KB6NU's Ham Radio Blog

///////////////////////////////////////////
2016 Extra Class study guide: E6B - Diodes

Posted: 21 Jan 2016 01:34 PM PST
http://feedproxy.google.com/~r/kb6nu...m_medium=email


NO questions were changed in this section! Dan
E6B Diodes

Diodes have two terminals and conduct current in only one direction, from
the anode to the cathode. By manipulating the characteristics of the
semiconductor material, manufacturers can make diodes useful in a wide
variety of applications.

Take, for example, the Zener diode. The most useful characteristic of a
Zener diode is a constant voltage drop under conditions of varying current.
(E6B01) This makes it useful in voltage regulator circuits.

Another example is the varactor diode. The varactor diode is a
semiconductor device designed for use as a voltage-controlled capacitor.
(E6B04) Varactor diodes are often used in tuning circuits.

A PIN diode is a semiconductor device that operates as a variable resistor
at RF and microwave frequencies. One common use for PIN diodes is as an RF
switch. (E6B12)The characteristic of a PIN diode that makes it useful as an
RF switch or attenuator is a large region of intrinsic material. (E6B05)
The forward DC bias current is used to control the attenuation of RF
signals by a PIN diode. (E6B11)

Two types of diodes used in RF circuits are the tunnel diode and
hot-carrier diode. The tunnel diode is a special type of diode is capable
of both amplification and oscillation. (E6B03) Tunnel diodes are capable of
operating well into the microwave region. A hot-carrier diode is commonly
used as a VHF / UHF mixer or detector. (E6B06)

Metal-semiconductor junction is a term that describes a type of
semiconductor diode. (E6B08) A Schottky diode is an example of a
metal-semiconductor diode. An important characteristic of a Schottky diode
as compared to an ordinary silicon diode when used as a power supply
rectifier is that it has less forward voltage drop. (E6B02) This
characteristic also makes them useful in digital logic circuits. The lower
forward voltage drop allows the digital ICs to switch faster.

Another type of diode is the point-contact diode. A common use for
point-contact diodes is as an RF detector. (E6B09)

In Figure E6-3 (below), 5 is the schematic symbol for a light-emitting
diode. (E6B10) Forward bias is required for an LED to emit light. (E6B13)



No matter what kind of diode you are using, it’s very important to not
exceed the forward current specification. Doing so, will cause it to fail.
Excessive junction temperature is the failure mechanism when a junction
diode fails due to excessive current. (E6B07)

The post 2016 Extra Class study guide: E6B Diodes appeared first on KB6NUs
Ham Radio Blog.


///////////////////////////////////////////
Tips for beginning net control operators

Posted: 21 Jan 2016 11:56 AM PST
http://feedproxy.google.com/~r/kb6nu...m_medium=email


I found this is the February 2016 issue of Squelch Tales, the newsletter of
the Merrymeeting Amateur Radio Association. It originally appeared in the
January 20, 2016 ARES E-Letter. I have republished it here with permission
of the authorDan

By Steve Bellner, W8TER

Here in northwest Ohio, we have acquired many new hams and encourage them
to operate as net control station (NCS) for various routine nets to gain
them experience, providing us with a pool of competent net controllers in
the event of an emergency/disaster. Here are some of the basic tips we
convey to our novice net control stations for a smoothly running net:

Get a glass of water or something to drink.
Make yourself comfortable. Sit in a good location with plenty of room on a
desk or table to write.
Have a good writing instrument and a back-up along with an extra piece of
paper in case you need to jot down notes.
Take your time; go at your own pace. Remember, you are in control of the
net and the frequency.
Dont worry about making mistakes; there are no mistakes to be made.
To handle the crowd that is trying to check in, you will develop your own
way.
Stop stations from checking in (Lets hold it for a minute) until you are
caught up.
Weak stations and stations who give their call signs too fast, are always a
problem skip them at first. Go back later for repeats.
Write your log as you see fit. You are the one that has to read it.
Headphones are a good idea they help you focus on what you are hearing and
help keep you from getting distracted.


As I mentioned before, there are no mistakes, only experience. When youve
finished the net that is what you will have. Steve Bellner, W8TER, Maumee,
Ohio

The post Tips for beginning net control operators appeared first on KB6NUs
Ham Radio Blog.


///////////////////////////////////////////
Do you use WSPR beacons?

Posted: 20 Jan 2016 05:11 PM PST
http://feedproxy.google.com/~r/kb6nu...m_medium=email


On the FPqrp-L mailing list, one ham asked, Do any of you use WSPR beacon
data to plan your CW communications? If not, do you use anything at all or
just kind of put yourself out there and see what you get back?

