WD4NKA/B Ten Meter Propagation Beacon

 

 

The Propagation Beacon

This is a quick update regarding a newer project I have engaged over the past month or so: a Propagation Beacon.  I have been fascinated with these beacons on ten meters for some years now.  The purpose of this program is to provide a "boots on the ground" source to determine propagation on ten meters, and, by extrapolation, the state of the Maximum Usable Frequency (MUF) on HF, ten meters being the highest portion HF region.  In other words the Maximum HF Frequency Band.   Beacons are typically very low power devices, ranging anywhere from 100 mW to 20 watts.  Most of them are about five watts.  The antennas are (or should be) omni-directional unless aiming at a specific direction for a specific utilization.  

The idea: if I can copy a five watt signal from 2000 miles away emanating from a simple antenna of no great height, the band must be propagating well.  We can safely assume the MUF is at least reaching the beacon's frequency.

While many profess to use the FT8 frequencies as a "tell tail" for MUF, that can be very misleading.  While it is true there are 100 watt beacons on ten meters, I can count them on one hand.  The IARU discourages that level of  power, it defeats the purpose of the Propagation Beacon!  FT8 stations are all over the place with power, high gain antenna systems, etc.  One cannot accurately ascertain the level of propagation, not with any degree of certainty.  I know.  I do FT8 myself, and I know what some of these stations are running.  One I know runs a full kilowatt on a yagi system up over 70 feet in elevation.  One visit to QRZ.com, looking over the photos and station description reveals these stations run very high gain systems.  They approach FT8 like a contester, and honestly so: that is how FT8 is set up.  It wasn't meant to be that way originally but it is what it has become.

Ergo, FT8 does not replace the classic low power propagation beacon when it comes to propagation assessment.

 

Registered vs Unregistered

There are two types of these beacons: the Registered Beacon and the Unregistered Beacon (often referred to by the beacon community as a "rogue" beacon.)  Let me comment on this:

The Beacon Program is just that, a program.  As such, there needs to be something of an organized approach.  At this point the primary organizer is the International Amateur Radio Union (IARU), in cooperation with the ARRL, which has an appointed representative and contact person for each region.  This person establishes your registration and "assigns" a frequency, which is based on a coordinated schedule.  Coordination is necessary so as to not cause unnecessary QRM to other beacons or services worldwide.  This is owing to the international propagation possible on Ten Meters.

"Beacon Protocol"

What I call "Beacon Protocol" is actually quite simple, and technically not official.  Stations are requested to be frequency stable,  not to exceed 20 watts. The ten meter "beacon sub-band"  in Region 2 ranges from 28.2 to 28.3 MHz, limiting emissions to data or CW.  Suggested antennas are omnidirectional in orientation, and what I would call average residential, mast mounted height. (mine is a half wave "Ringo" at 20 feet, bolted to the gable end of my house.)  

 

Beacons are not meant to be DX machines, they are meant to provide data sufficient to fairly assess propagation conditions. Universally, Beacons offer a constant rotation CW transmission indicating the beacon call, beacon suffix (/b or bcn), location and/ or grid square. CW is typically the primary emission, however data signals are also permissible.   What is sent on each rotation can differ from beacon to beacon.  Some even offer email addresses for reporting reception.  Beacon monitoring has become something of an SWL interest, you can find articles posted online, dedicated entirely to beacon monitoring.

On the other-hand there is the unregistered beacon.  Essentially someone gets a beacon going, and parks it wherever so desired, typically with minimum regard to any established band organization.  "Rogue" beacons are not illegal per se.... but are usually not coordinated with the beacon community which means that there are risks of doubling signals and potential interference. All this to say: if you are inclined to become involved with the Beacon community, don't be a lone wolf.  Please become involved constructively!

Our Rep for Region 2 is Jerry AC5JM.  I linked his email, but if that link fails, copy and paste:

ac5jm@aol.com

Jerry's a great fella to work with, is responsive, and very helpful and encouraging.  Do reach out to him.

 

The Function of WD4NKA/B

Currently, my beacon serves a twofold purpose.  Primarily, it is a 3-5 watt propagation beacon.  Secondarily, it transmits weather information for local consumption during local storm events.  This weather retransmitted directly from our local Aviation Weather station at Orlando Sanford International Airport, Sanford Florida (KSFB).  The transmission mode is PSK31.  Jerry did some footwork for me and we determined that digital beacon transmission is legal.  During these weather events the power is elevated to 20 watts.  Those of us who entered ham radio from out of the CB ranks can remember how well a 5-watt base station on a half wave ground plane could cover an area on AM.  Imagine what local coverage a 20 PSK signal has using the same antenna at the same height, 20 feet.   WD4NKA/B can operate on independent D.C. sources.... just in case.  (read: I keep a few car batteries under charge at all time.)

Currently, my Icom IC740 provides the PSK via FLdigi, but soon another HTX-100 will fill that role. 

Of course, after storm weather events the beacon returns to it's normal cw ID rotation.

 

Beacon I.D. rotation

The current identification in rotation reads: "v v v   v v v  de wd4nka/b wd4nka/b  deltona fl el98iv pwr 5w"

After 20 seconds there is a ten second tone (used to check the system) and the rotation recycles.

