Posts Tagged ‘Wellbrook ALA100LN’

Recent BCB Loop DX / Upcoming CLE248

This past week has seen a welcome return to better band conditions on the lower frequencies.

I’ve had my 10' x 20' loop and Perseus SDR combination running a few overnight recordings on the AM broadcast band ... two mornings pointing at Asia and two overnights looking for domestic signals from the east.

The Asian signals have often been very strong, with many signals reaching S9 or higher. I’ve chosen some of the better ones below. Unlike those situated right on the west coast, my location here on Mayne Island gives me a nice shot towards Japan albeit not directly over the ocean, but close enough, as the path crosses islands to my north and then over northern Vancouver Island.

Looking towards eastern North America is a different story, with an unobstructed ocean view from due north to the south east.

As is often the case with overnight recordings, I did not get nearly enough time to thoroughly check them out but one catch caught my attention. It was from WPTX in Lexington Park, Maryland, on 1690kHz. This station supposedly runs 1kW at night and 10kW during the day but on this night (Sept 16), I heard their top-of-hour ID for three consecutive hours! I wonder if someone ‘forgot’ to switch to nightime power or if conditions were just really good? I have heard them again since with two TOH IDs but much weaker and sounding more like a 1kW station should sound!




JOAK - 594kHz in Shobu, Japan (13:30 UTC Sept 20)


JOUB - 774kHz in Akita, Japan (14:00 UTC Sept 20)
(with English lessons)


HLAZ - 1566kHz in Cheju, South Korea (13:30 UTC Sept 20)
(broadcasting in Japanese in this time slot)


Voice of America (VOA) - 1575kHz in Ban Phachi, Thailand (13:30 UTC Sept 20)
(listen for "This is the Voice of America" ID and then into "Yankee-Doodle-Dandy")


                                   ************************

Hunting For NDBs In CLE248


Yes! Another month has passed and it's CLE time once again.

This time the hunting grounds will be: 275 kHz - 425 kHz.   

For those unfamiliar with this monthly activity, a 'CLE' is a 'Co-ordinated Listening Event', as NDB DXers around the world focus their listening time on one small slice of the NDB spectrum.

If you've been meaning to participate in  CLE, then maybe this weekend is a fine time to try! Lately, we've had a lot of first time submissions so you won't be alone!

As well, if you're trying to learn CW, copying NDBs is perfect practice, as the identifier speed is generally slow and the letters are repeated again every few seconds!

At this time of the season, summer lightning storms should be starting to wane and propagation can often be as good as mid-winter if the lightning cooperates.

When tuning for NDBs, put your receiver in the CW mode and listen for the NDB's CW identifier, repeated every few seconds. Listen for U.S. NDB identifiers approximately 1 kHz higher or lower than the published transmitted frequency since these beacons are modulated with a 1020 Hz tone approximately.

For example, 'AA' near Fargo, ND, transmits on 365 kHz and its upper sideband CW identifier is tuned at 366.025 kHz while its lower sideband CW ident can be tuned at 363.946 kHz. Its USB tone is actually 1025 Hz while its LSB tone is 1054 Hz.

Often, one sideband will be much stronger than the other so if you don't hear the first one, try listening on the other sideband.

Canadian NDBs normally have an USB tone only, usually very close to 400 Hz. They also have a long dash (keydown) following the CW identifier.

All NDBs heard in North America will be listed in the RNA database (updated daily) while those heard in Europe may be found in the REU database. Beacons heard outside of these regions will be found in the RWW database.


From CLE organizer Brian Keyte, G3SIA, comes the details:

Hi all

Our 248th Listening Event just squeezes into the last weekend of this month.
Worth waiting for because it is a 'Special', our fifth 'Channels Challenge'.
It's a simple idea, but one that we always seem to enjoy:

    Days:      Friday 27 September - Monday 30 September
    Times:     Start and end at midday, your LOCAL time
    Range:     275 kHz - 425 kHz   (see below)
    Target:    Try to log ANY ONE NDB in each channel

The 'channel' means the NDB's nominal (published) frequency.
EITHER  321.0  OR  321.5 kHz would be OK for channel 321, etc.

So it means a possible maximum of 151 loggings in all, though that would
probably be miraculous, even for the best placed of us!

All the NDBs must be 'normal' ones (no DGPS, Amateur, etc.) and
no UNIDs in your main list.   Yes, it does include those more
challenging frequencies in the DGPS range.

