Presentation on theme: "6 Meters The Mystery Band by Marc C. Tarplee, Ph.D. N4UFP."— Presentation transcript:
6 Meters The Mystery Band by Marc C. Tarplee, Ph.D. N4UFP
6 Meters: Rhetoric vs. Reality No one is on 6 meters –(I’ve made over 1900 QSO’s on 6 m since 1992) There is no DX on 6 meters –(I’ve worked 46 states and 38 countries on 3 continents) 6 meters is the TVI band –(I have never had a TVI complaint from my neighbors)
What makes 6 m interesting? A wide variety of operating modes is available No band offers a wider range of propagation phenomena than 6 m Station equipment requirements are modest Antenna experimentation is much easier on 6 m than the HF bands
6 Meter Band Plan CW, beacons (beacon sub band = MHz) SSB, CW (SSB calling frequency = MHz) DX window All modes Nonvoice communications (digital calling frequency = MHz) Radio remote control (20-kHz channels) Pacific DX window Repeater inputs (19 channels, digital repeater inputs are MHz) Repeater outputs (19 channels, digital repeater outputs are MHz) Repeater inputs (except as noted; 23 channels) 52.02, 52.04FM simplex 52.2TEST PAIR (input) Repeater output (except as noted; 23 channels) Primary FM simplex 52.54Secondary FM simplex 52.7TEST PAIR (output) Repeater inputs (except as noted; 19 channels) 53.0Remote base FM simplex 53.02Simplex 53.1, 53.2, 53.3, 53.4Radio remote control Repeater outputs (except as noted; 19 channels) 53.5, 53.6, 53.7, 53.8Radio remote control 53.52, 53.9Simplex
6 Meter Propagation Every type of propagation is possible on 6 m : –Line of Sight –Tropospheric Propagation –Sporadic E –Meteor Scatter –Auroral Scattering –Transequatorial F –Ionospheric F2
Line of Sight (LOS) and Tropospheric Propagation Line of Sight –LOS coverage is determined primarily by the height of the transmitting and receiving antennas –For typical amateur 6 m stations LOS coverage is about 20 miles –LOS propagation is unaffected by solar conditions, time of day or the seasons Tropospheric Propagation –Variations in the humidity of the troposphere cause RF to be scattered over the horizon. This is known as tropospheric scatter –Temperature inversions (warm dry air located above cool moist air) refract RF in the VHF range back towards the earth. Temperature inversions occur daily in the middle latitudes at sunrise and sunset. Communications are possible over a ranges up to 600 miles –Over the oceans, stable temperature inversions can create a duct, through which VHF can travel without significant loss up to 2500 miles
Tropospheric Scatter Tropospheric Ducting
Sporadic E (E S ) Clouds of high density ionization form without warning in the ionosphere’s E layer E S is not dependent on solar activity. It may occur any time, but is most frequent between May and August, with a smaller peak of activity in December Single hop E S has a range of ~1400 mi Double hop E S has a range of ~ 2500 mi Cause of Sporadic E is not known: high altitude wind shear may be responsible.
Sporadic E (E S ) The ionized clouds that cause sporadic E propagation can move. This animated sequence shows grid squares contacted in ½ hour intervals during an E S opening beginning at 0500 Z, 10 June 2001
Meteor Scatter As meteors are vaporized in the upper atmosphere, they leave behind ionized trails at heights of 60 – 70 miles that are sufficiently dense to reflect VHF A long trail lasts only 15 seconds so contact must be made quickly on SSB SSB QSO’s via meteor scatter are usually possible only during a meteor storm Short trails that occur continuously may be used for high speed CW QSO’s (> 100 wpm) Best time for meteor scatter is after midnight or during a meteor storm
Aurora (Au) During periods of intense auroral activity, charged particles in the auroral zone can scatter 50 MHz RF The RF interacts strongly with the aurora, resulting in significant distortion of the signal. Only narrow band modes such as CW are used during Au openings To work Au, the transmitter and receiver point their antennas at the auroral zone, not each other.
