Presentation on theme: "Rudy Severns N6LF, WD2XSH/20"— Presentation transcript:
1Rudy Severns N6LF, WD2XSH/20 email@example.com, www.antennasbyn6lf.com The New 630m Amateur BandRudy SevernsN6LF, WD2XSH/20
2A New Amateur BandAfter many years on the air using experimental licenses and intense politicking, at the 2012 World Radio Conference (WRC) amateurs were allocated a new MF band: kHz. Telecom authorities in various countries are now in the process of authorizing their amateurs to use the band. Many Europeans, VE, VK, ZL and even XV are on the air and we’re bugging the FCC to move!
3630 m Band 472-479 kHz. Emissions: CW and digital modes Radiated power limited to 5W EIRP (Effective Isotropic Radiated Power)No limitations on transmitter power or antenna size. i.e. you can use a small transmitter with a large antenna or a high power transmitter with a small antenna.
4Common Perceptions! None of this is true! A 7 kHz band is too narrow to be of use! The QRM will kill you!At such a low frequency with only 5W you can’t be heard down the block!The manmade and natural noise levels are so high you can’t hear anything!It’s impossible for amateurs on city lots to erect an effective antenna.No amateur equipment transmits on 630m.None of this is true!
5Why go to 630m?If you’re a bit tired of the same old stuff 630m is a fresh challenge:Very different propagationNew very narrow digital modesBut also the oldest mode – CWStation-computer integrationReceiving and transmitting equipmentAntennasBoat anchor resurrection
6AcknowledgementsMuch of the material presented here has been excerpted from the presentations of other amateurs:Fritz Raab W1FR, WD2XSH/14John Langridge KB5NJD, WG2XIQNeil Klagge, W0YSE,WG2XSV
7500 kHz History 500 kHz now unused except by museum stations Maritime CW calling/distress frequency since 1906kHz commercial ship-ship and ship-shore working frequencies also NavyRich traditions and historyAmateurs banned for >100 years!Automated satellite reporting adopted in 1980sCW and monitoring of 500 kHz ceased in 1990s500 kHz now unused except by museum stations
8The spectrum below the BC band Navigational telex
9ARRL experimental group First operation September 2006, W1FR experiment coordinatorOriginally 23 stations were licensed (WD2XSH/1 thru WD2XSH/23)Frequency allocation: kHz, 20W ERPUltimately it was expanded to 45 licensees with added frequencies: kHzThis operation and that of many others provided the ammunition for the WRC allocation battle!
25MF antenna basics!Succinct summary of LF/MF antennas by Woodrow Smith some 65 years ago:"the main object in the design of low frequency transmitting antenna systems can be summarized briefly by saying that the general idea is to get as much wire as possible as high in the air as possible and to use excellent insulation and an extensive ground system.”
26In order of priority Make the vertical as tall as you can. Use as much capacitive top-loading as practical.Use loading coils with as high a Q as possible.Put a lot of effort into the ground system, making the radial density high near the base of the vertical and under the top-loading hat.Try to minimize conductor losses by using multiple wires and/or large diameter conductors (tubing!)Use high quality insulators, both at the base and at wire ends.
45Propagation Daytime – ground wave WG2XIQ range at 1W ERP = about 225 miles on a quiet day for a typically equipped receive stationNighttime – sky wave dominates plus some ground waveSky wave can extend thousands of milesBehavior similar to bottom of the BC band at 630-metersSometimes there are surprises
47Transmission modes CW QRSS – ultra slow CW WSPR-2 & -15 (weak signal propagation reporter). SNR down to -30 dB or lower!2-way digital modes: BPSK31, JT9, JT65, RTTY, hellschriber and a wide variety of new modes being created and tested almost daily!
