Sunday, 7 July 2019

Magic Band Mid-Season Observations

courtesy: KC8RP FT8 Info

We are now half-way through this summer’s Sporadic-E season, normally the magic band’s best time of the year. The only exception to this being the winter months of those solar cycles that are robust enough to raise the F2 MUF up as far as 50MHz ... something that occurred for only two or three days during the peak of Solar Cycle 24.

Unfortunately, it really looks as if the old reliable bread and butter modes on 6m, CW and SSB, are fast going the way of the dodo bird, as very few signals on either of these modes have been heard here this summer. As speculated last year at this time, it seems as though the weak signal (WSJT) FT8 mode now reigns supreme on the band, which has come as a great disappointment to myself and many other diehard CW ops.

At the start of this year’s season I reluctantly decided to pay more attention to this mode and see if it could put any  new DXCC entities into my 6m log ... if so, it would be time well-spent.

For the past several years, my main 6m interest has focused on European or South / Central American openings, which are usually unpredictable and short-lived. As usual, most of the season’s openings have been domestic, with signals from the central and south-eastern states being the ones most often heard. Usually, signals during these openings are strong and fairly reliable and lend themselves to easy two-way work on either CW or SSB. For the vast majority of summer time openings, FT8 is not needed, as signals are not weak.

For some reason, the popularity of this weak-signal mode on 6m continues to grow in popularity even though signals are so strong! Where this mode really shines is on the short-lived long haul openings to EU or on similar long paths from the PNW, of which there have been very few this season.

With everyone crowded into a narrow passband of ~ 2kHz, it doesn’t take much to mess things up for your neighbours if you don’t think carefully about how your operating can affect other users of that small sliver of space.

One of the most common examples of poor operating skills that I see is the seemingly endless CQ. This is much easier to do on FT8 than with conventional modes, as the software used can do this automatically for you, every 15 seconds ... while you fiddle with something else in the shack. I’ve seen some nearby stations call CQ continuously for over 60 minutes at a time, with no replies. What this does is make it difficult for other nearby users to actually hear / decode any weak signals on the band that are being covered by the loud CQing station(s) during this entire span of time. Strong local signals can wreak considerable havoc with weak-signal mode software as it's just not designed to happily handle strong signals and do a good job of decoding weak ones at the same time! Please think about this if you are one of those long CQers ... you are not the only one trying to use the band.

Another observation has to do with 'sequencing'. FT8 users must decide if they will transmit on the ‘even’ or on the ‘odd’ 15-second sequence. If you, and all of your neighbours are loud with each other, then it makes sense that everyone is better off operating on the same sequence. This way, all locals are transmitting at the same time which means they are all listening at the same time as well ... nobody causes QRM for one another if everyone uses the same sequence.

This comes off the rails very easily when just one or two strong neighbours choose to transmit during the receive sequence being used by everyone else.

There has been a long-standing precedent for sequencing, established and utilized by meteor-scatter operators for several decades. It calls for stations on the eastern-most end of a path (Europeans for example) to transmit on ‘evens’ ... the ‘0-15’ and ‘30-45’ second segment of each minute. Stations on the western-end of the path (NA) transmit on the ‘odds’ ... ‘15-30’ and ‘45-60’ second portion of each minute. When looking towards JA later in the day, everything reverses for NA stations, as they now become the eastern-end of the path.

Some operators seem to get totally confused by this or don’t check to see what sequence is being used locally before starting to operate ... while some don’t really seem to care.

I’m not complaining about what a given amateur chooses to do but simply describing some of the roadblocks to better use of FT8 and why it is not necessarily very well-suited for 90% of the typical propagation seen on 6m Es.

Many of the newer stations often seem to be using poor or makeshift antenna systems on 6m and are often not able to hear stations responding to their CQs, which may be strong enough locally to disrupt reception for those that are able to hear weaker signals.

I have deliberately made a point of never calling CQ on FT8. From decades of CW DXing I have come to understand that it’s much easier to work DX, on any band, by spending your time listening ... and then calling when the time is right. It’s no different with FT8, yet I see CQs that go on forever. Some will argue that if nobody called CQ, then there would be nobody to hear, which is of course valid ... the reality is, most amateurs cannot resist calling CQ, especially DX stations who enjoy working a pileup. There seems to be no shortage of CQers and those seeking DX should take advantage of that fact.

