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The New 630m Amateur Band
Rudy Severns
N6LF, WD2XSH/20
n6lf@arrl.net,
www.antennasbyn6lf.com
A New Amateur Band
After 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: 472-479 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!
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630 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.
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Common Perceptions!
• 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!
Why go to 630m?
• If you’re a bit tired of the same old stuff 630m
is a fresh challenge:
– Very different propagation
– New very narrow digital modes
– But also the oldest mode – CW
– Station-computer integration
– Receiving and transmitting equipment
– Antennas
– Boat anchor resurrection
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Acknowledgements
• Much of the material presented here has been
excerpted from the presentations of other
amateurs:
• Fritz Raab W1FR, WD2XSH/14
• John Langridge KB5NJD, WG2XIQ
• Neil Klagge, W0YSE,WG2XSV
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500 kHz History
•Maritime CW calling/distress frequency since
1906
•415-495 kHz commercial ship-ship and shipshore working frequencies also Navy
•Rich traditions and history
•Amateurs banned for >100 years!
• Automated satellite reporting adopted in 1980s
• CW and monitoring of 500 kHz ceased in 1990s
• 500 kHz now unused except by museum stations
The spectrum below the BC band
Navigational
telex
ARRL experimental group
• First operation September 2006, W1FR
experiment coordinator
• Originally 23 stations were licensed (WD2XSH/1
thru WD2XSH/23)
• Frequency allocation: 495-510 kHz, 20W ERP
• Ultimately it was expanded to 45 licensees with
added frequencies: 461-478 kHz
• This operation and that of many others provided
the ammunition for the WRC allocation battle!
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ARRL experimental stations
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WD2XSH CW QSO’s
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CW DX reception reports
V73
12
CW beacon reception reports /20
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WD2XSH/14 (W1FR)
14
Original WD2XSH/20 (N6LF)
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Latest WD2XSH/20 (N6LF)
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Latest WD2XSH/20 (N6LF)
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Filters!
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Boat anchors at N6LF
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WD2XSH/5 (KW1I)
RBA receiver and an ART13 transmitter
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WD2XSH/9 (W2ILA)
Maritime reserve XMTR
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WD2XSH/12 (AI8Z)
HB pair 6146’s
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WD2XSH /15 (W5OR)
SAC H-25 NDB XMTR
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Nice but you don’t have to have it!
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MF 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.”
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In 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.
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T and L antennas
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Use the available supports
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Umbrella vertical 1
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Umbrella vertical 2
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WD2XSH/14
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WD2XSH/13 antenna
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WD2XSH/19 antenna
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WD2XSH/6 (W5THT) antenna
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ATU box
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Inside the ATU
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Tuning the ATU
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WD2XSH/20 antenna
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Latest antenna at N6LF
95’ high, 240’ across, 128 150’ radials on the ground
There’s a very extensive discussion of MF antennas
at: www.antennasbyn6lf.com
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Antenna poles at N6LF
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Base tuning box
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Tuning-matching inductor
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Poles assembled on the ground
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Pole erected with a crane
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Propagation
• Daytime – ground wave
– WG2XIQ range at 1W ERP = about 225 miles on a quiet day
for a typically equipped receive station
• Nighttime – sky wave dominates plus some ground
wave
– Sky wave can extend thousands of miles
• Behavior similar to bottom of the BC band at 630meters
• Sometimes there are surprises
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Start by listening…
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Transmission 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!
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WSPR –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:
Timestamp
2014-01-30 17:34
2014-01-30 17:36
2014-01-30 17:38
2014-01-30 17:40
Call
WG2XIQ
G3XIZ
WG2XIQ
DL8YCA
MHz
0.475666
0.475700
0.475666
0.475782
SNR Drift Grid
-17 0 EM12mp
-29 0 IO92ub
-17 0 EM12mp
-11 -1 JO31or
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Pwr
0.05
0.5
0.05
0.01
Reporter
WG2XXM
DD7PC
WG2XXM
PI4THT
RGrid km
EM15lj 306
JN49ax 627
EM15lj 306
JO32kf 60
AZ
359
108
359
338
WSPR Mapping
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WSPR Data
5
0
SNR [dB]
-5
WE2XPQ WSPR reception
of WD2XSH/20
29 Jan 2014
CW QSO
possible
-10
-15
-20
-25
-30
2:00
3:00
4:00
5:00
6:00
7:00
8:00
Time [UTC]
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9:00
10:00
11:00
12:00
13:00
14:00
Software audio spectrum analyzers
• Waterfall and spectrum displays
– ARGO – I2PHD
– Spectran – I2PHD, www.weaksignals.com
– Spectrum lab – DL4YHF www.qsl.net/dl4yhf
• These are all freebies!
