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ให้ เงิน เล่น ฟรีWYFR shortwave signing off

Family Radio’s WYFR shortwave service will be ending on June 30, 2013.

WYFR 50 years

WYFR 50 years

Shortwave transmitting is very expensive, and no doubt, competing IP distribution technology and diminishing returns on such investment must play a factor in this decision.? Family radio has been struggling ever since the world did not end as predicted in 2011.

I believe that site has fourteen 100KW HF transmitters and eighteen antennas of various type.? There is a complete photo album here: https://picasaweb.google.com/115519153277489147905/WYFR?noredirect=1#5149450014785168130 courtesy of Kent.

Kind of sad to see them go, I don’t know what their plans are after June 30.

HF VHF receiver diplexer

This is one of those posts that I started long ago and never finished. No time like the present to do the final revision and get it out there.

I have acquired one of those broad banded software defined radios, an Icom PCR-1000 to be precise, and all is well.? I am enjoying listening to various MF, HF and VHF radio stations.? However, there is a slight problem.? Very slight, almost too small to even mention, more of an inconvenience than a problem.? Still, if I am being inconvenienced, than others are too.? This issue is with the antennas.? My K9AY antenna works wonderfully from 500 KHz to 25 MHz or so.? My discone antenna works wonderfully from about 30 MHz all the way up to about 1 GHz.? In order to enjoy the full range of the receiver, I need to switch antennas.? I have a small switch on my desktop, but it seems inconvenient to reach over and switch it when going from the AM band to the FM band or something similar.? Therefore, I have decided that I need an HF/VHF receiver diplexer.? One would think that such hardware is ready made for such instances.?? However, nothing I could find commercially would do the trick.

Thus, since I could not buy one, I decided to build one to add to my collection of receiver doo-dads and nick knacks.? The design is relatively easy, a back to back low pass/high pass filer system with a 50 ohm impedance throughout.? Something with a sharp cut off around 30 MHz or so:

Diplexor plot

Diplexor plot

Looks pretty good, 5th order Chebyshev filter, perhaps .1 dB ripple in the pass bands if well made.? Schematically:

HF VHF diplexor schematic diagram

HF VHF diplexor schematic diagram

Then it comes down to the building. Since this is going to be used in the UHF range, care and attention needs to be paid to the layout of the components and the design of the circuit board.? Some of those capacitance values are not standard, however, by using two capacitors in parallel, one can get pretty close.? Since this is going to be used for receiving only, I may be splitting hairs, however, I have found that well designed and built equipment is worth the extra effort.

The board layout looks like this:

HF VHF receiver diplexer board

HF VHF receiver diplexer board

I tried to keep the traces as close to 50 Ohm impedance as possible.

As one may be able to discern, C2 and C3 are in parallel to make 192 PF, C5 and C6 are in parallel to make 60 PF, and C7 and C8 are in parallel to make 163 PF.

The input and output RF connectors are whatever the builder wants to use, however, I would recommend at least BNC or type N for the VHF/UHF side.? My unit has all type BNC female connectors.?? Parts list:

Nomenclature Value Mouser number Cost (USD)
C1 150 PF SMT 581-12065A151FAT2A 0.60
C2 12 PF SMT 581-12061A120JAT2A 0.25
C3 180 PF SMT 810-CGA5C4C0G2J181J 0.37
C4 68 PF SMT 77-VJ1206A680FXACBC 0.40
C5 50 PF SMT 80-C1206C500J2G 0.45
C6 10 PF SMT 80-C1206C100J2G 0.27
C7 3 PF SMT 581-12061A3R0CAT2A 0.22
C8 160 PF SMT 581-12063A161JAT2A 0.11
Case Diecast, 4.3 x 2.3” 546-1590WB 9.50

I chose a smallish, diecast aluminum case, which matches my other receiver gear.? The circuit board noted above is 2.9 x 1.7 inches, which is a little bit small.? I used 18 gauge wire between the input/output connectors and the board.

The inductors were made by hand.? I used a small screwdriver as a winding form, making the turns tightly then spreading them out to the proper distance.

Inductor chart:

Inductor Value (nH) Diameter (mm) Turns Length (mm)
L1 173 8 6 9.5
L2 468 8 10 9.8
L3 414 8 9 8.7
L4 146 8 5 7.2
L5 186 8 6 8.6

The most expensive part was the circuit board, which cost about $16.00.? The rest parts were about $18.00 including shipping.