One loud station was seen yesterday calling another for over 90 minutes-straight. Perhaps he had wandered away from his shack and had forgotten to ‘Halt Tx’ before leaving! FT8 users need to understand how to use their software efficiently.

As for PNW to EU propagation this summer, it has been almost non-existent although I have worked CT1HZE in Portugal and JW7QIA in Svalbard ... by listening ... listening ... and calling briefly, both on FT8. In both cases, signals were brief but strong enough for CW! During the short-lived appearance of the JW7, two NA stations were noted calling ‘CQ JW’ the entire time. Perhaps if they had spent this wasted time more wisely by listening, they would have worked JW.

I’m happy to report that Svalbard was a new DXCC entity for me on 6m, #88, and the first 'new one' in a few years.

It seems that when used sensibly, FT8 is a useful application to have in your DX toolbox ... but for most daily summer Es operation, it’s just not needed. CW or SSB is well up to the task most of the time, even for small stations. Where FT8 shines is on the very brief, often unstable, long haul (EU-NA or JA-NA) paths and then, only if your neighbours don’t do things that will get them into the naughty-corner!

Now, let’s see what the second half of the season has in store for the magic band .... maybe the best is yet to come.




Monday, 1 July 2019

Building A '37-Style 'RK-39' Crystal Power Oscillator



When I completed my ‘Jones 6L6 Push-Pull Oscillator’ project in the spring, I made a start on a new ‘spring-summer radio project’ which was to be based on some 1937 RK-39 tubes that had been gathering dust here for many years.

With an unusually sunny and warm spring, I soon found that my radio-bench time was being hi-jacked with a lot of outside yard work and getting all of next winter’s firewood split and stacked away before the really hot weather arrived.

I found myself working on the project in tiny bites, sometimes not making any progress at all during the passage of a week. Headway was also tempered by the fact that I’ll often deliberate for several days over the placement of a single component or the selection of one component over another. I find this slow pace and decision ‘pondering’ during the design phase of any project to be most enjoyable as it gets my old brain working more than normal, on things that really interest me.

I’m happy to report that my latest project is now complete and fully operational and ready for operation!

As usual, I have written and published a web page fully describing the project and some of the background details of the building process.

My ‘Building A ‘37-Style ‘RK-39’ Crystal Power-Oscillator' page can be found here.

Hopefully we can have a CW QSO with it in the near future!

Tuesday, 25 June 2019

An RF-Quiet Light Dimmer


This blog first appeared in February 2016 but is just as relevant today as it was then!


 I admit it. I have an extraordinarily kind next door neighbour!

Ever since erecting a new, much bigger LF antenna several years ago, she has allowed me to run its large, three-wire 100' tophat, directly over the top of her house to a tree on the far edge of her property. As well, she removed her only light dimmer, knowing that it was creating a LOT of nasty RF 'hash' throughout the LF / MF spectrum, seriously degrading my LF reception. To hear the RF noise-signature of a typical light dimmer, listen here, on the ARRL's helpful page of 'household' RFI recordings ... that's just how it sounded here as well!

She recently did a major renovation, which included a new multi-light dining-room fixture and expressed to me a desire to be able to dim it ... oh-oh, I was definitely not looking forward to this.

I did a little web-research and soon learned that some of the most RF-quiet dimmers were being produced by Lutron. One model in particular, claimed to pay special attention to RF noise-filtering and that was the "Centurion", whose smallest model is a 600 watt-capable unit, with a large finned heatsink front plate ... model #C-600P-WH.

I decided to order one from the only dealer I could find in Vancouver that seemed to carry this line of dimmers. The cost was just a little over $40 Canadian (sells for about $25 in the U.S.A.) ... cheap enough if it would do the job!


When the unit came in, I picked it up on my next ferry trip to the city and upon my return, installed it the following afternoon. Before doing the installation, I fired-up the receiving system, tuned to 300kHz, and with the baby monitor set up beside the speaker, took the portable monitor with me.

