From my Twitter feed: club resources

arrl's avatarARRL @arrl
ARRL Atlantic Division Adds Resources to Aid Amateur Radio Clubs: The ARRL Atlantic Division leadership has cr… bit.ly/1gB2ptw

Atlantic Division director Bill Edgar, N3LLR, is truly one of the directors that knows what he’s doing.

 

qrparci's avatarQRP ARCI @qrparci
The Rockmite is back ! A HF transceiver with built in keyer for $40 – qrpme.com/pages/RM%20][.… #hamr #hamradio #qrp

The Rockmite is a classic. If you haven’t built any kits lately, consider picking up one of these and doing so.

 

AlanAtTek's avatar

Alan Wolke W2AEW @AlanAtTek
Lots of folks liked my “how to test BJTs” video, and asked for a similar one on MOSFETs. Here it is: youtube.com/watch?v=gloikp…Another great W2AEW video. I don’t know how he has time to do these, but they’re certainly worth watching.

From my Twitter feed: weather radio, drones, DMR

TAUTIC's avatarJayson Tautic @TAUTIC
Really cool project! “@chasxmd: Project: Si4707 Weather Radio wp.me/p3oePO-7Q

 

XE2K's avatarJ.Héctor García XE2K @XE2K
After so many Drones in the news, Why not an 160m Vertical wire array supported by Drones ? can be the future?

 

VA3XPR's avatarVA3XPR Repeater @VA3XPR
Teach your local radio club all about Digital Mobile Radio at their next mtg. #hamr #hamradio ow.ly/tkdCb pic.twitter.com/v2cDxOoYdz

From my Twitter feed: SDR, spider coils, smart scope

vielmetti's avatarEdward Vielmetti @vielmetti
decoding radio digital modes without a radio, using WebSDR and fldigi /cc @kb6nu #hamr bit.ly/1o678qG

mike_n8wc's avatarMike Comer @mike_n8wc
@kb6nu great info! Back to radio after several years. Enjoy how the internet has enhanced enjoyment of a great radio hobby.

AK6L's avatarRobert Liesenfeld @AK6L
Taught myself PostScript and wrote a template generator for making spider-wound coils. Inspired in part by .@vk2zay. github.com/xunil/spider_c…

DH1TW's avatarTobias @DH1TW
“SmartScope – Kickstarter campaign for an open source 100MS portable oscilloscope #hamradio #diy feedly.com/k/1gr8jQm

From my Twitter feed: deep-space signals, making PCBs, SWL skeds

VoiceOfHamRadio's avatarVoice of Ham Radio @VoiceOfHamRadio
Radio Amateurs Receive Rosetta Spacecraft Signals from Deep Space zite.to/1nxMq2L via @Zite

 

hackaday's avatar

hackaday @hackaday
New post: [CNLohr] Demos His Photoetch PCB Process bit.ly/1a8TQpm

 

QSLRptMT's avatarGayle Van Horn @QSLRptMT
Still looking for winter shortwave schedules to compliment your listening ? Details at: mt-shortwave.blogspot.com

2014 Tech study guide: schematics and components (part 4)

My study guide covers the questions in T6C and T6D of the question pool in four separate sections. Overall, the question pool committee added several questions to T6C and T6D. In this section, T6D12 is an added question…Dan

There are many different types of components in modern radio equipment. Below, we will describe the types of components you will need to know about to pass the Technician Class license examination.

A relay is a switch controlled by an electromagnet. (T6D02)

Meters are devices used to indicate many different values. For example, a meter can be used to display signal strength on a numeric scale. (T6D04) Meters are also used to indicate the output voltage of a power supply, the output power of a transmitter, and many other parameters.

Integrated circuit is the name of a device that combines several semiconductors and other components into one package. (T6D09) Integrated circuits may perform either analog or digital functions. One type of analog integrated circuit that is very common is the voltage regulator. A regulator is the type of circuit that controls the amount of voltage from a power supply. (T6D05)

An LED is commonly used as a visual indicator. (T6D07) LED is short for light-emitting diode. They come in a variety of colors.

