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)

From my Twitter feed: Ecommin in CO, vintage radio, JT9

RadioGeek's avatarKKØHF@RadioGeek
Ghostbusters-like crew of amateur radio operators help in emergencies denverpost.com/breakingnews/c…

This is one of the better-written newspaper stories that I’ve seen in a while….Dan

 

MrVacuumTube's avatarGregory Charvat @MrVacuumTube
For a good series on how to restore antique radio gear, see youtube channel ‘bandersontv’ and (@YouTube youtu.be/TnRP1BcwRRk?a)

I have some antique radios that need restoration…..Dan

TWIAR's avatartwiar.org @TWIAR
ARRL: Have a Great Time with JT9 dlvr.it/3ybncz #hamr

From my Twitter feed: SDR rx, cool projects, JT-65

sparky73dx's avatar

roteno's avatar
Victor Laynez @roteno

July Call for Projects! Send links/pictures of your cool projects. One of mine: @eevblog uCurrent for my bench pic.twitter.com/ps9giFTB7x

 

w0sun's avatar
Bill WØSUN ? @w0sun

“JT65 – Easy as Pie!” feedly.com/k/1e6pEHI #hamr #Hamradio

Amateur radio in the news: Bob Heil K9EID, HSMM-Mesh wins award, teens help win WWII

Bob_HeilThe sound of Heil. He saved tours of the Grateful Dead and The Who, and is credited with the birth of modern live sound by revolutionizing the equipment that bands used, starting in the 1960s. In fact, Bob Heil, ham radio operator, sound equipment inventor, and founder of Heil Sound, is the only manufacturer to have equipment on display at the Rock and Roll Hall of Fame.

Ham ops win iAEM-Global technology & innovation award. Broadband HamnetTM, developed by amateur radio operators to provide a high speed digital wireless communications mesh network, has won the IAEM-Global Technology & Innovation Award, Division 2.. The firmware is available at no charge via the project website at www.hsmm-mesh.org.

The teenage radio enthusiasts who helped win World War II. There were about 1,500 so-called voluntary interceptors during WWII – civilians helping to intercept secret Nazi code. To mark the centenary of the Radio Society of Great Britain, one of its members recalls how the amateur organisation played a key role in a covert operation to safeguard the country’s independence.

From my Twitter feed: scholarships, testing power supplies, MT63

Lots of cool things in my Twitter feed this morning…….Dan

k9hi
Apr. 15 deadline is fast approaching for FAR scholarship applications. Seehttp://t.co/8eCHFvTM1x #hamr

dangerousproto
How to measure stability when testing power supplies http://t.co/WkzW6ZXMKD

hamradiopodcast
VOA Radiogram features MT63http://t.co/gslMp6qukr

Operating Notes: Africa, four new countries, JT65

Operating notes from the last couple of days:

Africa
I finally worked the 5X8C DXpedition in Uganda Thursday night on 40m. They must have worked nearly everyone that’s wanted to work them because they were actually calling CQ. I got them on the second or third call.

On Friday night, after the DX contest had started, I worked 9U4U DXpedition in Burundi on 30m. I thought this a bit odd because I would have thought they would be operating the contest, but apparently not. That made it much easier for me to work them. They were actually calling CQ, and I was able to get them on the second call.

Three new countries for WA2HOM
Yesterday, I went down to WA2HOM. I hadn’t really intended to participate in the ARRL CW DX contest, but after making a couple of phone contacts, I couldn’t resist tuning around to see how conditions were. As it turned out, conditions were pretty good on 10m and 15m. Ii was able to add four new countries (errrrrr, DXCC entities) to the WA2HOM log:

  • New Zealand: ZL3IO, 15m.
  • Peru: OA4SS, 15m
  • Senegal: 6V7S, 10m

@kb6nu
I’m @kb6nu on Twitter and enjoy tweeting about my operating activities there. Several of my followers have said that they enjoy reading my reports. One night last week, after complaining about not getting any replies to my CQs, @VA5LF saw that tweet, fired up his rig, and came back to me. We were having a nice chat until his QRN level jumped.

