1. Rudy Severns N6LF, WD2XSH/20 n6lf@arrl.net, www.antennasbyn6lf.com
The New 630m Amateur Band
Rudy Severns
N6LF, WD2XSH/20

2. 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: 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!

3. 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.

4. Common 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!

5. 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

6. 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

7. 500 kHz History 500 kHz now unused except by museum stations
Maritime CW calling/distress frequency since 1906
kHz commercial ship-ship and ship-shore 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

8. The spectrum below the BC band
Navigational telex

9. ARRL experimental group
First operation September 2006, W1FR experiment coordinator
Originally 23 stations were licensed (WD2XSH/1 thru WD2XSH/23)
Frequency allocation: kHz, 20W ERP
Ultimately it was expanded to 45 licensees with added frequencies: kHz
This operation and that of many others provided the ammunition for the WRC allocation battle!

10. ARRL experimental stations

11. WD2XSH CW QSO’s

12. CW DX reception reports
V73

13. CW beacon reception reports /20

14. WD2XSH/14 (W1FR)

15. Original WD2XSH/20 (N6LF)

16. Latest WD2XSH/20 (N6LF)

17. Latest WD2XSH/20 (N6LF)

18. Filters!

19. Boat anchors at N6LF

20. WD2XSH/5 (KW1I)
RBA receiver and an ART13 transmitter

21. WD2XSH/9 (W2ILA)
Maritime reserve XMTR

22. WD2XSH/12 (AI8Z)
HB pair 6146’s

23. WD2XSH /15 (W5OR)
SAC H-25 NDB XMTR

24. Nice but you don’t have to have it!

25. 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.”

26. 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.

27. T and L antennas

28. Use the available supports

29. Umbrella vertical 1

30. Umbrella vertical 2

31. WD2XSH/14

32. WD2XSH/13 antenna

33. WD2XSH/19 antenna

34. WD2XSH/6 (W5THT) antenna

35. ATU box

36. Inside the ATU

37. Tuning the ATU

38. WD2XSH/20 antenna

39. Latest antenna at N6LF
95’ high, 240’ across, ’ radials on the ground
There’s a very extensive discussion of MF antennas at:

40. Antenna poles at N6LF

41. Base tuning box

42. Tuning-matching inductor

43. Poles assembled on the ground

44. Pole erected with a crane

45. 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 630-meters
Sometimes there are surprises

46. Start by listening…

47. 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!

48. 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:

49. WSPR Mapping

50. WSPR Data

51. Software audio spectrum analyzers
Waterfall and spectrum displays
ARGO – I2PHD
Spectran – I2PHD,
Spectrum lab – DL4YHF
These are all freebies!
All these require is an audio signal from your receiver.
They work with modern or boat anchors rx

52. Waterfall displays
WD2XSH/6 MS, /15 AR and /19 IL

53. 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

54. Testing your receiver NAVTEX Non-directional beacons (NDB)
Maritime WX reports
518 KHz and 490 KHz
RTTY
Non-directional beacons (NDB)
Low power, omnidirectional
Numerous
Part 5 Stations CW
PC based digital modes – WSPR, MSK, OPERA

55. THE QUEST CONTINUES ...
Amateurs commercial interests

56. Resources 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.

57. Resources 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".

58. Resources 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.

59. Resources 4
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.
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.

60. Software/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