48WSPR –K1JT WWW.physics.princeton.edu/pulsar/K1JT/wsjt.html WSPR-2 and -15 is a tool for quantitatively testing propagation between a transmitting station and a receiving station. Typically the WSPR signals are transmitted periodically over a period of many hours with the receiving station recording the decodes and forwarding them on to WSPRnet.org where they are available in the database. Example:
51Software audio spectrum analyzers Waterfall and spectrum displaysARGO – I2PHDSpectran – I2PHD,Spectrum lab – DL4YHFThese are all freebies!All these require is an audio signal from your receiver.They work with modern or boat anchors rx
52Waterfall displaysWD2XSH/6 MS, /15 AR and /19 IL
53RX antennasUse vertical polarization – horizontal antennas tend to be very noisyLoopsvertical loops, shielded or not, a quad loop works wellK9AY terminated loopsE-probe (very short vertical) with or without ampExisting HF Antennas – dipole, random end fed wires, etc.Beverages and “Snakes” (BOG)Phased arrays of E-probes
54Testing your receiver NAVTEX Non-directional beacons (NDB) Maritime WX reports518 KHz and 490 KHzRTTYNon-directional beacons (NDB)Low power, omnidirectionalNumerousPart 5 StationsCWPC based digital modes – WSPR, MSK, OPERA
56Resources 1 Compiled by WA3ETD/WG2XKA with minor editing by N6LF. : Main Web Presence for WD2XSH ARRL MF Experiment. Lots of links and personal web sites from heavy hitters.: Jay Rusgroves MF/LF Site - gear and info. Jay is the guy behind Advanced Antenna Research (AAR). Good stuff and a fantastic craftsman.: The updated daily "action“ report from previous day MF activity. Also contains live links to many personal Ham/MF websites. Check this one for sure! Includes DX records...: Details on broadband MF/HF receive loops and preamps. Good Stuff, easy to build.
57Resources 2: Details regarding small antenna efficiency and calculations.: A VERY detailed and heavy analysis of LF/ MF antenna design. Hours of valuable reading. Don't be discouraged when he says it won't work…: Current list of MF Navigation Beacons in the US…: THE PREMIER list of MF Beacons (Hepburn) continuously updated, very organized. Use this to correlate calls and frequency.: Rog's 100W TX and many cool designs. Homebrew Heaven...don't miss. Check "MF Test Gear".
58Resources 3: Toroid specs and inductance/turn calculator- Get your Al values here. (Kits 'n Parts site): Everything MF and more. Guy never sleeps! There is no way Roger has a life outside his garden...currently into EARTH ANTENNA systems.: 2009/13 series of QEX articles on ground system experiments and analysis. Articles on 630m antennas. Required reading!: Fun site dedicated to old-time marine MF.ID your mystery toroid.
59Resources 4Deep traps for our transmitters - 2nd and 3rd of 475 right in the AM BCB and we can't have that! Cap across coil, easy. Well, a spectrum analyzer sure helps.Hard core guy way out west. Check out his MF preamp.Jack Smith - massive line of preamps, filters,active antenna. Plus a wealth of analysis, reviews and tech talk. MF oriented. Includes improved LPF for the Jackson Harbor $14 up-converter. Fun spot on the net.Jackson Harbor Press, home of the $14 up-converter. You get both a 4 and 10 mHz crystal, he's not making much on this unit.John sells the 20W TX converter as a complete kit with silk-screened PCB, available with 3.2 or 4.0 MHz I-F crystal. Optional GPS 10 MHz input.
60Software/Hardware Resources Filter design and analysis package by the maker of the AADE L/C meter.WSPR automated beacon reporting system: Really good filter design, using standard values with analysis and Monte Carlo.by I2PHD, home for Spectran and ARGO weak signal viewers - sound card based, MUST HAVE...Home of HDSDR package, my favorite, works best with the ensemble II LF receiver. Based upon WINRAD system, now free.Tony Parks SOFTROCK page. Get your Ensemble II. Also links to Yahoo Softrock users group. Lots of really tiny toroids to wind.: CMSK Software