A lot of the guys on Twitter seem to enjoy working JT65. I’m going to have to look into that.

Extra Class question of the day: Television practices: fast scan television standards and techniques; slow scan television standards and techniques

Although we are called “radio” amateurs, we can also send and receive television signals.  There are several ways that amateurs communicate by television. Perhaps the two most popular ways are standard fast-scan television and slow-scan television (SSTV).

The video standard used by North American Fast Scan ATV stations is called NTSC.(E2B16) The NTSC, or National Television Systems Committee, is the body that set standards for the analog television system that was used in the U.S. and many other parts of the world. After nearly 70 years of using the analog NTSC system, U.S. broadcasters switched over to a digital broadcasting system on June 12, 2009.

A fast-scan (NTSC) television frame has 525 horizontal lines (E2B02), and a new frame is transmitted 30 times per second in a fast-scan (NTSC) television system. (E2B01) NTSC systems use an interlaced scanning pattern. An interlaced scanning pattern is generated in a fast-scan (NTSC) television system by scanning odd numbered lines in one field and even numbered ones in the next. (E2B03)

In order for the scanning beam to only show the picture, a technique called blanking is used. Blanking in a video signal is turning off the scanning beam while it is traveling from right to left or from bottom to top. (E2B04)

NTSC signals are amplitude modulated (AM) signals, but use a technique called vestigial sideband modulation. Vestigial sideband modulation is amplitude modulation in which one complete sideband and a portion of the other are transmitted. (E2B06) The reason that NTSC TV uses vestigial modulation is to conserve bandwidth. Even using this technique, an NTSC signal is 6 MHz wide. One advantage of using vestigial sideband for standard fast- scan TV transmissions is that vestigial sideband reduces bandwidth while allowing for simple video detector circuitry. (E2B05)

Amateurs can transmit color TV as well as black-and-white TV. The name of the signal component that carries color information in NTSC video is chroma. (E2B07)

There are a number of different ways to transmit audio with an NTSC signal. The following are common methods of transmitting accompanying audio with amateur fast-scan television:

  • Frequency-modulated sub-carrier
  • A separate VHF or UHF audio link
  • Frequency modulation of the video carrier

All of these choices are correct. (E2B08)

Slow-scan TV
Because of the bandwidth requirements, amateurs can only transmit fast-scan TV above 440 MHz. FM ATV transmissions, for example, are likely to be found on 1255 MHz. (E2B18) In fact, one special operating frequency restriction imposed on slow scan TV transmissions is that they are restricted to phone band segments and their bandwidth can be no greater than that of a voice signal of the same modulation type. (E2B19) The approximate bandwidth of a slow-scan TV signal is 3 kHz. (E2B17)

SSTV images are typically transmitted on the HF bands by varying tone frequencies representing the video are transmitted using single sideband. (E2B12) The tone frequency of an amateur slow-scan television signal encodes the brightness of the picture. (E2B14)

128 or 256 lines are commonly used in each frame on an amateur slow-scan color television picture. (E2B13) Specific tone frequencies signal SSTV receiving equipment to begin a new picture line. (E2B15)

There are a number of different SSTV modes. The function of the Vertical Interval Signaling (VIS) code transmitted as part of an SSTV transmission is to identify the SSTV mode being used. (E2B11)

Digital Radio Mondiale is one way to send and receive SSTV signals. No other hardware is needed, other than a receiver with SSB capability and a suitable computer, is needed to decode SSTV using Digital Radio Mondiale (DRM). (E2B09) Just like any SSTV transmission, 3 KHz is an acceptable bandwidth for Digital Radio Mondiale (DRM) based voice or SSTV digital transmissions made on the HF amateur bands. (E2B10)

More interesting stuff from the Internet – 8/5/12

Here are some interesting items I’ve gleaned from Google+ and the amateur radio mailing lists that I’m subscribed to:

simple emf probeSimple EMF probe. EMF probes for professional use can be very pricey, but if you just want to get an idea of what’s happening with the electromagnetic fields in your vicinity, you could build this simple probe (see right) and connect it up to your oscilloscope.

