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

Current Operating Frequency and Mode

OFF AIR but returning after dark on Saturday night

Kp elevated to storm levels during a reporting cycle but generally average session for Summer

– Posted in: 630 Meter Daily Reports, 630 Meters

This session was relatively typical for early Summer in the northern hemisphere.  Several stations suggested that their numbers were down compared to previous session while others experienced better conditions.  It really depends on where you are located and what the regional storms are doing to the noise level.

Geomagnetic activity had been very quiet until a spike in Kp during the session resulted in storm levels for a reporting period followed by unsettled and elevated numbers.  The Bz is currently pointing to the North but the solar wind velocities are variable into the moderate category above 400 km/s.  Steve, VE7SL, noted this morning that light auroral conditions were observed on 50 MHz during the evening.

planetary-k-index 062316


Kyoto 062316


Australia 062316


Ken, K5DNL / WG2XXM, reports that he decoded five WSPR stations and was decoded by sixteen unique stations.  He was also decoded by WH2XCR 22 times over night.

Roger, VK4YB, observed that WH2XGP was only a couple of dB beyond the WSPR decode threshold at the same time that he was -6 dB S/N at WH2XCR followed by  -9 dB S/N in the next transmit cycle.  Roger notes that not even single digit reports at the half-way point will always result in decodes on the longer path.  I think Larry has quite a bit of land between his QTH and sea water and there might even be a mountain range.

Steve, VE7SL, reported that he decoded nine WSPR stations and was decoded by three unique stations.

John, W1TAG / WE2XGR/3, reports that he decoded one WSPR station and was decoded by two unique stations.

Neil, W0YSE/7 / WG2XSV, had a nice session with reports with Hawaii and Oklahoma:

WG2XSV 062316


I don’t typically operate my station during the daytime in the Summer unless I am testing something.  Yesterday was one of those days and it triggered a number of events as I tried to diagnose a potential system problem.  I was observing what looked like an AMing of the current waveform on the scope match.  It wasn’t fast but would change on an irregular schedule during a long transmit carrier.  This was observed during the midday.  A reduced base current was also observed during this time frame but I suspect that was the result of the temperatures which were even higher in the ATU.  I suspected a large Mica transmitting capacitor and I found that one had been leaking so I replaced it but the problem continued.  After checking the system into a dummy load where no problems were observed, my concern turned to a potential problem with the top loading wires.   If I had to take this system down I have my doubts that I could get it back up in the air without a helicopter or crane.  I also considered the possibility that the coil was changing shape slightly on the ATU in spite of being lightly coated in shellac due to the high temperatures.  This seems to be the most likely situation as the system settled down in the late afternoon and base current returned to normal levels.  There may be another scenario in play that was also observed about 15 years ago:  When I began operating QRO 160-meters from this location I would observe periodic changes in antenna impedance that I could never isolate to the actual antenna.  Through dumb luck I found that the metal liner in my chimney and fireplace was rectifying between junctions and arcing which changed the resonance of the entire antenna structure in the near field.  I could literally hear “pop pop pop” when listening in the fire place.  The problem cleared up on its own but I had plans to skirt the chimney’s metal core to “tune it out” with a capacitor.  It was warm enough this Winter that I did not use the fire place so its possible that the structure is once again “in flux”.  I will continue to make observations but I think everything is fine with respect to the antenna system and should be OK for Field Day.  Last night appears to have been “situation normal”.

Regional and continental WSPR breakdowns follow:

NA 062316

North American 24-hour WSPR activity


EU 062316

European 24-hour WSPR activity


JA 062316

Japanese 24-hour WSPR activity


VK 062316

Australian 24-hour WSPR activity


There were no reports from the trans-Atlantic, trans-African, or trans-Equitorial paths.  UA0SNV was present but no reports have been filed at this time.

