News Digest 1997-2000

Excerpts from VK1 News Broadcasts
Compiled by Waldis Jirgens, VK1WJ
Latest Update: December 5, 2012.

Contents
Homebrew
Antennas for The ACT
Meteor Showers
VHF Propagation Depending on WX
EWWA Countries List

Homebrew

Az-El Rotator

Do you think to rotate a Satellite Antenna array in azimuth and elevation costs and arm and a leg? Think again. To rotate two crossed yagis in elevation a simple TV antenna rotator is strong enough. In azimuth just add a horse-bridle like rope contraption around a support at the mast, run it to the shack door, and Bob's your uncle!

Mode A Receiving Loop

Jim, NU0C passed along a nice construction idea for a mode A RX loop. He suggests to "check with your local CB crowd and see if you can find anyone with a busted-up 'Moonraker 4' antenna." Jim says it looks to be fairly rugged, and should work well flipped over on its side as the framework for a RS-13 style 10-metre loop with a single support point.

VHF/UHF Yagis

Rod VK2BQJ suggests: For yagis try Aluminium TIG rods. 5mm is a standard size. Your friendly welding shop usually has these loose. Not quite as stiff as 3/16" tube but quite satisfactory.

And while on the subject of things aluminium, try Techni-2000 aluminium brazing rods and make an all metal aluminium array. Working temperature around 400 centigrade. An LPG gas torch is satisfactory but an LPG-oxy torch is better. Oxy-acetylene is too hot, unless a very big job and TIGing is probably more in order. No flux is required, just a conventional brushing of the job with a stainless steel wire brush. If you have tried all the rest, try this material. Is total magic. Is a fraction the price of AluTin 51, and while the latter can be quite successfully worked with a very very hot iron, it must be coated with preferably a two pack polyurethane to prevent erosion of the alloy. Not a problem with Techni-2000.

WIA SA Division

The Wireless Institute of Australia (SA Division) Equipment Supply Committee catalogue is now back on-line. At the moment, only the kits have been placed in the catalogue, but the components will follow shortly. You can access the catalogue at:

http://www.ozemail.com.au/~tecknolt/ESC.html

The catalogue will be updated bi-monthly. It's well worth a look! Currently most of the kits are VHF/UHF related.
Antennas for The ACT
In the ACT all structures (except TV antennas) which are more than 5 metres high have to be approved by the Canberra local government. This also applies for wire antennas for Amateur Radio use. In our view this is a ridiculous situation. We from the News Team will present in the news a new section: "Antennas for The ACT", which will show ways around this restriction.
New info: The mentioned restriction applies only in areas with underground powerlines!

Horn Ant A very effective broadband antenna for VHF/UHF/SHF is the simplified horn radiator. It consists of 2 sheets of metal, each forming an equilateral triangle. The length of the sides should be at least half a wavelength at the lowest frequency used. The 2 sheets are mounted like 2 opposing sides of a pyramid, just not touching at the apex, which is the feedpoint. Maximum radiation occurs towards the base of the pyramid. The input impedance at the lowest frequency is around 380 Ohms, slightly increasing with frequency. This antenna can be used with increasing gain throughout the VHF/UHF spectrum, without any resonance gaps. Thus it is the ideal TV antenna and works also on the various VHF/UHF amateur bands. Gains claimed are 7 DBD at the lowest frequency, rapidly increasing. A prototype with 2.5 m side length, the sides made out of chickenwire with 2cm gaps showed a gain of 16 DBD on 2 m. It should be noted, that for UHF and SHF the wire-mesh is unsatisfactory, and the antenna should be full metal. I myself use a 40 cm side length version of this antenna for UHF TV reception with excellent results. Being a TV antenna, this aerial does not fall under the 5 m maximum height law!