• All these require is an audio signal from your
receiver.
• They work with modern or boat anchors rx
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Waterfall displays
WD2XSH/6 MS, /15 AR and /19 IL
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RX antennas
• Use vertical polarization – horizontal antennas tend
to be very noisy
• Loops
– vertical loops, shielded or not, a quad loop works well
– K9AY terminated loops
• E-probe (very short vertical) with or without amp
• Existing HF Antennas – dipole, random end fed wires,
etc.
• Beverages and “Snakes” (BOG)
• Phased arrays of E-probes
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Testing your receiver
• NAVTEX
– Maritime WX reports
– 518 KHz and 490 KHz
– RTTY
• Non-directional beacons (NDB)
– Low power, omnidirectional
– Numerous
– http://fivegulf.com/ndb/
• Part 5 Stations
– CW
– PC based digital modes – WSPR, MSK, OPERA
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THE QUEST CONTINUES ...
Amateurs
commercial interests
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Resources 1
• Compiled by WA3ETD/WG2XKA with minor editing by N6LF.
• http://www.500kc.com : Main Web Presence for WD2XSH
ARRL MF Experiment. Lots of links and personal web sites
from heavy hitters.
• http://www.w1vd.com : Jay Rusgroves MF/LF Site - gear and
info. Jay is the guy behind Advanced Antenna Research (AAR).
Good stuff and a fantastic craftsman.
• http://www.500kc.com/W0RPK_Report/W0RPK_Report.htm :
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...
• http://members.shaw.ca/ve7sl/ : Details on broadband
MF/HF receive
loops and preamps. Good Stuff, easy to
build.
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Resources 2
• http://www.w8ji.com/radiation_resistance.htm : Details
regarding small antenna efficiency and calculations.
• http://www.strobbe.eu/on7yd/136ant : 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…
• http://www.russthom.com/ndb : Current list of MF Navigation
Beacons in the US…
• http://www.dxinfocentre.com/ndb.htm : THE PREMIER list of
MF Beacons (Hepburn) continuously updated, very organized.
Use this to correlate calls and frequency.
• http://www.gw3uep.ukfsn.org/index.htm : Rog's 100W TX
and many cool designs. Homebrew Heaven...don't miss.
Check "MF Test Gear".
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Resources 3
• http://toroids.info/T37-2.php : Toroid specs and
inductance/turn calculator- Get your Al values here. (Kits 'n
Parts site)
• http://g3xbm-qrp.blogspot.com : Everything MF and more.
Guy never sleeps! There is no way Roger has a life outside his
garden...currently into EARTH ANTENNA systems.
• http://www.antennasbyn6lf.com : 2009/13 series of QEX
articles on ground system experiments and analysis. Articles
on 630m antennas. Required reading!
• http://www.radiomarine.org/#pab1_12 : Fun site dedicated
to old-time marine MF.
• http://www.dl5swb.de/html/mini_ring_core_calculator.htm
ID your mystery toroid.
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Resources 4
•
http://www.electronics-tutorials.com/filters/trap-filter.htm
Deep 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.
•
http://w7iuv.com/:
•
http://www.cliftonlaboratories.com/ 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.
•
http://wb9kzy.com/ham.htm
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.
•
WG2XKA@gmail.com
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.
Hard core guy way out west. Check out his MF preamp.
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Software/Hardware Resources
•
http://aade.com/filter.htm
meter.
Filter design and analysis package by the maker of the AADE L/C
•
http://wsprnet.org/drupal/
WSPR automated beacon reporting system
•
http://tonnesoftware.com/svcfilter.html : Really good filter design, using standard values with
analysis and Monte Carlo.
•
http://www.weaksignals.com/ by I2PHD, home for Spectran and ARGO weak signal viewers - sound
card based, MUST HAVE...
•
http://www.hdsdr.de/
Home of HDSDR package, my favorite, works best with the
ensemble II LF receiver. Based upon WINRAD system, now free.
•
http://fivedash.com/
Tony Parks SOFTROCK page. Get your Ensemble II. Also links to
Yahoo Softrock users group. Lots of really tiny toroids to wind.
•
http://www.qsl.net/zl1bpu/CMSK/cmsk.htm : CMSK Software
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