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Hearing Weak DX on 80 & 160

Hearing Weak DX on 80 & 160. Bill Tippett W4ZV October 1, 2005 SEDCO – Ten-Tec Hamfest. Introduction. “You can’t work ‘em if you can’t hear ‘em!” ~ The Old Timer K4RID – QRV 80m 1960 W0ZV – QRV 80m ‘80, 160m ‘84 80m DXCC 339 (need 4 more) 160m DXCC 317 (need 22 more).

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Hearing Weak DX on 80 & 160

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  1. Hearing Weak DX on 80 & 160 Bill Tippett W4ZV October 1, 2005 SEDCO – Ten-Tec Hamfest

  2. Introduction • “You can’t work ‘em if you can’t hear ‘em!” ~The Old Timer • K4RID – QRV 80m 1960 • W0ZV – QRV 80m ‘80, 160m ‘84 • 80m DXCC 339 (need 4 more) • 160m DXCC 317 (need 22 more)

  3. Weak Signals in Noise • “Since you can’t increase the weak signal, reduce the noise!” ~The OT • 1. Noise reduction (S/N issues) • 2. Signal strength (propagation issues) • 3. Other (experience, practice)

  4. Noise Reduction • Different types of noise: • Atmospheric (lightning-induced) • Man-made (power lines, electric fencers, FCC part 15 devices) • Precipitation static (rain, snow, dust)

  5. Antenna Metrics • Beamwidth – included angle for 3 db gain reduction (azimuth or elevation) • RDF – W8JI definition based on Eznec calculations of max forward gain versus 3D gain at all azimuths and elevations • DMF – ON4UN calculation based on forward gain versus averaged F/R in rear 180 degrees (best F/R metric)

  6. Azimuth Example

  7. Elevation Example

  8. Where ’s the noise coming from?

  9. Lightning Strikes

  10. Noise Reduction – Forward Direction • If the noise is from the same direction as the signal, minimize forward beam width to “slice through” the noise • BSEF 8 el / 4el BS vert = ~25 deg. (but not practical to cover 360 degrees) • Parallel 2wl Bev = 44 deg. • W8JI 8-circle vert = 55 deg. • Single 2wl Bev = 62 deg. • Single 1wl Bev = 78 deg. • 4-square vert = 86 deg.

  11. …but, Optimize S/N • If noise not exactly same direction, use knowledge of geography and antenna patterns. • Example: FT5XO’s bearing SE and thunderstorm noise South. • Solution: ESE Beverage includes FT5XO but attenuates noise.

  12. Noise Reduction – Rear • Most wintertime DX not the same direction as storm QRN…don’t need narrow forward beamwidth. Winter storms from Texas to Caribbean are very common...thus need maximum F/R performance toward EU (JA normally not an issue). • ON4UN’s DMF is the most useful metric for F/R performance.

  13. Directivity Merit Factor • 2X 2wl Beverages EF – 33.8 dB • 2X 1wl Beverages EF – 30.1 dB • 4-square – 24 dB • W8JI 8-circle – 22.6 dB • Conclusion: 1wl Beverage EF pair extremely effective for Middle East, Europe and Africa…not much more space than single Beverage

  14. For City Dwellers… • Acreage matters! So don’t set unrealistic expectations. • K9AY/Flag/Pennant/EWE arrays quite effective but cannot compare to phased Beverages or large vertical arrays. • K2UO has ~225 DXCC on 160 from a city lot so you can still have lots of fun!

  15. High-angle Antennas • Sometimes high-angle antennas are optimum. Most common at your sunrise and sunset. • Beverages and vertical arrays are all low-angle antennas, so consider an inverted-V or dipole as a complement. In this case use the same antenna for both transmit and receive.

  16. Inv-V vs 3el Vertical TOA

  17. Man-made Noise • Noise audit (home, neighborhood, power lines) and remove at the source (or move!) • SWL RX and whip or loop antenna • MFJ-852 (for power lines) • Tune 1710 kHz on your car radio • RX noise blankers work well for modern electric fencers (but RX overload) • MFJ-1025 for local single-point noise

  18. Precipitation Static • Verticals are bad • Beverages are good • Noise blankers sometimes work • Sometimes nothing works

  19. About That Weak Signal • You can’t make it stronger but Mother Nature can! Remember the 3 P’s --- Propagation, Patience and Persistence. • Propagation – Know when the DX signal may peak and watch azimuth changes. • Patience – Propagation may move toward you. Don’t call if you can’t hear! • Persistence – Keep trying! JT1CO and UK8DAN literally took seasons to work!

  20. Other Issues • Practicelistening to weak signals. N2XE’s Beacon starts in October; YR2TOP on 1810.5. • Modern receiver sensitivity (MDS) not a factor, but learn which settings work best for your ears (i.e. Pitch, Bandwidth, AGC, RF Gain, NR, NB, Diversity, etc).

  21. Need more info? • ON4UN’s Low-Band DXing 4th edition (the only book you need) • W8JI.com (many pages of info) • Topband reflector archives

  22. Conclusion • Low Bands are challenging but fun! • Great conditions are just ahead. • Good RX antennas are a must. • Nobody said it would be easy! • Get in there and have some fun!

  23. Beverage Kits - $10 • Transformer (50 or 75 ohm coax), non-inductive termination & instructions

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