The strong propagation that settled over the Pacific Rim during the past few sessions has relocated to the East, with strong domestic conditions in North America, trans-Atlantic reports by a number of North American stations, and propagation rarely observed between Europe and Asiatic Russia.
The geomagnetic field was quiet with a Bz pointing slightly to the South. Solar wind speed was less than 350 km/s.
Numerous reports of VE3OT’s CW beacon on 475 kHz were submitted last night and this morning on a variety of email reflectors. Steve, VE7SL, noted this morning in the ON4KST chat/logger that Mitch was RST599 at 0752z. It seems the time is now for a QSO between those two on a path that is often not reported to be very good. Steve sent the following audio which was recorded with the Perseus SDR and receive loop around 0200z:
During the evening in Texas, Mitch was easy armchair copy, and sounded like this while listening from the WSPR passband:
John, WA3ETD / WG2XKA, reported very strong domestic conditions including an open path to WH2XCR in Hawaii. John had over 1000 WSPR reports for the session.
Mike, WA3TTS, reported good conditions during the session. While he was not one of the stations to catch DK7FC (see note below), he did observe good propagation to the Pacific Northwest and Hawaii:
Neil, W0YSE/7 / WG2XSV, also reported good conditions to his East in this report:
WSPR activity was moderate for the session and still down from the highs. I only made a single check of the WSPRnet activity page during the evening and only 66 MF WSPR stations were reported at that time but it seemed like a strong 66. Two new receive stations were observed and neither had reports in the database: WC9C and KJ4RWD. KJ4RWD’s software was reporting that he was on the old WSPR frequency of 503.9 kHz and his QRZ page listed no email address. If you know him, please ask him to contact me or send him details on the updated frequencies currently in use on 630-meters. Steve, W6SJP/BY was also present during this session from Beijing.
Regional and continental WSPR breakdowns follow:
There were no trans-African reports during this session.
A remarkable path opening was observed between Europe and Asiatic Russia. DK7FC and DJ0ABR were both reported by UA0SNV and as Stefan, DK7FC, indicates in a post of the RSGB “Blacksheep” reflector that 5000 km over land is a very long distance on 630-meters. Vasily, UA0SNV, began listening to 630-meters last Fall in hopes of providing reports to Merv, K9FD/KH6 / WH2XCR. While that path has so far been unsuccessful, its fascinating to see such a long land path developed and there is renewed hope in the water paths. Congratulations to all involved!
Trans-Atlantic reports were submitted by a number of North American stations for DK7FC:
Halldor, TF3HZ, provided a large number of reports for stations in Europe.
Eden, ZF1EJ, and Roger, ZF1RC, experienced a good session with reports for all the same stations but Roger noted in the ON4KST chat/logger that the band was very slow to open and then reports began coming in for no apparent reason, as if someone had turned on a valve.
In Alaska, Laurence, KL7L / WE2XPQ, experienced a relatively poor session but it may have had a lot to do with fewer receive stations active in the Western US during the session. KL7L which was designated as receive-only through the session, reported my station in Texas which is usually indicative of reasonably good conditions. You decide.
In the Pacific, Merv, K9FD/KH6 / WH2XCR, had a pretty good session in spite of the eastward shift in propagation. Merv decoded VK3ELV and was decoded by VK2XGJ, JA3XCU and WE2XPQ / KL7L on the Pacific front. Where Merv really shined was in the North Central and North Eastern portions of the mainland US.
Additional anecdotes, comments, statistics and information:
Ken, K5DNL / WG2XXM, noted that he decoded 8 unique stations using the High-Z receive vertical.
After the recent and upcoming commentaries provided by Jim, W5EST, on the topic of antenna matching with respect to changing frequency and the use of scope match, I related a few comments to Jim in an email about my personal experiences. Jim asked that I share these comments so here is a snap shot of those unedited stream-of-consciousness thoughts on theses topics:
Jim, W5EST, brings his next commentary on the use of scope match when changing frequency:
630M TX FREQUENCY CHANGE: ADJUSTING SCOPE MATCH
For the 630m event last weekend, some transmitter operators tuned up at a frequency 1 kHz or more away from their usual WSPR frequency. They adjusted their match to the transmit (TX) antenna in the process. Why and by how much adjustment would anybody take the effort to do this when changing frequency so little?