As built photos:

HF VHF diplexor with components installed

HF VHF diplexer with components installed

HF VHF diplexer input side

HF VHF diplexer input side

HF VHF diplexer completed.

HF VHF diplexer completed.

I have installed this already and it works great. I will need to get the spectrum analyzer out and run some signals through the various ports to see the attenuation and 3 db roll off points.

Goodbye, RCI 1945-2012

RCI logo

RCI logo

In yet another example of government sponsored international broadcasting ending, Radio Canada International calls it quits after 67 years.? Effective June 24, all broadcasts from RCI’s Sackville shortwave relay site will cease.? All satellite distribution will end and seventy five percent of the RCI workforce will be laid off.? This means the end of almost all RCI original content.? The good news, according to the press release, is that RCI will continue on webcasting.

This is due to budget cuts to the CBC, which administers RCI.? The Canadian Parliament cut the RCI budget from $12.3 million CAD to $2.3 million CAD for 2012.? This cut in expenditures is saving each Canadian resident approximately $0.35 CAD per year.

Thus, this weekend is the last chance to hear RCI or CBCNord Quebec on any HF frequency.

I listened to RCI for many years, until they drastically reduced their English language shortwave broadcasts to North America in 2006.? Simply put, HF broadcasters are folding up shop and moving toward web based distribution networks.? Those HF transmitters are expensive and they do not maintain themselves.

One drawback of this scheme is government censorship.? It is very easy to the government to block access to sites via internet firewalls.? It is very difficult to completely jam a radio station.

And perhaps those considerations are not important.

RCI transmitter site, Sackville, NB

RCI transmitter site, Sackville, NB, courtesy of Wikipedia

I wonder what will happen to their transmitters after sign off?? According to the wikipedia article there are nine HF transmitters in use, with power levels ranging from 100-300 KW.? They are likely to be hauled away and scrapped, the building torn down.


Shortwave Radio picks

Winradio G303i software defined radio, 7490 KHz WBCQ

Winradio G303i software defined radio, 7490 KHz WBCQ

I enjoy listening to radio, however, there seems to be a dearth of good programming on the conventional frequencies. ?Somehow, personality-less robo programmed hit music and right wing talk radio just doesn’t seem to cut it anymore. ?Thus, I have taken to listening to the shortwaves. ?Truth be told, the availability of good programming is dwindling there as well, but good things can still be found. ?Here is my list of interesting and or entertaining programs found on the shortwave:

  1. Radio Australia International – 9580 KHz mornings from 6-9am EST (11-1400 UTC). ?There are a variety of good programs on this station including Asia-Pacific, Saturday Night Country and others. ?Good to listen to with my morning cup of coffee.
  2. WBCQ – Several good selections here including Alan Weiner World Wide (Fridays 8-9pm), World of Radio (Glen Hauser, Thursdays 5:30-6pm), Marion’s Attic (Sunday 5-6pm), Le Show (Harry Shearer, Sundays 7-8pm) Amos n’ Andy (Tuesdays 5-5:30pm). ?New 41 Meter Frequency 7490 KHz is clearer than previous frequency. ?5110 KHz is hit or miss in this location, however Area 51 is worth a listen (Saturdays and Sundays 7-11pm) if reception is good. ?Check their schedule on line as program time change.
  3. WWCR – 12160 KHz 12-3pm EST (17-2000 UTC) Alex Jones, entertaining if not a bit over the top, tends to rant, makes some good points when calm. ?Other programs like World Wide Country Radio, The Pat Boone Show, etc are available at various times on various frequencies.
  4. CBC North – 9625 KHz Continuous Sackville feed of CBC Radio One, mostly in English, occasionally in Inuktitut or French. ?Good for news from the Great White up.
  5. CFRX – 6070 KHz shortwave feed of News/Talk CFRB Toronto. ?Conservative news talk programming Canadian style, some good trivia games and whatnot.
  6. WEWN – 15610 KHz Catholic Mass (8-9am Sundays) although lately they have been re-runs, which is goddamned annoying.