If you want to add extra interest you could also choose to:
    Maximise the number of radio countries you hear    or
    Maximise the total distance to the NDBs you hear    or
    Maximise the number of 'midday' loggings - i.e. NDBs logged
      within 2 hours of midday by your local winter clock time.

It will be extra tough for North American listeners, with their many 'empty'
channels. Southern Hemisphere and Europe listeners should be more lucky.

Our last 'Channels Challenge' was CLE231 in April 2018.
Please look out for the 'Final Details' a few days before the start.

73
  Brian
-------------------------------------------------------------------------
From:   Brian Keyte G3SIA               (CLE coordinator)
ndbcle'at'gmail.com
-------------------------------------------------------------------------

These listening events serve several purposes. They:
  • determine, worldwide, which beacons are actually in service and on-the-air so the online database can be kept up-to-date
  • determine, worldwide, which beacons are out-of-service or have gone silent since the last CLE covering this range
  • will indicate the state of propagation conditions at the various participant locations
  • will give you an indication of how well your LF/MF receiving system is working
  • give participants a fun yet challenging activity to keep their listening skills honed

The NDB List Group is a great place to learn more about the 'Art of NDB DXing' or to meet other listeners in your region. There is a lot of good information available there and new members are always very welcome. As well, you can follow the results of other CLE participants from night to night as propagation is always an active topic of discussion.

You need not be an NDB List member to participate in the CLEs and all reports, no matter how small, are of much value to the organizers. 

Remember - 'First-time' logs are always VERY welcome!

Reports may be sent to the NDB List Group or e-mailed to CLE co-ordinator, Brian Keyte (G3SIA), whose address appears above. If you are a member of the group, all final results will also be e-mailed and posted there.

Please ... give the CLE a try ... then let us know what NDB's can be heard from your location! Your report can then be added to the worldwide database to help keep it up-to-date.

Have fun and good hunting!

My 10’ x 20’ Active Loop

courtesy: americanradiohistory.com



After recently installing a new coax run out to the loop and after five years of summer sunlight, the plastic food-storage container used to house the loop’s preamp (Wellbrook ALA100LN ... LF-30MHz) finally bit the dust ... literally.


Last week I replaced the housing with a slightly larger plastic box but I’ll still be faced with the UV bombardment and eventual deterioration of the clear plastic and lid unless I do something different.


I’ve a couple of thoughts but am hoping for some other suggestions from blog readers.

I have thought about spray painting the container, which may (or may not) prevent UV damage, but wonder if paint will stick to the smooth plastic surface? Maybe if scuffed-up a bit it would stick ... if so, the coating could be annually renewed.

Another idea is to cover it with duct tape ... not pretty, but possibly doing the job. Any other thoughts out there?



Part 2 and Part 3 of this blog were originally published when the loop was first built (2014) and describe the antenna details as well as showing the loop in action ... listening on the NDB and broadcast band as well as showing its nulling capability. It’s been a great performer and  I can highly recommend the ALA100LN for a large aperture receiving loop. I’m looking forward to what will hopefully be a good winter of exciting loop DXing.

Part 2 - New LF / MF Loop



Some may recall my blog back in July (Wellbrook Loop Plans) describing a new loop that I had been thinking about as a possible replacement for my 10' shielded loop. I had been doodling various construction ideas using PVC tubing in an effort to keep it as light as possible, without introducing any metal near the loop. On Monday of this week, I dismantled the 10' loop in preparation for my new experimental rectangular loop.
I've had the Wellbrook loop preamp here for a few months, so it was now or never, while the weather was still 'antenna-friendly'. Now I do understand that this goes against one of ham radio's long-standing traditions that dictates all antenna work must wait until the weather can't get any worse. Antennas built in the winter rain always work much better than ones put up in the summer. Hopefully it's not Wouff-Hong or Rettysnitch punishable but the fall DX season is almost upon us and I'm not waiting for the rain!

The new 'loop' is not really loop-shaped but is rectangular (10' x 20') and more like a Flag antenna shape. I considered a Flag but really don't need any back-end nulling capability since I'm mainly interested in listening to the east and to the north.


