Radio: it's not just a hobby, it's a way of life

Current Operating Frequency and Mode

OFF AIR for storms, probably for much of the week if the forecast holds

Its like the sky just opened up – what a great night on 630-meters! – Trans-Atlantic and trans-Pacific paths have a panic attack; PA0A -> UA0SNV with multiple reports!

– Posted in: 630 Meter Daily Reports, 630 Meters

This was a good one.  Noise was very low and geomagnetic conditions were very quiet.  In the past we might have said that there wasn’t enough spark for openings to develop but that was not the case last night.  This morning storms developed again along the Kansas / Oklahoma border and for about ten minutes at the beginning of my CW sked at 1030z I had to resort to the loop to pull out the micro-watt ERP signal consistently.  After that the band went very long and the storms were not heard here but Steve, VE7SL, reported periods of high noise during a morning CW QSO attempt with Roger, VK4YB.  Its amazing to observe such wonders of nature.  I was happy the band was long for a number of reasons, not the least of which being the noise that the local storms had generated earlier.


11-hour North American lightning summary


The geomagnetic field was very quiet.  The Bz is at unity and solar wind velocities are low at 360 km/s.  DST values are nominal and tending to positive levels.  A CME that erupted on Sunday may provide a glancing blow during tomorrow’s session and what we experienced today may be the calm before the storm.  We will know in a few days!







Band conditions were surprising during this session.  The trans-Atlantic path opened for a bit to the Northeast, including reports for WE2XGR/3 and WG2XKA at G0LUJ but I also had a single report from G3XKR.  I have speculated in the past that we may be victims of our own success on the trans-Atlantic path because of the success of WSPR in Europe.  Its possible that the path is open much more than we realize but since there are so many stations so close together, even on top of one another, openings are missed.  I was happy to make it from the central US:


WE2XGR/3, as reported by G0LUJ



WG2XKA, as reported by G0LUJ



WG2XIQ, as reported by G3XKR


John, W1TAG / WE2XGR, reports that the session was “Like Monday.  Heard 14 inc. WH2XCR (2x), WI2XBQ (1x), VE7SL (38x); Heard by 21 inc. G0LUJ (5x)”

John, WA3ETD / WG2XKA, showed what can happen at low transmit percentages on these really strong nights.  He offered the following details:

“This session was the most active so far this season, with over 1000 total spots at a 15% TX cycle.  Noise levels increased relative to the past two evenings, but didn’t seem to impact much.  XKA was spotted by 33 unique stations and heard 12 uniques.  The PNW was strong in both directions, and both TP and TA appeared…WH2XCR and G0LUJ spotted this station at -29.”

WG2XKA session WSPR activity


Albert, PA0A, experienced a remarkable session with very long reports from Vasily, UA0SNV, in central / Asiatic Russia, just North of Mongolia.  I am very happy to see this opening and see Vasily receiving stations once again.  It has been a very long Summer for sure!


PA0A making the very long haul trip to UA0SNV



PA0A, as reported by UA0SNV


Dionysious, SV8RV, reported the following WSPR statistics from his stations overnight:


Doug, K4LY / WH2XZO, reported a season best, decoding twelve WSPR stations and being decoded by 34 unique stations.

The trans-Pacific path was also very robust during this session.  Roger, VK4YB, issued an astonishing “Code-8(!!!)” and he and Steve, VE7SL, began their pursuit of a CW QSO.  Neil, W0YSE/7 / WG2XSV, sent this screen capture from his WSJT session showing Steve’s strong signal as he called Roger:




The CW QSO with Steve was not completed during this session but Roger, VK4YB, reports that he heard Steve at 1119z and had hoped propagation would have improved.  Roger also had a nice night of WSPR reports.  His  statistics and unassociated details follow:

“Rx 14*wg2xxm (-20) 14*wh2xgp (-18) 16*wh2xxp (-14) 4*ve7cnf (-27) 2*ve7bdq (-24) 6*wi2xbq (-18) 1*we2xpq (-25) 14*wh2xcr (-16)

Tx 1*wh2xgp (-22) 6*we2xpq (-21) 22*wh2xcr (-6) 1*jh1inm (-28) 1*jh3xcu (-26)”


VE7BDQ, as reported by VK4YB



VK4YB, as reported by JH1INM



VK4YB, as reported by JH3XCU


Joe, NU6O / WI2XBQ, received reports from JA and VK during this session.  He also reported that a Japanese broadcast station on 774 kHz was S8 (-80 dBm) on his receiver.


