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Episode 11 -- April 25, 2016 -- Amplifiers Classes, Oscillators, Modulation Modes with examples, Radio Dave guest stars.
Listen to the episode 62.2 MB MP3
More Introductory Radio Theory
Decibles and S-Units (3 questions); Db = 10 Log(10) [ i(in) ÷ i(out) ]
AF, IF and RF
Audio Frequency -- signals which can be used to vibrate a speaker to produce sound
Intermediate Frequency -- signals mixed with an oscillator to make an intermediate signal inside a receiver or transmitter on its way to either the antenna (RF) or the speaker (AF). Often 10.7 MHz and 455 KHz.
Radio Frequency -- signals going to or from an antenna.
Why do we shield wires? Their resistance doesn't change. They can't handle more power if shielded. We shield wires to prevent them from behaving like an antenna, either receiving or transmitting stray signals.
Colpitts Oscillators are tuned with an LC circuit. That is, an inductor and capacitor in parallel determin the output frequency. You can easily calculate that based on the component values of the capacitor(s) and indoctor(s) involved.
Hartley Oscillators also use an LC circuit, but...
The USA is a Democratic Republic
So we don't actually get to vote directly for the president and vice-president. Instead, if we are a member of a party, we can vote for "electors" which are district representatives for each Congressional District in each state from each party which then represent us at the National Democratic and Republican Conventions, held in July every 4 years.
We vote for Republican and Democratic Party Nominees. If you are registered with the American Independant Party (as opposed to actually being registered as and Independant Voter, which one can do here in California, but is a very different thing) then you can vote for a nominee candidate from the American Independant Party. Ditto Green Party, etc. If you are actually registered as an Independant Voter, then you can vote for any one of them.
Because of the size of each congressional district, a certain number of delegates from each district can be chosen to attend the national convention. Here in Lake County, California, we can send 3 male district delegates and 3 female district delegates (Because the population of congressional district 3, in which we reside, gives us that many) and one female alternate, for some unknown (to me) reason.
The males and females have separate contests to ensure that the same number of men and women reprsent us.
If, for example, Bernie Sandars and Hillary Clinton both get approximately 50% of the vote, then half of the 6 delegates our district gets to send to the convention will be the Hillary Clinton Candidate Winners and half will be the Bernie Sandars winners. If, on the other hand, Sanders wins 75%, then we send 4 Sanders Delegates and 2 Clinton Delegates. If Sanders wins 83% of the popular vote, then 5 of the Sanders Delegates get to go and only 1 of the Clinton Delegates, etc.
At the Democratic Convention in Philidelphia, PA in July, the delegates we send will have some sort of process and jump through some sort of set of hoops laid out by the national democratic party so that a winner will be picked. The rules are all set by National Democratic Party Insiders -- the same people who approved last August when the Clintons laundered millions of dollars of donations to themselves through 33 of the 50 states' democratic party organizations. But they assure us that, even though they lied and cheated in Arizona, Illinois, New York, Wyoming and Massechusetts, they'll be totally honest in Philidelphia. :o|
If you would like to be a candidate to be a district delegate to represent either Clinton or Sanders at the convension, then sorry, it's too late -- the deadline was April 13, 2016.
If you wish to vote for delegates to represent Hillary Clinton at the national convention in July, you must attend the Clinton Democratic Caucus in Vaccaville on May 1st. at this location:
PSK-31, BPSK31 and QPSK-31 are all so named because they send Varicode data at 31 bits per second. Varicode is just a very effient way to encode the alphabet and numbers as well as a bit of punctuation into easily computer-decodeable sounds. These are the very best on the HF Bands for computer to computer communications in realtime. It works at a good typing speed for some of us and they even include elementary error checking. But these formats, particularly psk-31 use a very tiny amount of bandwidth, arguably even less than CW because they're decoded by computers instead of people so more signals can exist together in a crowded band and everybody can still maintain communication. Less bandwidth also means the very highest effiency for communicating from a portable (pocket-sized) radio using a wire antenna in a tree (say, 70 feet long) and batteries that can also fit in your pocket for instant world-wide communication. Here is a lot more information.
There are several different varieties of MT-63 and Olivia. I've heard these on the HF Bands.
A couple diffent manufacturers make different and incompatible kinds of Digital FM. These are used -with mixed results- on VHF and UHF to try to hold down bandwidth in conjested areas such as big cities.
Yaesu has one. I haven't made a recording of it yet.
MOTOTRBO is the standard made by Motorola Digital Two-Way Radio and is compatible with Digital Mobile Radio (DMR) Tier 2 commercial standard
There are quite a few different variations of the Hellshreiber format.
AMTOR and PACTOR2 are popular formats on HF for digital communication because they incorporate more rhobust error checking and correction. A commercial version of PACTOR (pactor 4) is used commonly by ships at sea.
JT-65A is designed to communicate successfully by bouncing very high power UHF or VHF signals against lots of tiny rocks hitting the upper atmosphere all the time in sheets or waves. "Meteor-Scatter" is the name of this type of communication because lots of little meteors are scattered across the sky. Or maybe we scatter our signals across the sky looking for lots of tiny rocks to bounce them off of?
Slow Scan TV paints a picture using audio tones, 30 seconds per frame. Obviously, color takes 3 times longer than black and white.
TV on 70cm = 6 MHz bandwidth (Question)
WeFAX signals are the oldest digital broadcast. They're sent from weather satellites to ships at sea. Actually, they're sent from the satellite down to a ground station at which a meteorologist draws little lines and arrows on them (or, in the case of the 26 April 1986 Chernobyl disaster, blocks out all the data entirely so nobody can guess where the fallout will land in northwestern Europe) and sends these edited pictures back up to the satelitte to be re-broadcast down to all the ships at sea. (I was working for a weather computer company that year).
If I've made any mistakes, please Call me or email Kila or you can call us directly at (707) 413-6435. Here is my main website.