the directional wattmeter, there are a couple of other types of test instruments commonly found in an amateur’s “shack.” One instrument that every shack should have is the dummy load. A dummy load consists of a non-inductive resistor and a heat sink. (T7C13) The primary purpose of a dummy load is to prevent the radiation of signals when making tests. (T7C01)

Another common test instrument is the antenna analyzer. An antenna analyzer is an instrument that can be used to determine if an antenna is resonant at the desired operating frequency. (T7C02) You can also make a number of other measurements that will help you set up an antenna system, such as SWR, capacitance, and inductance.

From my Twitter feed: spy tech, signal sampler, SWL guide

maximus_freeman's avatarmaxp @maximus_freeman
Interesting bit of RF engineering leaksource.files.wordpress.com/2013/12/nsa-an… (cc @kb6nu)

 

dangerousproto's avatarDangerous Prototypes @dangerousproto
Variable RF signal sampler goo.gl/f7vIMM

 

hamrad88's avatarTom Stiles @hamrad88
TRRS #0212 – Shortwave Listen Guide – eBook: youtu.be/RJxclPd1bLk?a via @YouTube

From my Twitter feed: lightning, HackRF, Arduino Morse

va7vm's avatarMerrick Grieder @va7vm
” So, yes, lightning could strike, but it just doesn’t strike like it used to.” theatlantic.com/technology/arc…

 

dangerousproto's avatarDangerous Prototypes @dangerousproto
DCC/TAPR video: HackRF – A Low Cost SDR Platform goo.gl/f4hkJs

 

hackaday's avatar

hackaday @hackaday
New post: Magic Morse Arduino Trainer bit.ly/LhxZ3J

From my Twitter feed: radio gifts,

RadioSurvivor's avatarRadio Survivor @RadioSurvivor
There’s got to be someone on your list who wants a radio purse radiosurvivor.com/2013/12/02/hol…

Check out the radio tower tie….Dan

HamRadioSupply's avatarAmateurRadioSupplies @HamRadioSupply
New post: What the heck is a grid dip meter? goo.gl/C9BTnR

I wrote this yesterday for the AmateurRadioSupplies.Com blog…Dan

ARRL_PR's avatar

ARRL Media & PR @ARRL_PR
Get tips on #HamRadio PR & promotion! The December issue of #ARRL‘s CONTACT! has been posted! bit.ly/bRzdks

Being the greedy sot that I am…

…I’m going to try another way to “monetize” this website. What I’ve done is to add a page thats list ham radio products sold on Amazon. If you purchase a product on Amazon using one of the links there, I’ll get a cut. You can get to that page by clicking on the “Ham Stuff (from Amazon)” link above.

Taking that a step further, I’d love to get your suggestions for products to list there. You don’t have to have purchased it on Amazon, but it needs to be sold by Amazon. Please feel to either e-mail me your suggestions or enter them in the comment section below.

A quick comparison of the Baofeng UV-5RA and Wouxun KG-UVD1P

About eight months ago, I purchased a Wouxun KG-UVD1P two-band HT. Overall, I’ve been very happy with it. Last week, I purchased a Baofeng UV-5RA. Apparently, Baofeng is coming out with a new model soon, and as a result, are trying to dump these units. I bought mine for $30 from some vendor selling through Amazon, although now it looks like the cheapest price is $33.55.

Wouxun KG-UVD1PBaofeng UV-5RA

It’s been interesting to compare the two units. This is by no means an exhaustive comparison, but just a few things that hit me from playing with the Baofeng for the last couple of days:

  • Programmability. As is commonly noted, the Wouxun is much more easily programmed than the Baofeng. It was relatively easy for me to figure out how to program the memory channels of the Wouxun. So much so that I decided not to purchase the programming cable. I still have not been able to program the memory in the Baofeng. Unlike the Wouxun, you have to separately program the transmit frequency and the receive frequency. I still have not mastered this procedure.
  • User documentation. The user documentation for the Wouxun is much better than the documentation for the Baofeng. The Wouxun comes with both a user manual and a quick reference card. The Baofeng come with a very thin manual that doesn’t seem to include instructions on how to program repeater frequencies into the memory channels.
  • Voice. Both radios can be programmed to announce, in either English or Chinese, things like operating mode and memory channel. The Baofeng voice sounds much more like a computer generated voice. The Wouxun English voice has a notable Chinese accent.
  • Antenna. Since I purchased it, I’ve only been using the  antenna that was supplied with the Wouxun. It seems to perform pretty well. I’m not so impressed with the Baofeng antenna. Not only does it not do a good a job as the Wouxun, it actually gets a little warm when I transmit on high power. I’m going to have to replace it.

All things considered, I’ve decided to do one of two things with the Baofeng. I’m either going to pass it on to one of my Tech class students or hack it like KK6BWA has done. I think that either would be a worthwhile thing.

From my Twitter feed: #hamradio t-shirts, cheap key, Broadband HamNet

I don’t usually include two Tweets from the same guy, but the two below from KE9V are great…Dan

ke9v's avatarJeff Davis @ke9v
Get the #hamradio Beefy-T shirt. ke9v.net/tees

 

ke9v's avatarJeff Davis @ke9v
My straight key it’s nicer but this one is more affordable. #hamradio pic.twitter.com/F563k9QPJI

 

ZionArtis's avatar

Zion Artis KF4NOD @ZionArtis
I find this very interresting. Introduction to HSMM-MESH or Broadband-Hamnet: youtu.be/hUeW2ju-RZk via @YouTube

Lack of standardization holding back amateur digital communications

Via Twitter, I recently found out that Yaesu had introduced a new digital communication system—called System Fusion—at the ARRL/TAPR Digital Communications Conference in Seattle, WA. When I asked KE9V, the guy who posted this announcement to Twitter whether or not Fusion was going to be more than a niche product, he replied, “I think it’s a long-shot at best. ICOM has dumped a lot of cash in D-STAR and now years later it’s just catching on. Tough road.”

Compounding the fact that Yaesu is late to the party is the fact that the radios are probably going to cost an arm and a leg, just like the D-STAR radios. Call me an old fart—and I have been called that and worse—but I just don’t see where the digital features are worth the extra bucks. (I would be happy to be convinced otherwise, though. Please feel free to comment on this below.)

Wouldn’t it have been nice if Yaesu and Icom, and maybe even Kenwood, had gotten together and developed a digital communication standard that both companies could support? Not only would have it made it more palatable to invest in such a radio, I bet those radios and repeaters would cost less than the current D-STAR and Fusion offerings. That’s just what happens when companies adopt standards.

As Bob, K0NR, tweeted, “File this under ‘missed opportunity.’” I agree.

p.s. I wanted to include a picture of the system, but the Yaesu website doesn’t yet have any yet on their website. There is, however, a YouTube video of the DCC meeting at which Yaesu introduced the product.