In the Caribbean, Eden, ZF1EJ, reported WG2XXM, WH2XZO, and WG2XIQ:

ZF1EJ 062316

ZF1EJ 24-hour WSPR activity


Laurence, KL7L / WE2XPQ, reports that he was only transmitting during this session:

WE2XPQ 062316

WE2XPQ 24-hour WSPR activity


WE2XPQ WH2XCR 062316

WE2XPQ, as reported by WH2XCR


Merv, K9FD/KH6 / WH2XCR, experienced a relatively similar session compared to other recent nights.  The path to the central US is consistent with the usual suspects in the West and Alaska as well as Australia.  Consistency when the days are long and the sun is high in the sky is a good thing:

WH2XCR 062316

WH2XCR 24-hour WSPR activity


VK3ELV WH2XCR 062316

VK3ELV, as reported by WH2XCR


VK4YB WH2XCR 062316

VK4YB, as reported by WH2XCR


WH2XCR VK2DDI 062316

WH2XCR, as reported by VK2DDI


WH2XCR VK2XGJ 062316

WH2XCR, as reported by VK2XGJ


WH2XCR VK3ELV 062316

WH2XCR, as reported by VK3ELV


WH2XCR VK4YB 062316

WH2XCR, as reported by VK4YB



“This is a blue-sky topic that may be achievable now or in the next few years. I wonder if combining a commercially available tablet computer with an SDR (software defined radio) could be an interesting homebrew project for MF/LF.  You would use the touch-screen feature of the tablet to load the software and control the SDR. Couple the SDR USB output into a microUSB port of the tablet if that’s possible.  USB may be expandable to provide this connectivity and provide control input to/from a transmitter microcontroller as well.  Bluetooth® wireless connectivity can couple the tablet to likewise enabled devices.

Compare the approach with Flex Maestro SmartSDR in their Maestro™ transceiver. http://www.flexradio.com/amateur-products/flex-6000-signature-series/maestro/  That unit uses an 8” touch screen with pull down menus to perform a variety of reception display and noise mitigation functions.  https://www.flexradio.com/downloads/smartsdr-software-users-guide-pdf/

What would be the difference between a tablet MF/LF receiver and any other SDR with PC/laptop or recent transceiver with built-in SDR? The light weight of the tablet and touch control would make a homebrew physical combo possible and give the combo portability for use with battery power for extended periods in at least a receive-only mode.  You can load a lot of apps into a tablet, which MF/LF seems to invite what with digital modes, decoders and display software.

At home, one can load various LF/MF-specific software packages, links and apps from the internet using the internet connectivity a tablet computer comes with.  At home, internet access for a tablet computer to upload its WSPR spots is likewise right at hand.

In the field, consider how to obtain internet access for a tablet computer to upload its WSPR spots.  If the portable operation is near a friend’s house, then the friend may be willing to have you link through a wireless modem there.  Hams in some regions may have mesh networks with internet connectivity.  What tips can you offer?

Since the tablet touch screen mediates primary user commands, it needs to be convenient to reach and control by touch.  Slant the tablet to your taste in a homebrew physical combo instead of mounting it straight up in the usual all-rectangular homebrew type of unit.

A tablet works nicely with a wireless keyboard and wireless mouse if you prefer entering information that way. Otherwise, summon the usual tablet virtual keyboard on its touchscreen. Doing things homebrew allows you to use a larger sized tablet than a manufacturer’s touch screen might provide.

If you already have a tablet on hand, it costs you nothing more to reuse it. Purchased or reused, you can occasionally disconnect it from a homebrew combination and use it for other purposes whenever you like.

Some tablet questions to think over when planning such a project:

1)     Can the tablet’s microUSB to expandable connectivity couple USB to SDR, etc.?

2)     Can you get wireless connectivity to/from SDR and other shack devices instead?

3)     Does the tablet have the processing power to load SDR software and run it satisfactorily?

4)     Is tablet’s RF noise minimal already or can you RF-isolate the SDR from tablet noise?

5)     Can you control the transmitter and T/R switching with the tablet if you wish? Or vice-versa?

6)     Can you play the tablet through a shack projector for station visitors and still maintain the other connectivity and run the system at full speed?

Local noise isolation and thermal compatibility are plainly vital to a homebrew combination of a commercial tablet with an SDR. I recently investigated one commercial tablet’s noise performance on 630m. With good circuit positioning and design, the noise or thermal issues should be minimal and able to accommodate LF/MF signal reception.  Prefer toroid cores, and avoid inductors wound on ferrite rods.  If you use a loopstick antenna, mount it as far as you can from the tablet, which should be noise-isolated to the extent possible.

This post has suggested a few pieces of the puzzle of homebrewing a combo of tablet and MF/LF receiver. Can it indeed be done? Are we still a couple years away from the right tablets at the right prices?  Please tell us any pertinent experience you may have on construction and performance of a tablet integrated with an MF/LF SDR. A tablet can be expensive, so if you know a less expensive and equally-effective touch screen system for homebrew purposes, please tell us about it. Thanks & GL!”


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