WI2XBQ, as reported by JE1JDL/1



WI2XBQ, as reported by JE1JDL



WI2XBQ, as reported by JH1INM



WI2XBQ, as reported by VK2XGJ



WI2XBQ, as reported by VK3ELV



WI2XBQ, as reported by VK4YB



WI2XBQ, as reported by VK5ABN


Joe provided this recording and capture of his SDR screen:



WI2XBQ SDR showing very strong Japanese broadcast station on 774 kHz


Ken, K5DNL / WG2XXM, reports that he was decoded by 51 unique stations including VK4YB and VK2XGJ:


WG2XXM, as reported by VK2XGJ



WG2XXM, as reported by VK4YB


Larry, W7IUV / WH2XGP, reports very good band conditions as he decoded fifteen WSPR stations including VK4YB, WE2XPQ, “and some east siders, all using the omni antenna.”  He was decoded by 54 unique stations, “including VK4YB, VK2XGJ, VK3ELV, VK3HP, VK5ABN, VK7TW, ZF1EJ, and many east siders.”:


WH2XGP session WSPR activity. Note that WD2XSH/26 is missing from the “hearing” list (Courtesy NI7J)



VK4YB, as reported by WH2XGP



WH2XGP, as reported by VK4YB



WH2XGP, as reported by VK2XGJ



WH2XGP, as reported by VK3ELV



WH2XGP, as reported by VK3HP



WH2XGP, as reported by VK5ABN



WH2XGP, as reported by VK7TW


Ward, K7PO / WH2XXP, reports that he was decoded by 62 unique stations with seven VK’s and four JA’s.


WH2XXP, session WSPR activity (courtesy NI7J)



WH2XXP, as reported by JE1JDl/1



WH2XXP, as reported by JE1JDl



WH2XXP, as reported by JH1INM



WH2XXP, as reported by JH3XCU



WH2XXP, as reported by VK2DDI



WH2XXP, as reported by VK2XGJ



WH2XXP, as reported by VK3ELV



WH2XXP, as reported by VK3HP



WH2XXP, as reported by VK4YB



WH2XXP, as reported by VK5ABN



WH2XXP, as reported by VK7TW


Neil, W0YSE/7 / WG2XSV, reported that he decoded ten WSPR stations and was decoded by 24 unique stations.  He adds “Lots of stations out there receiving my 1w ERP.”:



Toby, VE7CNF, reports that he was finally decoded by VK4YB.  He decoded ten WSPR stations and was decoded by 33 unique stations:


VE7CNF, as reported by VK4YB


Steve, VE7SL, reports that he decoded fifteen WSPR stations and was decoded by 42 unique stations during this session.

John, VE7BDQ was additionally decoded by Phil, VK3ELV:


VE7BDQ, as reported by VK3ELV


Phil, VK3ELV, received late reports from the previous session at JH3XCU:


VK3ELV, as reported by JH3XCU


Mike, WA3TTS, experienced a big night or reports from Pittsburgh and offers these details and statistics:




Neil, W0YSE/7 / WG2XSV, provided a screen capture of an oddity.  It seems VE7BDQ was IDing his WSPR in RTTY:




Rick, W7RNB / WI2XJQ, reports a good session with decodes of the East coast and Hawaii:



I noticed this morning on entering the ham shack that WH2XCR was decoding me at CW levels  and I felt like the band was very long as the storms in Oklahoma were moderate or not heard here at all.  I sent Merv an email hoping to catch him up late and called CQ.  I heard someone calling me but it may have been a “phantom ditter” that didn’t respond to my QRZ’s.  The morning CW sked went fine although there was a brief period where I had to switch to the loop that was broadside to the storms to hear the other end of the QSO.  That lasted about ten minutes.   Steve, VE7SL, reported that I was RST 599 at 1057z as my sked was finishing up so I continued to call CQ until after local sunrise.  Aside from a few dits I never heard any legitimate calling stations.  Hopefully we can predict such openings better in the future.  We had some idea it might happen with good WSPR reports overnight.  David, G0MRF, reported in the ON4KST chat / logger last evening that the opening between PA0A and UA0SNV may signal very good things.  My WSPR transmit reports can be seen here and my WSPR receive reports can be seen here:


WG2XIQ 24-hour WSPR activity


There were a lot of stations on the air.  102 WSPR stations were observed on the WSPRnet activity page at 0330z.  KS9A was observed as a new stations during this session but I think he may have been receiving in past seasons.  I do not have a record for him on my list.  Welcome aboard!

Regional and continental WSPR breakdowns follow:


North American 24-hour WSPR activity



European 24-hour WSPR activity



Asiatic Russian 24-hour WSPR activity



Asian 24-hour WSPR activity



New Zealand and Australian 24-hour WSPR activity


There were no reports from the trans-African path.

