Last night wasn’t as bad as it sounds but most stations, particularly stations at higher latitudes, will agree that conditions were worse than the previous session. While conditions were generally quiet through the early part of the session, the turbulence created by the shock wave that likely helped conditions for a while during the previous session(onset event) settled and culminated with a return to K-indices in excess of 5 and a south-pointing Bz. Solar wind remained low, near 350 km/s, however.
Here in Texas the session started with consistent WSPR reports through the day from W0JW in Iowa. Most of these reports appeared to be at JT9 levels. Additional reports through the afternoon came from WB0VAK in Minnesota and KG5KOG in East Texas, about 90-miles away.
John, WA3ETD / WG2XKA, reported “OK” domestic conditions with an open high latitude transcontinental path which yielded reports to and from Larry, W7IUV / WH2XGP, and Steve, VE7SL. Given the regularity of these long-haul paths being open, its curious why the more efficient path over salt water is not yielding trans-Atlantic reports from John’s station in Vermont more often than it does. Is it because there are fewer active stations in Europe that are qualified to hear the lower level DX signals or could it be that because there are so many active stations that the noise floor overall is too high on most occasions for weak signals to be detected and decoded? its an interesting problem and one that generally does not make sense. John provided the following screen shot from his session:
Doug, K4LY / WH2XZO, reported mixed conditions with poorer propagation to the Northwest, West, and even South which has historically yielded very good reports from Eden, ZF1EJ. Doug also noted that reports of my station were down 3 db from the previous session. Curiously, the path to the North was better, with WG2XKA reported 3 db better than the previous session and all-time best reports from WA3TTS/3 and WA9CGZ at +17 db and +12 db S/N, respectively. Doug indicated that reports from AA1A were about 1 db off of record highs at +9 db S/N.
Larry, W7IUV / WH2XGP, reported that conditions seemed down from his station in Washington state, hearing nine stations and being reported by 29 unique stations included stations on the transcontinental path.
The late evening saw Joe, NU6O / WI2XBQ, experimenting with MFSK8. He was not seen here in Texas at the time, presumably operating QRP, but there was some activity from Neil, W0YSE/7 / WG2XSV, John, VE7BDQ, and Toby, VE7CNF. These stations appear to have had moderate success and discussed the impact of signal bandwidth versus antenna bandwidth.
WSPR activity during the evening was at 72 MF WSPR stations, as reported by the WSPRnet activity page. K5ACL in Austin, Texas was the only “newer” station reported through the session. I believe that he has made reports in the past during this season but has been away for some time.
Regional and continental WSPR breakdowns follow:
There were no reports from the trans-African path during this session. UA0SNV was present from Asiatic Russia but no reports were found in the WSPRnet database from him.
AA1A reported four trans-Atlantic stations during this session, including DK7FC, EA5DOM, G3XIZ, and PA3ABK/2.
EA8BVP provided reports for EA5DOM and DK7FC on the continent:
Eden, ZF1EJ, provided reports for many stations on the mainland US in the South and Eastern US.
In Alaska Laurence, KL7L / WE2XPQ, experienced a generally poor, but typical night, with the bulk of the reports from the Pacific Northwest. Reports from Hawaii were quite numerous, however. KL7L was designated as receive-only through the session.
In the Pacific Merv, K9FD/KH6 / WH2XCR, experienced a good session, with reports from JH3XCU and JA1NQI-1. There were no reports from VK2XGJ. Merv was reported in the eastern US by WG2XJM and WH2XZO. WB0VAK and W0JW provided solid reports from the north central US.
In Australia, Phil, VK3ELV, was QRV again, with reports around VK and JH3XCU, some of which were decoded after the reporting period in the previous session:
Other statistics, information, comments and anecdotes:
Neil, W0YSE/7 / WG2XSV, noted that his reported power of 0.2 watts ERP after 0600z was actually 1-watt ERP.
Joe, NU6O / WI2XBQ, reports that his son, KJ6ICA, is working on an alternate solution to WSPRnet in order to counter some of the recent reliability problems that have been experienced. The goal is not to replace WSPRnet but to have a parallel operation where data can be rendered much like it is on WSPRnet. Currently the same model is being used by PSKReporter but the data comes from WSPRnet which means if WSPRnet is down, there is no data to feed PSKReporter. This new, parallel system will be the first entry point for WSPR data and forwarded on to WSPRnet.
I was recently contacted by Steve, W6SJP, who is currently working on projects in China and South Korea. He indicates that he is going to test his noise conditions on 630-meters to determine if WSPR receptions might be possible from both countries. With the persistence of WH2XCR’s signal in JA, it may be possible for Steve to make reports from a quiet location. Laurence, KL7L / WE2XPQ, has noted in the past that the bands are very noisy in China so success will come down to finding a quiet receive location, if it even exists.