After installing the new dimmer, I turned on the baby monitor, held my breath ... and turned on the light fixture. Wow ... not a trace of hash could be heard! Adjusting the dimmer from high to low produced no difference in the noise level. I later did a more thorough bandscan and could find no evidence of RFI, on any frequency. The only RFI that I could detect was when placing my Sony ICF-2010 close to the actual dimmer. I was unable to detect any noise further than 6" away from the lights or the dimmer!

So it seems that this model can be highly recommended, for your own home or if you have a next door neighbour 'light-dimmer problem'.

Wednesday, 12 June 2019

Back To The Magic

The magic band has always had a strong pull on me, ever since being put under its spell in the late 60s. I quickly learned that the surest way to guarantee a band opening was to leave the house for a few hours. Invariably when returning, the other local 6m addicts would gleefully describe everything that you had ‘just missed’. The 6m gods were rarely forgiving and this unfailing behaviour became part of the band's mystique.



This odd love-hate relationship continues to this day but with the FT8 mode being used almost exclusively now on 6m, it’s your computer that now snickers at you for any untimely excursions from the shack ... showing you, in any delightful color scheme that you choose, all of the DX that you 'just missed' once again!

It happened to me again yesterday, while out in the yard stacking next winter's firewood.

It was just a short excursion, as the eastern stations were working Europeans and all of the VE4 beacons were very loud back here on the coast. The possibilities of a link to the European path kept my excursion to only 10 minutes but sure enough, there it was on my WSJT-X list of decodes .... several CQs from CT7ANG in Portugal! My laptop could barely stop giggling. This would have been the first PNW-EU QSO of the summer had I been maintaining vigilance!

163315 -14 0.1 738 ~ CQ CT7ANG IM67

I continued to stack firewood and to watch the band more closely, knowing that every once in awhile, for entertainment purposes, the prop gods will toss out a bone or two, just to keep you on the hook.

A later check indicated that CT1HZE’s CQs had been decoded just a few moments earlier ... there was renewed hope!


185100 -2 0.2 2134 ~ CQ NA CT1HZE IM57


Joe’s strong FT8 CQ popped-up again a few minutes later and he came right back to my initial call. Although that was it for the day, the 2019 PNW-EU path had begun!

courtesy: PSK Reporter

I’m still somewhat ambivalent about FT8 and its ‘coldness’ when it comes to person-to-person interaction, but since most of the DX action on 6m is now digital, it’s either embrace it or miss out. At the moment, I’m at least prepared to hug it and see how it behaves. If it puts more Europeans and new DXCCs into my magic band log, then that’s a worthwhile investment.

Unlike way too many others, I’m not prepared to let my computer endlessly CQ for hours at a time. In a crowded local environment, with big strong signals being the norm, this method of operating is simply disrespectful to other amateurs as this mostly useless CQing will usually make reception of any weaker signals impossible.

FT8 is a weak-signal mode and the interfaces used do not handle extremely strong local signals very well. I would urge others to think about this poor operating practice and adopt what has always proved to be the best tactic for catching DX ... listen, listen, listen. The same tactic works just as well on FT8 as it does on CW.

Back to stacking firewood but having tossed me a bone yesterday, I’m sure the prop gods will be out to get even for awhile!

Monday, 3 June 2019

The Enigmatic Heathkit CR-1 Crystal Radio

For the past several months my interest in ‘DX-crystal radio’ construction has been percolating once again. It began when I ran across an interesting description of Heathkit’s legendary CR-1, a double-tuned good performer and very much sought-after by collectors as well as by users. The article described one homebrewer’s attempt to duplicate the receiver and to learn more about the detector and antenna tuning ferrite-loaded coil's secrets.


When it comes to crystal radios, there is nothing revolutionary regarding the CR-1’s basic circuitry but for some odd reason, it has achieved cult-like status as well as high dollar value.


courtesy: Scotts Crystal Radios
I've been eager to get my mitts on one to see how it performs after reading of one DXer's fifty-eighth catch with his own CR-1!