There are others from overseas, but many of the English broadcasting services are being scaled back or eliminated. ?A few broadcasts that one is sure to come across when tuning around; The Voice of Russia (bland, predicable, promos sound like they are recorded in the bathroom), Radio Romania (meh), China Radio International (100% propaganda), Radio Havana, Cuba (campy, mildly entertaining in an absurd way), etc.

Pirate Shortwave broadcasters roam around in the 6890-6970 KHz range. ?They are irregular in schedule, low power and often contain an obscure dialog or some selection of 80’s hair band music. ?Still, if one has some time, they can be entertaining too.

A good source of information on shortwave broadcasts is Short-wave.info?which has a pretty accurate searchable database and a great feature called “Find out what stations are broadcasting on a frequency of (fill in frequency) Now.” ?That is very helpful for figuring out what a station is without waiting for station ID or if broadcasting in another language.

With winter coming and the sun spot cycle on the upswing, the HF bands should be open for business.

Shortwave Pirate Broadcasting

And now, something completely different. It seems there is quite a kerfuffle going on in shortwave (AKA HF) pirate land. ?It seems there has been some FCC enforcement action of late, leading to at least one HF pirate being closed down, while some others are pointing fingers at another saying he is a rat, or a rabbit. ?Or something. ?I dunno, it gets a little hard to follow.


I have written about this in the past; Pirate Shortwave broadcasting. It is a very interesting phenomena that compels a person to gather together all the parts necessary, usually at some expense, and assemble a station. ?Further, keying the transmitter and broadcasting without benefit of a license is a violation of federal law, which can bring heavy sanctions. ?While most pirate broadcasters seem to get a slap on the wrist, this lax FCC attitude can change. ?There have been several steep fines lately for repeat offenders in the FM band. ?At least on the FM band and somewhat the AM band too, a unlawful broadcaster is assured of some public audience. ?On the shortwave bands, a pirate broadcaster’s audience is limited to only those that are looking for them, which is a very narrow segment of ?the population.

What are they trying to accomplish? ?Most of the shortwave pirate broadcasts that I have listened to are limited to a couple of songs from one particular genra, send an ID and then are off. ?Some will send a QSL card via slow scan TV. ? What compels these operators to go through all the trouble for a few minutes of irregular operation? ?Some of them have well equipped studios to go along with the transmitting equipment. ?Then there is the clandestine nature of the undertaking, often with mail drops and spoofed e-mail addresses.

Some seem to exult ?in sticking it to the man, that man being the FCC, big media corporations or any authority that tells them they are doing wrong. ?Acts of civil disobedience against authority perceived (rightly or wrongly) as oppressive or evil. ?Others seem to have some need to perform, no matter how small the audience may be. ?Some are just fooling around and do it simply because they can. Finally, others like the challenge of building a low power shortwave transmitter from scratch and seeing it to through to it’s end.

If the so said station is broadcasting with any appreciable power, it will get noticed quickly and sooner or later, the FCC will pay a visit. ?That is a foregone conclusion. ?The FCC has quite a few new tricks up its sleeve when it comes to direction finding and RF finger printing. ?That’s right, RF finger printing, it is exactly what it sounds like. ?Super resolution HFDF eliminates the need for triangulation, multiple vehicles, and wasting a lot of time driving around neighborhoods trying to figure out which residence an illegal broadcaster is using.

While I understand the compulsion to broadcast free radio; the need to inform under served communities, the fact that what we used to rely on for information and news is gone, a once vibrant and exciting art form has been reduced to a hollow shell of its former self, however, we have not yet reached a Magna Carta moment. There are still some legal methods of getting the word out on radio, both conventional and shortwave. ?International Broadcasting stations WBCQ and WRMI offer time brokered programming and are pretty liberal in the types of programs they accept. ?Not all US shortwave broadcaster are thus, many allowing only religious programming. ?Those shortwave stations have large coverage areas and existing audiences. ?There are also may AM radio stations that will do block programming over the weekend, for a price, of course. ?Then there is the possibility of setting up an internet station. ?Eventually, the new Low Power FM (LPFM) rules will go into affect and interested groups will be able to apply for licenses in that service.

The point is, while the deck is stacked against the local or community radio broadcaster, it is still possible to get the word out in a legal way. ?The cost of buying block programming will likely be the same or less than buying all the equipment to set up a pirate station. ?Further, if the programming is compelling, you may get noticed and be able to flip the equation and actually get paid to do it.