The main boom section is composed of two sections of 1" PVC thick-wall (Schedule 40) pipe joined at the center and reinforced with a 10' section of 2" x 2" Douglas Fir. In addition, the boom has a truss of 1/4" Dacron to take out any end-loading sag. The vertical end sections are 3/4" Schedule 40 PVC pipe, fastened with a T at the boom end. The center mast is made of 2" Schedule 40 ABS pipe with a long section of 1 1/2" ABS nested inside that telescopes upward to anchor the truss ropes and give some additional rigidity to the mast.


Main boom and mast construction
This type of construction would lend itself well to anyone interested in a rotating Flag antenna for the BCB / LF or 160m. The costs are very low, the structure is lightweight and the materials are readily available at most hardware outlets.


Looping E/W


Although the preamp is completely sealed and weatherproofed, I still decided to mount it inside a container. The container also provided a convenient anchor to terminate the loop end wires (PVC-coated #18 stranded) without putting any tension on the soldered terminals.

Although I have not had much time to listen, and conditions are still in 'recovery' mode from earlier disturbances, initial indications are that everything is performing as well, if not better, than expected. It certainly outperforms my 10' active shielded loop by a large margin. I have yet to do any serious S/N comparisons between it and my primary LF receive antenna, a large inverted L, which must be tuned to resonance for the desired listening range. I believe that the very quiet loop / Wellbrook combination will provide an overall S/N improvement.

I have always believed that smaller loops provide deeper and sharper front-to-side nulls so I was pleasantly surprised to measure (using Perseus) null depths from 25-30db, on various groundwave signals ... more than expected. Skywave signals also deliver sharp deep nulls in the order of 22 - 25db ... again surprising, but I'll take them!

A brief listen while pointing S-E last evening turned up good signals from 1 kW'ers KYHN (1650kHz) in Fort Smith, Arkansas and KKGM (1630kHz) in Fort Worth, Texas. An early morning listen revealed good audio from JOIK (567kHz) Sapporo, Japan and JOAK (595kHz) in Shobu. Down in the ndb band, little 25-watter 'IP' on 210kHz was an all-time new catch from Mobile, Arizona.

There is still much to learn from this new antenna system but the biggest challenge will be keeping it up all winter. I did lose one of my 10' loops after several years, due to wind, when the main (un-reinforced) PVC mast eventually failed from flexing fatigue. I will tie the ends of the new antenna down when the winds get strong to reduce as much mast flexing as possible. I could however, run the risk of violating another long-standing radio adage ..."if your antenna stays up all winter, it's not big enough". I just can't win.

Part 3 - Loop Listen 


As Murphy would have it, and in spite of the low amount of solar activity, LF/MF propagation has been very poor since getting my new 10' x 20' loop in place. The few front-to-side nulling checks that I have done, have produced results varying from around 20db to 30db, depending upon the signal. I suspect the depth of null is also affected by the signal's arrival angle but there is still more to learn. The pattern seems to be very close to that of a typical circular loop...the classic figure-8 pattern illustrated below as shown on the Wellbrook data that came with my ALA100LN preamp.

Courtesy: http://www.wellbrook.uk.com

More typically, the null is around 21-22 db as shown on this test while listening to the ground wave carrier of the 'YZA' NDB (236kHz) located in Ashcroft, B.C., about 150 miles to the NE. As expected, the null is fairly sharp and the front / rear lobe, fairly broad.



One short check at dusk produced nice signals from  CJBC, the French-language station in Toronto. The past few nights it has been very strong but with a strong echo effect. I wonder if there is more than one CBC outlet here (860kHz), such as a low-power repeater, causing the echo.



At the same time, while still fairly light outside, WCCO in Minneapolis had a nice signal just before sunset.



No matter how poor conditions become, it seems that the Hinchinbrook (Alaska) NDB, 'ALJ' (233kHz), is always strong ... looping north.



Courtesy: https://www.google.ca/maps
My apologies for the video quality. If you know of any software available for making full-screen Perseus video captures so that I might improve my technique, please let me know. Presently I am just capturing them on my I-Pad which leaves a lot of room for improvement.

(Since originally posting the above, I have been using the Tiny Take free screen capturing software, to produce better quality catures of my Perseus recordings. It's also probable that my new iPhone would produce a high quality video of my computer screen compared to the older iPad used for these ones, but it's something yet to be tried.)

Hopefully conditions will only get better as the season progresses and I am able to give the loop a good workout ... before it gets too windy!


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