The antenna used for WD4NKA/B is a Cushcraft AR10 "Ringo", mounted at 20ft.  Since the HTX-100 has a low-power input of 5 watts, the output is about 3.5 watts.  By the time the antenna sees the signal at the input, it's more like 3 watts.  Nonetheless, I report the power input to the final.

That's pretty much it for now.  Listen out for WD4NKA/B on 28.299.5 MHz sometime.  If you hear it, drop me a line at wd4nka@gmail.com .  Let me know how it sounded, along with signal strength near as you can tell, and band conditions at time of copy.   Date and time would be helpful as well.  In time I hope to have a special QSL card to send back in acknowledgement.  

That's all for  now.  I may edit this post as needed.  This is a work in progress.

73, de wd4nka ar k

 

 

The Classic "Sleeve" Dipole for Ten Meters

 

 A Ten Meter Sleeve Dipole Antenna

This was my first Ten Meter beacon antenna.  It made a good showing for itself.  The "Sleeve" antenna is probably better known as a VHF antenna, but it has a fairly long history on Ten and Eleven Meters.  Especially in the Marine community.  Shakespeare made their "Big Stick" fiberglass CB antenna for many years, and as well the Antron-99, both are, I believe, sleeve type dipoles.  I know the Big Stick was, I had one.  It has a few things going for it.

1.  No need for radials.  Yes, you can mount three or four radials about a quarter wave below the base of the antenna, but I doubt on Ten Meters, you will see much of a difference.

2.  Self Shielding.  I still use a coaxial RF choke, but typically a 50 ohm coaxial feed will directly feed this antenna, despite the fact that it is a balanced feed like any dipole.  However, the bottom "leg" is a hollow tube and the coax runs inside and connects to the center point from within.  That bottom tube actually shields the feed line.  Finding discussion about this phenomena on line is rather scarce, but it has been my own observation: I never had RF on the coax surface with a sleeve dipole.... just as I never had that problem with the Shakespeare.

3.  All parts come from the local Hardware store.  Except for the 102" stainless whip and the screw mount, of course.  Those you can get on eBay or Amazon.  I used a copper pipe cap which I drilled out to receive the whip's screw mount, and and which screws on to the down tube.  Being copper, I was able to solder the coax braid to it directly.  The down tube is a 1" diameter aluminium tube cut to 102" or so.  I also did an extra maneuver by cutting a 12" piece of aluminum tubing to slide into the bottom of the bottom tube which can slide in or out.  It's a "trombone" tuner.  You will not set the antenna for minimum swr as a regular centerfed dipole by trimming the ends.  Not with a stainless steel whip with a corona ball at the end.  But just adjusting the length of one side actually does a pretty good job.  I used a length of Schedule 40 PVC to cover the bottom tube.  The copper end cap size is selected to fit over the PVC pipe.  It is drilled to receive screws on three sides, equidistant, which go through the cap, through the PVC, and through the bottom tube.  Make sure those screws are stainless.

4.  Very good wind resistance.  One of the reasons why this type of antenna is popular with the Marine community.  It poses minimal wind resistance.  Now, this antenna is not what I call "heavy", but it does have some heft to it.  I used U-clamps to bolt the bottom to a mast.  I selected a ten foot length of PVC to cover the bottom tube, cutting it about 18" longer than the actual bottom tube inside.  Use that 18" to bolt the antenna to a metal mast.  This will keep the bottom tube from paralleling the mast itself.  On the bottom of the PVC, you could mount a cap with an SO-239 coax female jack.  If you want.  I just ran the coax out of the open bottom with a barrel connector (double female) and attached my coax feed to it. 

That's pretty much all there is to it!  I will post a drawing I made some years ago that illustrates how this antenna comes together  to see it better, just click on the image itself.  Note that in this diagram, I use a copper pipe.  Substitute that with aluminium.  A lot of freedom here.  You can even use flexible metal conduit that comes in rolls.  The idea is to make the bottom part of the dipole hollow so the coax can feed through it to the center feed point. :

Here are some photos I took while putting mine together:

This is the copper end-cap that serves as the dipole center.  The stainless steel whip mount is mounted as you can see.  The coax feeds through the bottom tube and attaches here.  The braid of the coax becomes common to the copper end cap itself.  The whip is, of course, insulated from it.

 

Here is a view of the mounted whip, the aluminium tube already inserted into the PVC (which I already had.  There's a little rust on it from the last antenna project it was involved with. And, of course, there's the coax which will feed through that bottom tube.

 

 

Here it is, coax through the tube, connected to the end cap.  The holes are drilled into the cap.  When the cap is set on the PVC, I will drill pilot holes through these pre drilled holes, through the PVC and through the down tube.  Then I will screw three stainless sheet metal screws through the cap, PVC and aluminium tube.