Jim, W5EST, offers this commentary on calculations with transmit antennas as part of a recent discussion with Pat, W5THT / WD2XSH/6:
Thanks to Pat WD2XSH/6, W5THT, on the Gulf coast in Long Beach, Mississippi, for this contribution on the subject of 630m TX antennas! Don’t miss his remarkable station photos at http://500kc.com/about_stations/6/index.htm .
Pat says: Assume lossless ground and calculate antenna current for maximum allowed power. Your antenna is imperfect, so for the same antenna current the real radiated power will be less. Radiation resistance changed summer to winter and as I added grounding. Two days of freezing temps to stop the tree sap, and I could QSO or copy the entire northeast!
For background, scroll to technical files on: http://www.500kc.com/downloads1.htm
HOW I DID IT: With calibrated equipment, I measured the accuracy of the base ammeter. I then calibrated a remote ammeter against the known base ammeter. Measure the current into the radiator, NOT current into the matching network, SEE http://www.w5jgv.com/rfa-1/rfa-1.htm. The antenna current meter must be the last thing between the tuning and the antenna.
WD2XSH’s experiment coordinator gave me formulas.*
Total Radiated Power: TRP =I2 Rradiation .
Unlike a fictitious isotropic antenna, an E-probe (short vertical or inverted-L) radiates to only the half-sphere above ground and avoids the zenith. So total radiated power TRP gives more EIRP and ERP:
Effective Isotropic Radiated Power EIRP = 3 x TRP specifically for an E-probe.
Since ERP = EIRP/1.64 for any antenna,*
Effective Radiated Power ERP = 1.83 x TRP specifically for an E-probe.
LF antenna graphs cover fully top-loaded antennas and non-top-loaded (whip). Jasik, H. Antenna Engineering Handbook.
My top-loaded antenna had its coil suspended from a spreader. See the final two station photos where you see the spreader held one end of a ten foot wide 11-wire flattop 120 feet long. My antenna height was 50 feet of 11 strands #20 insulated wire twisted to approximate a cage radiator. (Paralleling small wires gives less RF loss than using heavy gauge wire due to skin effect.) At my station:
1.7 amp indicated = 72.25 watts to total R = 2.312 watts TRP, = 6.9 watts EIRP, = 4.229 watts ERP.
But the best way to measure radiated power is actual field strength measurement!
I developed antenna base RF current using transmit power through T/R relay and 3-section toroid filter into a matching auto-transformer made of tapped ferrite E-core, and from there to the antenna system using a motorized fine tuning coil. See all-weather plastic box opened in 6th station photo. I calculated maximum allowed antenna current from calculated radiation resistance, NOT the total resistance R that is mostly losses. Sap in antenna support trees dissipated some RF like dummy loads. Also, outbuildings lie within 10 feet of the base, losing some RF.
Only later did I add an amp and enhance the grounding with chicken wire and 3000 feet more radials on my 120 foot square lot.
Jim W5EST notes: Working backwards using Pat’s stated power and current,
Rradiation = 2.312 watts TRP / (1.7 amp)^2 = 0.80 ohms. Radiation resistance.
R = 72.25 watts / (1.7 amp)^2 = 25 ohms. Total antenna/ground resistance at resonance.
Pat used a calculator to estimate radiation resistance first based on 50 foot height of loaded antenna, and then calculated TRP.
Suppose a station needs to stay under 5 watts EIRP.* Then you work equations in reverse. Establish an antenna current less than Iantenna < sqrt [5watts/3Rradiation].
Radiated power and antenna height limits of Part 5 licensees depend on the terms of their license grants, which may vary. Adjust TX power output TPO to achieve desired antenna RF current leaving the tuning box. Until FCC acts, MF/LF transmissions are off-limits to Part 97 USA hams.
*See FCC NPRM 15-50, n. 37: “EIRP is the product of the power supplied to the antenna and the antenna gain in a given direction relative to an isotropic antenna (absolute or isotropic gain). Effective radiated power (ERP) (in a given direction) is the product of the power supplied to the antenna and its gain relative to a half-wave dipole in a given direction… ERP is equal to EIRP divided by 1.64, e.g., 1 W EIRP = 0.61 W ERP. See “Guidelines for Determining the Effective Radiated Power (ERP) and Equivalent Isotropically Radiated Power (EIRP) of a RF Transmitting System,” Office of Engineering and Technology, FCC, Nov. 30, 2010 (available at https://apps.fcc.gov/oetcf/kdb/forms/FTSSearchResultPage.cfm?switch=P&id=47469) .”
Additions, corrections, clarifications, etc? Send me a message on the Contact page!