VOA to end HF broadcasting

Several places have reported that The Voice of America will sunset it’s shortwave broadcasts in the not too distant future. Boing Boing reported yesterday, based on a paper titled “Broadcast Board of Governors 2010-2012 BBG Technology Strategic Plan and BBG Technology Update – 2009” received via FOIA last January.

The 2009 study notes that the weekly audience for radio is 101.9 million listeners, TV is 81.5 million and the Internet 2.4 million weekly listeners. ?I don’t know how much that has changed in the last two years, but I’d imagine some shift towards the internet has taken place in light of recent shortwave transmitter site closings.

There are several interesting aspects of this report, notably the disparity between what is termed “Classic Engineering” and “Classic IT” fields. ?This is the concept that radio engineers toil on RF and transmitters, while the IT guys work with computers.

As the dependence on shortwave continues to wane and the distribution focus shifts to third party operations, satellite and other direct-to-consumer methodologies, the skill sets of some engineering personnel become less and less relevant to the agency.

This issue is further compounded by the relatively difficult transition from a traditional RF, antenna, transmitter design, and maintenance knowledge base to the technologies involved in digital satellite and IP-based networking systems.

Perhaps that is how it is done in government circles, but I have found in private sector, most radio engineers know at least the computer automation systems that run the stations. ?Of course, everyone has preferences and we tend to gravitate toward things we like to do, especially in a field as diverse as broadcast engineering. ?When I was in the military, somebody posted the “Eleven Rules of Success.” ?The only one that I can remember now is this: “Pick the thing that you hate and become proficient at it.”

In order to stay relevant, broadcast engineers have to keep up with the technology while remaining proficient with RF and audio skills. ?Computers and automation programs are not terribly hard to understand, but each one is different and operates differently. ?Most, if not all automation companies offer some type of training, which is fine. ?Nothing can beat hands on installation and trouble shooting for learning the important details, however.

The report also mentions that morale is an issue for several reasons. ?First, it is noted that:

Despite several recent high profile station closings, the organization continues to employ shortwave as the most important transmission mechanism to many of the target areas around the globe. Often surge activities are enabled byvadditional shortwave transmissions that end up as an integral part of the ongoing schedule. Effectively, this diminution of transmission resources accompanied by no reduction or even an increase of reliance on this transmission methodology creates overburdened schedules and often the deployment of less than optimal assets for transmission into target areas.

This additional operational burden likely extends to other disciplines within the agency where programming staff must expend substantial additional effort to produce or adapt content for a multiplicity of transmission methods.

In essence, the decision process for station closing does not appear to follow an overt decision and stated plan to reduce shortwave usage.

That is known as the “more with less” paradox. ?In the private sector, more with less has been going great guns since the first loosening of the FCC’s ownership rules in 1994. ?For those that are used to working in optimum conditions, anything less is a shock to the system.

The issue of low morale is palpable and often present in conversations that address historical perspectives on a particular station closing, transfer of technologies around the network and any other such topics. Precipitated by the long periods of employment that are relatively standard in the Engineering area and perfectly understandable, this grieving process is a natural consequence of the pride involved in creating a state-of-the-art technical facility only to see it being dissected piece by piece as technology continues its relentless creative destruction.

An interesting statement and it shines a light on several things heretofore unsaid in broadcast engineering. ?We love our transmitters, as strange as that may seem. ?We love our towers and antennas. ?Parting with something that has become an integral part of our working environment is difficult to say the least. ?Watching something be signed off for the last time and then hauled to the scrap heap is very disheartening, especially if there is no replacement.

On the IT side, things are not so good either. ?The main concern is the infrastructure of the IT backbone. ?Several deficiencies are noted in the cabling and router; the cabling is in serious disarray and there is only one router for the facility. ?There is also other problems noted with personnel and lack of project management experience and/or IT department goals.

Overall, moving into new media fields makes sense. ?There are, however, many places where new media is unknown or at best, mostly unavailable. ?Moving content delivery from over the air broadcast to IP based distribution may be far less expensive to operate, that is true. ?It is also far more susceptible to being disrupted by accident or design. ?In those areas where the internet is spotty, shortwave radios are abundant and relied upon. ?If the VOA is not on the air, then some other station will be.