When connecting electronic assemblies together, we often use cables with one or more conductors. Some of those conductors may have a shield around them that is connected to ground. A common reason to use shielded wire is to prevent coupling of unwanted signals to or from the wire. (T6D12)

2014 Tech study guide: schematics and components (part 3)

T3

My study guide covers the questions in T6C and T6D of the question pool in four separate sections. Overall, the question pool committee added several questions to T6C and T6D. In this section, T6D11 is an added question…Dan

The circuit shown in Figure T3 is the output circuit of a transmitter. Component 3 in figure T3 is a variable inductor. (T6C10)

There are two variable capacitors in this circuit—component 2 and the unlabeled component. A capacitor is used together with an inductor to make a tuned circuit. (T6D08)

Component 4 in figure T3 is an antenna. (T6C11)

An inductor and a capacitor connected in series or parallel to form a filter is a simple resonant or tuned circuit. (T6D11) When the capacitor and inductor are connected in series, the circuit has a very low impedance at the resonant frequency. When the capacitor and inductor are connected in parallel, the circuit has a very high impedance at the resonant frequency.

2014 Tech study guide: semiconductors

The Question Pool committee made several changes to the questions in this chapter. I like the changes. They make it easier to understand the idea of a transistor, I think…Dan

A diode is an electronic component that allows current to flow in only one direction. (T6B02) Diodes have only two electrodes. Anode and cathode are the names of the two electrodes of a diode. (T6B09) A semiconductor diode’s cathode lead is usually identified with a stripe. (T6B06)

Light-emitting diodes are a particular type of diode. When current flows through them, they emit visible light, making them useful as indicators and as part of digital readouts. The abbreviation “LED” stands for Light Emitting Diode. (T6B07)

Transistors are electronic components capable of using a voltage or current signal to control current flow. (T6B01) The transistor is a component that can be used as either an electronic switch or amplifier. (T6B03) Gain is the term that describes a transistor’s ability to amplify a signal. (T6B12) The transistor is an electronic component that can amplify signals. (T6B05)

A transistor is a component made of three layers of semiconductor material. (T6B04) Bipolar junction transistors have layers that are either P-type, which means that it has a positive net charge, or N-type, which means it has a net negative charge. Each layer has an electrode, making the transistor a device with three leads.

There are two types of bipolar junction transistors: PNP or NPN. A PNP transistor has two P layers, with an N layer sandwiched between them. An NPN transistor has two N layers, with a P layer sandwiched between them. The three electrodes of a PNP or NPN transistor are the emitter, base, and collector. (T6B10)

Another type of transistor often found in amateur radio equipment is the field-effect transistor. The abbreviation “FET” stands for Field Effect Transistor. (T6B08) FETs, like NPN and PNP transistors have three leads. Source, gate, and drain are the three electrodes of a field effect transistor. (T6B11)

2014 Tech study guide: resistors, capacitors and capacitance, inductors and inductance, batteries

Below is the “Electronics principles and components: resistors and resistance, capacitors and capacitance, inductors and inductance, batteries” section of the 2014 edition of the No-Nonsense Technician Class License Study Guide. As always, comments welcome…Dan

A resistor is the electrical component used to oppose the flow of current in a DC circuit. (T6A01) Most resistors have a fixed value, which is specified in ohms.

Some resistors are variable, that is you can change the resistance of the resistor by turning a shaft or sliding a control back and forth. These variable resistors are called potentiometers. A potentiometer is the type of component that is often used as an adjustable volume control. (T6A02) Resistance is the electrical parameter that is controlled by a potentiometer. (T6A03)

The type of electrical component that consists of two or more conductive surfaces separated by an insulator is a capacitor. (T6A05) A capacitor is the electrical component that stores energy in an electric field. (T6A04) Capacitance is the ability to store energy in an electric field. (T5C01) The farad is the basic unit of capacitance. (T5C02)

The type of electrical component that stores energy in a magnetic field is an inductor. (T6A06) The electrical component that is usually composed of a coil of wire is an inductor. (T6A07) The ability to store energy in a magnetic field is called inductance. (T5C03) The henry is the basic unit of inductance. (T5C04)

A switch is the electrical component used to connect or disconnect electrical circuits. (T6A08)

A fuse is the electrical component used to protect other circuit components from current overloads. (T6A09)

As amateur radio operators, we often use batteries to power our radio equipment. Some types of batteries are rechargeable, while others are not. The battery type that is not rechargeable is the carbon-zinc battery. (T6A11) All of these choices are correct when talking about battery types that are rechargeable (T6A10):

  • Nickel-metal hydride
  • Lithium-ion
  • Lead-acid gel-cell

From my Twitter feed: space weather, SDR, trigonometry?