The article that piqued my interest appears on 'Scott's Crystal Radios' website and makes for an inspirational read, eventually revealing the inside core arrangement of the ferrite-loaded tuned circuits via an actual X-ray of the device! By the way, if you are looking for a nice set of older headphones, Scott's website is the place to visit!






courtesy: Scott's Crystal Radios






Scott was eventually able to achieve performance equal to that of his borrowed CR-1, with his own slightly modified versions, all in a similar-sized footprint. Perhaps this is one reason why the CR-1 is so much sought-after, as good performance in a very small package is not the norm when it comes to crystal radios. It's usually a case of ‘the bigger, the better’ when it comes to performance.


A recent search of my junque box revealed several NIB ferrite loopsticks that would allow a potntial reproduction of this interesting circuit.


Several years ago I spent an eye-opening winter learning about DX crystal radios as up to that time I had always believed it would be impossible to hear anything other than strong local signals on a crystal radio. I quickly discovered that there was a very large Crystal Radio Yahoo Group where members were working at the leading edge of crystal radio design. I also found that the group sponsored an annual Crystal Radio DX Contest which inspired me to dig deeper.

It wasn’t too long before I decided to join the fun and attempt to build a crystal radio DX-machine but I was in for a few surprises and a long learning curve ... it seemed that hearing broadcast band ‘DX’ on a crystal radio (anything other than loud locals) was not going to be an easy task!

Over the course of several months I tried many types of variable capacitors, tank coil configurations and antenna tuning circuits. I even erected a dedicated antenna system for the various experimental circuits I was putting together ... an 'Inverted-L', 50’ straight up and 70’ horizontal, along with a ground rod connected to several buried radials.

I quickly learned about something I normally didn’t have to worry about when working with ‘active’ devices and that was overcoming system and component losses. In critical crystal radio design, it’s all about minimizing the losses in every stage and every component in the system since there are no amplifiers to help overcome these losses. Your system is only as good as the weakest link. In true crystal radio DXing, no active devices are permitted ... it’s just your crystal radio and the energy generated at some, hopefully far away, transmitter site!

After several months, I eventually ended up with a well-performing triple-tuned set that used lots of 'trapping' because of all of the very strong nearby signals here ... eight 50kW locals!



A description of the learning curve, with several do's and dont's to help new builders, can be found on my website here.

Back then, 80 stations were logged (from my location on Mayne Island in SW British Columbia) over the one-week Crystal Radio DX Contest.