I will listen to the shortwave broadcast, but not the web stream

Here’s a secret to all those broadcasters that think streaming on line is the answer to all the worlds problems: It isn’t all that. ?I used to like listening to Radio Netherlands (Radio Nederland) on the shortwave. ?They have some excellent programs like The state We’re In. ?One problem, the only way to get it these days here in the US is via webstream.

The same for many other world broadcasters like the BBC, CBC, HCJB, et. al. ?Most of these former big shortwave broadcasters have greatly reduced their operating hours or left the air waves all together.

Issoudun HF antenna, courtesy wikimedia

Issoudun HF antenna, courtesy wikimedia

Streaming content on the world wide web is not broadcasting, nor can the quality and reliability be compared. ?Web streaming is far less reliable and offers lower quality than does HF broadcasting. ?The former broadcasters which have abandoned the airwaves to the likes of Radio China International will say otherwise, but that is their spin on the situation. ?Of course, using and maintaining high powered broadcast transmitters is expensive, especially for governments that are faced with tough financial decisions.

First and foremost, streaming requires that I use my computer as a radio while I am trying to do other things on it. ?I bit of background on my computer; I have a 8 year old Dell Inspiron 5150 that I purchased when I was working on my degree. ?When I got it, I asked our IT department guys what was the best course for buying a new computer. ?Their answer was to get the best, fastest processor available because everything else can be replaced/upgraded. ?I did just that, with a 3.06 GHz intel mobile P4. ?I have replaced the hard drive with a 200 GB unit and upgraded the RAM to 2.2 GB. ?The keys have most of the letters worn off, it has very distinctive wear marks on the case where I place my hands, etc. ?It has lived up to my expectations for serviceability and then some.

Even so, it does have it’s limitations. ?Listening to streaming audio of watching streaming video is not one of it’s strong points, especially when engaged in other tasks. ?Often, when listening to streaming, there are drop outs and other interruptions and the audio just doesn’t sound great coming from the computer speakers. ?Even external speakers leave something to be desired, quality wise. ?Something about the digitized sliced and diced bit reduced stream that I find annoying and worse yet, fatiguing.

We live out in the sticks. ?Our local phone company, in spite of being the largest dial tone provider in the nation, has some reliability issues when it comes to their DSL service. ?Several times, the DSL goes out for not apparent reason, returning several hours or days later without comment from the TELCO. ?If you call in outage, they always act like they never heard of the problem.

Listening to my shortwave receivers offers better reliability and quality than streamed audio. ?I know I am not alone in this regard as several others have made the same comments. ?Listening to shortwave is listening to real radio, listening to tinny thin audio over a computer or smart phone is crap.

There is an ever dwindling selection of English shortwave broadcasters listenable in North America. ?Nature, as is said, abhors a vacuum. ?Therefore, in come the religious broadcasters, false prophets, anti government crack pots, hucksters, other governments with money like China and Russia, pirates and others to fill the void. ?That is all well and good I suppose, but I do miss that day that I could get BBC news at the top of the hour on 15400 KHz.

Stay tuned, 1994 redux

In case you haven’t heard, May 21, 2011 will mark the beginning of the end of the world. It is on this date, according to Harold Camping, the rapture will begin. For those not versed in bible lore, this is when God will take all of the saved souls directly to heaven, body and all. Further research reveals that it will begin at 6pm local time, in every time zone.

I’d imagine you can listen for updates on Family Radio stations or shortwave if there aren’t any local stations to listen to. ?Those on the west coast may want to tune into the shortwave broadcast (transmitters are in Okeechobee, Florida)?for a preview of coming events. ?You can try:

  • 5950 KHz 22:00 through 0100 UT (6pm through 11pm EDT)
  • 11470 KHz 22:00 through 23:45 UT
  • 15440 KHz 22:00 through 23:59 UT

The full shortwave schedule is available here. ?I am setting my clock so I can tune in and see what happens because I am curious; dead air? station sign offs? ?I really want to know how a station plans for the end of the world. ?Hopefully it will be marked by some program, announcement or something special. ?Operations as usual would be very boring, as most Family Radio programming is mundane and predicable.