The end cap is screwed on.  I do a continuity check with my VOM to make sure there are no opens or shorts.  After this, she's ready to be tuned if using the above mentioned trombone tuner (sliding tube).  It may not even be necessary to use one.  You'll know when you place an SWR bridge in line.   The version I used for the beacon did not need it.  An 8 ft tube gives me a 1.3:1.  Good enough!!  Do the tuning with a short mast and step stool to stand on.  When you are satisfied, go ahead and install it on your mast.  That stainless steel whip will do just that, whip around for a bit, but it will steady out once the gear is mounted.  I had mine on a 20 ft mast.  And as I mentioned, I did roll a coaxial RF choke at the feed point: RG58, wound with a 4" diameter, 20 turns, zip tied together.

I replace this antenna with the Ringo AR-10 because the Ringo is lighter.  Easier to take down in a tropical weather event.  I'm not getting younger.  I find the Ringo and the Sleeve Dipole perform equally well.  The Ringo may have a slightly lower angle of radiation.  But spotters on RBN report about the same level signals.

Check out this antenna, it may surprise you!

73, de wd4nka

An Update on What's Happening at WD4NKA.

 

Welcome Back!

 

WD4NKA as it is currently (23 August 2024)

 It has been about two years since my last entry on "All Things Wireless & Letterpress".  There have been a number of changes.  Probably the most notable change might be the AM equipment now in use.  That would be the operating position to the right, the Johnson Ranger and the Hammarlund SP-600-J.  Sitting atop the SP-600 is an RME 6900 speaker.  It has been repainted wrinkle finish grey, with black enamel escutcheon, sporting a pearl coloured grille cloth covering for a brand new 8" speaker.  Another new addition is a Dell Optiplex computer, wide screen monitor (to view FLDigi and wsjt-x).  To the immediate left of the AM rigs, atop the Hammarlund HQ-129-X is a very nice Model 2 National SW3, beside my trusty Regenerodyne.  The rig with the blue screen to the center of the left operating table is another new member of the staff, an Icom 7300.

 

 

The Primary Antenna: my rebuilt 40-meter Ground Plane. 

 I also rebuilt my 40 meter ground plane which I use on all bands 80 - 10 meters.  That coil you see at the base is my 75 meter loading coil.  The antenna is amazingly resonant on 40 and 15 meters, but surprising a pretty workable swr exists on 10 meters as well!  20 meters requires the Dentron MT-3000a tuner.  There are two 68 foot radials and five 35 foot radials spread across the roof from west to north to east.  This is the exact same antenna type I have used at this QTH since 1993.  This particular version was rebuilt two years ago with new tubing, pivoting base (DX Engineering) and all stainless hardware.  I also re-enforced the mast bracketing to the gable of the house.

 

I am still operating AM these days, although not quite as much.  I am rarely on 3885 KHz largely because I don't really do well with large roundtables.  Not when it takes 30 - 45 minutes before it's my turn again.  My mornings move too fast for that.  These days you can find me late evenings and early pre down mornings on 7287 KHz.  Normally I am calling out, the AM window on 40 meters is much less populated.  Groups, when they do form, tend small, maybe five or six stations, if that.   I run about 100 watts carrier.

 

I have to show this photo.  The AM Position when viewed from the table top, lol.  I restored the Johnson Ranger using Greg Latta's Frostburg site as a guide, which was amazing.  If you are planning a Ranger restoration, check out the link to his article.

 

Just to bring you up to speed with my latest project, I have an IARU registered Ten Meter beacon up and running now on 28.299.5 MHz.  The code ID is sent using an HTX-100 set on low power (5w input, about 3 watts reaching the antenna) sending a 70-second loop in a continuous rotation.  The IC-740 provides PSK weather information patched in from KSFB, the aviation weather station at Orlando Sanford international airport.  I switch over to PSK WX mode during Weather events, such our recent Tropical Storm (Debbie).  However I hope soon to replace the IC-740 (which does an excellent job with digital modes using the SignaLink USB interface!) with another HTX-100, which will serve as the PSK end of the beacon, plus serve as a back-up beacon, and also be available for portable use, doing field strength tests.  The IC-740 is slated for portable operation.  For a 40 year old HF rig, the '740 does a superb job.

 

 

 

 

 

The Beacon Antenna is a Cushcraft AR-10 "Ringo" half wave vertical, mounted at 20 feet.  This replaced the Sleeve half wave that I built initially (which I will describe in subsequent blog entries.)  Over the past two weeks, I seem to be heard pretty well from Costa Rica to Utah to California to Hawaii.  I use the Reverse Beacon Network (RBN) to monitor the spotters and their reception reports.  It's been a fascinating endeavour!

 

 

 The above image shows a series of spots from 15 August 2024.  While 7 dB is a common report, I have gotten reports as high as 35 dB.  Tune around and give me a listen on 28.299.5 MHz, and if you do copy WD4NKA/B, drop an email to:

 

wd4nka@gmail.com 

 

 Let me know how I sounded, where you are, and any other reception notes.  Remember, I am located in Deltona FL, so likely I will be heard in the mornings into Europe, Afternoons likely Central and South America, and as the sun goes down my time, the Pacific coast and Hawaii. 

 

Well, that's about all for now.  This short entry has taken much longer to type up than I thought it would.  Most of it is getting used to the editing controls again.

 

73, de wd4nka.