NOAA's avatarNOAA
Everything you ever wanted to know about #space #weather in 1 great guide (pdf) 1.usa.gov/19VPZMF via @NWS #SWPC pic.twitter.com/GBsY52qqCE
 

rtlsdrblog's avatarrtl-sdr.com @rtlsdrblog
RTL-SDR Now Supported by MATLAB rtl-sdr.com/rtl-sdr-now-su…

 

FRCBoys's avatarDate an FRC BOY @FRCBoys
What do farmers use when calculating trig equations? Swine and Coswine

2014 Tech study guide: math for electronics

Below is the “Math for electronics” section of the 2014 edition of the No-Nonsense Technician Class License Study Guide. As always, comments welcome…Dan

When dealing with electrical parameters, such as voltage, resistance, current, and power, we use a set of prefixes to denote various orders of magnitude:

  • milli- is the prefix we use to denote 1 one-thousandth of a quantity. A milliampere, for example, is 1 one-thousandth of an ampere, or .001 A. Often, the letter m is used instead of the prefix milli-. 1 milliampere is, therefore, 1 mA.
  • micro- is the prefix we use to denote 1 millionth of a quantity. A microvolt, for example, is 1 millionth of a volt, or .000001 V. Often you will see the Greek letter mu, or μ, to denote the prefix micro-. 1 microvolt is, therefore, 1 μV.
  • pico- is the prefix we use to denote 1 trillionth of a quantity. A picovolt is 1 trillionth of a volt, or .000001 μV.
  • kilo- is the prefix we use to denote 1 thousand of a quantity. A kilovolt, for example, is 1000 volts. Often, the letter k is used instead of the prefix kilo-. 1 kilovolt is, therefore, 1 kV.
  • mega- is the prefix we use to denote 1 million of a quantity. A megahertz, for example, is 1 million Hertz. The unit of frequency is the Hertz. (T5C05) It is equal to one cycle per second. Often, the letter M is used instead of the prefix mega-. 1 megahertz is, therefore, 1 MHz.

Here are some examples:

  • 1,500 milliamperes is 1.5 amperes. (T5B01)
  • Another way to specify a radio signal frequency of 1,500,000 hertz is 1500 kHz.
    (T5B02)
  • One thousand volts are equal to one kilovolt. (T5B03)
  • One one-millionth of a volt is equal to one microvolt. (T5B04)
  • If an ammeter calibrated in amperes is used to measure a 3000-milliampere current,
    the reading it would show would be 3 amperes. (T5B06)
  • If a frequency readout calibrated in megahertz shows a reading of 3.525 MHz, it would
    show 3525 kHz if it were calibrated in kilohertz. (T5B07)
  • 1 microfarad is 1,000,000 picofarads. (T5B08) (Farad is the unit for capacitance.)
  • 28.400 MHz is equal to 28,400 kHz. (T5B12)
  • If a frequency readout shows a reading of 2425 MHz, the frequency in GHz is 2.425 GHz. (T5B13)

When dealing with ratios—especially power ratios—we often use decibels (dB). The reason for this is that the decibel scale is a logarithmic scale, meaning that we can talk about large ratios with relatively small numbers. At this point, you don’t need to know the formula used to calculate the ratio in dB, but keep in mind the following values:

  • 3 dB is the approximate amount of change, measured in decibels (dB), of a power increase from 5 watts to 10 watts. (T5B09) This is a ratio of 2 to 1.
  • -6 dB is the approximate amount of change, measured in decibels (dB), of a power decrease from 12 watts to 3 watts. (T5B10) This is a ratio of 4 to 1.
  • 10 dB is the approximate amount of change (actually it is the EXACT amount of change), measured in decibels (dB), of a power increase from 20 watts to 200 watts. (T5B11) This is a ratio of 10 to 1.