Frankly, Camping has made these predictions before, the last was September 6, 1994, when the faithful gathered in the?Alameda’s Veterans Memorial Building, bibles open, hands out stretched, awaiting the moment. ?After a while, it became clear that something was amiss and everyone went home, wondering what went wrong. ?There have been many religious based predictions for the world ending: 1806; October, 1844; December 21, 1956; November 1982; January 1, 2000: etc. ? The Jehovah’s Witnesses alone have predicted the end coming in 1914, 1915, 1918, 1920, 1925, 1941, 1975 and 1994.

It’s either a really good radio stunt, which would go down as one of the greats of all time or they actually believe it’s the end of the world. ?In the case of the latter, does this mean they will be selling their radio stations? ?There are several around here that I’d be interested in getting my hands on. ?I’d even give a fair price, considering the circumstances and all.

Update: How do radio stations prepare for the end of the world? ?T -40 minutes and the answer appears to be play canned programming, or in other words, business as usual.

The World Turned Upside Down

I have been watching the events unfold in Japan. ?It is truly astounding the power of Mother Nature. ?While several US networks seem to be tempering their coverage of the nuclear fuel melt, and yes, there are multiple reactor fuel melts in progress, other sources are forthright. ?The BBC seems to be on top of things, as well as Russia Today.

Thus far:

  1. No fewer than four hydrogen explosions have taken place in all four reactors at the Fukushima-1 Power plant. ?The after the third explosion yesterday in unit 2, there are two major concerns; breach of the reactor vessel(s) and run away nuclear fission. ?After that explosion, the pressure in the unit 2 reactor suppression chamber dropped from three atmospheres to one atmosphere, indicating the suppression ring had breached. ?Currently the nuclear disaster is categorized as a 6/7, surpassing Three Mile Island. ?The worst case scenario: ?Reactor Unit #2 completely breaches, this unit contains Mox fuel Note: unit #3 contains the Mox fuel. (mixed plutonium/uranium oxide), which is far more dangerous than the fuels in the other reactor vessels. ?Mox fuel has a lower melting point and could potentially melt into a pool at the bottom of the reactor vessel resuming fission. ?Criticality? ?Yes, but not the high order type as seen in a nuclear weapon.
  2. The root cause of the disaster is loss of cooling after the reactors where shut down. ?The nuclear fuel cores require cooling for at least two to four weeks after shutdown. ?The backup diesel generators went off line approximately one hour after the units were automatically shut down during the earth quake. ?Three probable causes for this have been proposed; ?the electrical switch gear for the generators was in the basement of the generator building, which was flooded by the tsunami, fuel contamination/fuel loss, and submergence of the GENSETs by sea water. ?All of three of these scenarios points to a design flaw.
  3. Radiation levels have varied but are elevated, peaking at various times before and after each explosion. ?Until this morning, the major radiation plumes were being blown off shore. ?The wind has become variable, causing the down wind zones to shift.
  4. Prevailing east winds could blow some of the contamination to the west coast of the US within 36-48 hours, east coast by 48-72 hours and in 7-10 days there will likely be a band of radioactive particles in the jet stream that circles the globe in the northern high latitudes.

Good explanations: MIT NSE Nuclear Information Hub

I never though I’d recommend a Russian News media source, but they seem to be nailing it. ?There is also some coverage on NHK shortwave frequencies:

All times UTC / target areas: af (Africa) as (Asia) eu (Europe) na (North America) pa (Pacific)

0500-0530: 5, 975 KHz (eu) 6,110 KHz (na) 9,770 KHz (af) 15,205 KHz (as) 17,810 KHz (as)
1000-1030: 9,605 KHz (as) 9,625 KHz (pa) 9,840 KHz (pa) 11,780 ?KHz (as)
1200-1230: 6,120 KHz (na) 9,625 KHz (pa) 9,790 KHz (eu)
1200-1300: 9,695 KHz (as)
1300-1330: 9,875 KHz (as)
1400-1430: 5,955 KHz (as) 9,875 KHz (as) 21,560 KHz (af)

But not to worry, everything is okay. ?There will be no detrimental effects of this, whatsoever.

Regardless, I have headed down to the basement and dug up my CD V-700 RAD meter. ?I salvaged this from the dumpster at WPTR after one of the contract engineers threw it away in the early 1990’s. ?I believe I used this meter to measure the radiation from the tubes in the BT-25A and the MW50B transmitters.