CRYSTAL RADIO LOGBOOK


FRQ 
STATION
 LOCATION
POWER
540
CBK
WATROUS, SK
50KW
550
KARI
BLAINE, WA
2.5KW
560
KPQ
WENATCHEE, WA
5KW
570
KVI
SEATTLE, WA
5KW
580
KFXD
NAMPA, ID
5KW
580
KTMT
ASHLAND, OR
1KW
600
CKBD
VANCOUVER, BC
10KW
650
CISL
VANCOUVER, BC
10KW
670
KBOI
BOISE, ID
50KW
690
CBU
VANCOUVER, BC
50KW
730
CJNW
VANCOUVER, BC
50KW
750
KXL
PORTLAND, OR
20KW
770
CHQR
CALGARY, AB
50KW
780
KKOH
RENO, NV
50KW
790
KGMI
BELLINGHAM, WA
1KW
800
CKOR
PENTICTON, BC
500W
800
CHAB
MOOSEJAW, SK
10KW
810
KGO
SAN FRANCISCO, CA
50KW
820
KGNW
SEATTLE, WA
5KW
830
CKKY
WAINRIGHT, AB
3.5KW
840
KSWB
SEASIDE, OR
500W
840
CKBX
100 MILE HOUSE, BC
500W
850
KOA
DENVER, CO
50KW
860
KPAM
TROUTDALE, OR
10KW
870
KFLD
PASCO, WA
250W
880
KIXI
MERCER ISLAND, WA
10KW
880
COOL
EDMONTON, AB
50KW
890
CJDC
DAWSON CREEK, BC
10KW
900
CKMO
VICTORIA, BC
10KW
910
CKDQ
DRUMHELLER, AB
50KW
920
KXLY
SPOKANE, WA
5KW
930
KBAI
BELLINGHAM, WA
500W
940
CJGX
YORKTON, SK
50KW
950
KJR
SEATTLE, WA
50KW
960
CFAC
CALGARY, AB
50KW
980
CKNW
NEW WESTMINSTER, BC
50KW
1010
CBR
CALGARY, AB
50KW
1040
CKST
VANCOUVER, BC
50KW
1060
CKMX
CALGARY, AB
50KW
1070
CFAX
VICTORIA, BC
10KW
1090
KYCW
SEATTLE, WA
50KW
1130
CKWX
VANCOUVER, BC
50KW
1160
KSL
SALT LAKE CITY, UT
50KW
1170
KPUG
BELLINGHAM, WA
5KW
1180
KOFI
KALISPELL, MT
10KW
1190
KEX
PORTLAND, OR
50KW
1200
WOAI
SAN ANTONIO, TX
50KW
1210
KBSG
AUBURN, WA,
10KW
1210
KZTS
SUNNYSIDE, WA
1KW
1240
KGY
OLYMPIA, WA
1KW
1240
KOFE
ST. MARIES, ID
500W
1250
KKDZ
SEATTLE, WA
5KW
1250
KWSU
PULLMAN, WA
5KW
1260
CFRN
EDMONTON, AB
50KW
1260
KLYC
McMINVILLE, OR
850W
1270
CHAT
MEDICINE HAT, AB
10KW
1270
KTFI
TWIN FALLS, ID
1KW
1280
KIT
YAKIMA, WA
1KW
1290
KGVO
MISSOULA, MT
5KW
1290
KUMA
PENDLETON, OR
5KW
1290
KKSL
LAKE OSWEGO, OR
5KW
1300
KOL
SEATTLE, WA
5KW
1300
CJME
REGINA, SK
10KW
1310
CHLW
ST. PAUL, AB
10KW
1320
CHMB
VANCOUVER, BC
50KW
1340
KLKI
ANACORTES, WA
1KW
1360
KKMO
TACOMA, WA
5KW
1370
KAST
ASTORIA, OR
1KW
1410
CFUN
VANCOUVER, BC
50KW
1470
CJVB
VANCOUVER, BC
50KW
1510
KGA
SPOKANE, WA
50KW
1520
KKSN
OREGON CITY, OR
15KW
1530
KFBK
SACRAMENTO, CA
50KW
1550
KCCF
FERNDALE, WA
10KW
1590
KLIV
SAN JOSE, CA
5KW
1600
KVRI
BLAINE, WA
10KW
1620
KYIZ
RENTON, WA
1KW
1640
KPBC
LAKE OSWEGO, OR
1KW
1660
KXOL
BRIGHAM CITY, UT
1KW

Old notes indicate that there were 14 stations at S9 or higher, requiring heavy trapping to hear anything close to their frequencies. 

My recent interest made me wonder what the situation is today when it comes to the number of strong local ‘blowtorch’ signals, surely the bane of all crystal radio DXers? Although there have been a few changes over the years, a quick scan of the band during the prime DX evening hours found that although one of the blowtorch signals (at 600kHz) was now gone, another had appeared at 1200kHz ... sadly no net difference.

The top end of the band, always a prime area for good skywave DX, is unfortunately still dominated by a huge signal from KVRI just across the water near the Canadian / U.S. border. If KVRI were silent, the top end would be a wonderfully quiet hunting-ground for new catches. The new local blowtorch (CJRJ) on 1200 kHz will now cause problems for the middle of the band, which was always a good region for DX.

So it seems overall, there hasn’t been a huge change here other than in the middle of the band. It looks as though there are still some good watering-holes to be had but several traps will still be needed in any new system.

Once my present radio-bench project is finished (a '36 RK-39 crystal power oscillator) I’m looking forward to more research and design of a couple of new systems, starting with something similar to the CR-1 as well as some experimentation with toroidal coils. I always find the research and planning phase of any new project more interesting and fulfilling than the actual construction and implementation! Hopefully I’ll have something ready for the fall DX season!

Thanks to VA7MM, I will also have the loan of an original CR-1 next winter to make comparisons to any clone that I might build!

If building a DX-crystal radio is something that might interest you, there are several great websites offering inspiration and helpful info. The links for these may be found at the bottom of my own crystal radio page. As well, there are two active crystal radio groups on Facebook, where daily two-way discussion can be had.

Perhaps, with enough new interest, we can even revive the annual Crystal Radio DX Contest!