Transequatorial F (TE) The ionosphere’s F layer is most intense in the region of the geomagnetic equator. Stations within about 2500 miles of the geomagnetic equator can launch 50 MHz RF into these regions. The RF is refracted and travels across the equator and into the other hemisphere without scattering from the ground Stations using TE must be at approximately equal distances from the geomagnetic equator
F2 propagation Communications over long distances (> 2000 miles) are possible on 6 m via the F2 layer of the ionosphere during periods of high solar activity (solar flux above 220) Openings generally occur in spring and fall during daylight hours (similar to 10 m)
Propagation Example 2001 June VHF QSO Party 6 m QSO’s
Traditional 6m Operating Modes CW –Used primarily below MHz –Used during auroral openings – narrowband modes like CW are less susceptible to distortion HSCW –CW sent at high speeds (200 wpm or more) –Used with meteor scatter propagation –Most operation takes place near MHz SSB –Most common 6m mode - USB is the standard –Calling frequency is MHz – – MHz is the DX window
Digital 6m Operating Modes FSK441 –Uses triplets of 4 tones to transmit data 882, 1323, 1764, 2205 Hz Each character is sent as a 3 tone sequence 43 Character alphabet (letters, numbers., / ? # $ ) Single tone characters used for shorthand messages: –882 Hz - R Hz - RRR –1323 Hz – R Hz - 73 Data rate = 147 characters per second (3 tones/char) Used for meteor scatter communications Most activity takes place near MHz Messages sent in 30 sec intervals – westernmost station transmits during first 30 seconds of each minute.
Digital 6m Operating Modes JT65B –Narrowband PSK 64-ary PSK (6 bits per baud) ~2.7 Baud signaling speed ~5.4 Hz operating bandwidth Requires a stable receiver, good timing Messages sent in 60 sec intervals – westernmost station transmits during even-numbered minutes. Provides clear copy at SNR < 0 dB Used for moonbounce and troposcatter operation Most activity takes place near MHz
6 Meter Station Requirements Transceiver or Transverter –RF output of at least 10 W PEP (>100W for FSK441, JT65, ~1000W for EME) with multi-mode capability (CW/SSB/FM) ICOM 706, 746, 756 Yaesu FT-100, 817, 847, 920 Kenwood TS-570 Alinco DX-70TH Antenna –Gain of at least 5 dBd (> 15dBd for EME) –Should be rotatable (az-el rotation is very important for EME) –Should be at least 20 ft above ground –Use low loss coax (RG8 up to 75 ft, Belden 9913 for longer runs) Useful accessories –RF pre-amp (RF switched) –Grid Square Map –PC (for FSK441, JT65)
6 Meter Antennas 6 m antennas are relatively small, light and easily rotatable. Best choices for a new operator: –2 element quad –3 element Yagi –Extended Double Zepp –6/10 dual band dipole For weak signal work (CW/SSB) the antenna should be horizontally polarized For repeater operation, vertical polarization is the norm For EME an array of 4 long yagis is typical Meteor scatter operation requires an antenna with good gain and broad beamwidth – 5 to 9 element yagis work well.
6 Meter Quad and Yagi Antennas 2 element Quad (square loops of #14 ins. wire Z ~ 60 ohms Gain ~ 4 dBd) –ElementLoop Length (in)Position (in) –Reflector –Driver element Yagi (Aluminum tubing Z ~ 42 ohms gain ~ 5 dBd) –ElementHalf Length (in) (0.75 dia dia)Position (in) –Reflector –Driver –Director element Yagi (Aluminum tubing Feed Z ~ 35 ohms Gain ~ 8 dBd) – Element Half Length (in) (0.75 dia dia) Position (in) –Reflector –Driver –Director –Director –Director
Other 6 Meter Antennas Dipole –Length = 114 inches (#14 wire) Z ~ 70 ohms Gain ~ 0 dBd Extended Double Zepp –Length = 282 inches (#14 wire) Z ~ 45 ohms Gain ~ 4 dbd –Antenna is fed at the center through a inch length of 450 ohm ladder line (VF = 0.9) 6/10 dual band dipole –Length = 198 inches (#14 wire) Z ~ 64 ohms Gain ~ 1 dBd –Antenna is fed at the center through 32 feet 4 inches of 450 ohm ladder line (VF = 0.9) –Antenna also can be used on 10 meters (Z ~ 72 ohms)
6 Meter Activities Contests –ARRL January VHF Sweepstakes (3 rd weekend in January) –ARRL June VHF QSO Party (2 nd weekend in June) –SMIRK QSO Party (3 rd weekend in June –CQ WW VHF Contest (2 nd weekend in July) –Six Club 6 m Sprint (3 rd weekend in July) –ARRL September QSO Party (2 nd weekend in September) Operating Awards –VUCC – contacts with 100 Grid Squares, not difficult –WAS – tough, but not impossible –DXCC – very tough from North America, but it has been done Grid Square Hunting –There are over 500 grid squares in the continental US –No one has worked them all yet (except perhaps for W5FF)
What is a Grid Square? Almost all VHF operating awards and contests involve grid squares Grid Squares are 2º longitude x 1º latitude sections of the earth’s surface (there are 32,400 in total) Each grid square has a 4 character designator containing 2 letters and 2 numbers. –The two letters designate the field. There are 324 fields lettered AA through RR –Each field is divided into 100 squares numbered 00 through 99 The continental US includes grid squares in fields CM,CN, DL, DM, DN, EL,EM,EN, FM and FN Most of Rock Hill is in grid square EM94.