Here are some replies:

I look at various DX reflectors [dxsummit.fi, dxwatch.com] sometimes just
to see how active the bands are, and from where.
I dont check anything. I get on the air and tune around. If I dont hear
anyone calling CQ or hear a QSO Id like to join, Ill then call CQ myself.
Guess I am just old school.
Sometimes I use the Reverse Beacon Network to see if my signal is getting
out when I dont get a response to my CQ. [[I most often use ReverseBeacon
myselfDan]]
I just spin the dial and see whats out there. Ill CQ for a while on a dead
band, but it I dont hear something within 10 minutes I drop to the next
longer-wavelength band and try again. I have HamCAP installed, but rarely
use it.
I mostly use VOACAP or CONUS HF BAND CONDX



A typical screen shot from the CONUS HF BAND CONDX website that shows
real-time HF band conditions. None of the bands look too good at 3pm EST on
January 20, 2016, when I took this screen shot.

The post Do you use WSPR beacons? appeared first on KB6NUs Ham Radio Blog.


///////////////////////////////////////////
2016 Extra Class Study Guide: E6A - Semiconductor materials and devices

Posted: 20 Jan 2016 12:03 PM PST
http://feedproxy.google.com/~r/kb6nu...m_medium=email

E6A Semiconductor materials and devices: semiconductor materials;
germanium, silicon, P-type, N-type; transistor types: NPN, PNP, junction,
field-effect transistors: enhancement mode; depletion mode; MOS; CMOS;
N-channel; P-channel

While transistor theory is outside the scope of this study guide, I will
attempt to at least give you a basic understanding of how transistors are
put together and how they work. For more information, take a look at these
two links:

How Semiconductors Work
P-type and N-type silicon


Most transistors we use in amateur radio are made of silicon. Silicon is a
semiconductor. That is to say, it’s neither a conductor with a very low
resistance, like copper, or an insulator with a very high resistance, like
plastic or glass.

You can manipulate the electrical characteristics of silicon by adding
slight amounts of impurities to a pure silicon crystal. When transistor
manufacturers add an impurity that adds free electrons to the silicon
crystal, it creates a crystal with a negative charge. We call that type of
silicon N-type silicon. N-type is a semiconductor material that contains
excess free electrons. (E6A02) In N-type semiconductor material, the
majority charge carriers are the free electrons. (E6A16)

When you add other types of impurities to a pure silicon crystal, you can
create a crystal with a positive charge. We call this type of material
P-type semiconductor material. The majority charge carriers in P-type
semiconductor material are called holes. P-type is the type of
semiconductor material that contains an excess of holes in the outer shell
of electrons. (E6A15)

You can think of them as holes as spots in the crystal that accepts free
electrons into. Because of that, the name given to an impurity atom that
adds holes to a semiconductor crystal structure is call an acceptor
impurity. (E6A04)

Silicon isn’t the only semiconductor material used to make transistors. At
microwave frequencies, gallium arsenide is used as a semiconductor material
in preference to germanium or silicon. (E6A01)
Semiconductor diodes

Diodes are the simplest semiconductor devices. A PN junction diode is
formed when you join a bit of P-type material to a bit of N-type material.
When you join the two materials, some electrons from the N-type material
migrate over to the P-type material and fill holes there. As a result,
holes form in the N-type material. This migration of charge forms what is
called the depletion region at the PN junction, and an electric field forms
across this region. The electric field generates a voltage across the
junction.

The most important characteristic of a PN junction diode is that it only
allows current to flow when it is forward-biased, that is to say when the
voltage applied to the P-type material is more positive than the voltage
applied to the N-type material. When a PN junction diode is reversed
biased—that is when the voltage applied to the P-type material is more
negative than the voltage applied to the N-type material—the diode will not
conduct current. A PN-junction diode does not conduct current when reverse
biased because holes in P-type material and electrons in the N-type
material are separated by the applied voltage, widening the depletion
region. (E6A03) This makes it impossible for current to flow through the
region
Bipolar junction transistors

Perhaps the most popular type of transistor is the bipolar junction
transistor (BJT). Bipolar junction transistors are three-terminal devices,
called the emitter, base, and collector. In an NPN transistor, the emitter
and collector are N-type material and the base is P-type material. In a PNP
transistor, the emitter and collector are P-type, while the base is N-type.
The base is sandwiched between the collector and emitter, so there is a
diode junction between the base and the collector and the base and emitter.
The circuit diagrams for these transistors are shown below.



When the base-emitter diode is forward-biased, a current, called the base
current will flow. A silicon NPN junction transistor is biased on when the
base-to-emitter voltage of approximately 0.6 to 0.7 volts. (E6A07)

If there is an appropriate voltage between the collector and emitter, this
small base current will cause a much larger current to flow between the
collector, through the base to the emitter. The amount of base current
controls how much collector current flows. This is how transistors amplify
signals.

The change in collector current with respect to base current is the beta of
a bipolar junction transistor. (E6A06) This is also sometimes called the
hfe, or current gain, of a transistor. The change of collector current with
respect to emitter current is the alpha of a bipolar junction transistor.
(E6A05)

Another important characteristic of a bipolar transistor is the alpha
cutoff frequency. This is a measure of how high in frequency a transistor
will operate. Alpha cutoff frequency is the frequency at which the
grounded-base current gain of a transistor has decreased to 0.7 of the gain
obtainable at 1 kHz. (E6A08)

Field effect transistors

A field-effect transistor (FET) is a device that uses an electric field to
control current flow through the device. Like the bipolar transistor, a FET
normally has three terminals. The names of the three terminals of a
field-effect transistor are gate, drain, source. (E6A17)

FETs are normally made with a technology called Complementary Metal-Oxide
Semiconductor, or CMOS. The initials CMOS stand for Complementary
Metal-Oxide Semiconductor. (E6A13) FETs made with CMOS technology are
sometimes call MOSFETs.