Simple tilt-over tower. KD0ZZ has built a very simple tilt-over tower. Not only that, he’s also published the plans for it. If you have any questions, you can join the HamRadioHelpGroup Yahoo Group and ask your questions there.

WSPR Google+ page. If you are a Google+ user, you can follow this page to get news about WSPR.

 

 

SSTV Live

Jim, K8ELR, has really gotten into operating the digital modes down at the museum. So, I was interested to see a notice on the HamRadioHelpGroup mailing list that the KB7TBT SSTV Web Page was back online. On this page, James, KB7TBT displays a number of live feeds.

KB7TBT SSTV CQ ScreenDon, KB9UMT, the list moderator, asked if someone could explain SSTV and how to operate it. James replied:

Q. What is SSTV?
A. SSTV is a picture transmission method used by amateur radio operators to
transmit and receive static pictures via radio in either color or
monochrome.

Q. What does SSTV stand for?
A. SSTV stands for “Slow Scan Television.”

Q. What does one need to participate or use SSTV?
A. A Ham Radio license to transmit.

Q. What does SSTV sound like?
A. To listen to a sample of SSTV: http://www.qrp.org.uk/sstv_test-1.wav.

Q. Can someone just listen in or receive only for SSTV?
A. Anyone can receive, just like any radio receiving it does not require a
license. Install the software and place your computer microphone against the receiver speaker, it’s that easy!

Q. What frequencies are there or where does one listen on HF for this SSTV activity?
A. The most popular is 14.230 MHz during daylight hours (due to
propagation).

Q. Can this also be used on VHF/UHF?
A. YES! 145.500 simplex is a popular VHF frequency for SSTV. (I have even used
a 2M FM Repeater a few times). The ISS has SSTV on board and the downlink freq is 145.800 when in use. UHF is used as well but I am not familiar with the freq.’s.

Q. Can SSTV be used anywhere or is ther rules on this…and or band plans?
A. Analogue SSTV is classified as an IMAGE MODE. Voice and Image most of the
time go together. (Check your local band plans and rules.) There is some difference in opinion but analogue SSTV is NOT a digital mode. (I personally disagree)

Q. Is this a SSB mode always or can this be used FM also?
A. FM and SSB can be used, just remember to operate within your local band
plan.

Q. What software is there for this..or are there different kinds of SSTV?
A. Ham Radio Deluxe offers a fantastic program for SSTV and it is free. (HRD
Digital Master 780 – This is what I use.) There is also MM-SSTV, a bit outdated but still works well and is free. (Not sure how well it works on Win7 or Vista)

Q. Are there other online SSTV web pages to watch SSTV?
A. Why would you want to watch any other page but mine? ok, ok, there are many websites around the world. To see pictures from around the world go to my SSTV page and scroll down. All the thumbnails have links to the websites they come from.

Q. Can you DX using SSTV?
A. YES! I send and receive pictures from all over the world.

Q. Are there SSTV nets?
A. Yes, just do a search for SSTV Nets. One website I have found lists both analog SSTV nets and digital SSTV nets.

You Can’t Tell the Digital Modes Without a Scorecard

Unless you work the digital modes a lot, how do you tell which signal is PSK 31 and which is Feld Hell? By going to K2NCC’s YouTube page, of course! Frank has posted examples of nine different modes, including Domino, Feld Hell, SSTV, and MFSK16. What’s cool about these posts is that you not only hear what they modes sound like, but what they look like on a waterfall display.

Here’s what Domino EX16 sounds like and looks like:

Frank says, “Stay tuned for more!”