Today we see another characteristic of MF/LF bands for which HF experience does not fully prepare us. Frequency change using a short vertical on the MF/LF bands looks like 100-300 KHz of frequency change using a half-wave dipole on an HF band like 40 meters. Scroll down 1/3: http://www.nc4fb.org/wordpress/category/amateur-radio/page/4/
A one-percent frequency change +/-1% is same as 1% angular frequency change Δω/ω =+/-0.01. On 40m that’s +/-70 kHz. That percentage +/-1% easily surrounds each LF/MF band: +/-1.37 kHz on 2200m and +/-4.75 kHz on 630m! On top of that, LF/MF antennas are generally very high Q ~ 100.
Recall from yesterday that a 630m (ω= 3 x 106/sec) TX antenna amounts to 475.7 kHz RLC with R~30Ω, L ~1mH for j3000Ω, and C~110pF for -j3000Ω. Measurements: You can use an RF ammeter to measure antenna system resistance R = PTPO / I2RFrms by dividing transmitter power output by the square of rms RF antenna current. Most of the antenna system inductance L shows up in the loading coil or variometer, so measuring the loading inductance mH gets pretty close to L. Or bump up your measured mH number a little.
Frequency change off-resonance introduces significant net reactance j X = j 2L Δω. # X is reactance ohms, L is mH, and Δω is the frequency change in kHz times 2π (=6.28). j is the unit imaginary number.
At 630m with the example numbers above, going up just 1 kHz puts in j12.6Ω inductive reactance. Or going down 1 kHz confers –j12.6Ω capacitive reactance instead. Either way, that’s not insignificant compared to an antenna system resistance R~30Ω.
It means that on the oscilloscope,* 1 KHz will do a phase shift Δϕ= arctan(2L Δω/R). That’s 23° (1/8 of an RF half-cycle) in our example. Since antenna Q =ωL/R, that phase shift is also Δϕ= arctan(2 Q Δω/ω). The heads-up: Frequency changes on MF/LF bands with their very high Q antennas affect the match much more critically than on HF.
Perfect scope match makes exact same amplitude RF voltage and current curves coincide. A mismatch changes their amplitude ratio** given by sqrt[1+(2LΔω /R)2] = sqrt[1+(2Q Δω/ω)2]. The example antenna’s scope amplitude ratio is 1.084 (discrepancy 1/12) at +/-1 kHz of frequency departure going off 630m WSPR band from its resonant frequency there.
To re-resonate the antenna at a different 630m frequency, the % adjustment## of the loading coil inductance works out to %L = – 2 Δω/ω. Δω/ω = 0.2% is 1KHz, and %L=0.4% in the example.
If the loading coil has fewer than about 200 turns, resetting a coil tap turn-by-turn may only coarsely and imprecisely re-resonate the antenna. You can do more precise adjustment with a smaller diameter tapped series coil or a series capacitor, or with a variometer instead. What’s your actual experience?
#Get net reactance X = XL+XC = jωL(1+ Δω/ω) + 1/[jωC(1+ Δω/ω)]. Use ω=1/sqrt(LC) at resonance. XL+XC = j sqrt(L/C) [ (1+ Δω/ω) – 1/(1+ Δω/ω) ] = j sqrt(L/C) [ (1+ 2Δω/ω+(Δω/ω)2 – 1) / (1+ Δω/ω) ]. Sqrt(L/C) is not a typo; it’s used along with 1/sqrt(LC). Simplify, ignore denominator and small (Δω/ω)2. Now X= XL+XC = [j sqrt(L/C)] (2Δω/ω). Substitute ω=1/sqrt(LC) again. X = XL+XC = j 2L Δω .
*See a couple of scope match articles at http://myweb.tiscali.co.uk/wgtaylor/LFTA.pdf and
**Scope match amplitude ratio is magnitude of antenna impedance R+jX divided by its pure resistance R at resonance |(R+jX)/R| =|1+jX/R| =sqrt[1+(X/R)2]= sqrt[1+(2LΔω/R)2].
##To derive the adjustment, start with ω=1/sqrt(LC) at resonance. Divide that resonance into re-resonance using inductance L’. ω (1+ Δω/ω) =1/sqrt(L’C). The result is (1+ Δω/ω) = sqrt(L/L’). Rearrangement yields (L’/L) – 1 = – 2 Δω/ω, the percentage adjustment of inductance.
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!