In Figure E6-2 (below), schematic symbol 1 is the symbol for a P-channel
junction FET. (E6A11) In Figure E6-2 (below), schematic symbol 4 is the
symbol for an N-channel dual-gate MOSFET. (E6A10)



One characteristic of the MOSFET is that they have a high input impedance.
This makes them more attractive for use in many test equipment applications
than bipolar transistors. How does DC input impedance at the gate of a
field-effect transistor compare with the DC input impedance of a bipolar
transistor? An FET has high input impedance; a bipolar transistor has low
input impedance. (E6A14)

One disadvantage of using MOSFETs is that they are very sensitive to
electrostatic discharge (ESD). Sometimes, they are damaged by static
discharges so low that you never even see the spark or feel the shock. To
reduce the chance of the gate insulation being punctured by static
discharges or excessive voltages many MOSFET devices have internally
connected Zener diodes on the gates. (E6A12)

Most FETs are enhancement-mode devices. When using an enhancement-mode FET,
you must apply a voltage to the gate to get current to flow from source to
drain. Some FETs are, however, depletion mode devices. A depletion-mode FET
is an FET that exhibits a current flow between source and drain when no
gate voltage is applied. (E6A09)

The post 2016 Extra Class Study Guide: E6A Semiconductor materials and
devices appeared first on KB6NUs Ham Radio Blog.


///////////////////////////////////////////
From my Twitter feed: Tools for electronic hobbyists, ladder line, build a
radar

Posted: 19 Jan 2016 05:48 PM PST
http://feedproxy.google.com/~r/kb6nu...m_medium=email



Â*instructablesÂ*@instructables

Tools for the Electronics Hobbyist

bit.ly/1OtXadsÂ*pic.twitter.com/xBMyzlpom4




Â*DXER @kc9ldo

Comment on Ladder Line by kv5r: Yes, 80 feet is one of the good lengths to
use. See page 3 of this article. bit.ly/1V6p3fA




Â*hackadayÂ*@hackaday

Try #radar for your next project! @MrVacuumTube bit.ly/1Wpnbks
pic.twitter.com/n4FiLQYVKO


The post From my Twitter feed: Tools for electronic hobbyists, ladder line,
build a radar appeared first on KB6NUs Ham Radio Blog.


///////////////////////////////////////////
Gab away in Morse this February

Posted: 19 Jan 2016 01:45 PM PST
http://feedproxy.google.com/~r/kb6nu...m_medium=email


This just in from Bruce, N7RR. Looks like fun to me.Dan
Based on a program begun by Stan Schmidt N7OC at the Mount Baker Amateur
Radio Club in Washington State, we’re continuing the month-long February
operating event that encourages conversation using Morse code. Most
operators will use regular CW mode on MF and HF frequencies, but sending
Morse tones via FM is fine, too.
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Call CQ GAB.
Gabfest is not a contest, so any Amateur Radio band or combination of bands
may be used. There are only two required exchange elements:

Call signs
USA zip codes or Canadian postal codes or Maidenhead grids if away from
civilization or outside of the United States or Canada.

You need to log:

Date and time in UTC of the start and end of each QSO, e.g. 2016-02-14-1315
Band, e.g. 80 m
Output power, e.g. 3 W or 55 W or 400 mW

There are four entry classes:

QRPp: 1 W or less output
QRP: 5 W or less output
QRO: more than 5 W output
QROo: more than 100 W output

If you operate in different classes, submit separate logs for each class.
Don’t forget to include your full name and email address with each log.
The object is not to accumulate long lists of quick QSO’s. Those are
contests. The point is to use your time for gabbing. Gabfest begins at
2016-02-01-0001 Z and ends at 2016-02-29-2359 Z. Spend as much time as you
are able during the month of February gabbing in Morse code.
You are welcome to add notes for each contact and a soapbox at the end of
your logs.
Deadline: Submit your logs in any convenient format to the Morse Gabfest
Honcho,Â*Bruce Prior, by 2016-04-01.
Note: You don’t need to know Morse code in order to participate in the N7OC
February Morse Gabfest. There are computer programs which both decode Morse
code and display what is being sent and then you can use a computer
keyboard to send Morse. The higher-end Elecraft transceivers come with a
computer program which does those things. There is lots of Morse decoding
and sending software availableÂ*for free or for little cost. Maybe you’ll
have so much fun gabbing in Morse code that you’ll want to learn to decode
Morse code by ear and to send it with some device like a paddle plugged
into an electronic keyer.
73 and happy gabbing, Bruce Prior N7RR

The post Gab away in Morse this February appeared first on KB6NUs Ham Radio
Blog.