According to the “Operational Check Source” on the side of the meter, it still works and is pretty close to calibration level. ?Even if it is not totally accurate, it will still indicated an increase of radiation.

Anton Model 6 CD V-700 radiation meter

Anton Model 6 CD V-700 radiation meter

This is a Anton Model 6, which is the most sensitive of the V-700 series meters. ?It can be used to check background radiation levels and/or contamination of food or clothing. ?The best plan is not to ingest radioactive particles in food and water. ?Why wonder about it, when you can know?

The K9AY receiving loop antenna

Not to take anything away from Gary Breed, K9AY, who makes and sells these things under the corporate name AYTechnologies, I decided to make my own K9AY antenna system and controller. ?Basically, after looking at the currently available commercial version, I figured I could make a better unit for less money and be happy.

The basis for the K9AY antenna is that it has a steerable null. ?The gain around the antenna is close to unity, except for the terminated side of the loop, which has a deep null. ?This can be switched around using a combination of relays that change the loops and termination. ?This comes in very handy for MW and SW listening, when co-channel stations can create annoying interference and hetrodynes. ?I have had good success pulling many stations out of the muck, especially in the AM band using this antenna.

This antenna requires a good ground to work against. ?For optimum installations, I would recommend placing two radials under each side of the loops. ?This will keep the ground conductivity below the antenna fairly constant, thus the value of Rterm will remain consistent for each band.

My other idea is to add a preamp right at the antenna to overcome transmission line loss and the loss from a 4 port passive receiver coupler. ?Something around 10 dB, low noise (obviously), low parts count and rugged. ?I decided that a Norton preamp was a good design, with only one active device, a common 2N5109 BJT. ?Most of the time, this preamp is switched off and out of the circuit. ?There have been several occasions, however, where an extra 10 dB made the difference between no copy and good copy.

This is the schematic of the relay board and preamp combined:

K9AY antenna controller with preamp

K9AY antenna controller with preamp

The parts list is as follows:

Symbol Part Symbol Part
C1 – C5 Ceramic 0.1 uf capacitor R1 2 Kohm ? watt
FB-1 Ferrite bead, Amidon FB-43-101 R2 8.2 Kohm ? watt
K1 – K3 Omron G6K-2F-Y small signal relay R3 100 ohm ? watt
L1 22 uH ? watt R4 51 ohm ? watt
L2 100 uH ? watt T-1 9:1 balun
Q1 2N5109 w/heat sink T-2 Norton feedback trans

The 2N5109 transistor is a CATV unit and it has a 50 input and output, that reduces the number of impedance transformers required. The value of Rterm is determined by which band one wants to operate on. ?I used Omron G6K series low signal relays. ?Again, because this is a receive only antenna, those relays will work well.

Terminal board connections, TB1:

Terminal Use
1 SW loop
2 SE loop
3 NW loop
4 NE loop

Wire loops go between Terminals 1-4 and 2-3.

Control terminal board connections, TB2:

Terminal Use
1 Preamp power
2 Rterm
3 Rterm ground
4 Ground
5 Relay 2
6 Relay 3

To create a low noise preamp, I decided to use surface mount devices and to try and make all the traces as close to 50 ohm impedance as possible. ?I created this SMT printed circuit board:

SMT K9AY board, not to scale

SMT K9AY board, not to scale

From this, I ordered 6 boards from PCB express:



This is the board with all passive components installed:

K9AY loop antenna control board partial

K9AY loop antenna control board partial

This is the board completed:

K9AY antenna control board completed

K9AY antenna control board completed

My current K9AY is an amalgamation of parts removed from various equipment. ?The relays are large, 12 VDC units which do not have the best contacts. ?It works well enough, but I’d love to get one of these units into the control box at the base of the antenna. ?Unfortunately, my antenna field is still in about 18 inches of snow, so it will have to wait until some of the snow melts off.

I would position this antenna as far away from transmit antennas as possible to avoid overloading the preamp and or causing problems with the switching relays. ?For the average amateur set up, 75 to 100 feet separation should be more than enough.


A pessimist sees the glass as half empty. An optimist sees the glass as half full. The engineer sees the glass as twice the size it needs to be.

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