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 ¼ watt
FB-1 Ferrite bead, Amidon FB-43-101 R2 8.2 Kohm ¼ watt
K1 – K3 Omron G6K-2F-Y small signal relay R3 100 ohm ¼ watt
L1 22 uH ¼ watt R4 51 ohm ¼ watt
L2 100 uH ¼ 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:

K9AY PCB
K9AY PCB

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.

ABC turns to HF during tropical Cyclone

Super Tropical Cyclone Yasi, a category 5 storm, came ashore this morning between Cairns (pronounced Cans) and Townsville, Queensland around midnight Thursday (9 am Wednesday, NY time).

Tropical Cyclone Yasi, February 2, 2011
Tropical Cyclone Yasi, February 2, 2011

Radio Australia carried Australian Broadcasting Company (ABC) Queensland coverage of the storm, which was extraordinary.  Spot coverage, emergency information, sheltering information, updates and calls from listeners in the midst of the storm.  Some of it is pretty intense.  One fellow, John, out in the country all by himself in the height of the storm sounded somewhat forlorn, I hope he makes it.

Due to the size of the storm, wide spread power outages are expected and may last for weeks or months.  As a part of this, there are numerous outages and potential outages in their AM and FM broadcasting chain.  To that end, ABC has two shortwave frequencies available for their Queensland service; daytime (8 am to 8:30 pm local time, 2100 – 0830 GMT) on 9710 KHz and night time (8:30pm to 8 am local, 0830 – 2100 GMT)  is 6080 KHz.

Once again, HF (shortwave) radio gets the job done when local stations, cell towers, and internet connections to dead.  Sometimes it is the low tech answer.

MW/SW hybrid stations

There are four of these stations in Canada.  In my scanning of the shortwave frequencies, I have found CFRX on 6070 KHz to put a strong signal into my location pretty much 24/7. At night it is drowned out by interference from but daytime is listenable from local sunrise until about an hour before local sunset with a 100 uv signal.  A look at the map reveals the CFRX transmitter site is roughly 300 miles away.  CFRX is a relay of CFRB, 1010 KHz in Toronto, Ontario, Canada.  CFRB does not come in here at all due to protecting 1010 WINS in NYC.

1964 CFRX/CFRB QSL card
1964 CFRX/CFRB QSL card

What I find very interesting is the station uses 1 KW TPO into a single 50 foot (117 degree) vertical tower.  That is a pretty low tech transmission facility, nothing like the minimum 50 KW with a 10 dB antenna requirement the FCC stipulates for shortwave broadcasters in this country. Even so, it generates a big useable signal, in the case of CFRX, covering nearly 300,000 square miles very inexpensively.

CFRX has been relaying CFRB’s signal since 1937.  According to the ODXA site, the station uses a Bauer 701B modified to transmit on HF.    The Bauer transmitters were always solid units.  It went off the air in 2008 for several months while the transmitter was repaired, but eventually, it did return.  Obviously the station ownership finds value in the service and it continues on today.

I often wonder why the FCC won’t allow a similar HF relay service here in the US.  Daytime propagation on the tropical bands (75 and 60 Meters (3.9-4 MHz and 4.7 – 5.06 MHz respectively)) would allow low power relays to cover large areas like CFRX.  Tropical band propagation is such that night time coverage may degraded by interference from other, more powerful stations offshore.  Even so, it seems like a good way to cover a lot of ground in a economical way.

Other Canadian shortwave relay stations:

HF Call sign Power/frequency Parent station Location Power/frequency
CFRX 1000/6060 CFRB Toronto, ON 50 KW/1010
CFVP 1000/6030 CKMX Calgary, AB 50 KW/1060
CKZN 300/6160 CFGB (CBC R-1) St. Johns, NF 4.5 KW/89.5 MHz
CKZU 500/6160 CBU (CBC R-1) Vancouver, BC 50 KW/690

Power in watts, frequency is KHz unless otherwise noted.

I know the CRTC would like to do away with these stations, but I think that is foolish.