ae5ft, Gene, suggested that "The 2 Meter Band Plan" be a topic for the Tech Net. So tonight this is what we put forth. The following information was taken from an ARRL Repeater Director with a little info mixed in that I found on the net:
Frequency Spacing
States East of the Mississippi - 20 kHz
States West of the Mississippi (excluding Texas) - 15/30 kHZ
Popular Simplex Frequencies Nationwide
146.49
146.505
146.520 National Calling Frequency
146.535
145.55
146.56 (in Texas)
146.58
Simplex
146.4 - 146.58
147.42 - 147.57
SSB
144.200 Calling Frequency
144.20 - 144.275
ke5cub, Lee, was the first to check in with a question. The question was, "What's the difference between resonance of the antenna and low SWR, and how to they affect each other?
We had a few check-ins but no takers until ad5pe, Jay, offered an explanation to Lee's question. I wish that I could repeat Jay's answer, but I did not have my recorder set up and my note-taking failed me. With that in mind I will try to encapsulate that which I can remember. I will do this with the help of:
http://www.radio-electronics.com/info/antennas/basics/resonance.php
http://qsl.net/g3yrc/antenna basics.htm
To start off with, resonance is a vastly overrated concept. But what is antenna resonance?
An RF antenna is a form of tuned circuit consisting of inductance and capacitance, and as a result it has a resonant frequency. This is the frequency where the capacitive and inductive reactances cancel each other out. At this point the RF antenna appears purely resistive.
The capacitance and inductance of an RF antenna are determined by its physical properties and the environment in which it is located. The larger the antenna or more strictly the antenna elements, the lower the resonant frequency.
The magnetic field that your antenna puts out will produce an electric current on any metal surface that it strikes, however if the metal that the signal strikes has a length relation to itself, the current will be much stronger on the object. If the object that the magnetic wave strikes is 1/2 wave length, 1/4 wavelength, or 1 full wavelength, then the induced current will be much higher than if the signal struck an object that was not some appreciable fraction of the wavelength of the signal. An antenna is "tuned" at for an exact wavelength. For that exact frequency that antenna is resonant. Every antenna has at least one exact resonance point.
Antenna resonance is the frequency, in MHz, where the antenna is in a state of electrical balance, which is determined by the length of the antenna.
SWR (Standing wave reflected) is the phenomenon that exists when power which initially was sent into the antenna is reflected back toward the radio. The SWR is measured in a ratio, for example 1.5:1 (or 1.5 to 1). How much power gets reflected back into the radio is dependent on the impedance of the radio/coax/antenna. If it's matched perfectly, the power reflected will be near zero (or said another way, an exact match, 1:1).
The impedance of the antenna is a function of the frequency being transmitted and the point at which the antenna is resonant.
Though your antenna may be resonant at a particular frequency, It is more important that the SWR not surpass levels that would be harmful to your radio. You can talk fine on an antenna that is not very resonant, but a high SWR can burn up the
"finals" in your radio.
ke5cub, Lee, added that "Resonant means that the antenna vibrates at it's assigned frequency. Keep the SWR below 2.1:1."
ae5jz, Tom, checked in and said that on his "waterfall" on PSK 31, there is a signal line less than 7 cycles wide at various places along the band, without modulation. He asked if anyone had any ideas about what that was.
k5bbm, Brian, asked, "At what frequencies do you transmit PSK31 on 2 meters?
kk5edd, Ed, suggested that it may be (according to his reference material) that 144.144 for vhf and 432.2 for uhf.
I don't recall who it was, but I believe someone suggested that the 7 cycle line on Tom's waterfall may be associated to some of Tom's equipment.
With that there were no more check-ins, and the Net ended.
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