Eden, ZF1EJ, continues to hear stations from coast-to-coast, including stations in New England and the Pacific Northwest:


ZF1EJ 24-hour WSPR activity


Laurence, KL7L / WE2XPQ, shared two-way reports with VK4YB and was hearing well into the central US.  Laurence also reported that CW from Steve, VE7SL, was RST 549 at 1349z:


WE2XPQ 24-hour WSPR activity



VK4YB, as reported by WE2XPQ



WE2XPQ, as reported by VK4YB



WH2XCR, as reported by WE2XPQ


Merv, K9FD/KH6 / WH2XCR, blanketed much of North America, well into New England in addition to a very significant number of reports from Japan and Australia:


WH2XCR 24-hour WSPR activity



VK4YB, as reported by WH2XCR



VK3HP, as reported by WH2XCR



VK3ELV, as reported by WH2XCR




WE2XPQ, as reported by WH2XCR



WH2XCR as reported by 7L1RLL4



WH2XCR as reported by 7L1RLL_4



WH2XCR as reported by JA1PKG



WH2XCR as reported by JH1INM



WH2XCR as reported by JH3XCU



WH2XCR as reported by VK2DDI



WH2XCR as reported by VK3ELV



WH2XCR as reported by VK4YB



WH2XCR as reported by VK5ABN



WH2XCR as reported by VK7TW



WH2XCR as reported by VK3HP



WH2XCR as reported by VK2XGJ




“In yesterday’s blog we saw that preamp noise figure dB stated in the data sheet is based on the defensible fiction that input noise is thermal noise: -140dBm in 2500 Hz bandwidth. Different preamp designs will have datasheet noise figures that may differ significantly from circuit to circuit when you state noise figure based on such a small noise level.

Thermal noise is very small compared to 630m band noise from some antennas.   With that much antenna, the noise figure of almost any preamp or RX will more nearly approach zero dB in terms of 630m band noise as the noise factor basis!  You could just remove the preamp without degrading SNR.  Indeed, if the preamp intermod from nearby AM broadcast stations is significant at your QTH, you might even improve the SNR by removing the preamp!  Furthermore, a preamp won’t diminish the effect of neighborhood QRN originally reaching the antenna.

If all preamps decrease SNR, how can a preamp help? In low signal high-SNR antennas delivering antenna output approaching the thermal noise level, the reason is: A preamp increases overall system SNR, although its preamp output SNR is diminished somewhat relative to antenna SNR.

630m receiving system SNR is what specifically matters to us. We’ll look at an example of that tomorrow.  Preamp gain Gpreamp amplifies the antenna signal level. Preamp gain similarly amplifies the band noise level—and unfortunately any local QRN the antenna supplies. Not only can’t the preamp reduce those noises, it introduces some preamp noise–just not enough to offset the improvement in receiving system SNR when a preamp is the right choice for your system.


If the antenna delivers so little signal and band noise and local QRN that the receiver noise blankets them, a preamp can amplify the antenna output signal along with its band noise and hopefully little local QRN, so they predominate over the receiver noise. While a preamp can’t give better SNR than is available at the antenna itself, it can provide better SNR than the antenna output to a naked receiver delivered to you before you added a preamp.

A receiver makes almost all of its self-generated noise near its input and then amplifies it.  So (FRX -1) is the fraction of that self-generated RX noise. A gain discount (FRX -1)/Gpreamp discounts that extra receiver noise by preamp gain. That puts the receiver’s self-generated noise on par with, and in addition to, the noise degradation expressed by the preamp’s own noise factor Fpreamp.

Add the discounted RX noise and preamp noise to get system noise factor  Fsystem:

Fsystem = Fpreamp + (FRX -1)/Gpreamphttps://en.wikipedia.org/wiki/Noise_figure (scroll 1/2)

Each F is a noise factor (ratio form, not dB) and G is preamp signal power gain.  FRX noise factor is relative to 630m antenna noise from all 630m sources, both band noise and local QRN. So, FRX may be much closer to unity 1.0 than a datasheet noise factor for the RX relative to thermal noise would suggest.  More about that tomorrow.

System noise factor Fsystem outperforms receiver noise factor FRX when:

Fpreamp +  (FRX -1)/Gpreamp  <  FRX.

The SNR improvement a preamp gives the system is:

ΔSNR(dB) = 10log10{FRX – (Fpreamp+(FRX -1)/Gpreamp )}.  

Preamp gain needed to get system noise factor Fsystem to exceed RX noise factor FRX is:

Gpreamp >  (FRX -1) / (FRX –Fpreamp).

Alternatively, the preamp improves the overall system noise factor Fsystem when the preamp noise factor Fpreamp is sufficiently low compared to receiver noise factor FRX so that:

Fpreamp  <   FRX (1 – 1/Gpreamp)    +  1/Gpreamp.

 That’s a lot of formulae.  Tomorrow, let’s see how to use them for some 630m examples!”

Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com).