DDRR Ant A very low profile antenna is the DDRR. Contrary to what the name suggests, it was NOT invented in the former East-Germany, but stands for "Directional Discontinuity Ring Radiator". It is a thick radiator, a bit less than a quarter wavelength long, that forms a very short vertical portion topped with a coil with 1 winding only. Thus it can be viewed as an extreme form of the "Rubber Duck". The end of the radiator is grounded. It is fed via a gamma match without the series capacitor. Overall height above ground is, wait for it, 0.00875 lambda, that is 17.5 cm on 20 metres and only 1.4 metres on 160 metres. The thickness of the radiator varies. it is around 1/1000 of the wavelength, make it a bit thicker on VHF/UHF and a bit thinner on the low hf bands. The feedpoint for the gamma match must be determined experimentally, 0.002 lambda into the horizontal portion is a rough guide. At the high voltage end of the antenna a very high quality capacitor is used to resonate the antenna at the desired frequency (that's why the radiator length had to be shorter than a quarter wavelength). Values for the capacitor range between 5 pF on 2 metres and 150 pF on 160 metres. Of course if you can tolerate narrow bandwidth (like 50 kHz on 40 metres), you can dispense with the capacitor and lengthen the radiator slightly. Needless to say, that the antenna needs excellent ground. A sheet of chickenwire extending well beyond the ring is the minimum. Construction details can be found in the ARRL Antenna Book (14th edition). This news is being radiated using 3 watts power and a DDRR antenna on 2 metres. If you like some maths to calculate your own DDRR antenna, here is a formula for the inductance of a single turn loop (which is the basic ingredient for a DDRR): L = Mu0*R*(ln(8*R/r)-2) where R = loop radius in metres, r = wire radius in metres, ln = natural logarithm, i.e. the logarithm to base e, Mu0 = 4*pi*10**(-7) = 1.26 microH/m Contributed by: Ruud, PA2RHB @ PI8WFL

Mushroom AntThis is a more conventional antenna form, a dually loaded shortened quarter wave. It consists of a vertical section, which is loaded by a coil, and an umbrella-like top, that constitutes top loading via a capacitive hat. Thus it resembles a Hills Hoist or a big mushroom.

The dimensions will depend on the following:
1. The inductance of the loading coil (the more L, the shorter the vertical).
2. The placement of the coil (the further down, the shorter the antenna).
3. The size and shape of the capacitive hat (the higher its capacity towards ground, the shorter the aerial).

The ARRL Antenna book 14th edition shows a 40 m antenna being 1.80 m in height with a hat diameter of 2.10 m (8 spokes of 1.05 m length each, connected by wire at the outside). The loading coil is near the top. The vertical section is insulated against ground. An L/C network is used for impedance matching. The system is placed on a small ground mounted metal disk with 60 radials attached to it. These run just above ground.

Possible variations:
1. It is simpler to ground the antenna and couple the cable via a gamma match (forget about the series capacitor - it is unnecessary).
2. Instead of the 60 radials a mat of chicken-wire could be used - the bigger the better.
3. The loading coil could be brought closer to ground, decreasing the number of turns required. Be however aware, that the coil must be of very high quality wire. The closer to ground it is, the higher the currents induced will be. The efficiency is claimed to approach a full size vertical. The bandwidth is relatively narrow: 50 Khz on 40 m for an SWR of 1.5 or less. Again it must be stressed, that the dimensions given are not binding, and can be adapted to suit your local environment. To gain maximum bandwidth, use as much height as possible. To gain maximum performance, use the best ground (radial) system feasible.

Loaded Verticals

Tonight we will focus on a quite conventional antenna: The loaded vertical. As you will recall, the DDRR and the Mushroom antenna both fall into this category. The DDRR can be viewed as a one-loop loading coil on top of a very small vertical section, whereas the Mushroom antenna was doubly loaded: inductively by a coil and capacitively by a hat. If you take one of the loading elements away, you have a simple loaded vertical. The coupling to the coax is best achieved via a gamma match (as mentioned before, if the radiator is shorter than a quarter wavelength, you can dispense with the series capacitor in the gamma match).
  1. Top loading by a capacitive hat can be achieved by various means: An umbrella like configuration like the one with the Mushroom antenna. This can be made to slide up or down the vertical portion, thus enabling to tune the resonance throughout the band. This is particularly important for short verticals. Another possibility is to run a horizontal portion of wire at the top; that's for instance how you can use a 20 metre long Windom antenna on 80: By using the feedline as a loaded vertical.
  2. Base loading is achieved by a coil at the bottom of the antenna.As with the Mushroom antenna, this coil must be of very high quality. My first QSO on 160 ended, when my loading coil for a 7 metre vertical caught fire! And this with 100 Watts output only! It is questionable, if putting the loading coil higher up is of much help: You can get away with a lower quality coil, however you will have to increase the number of turns dramatically, the higher you go with the coil.
  3. Continuous loading can be achieved by using a "rubber duck" on the hf bands. I have seen a 2 metre long 160 metre antenna. The bandwidth however will suffer greatly with such a contraption.
As with all physically short radiators, an excellent earth is of utmost importance. A short antenna using a good earth will beat a full size antenna with a poor earth system hands down! And you even can compete with hams, who are the proud owners of beams. To illustrate the point, let's do a little calculation: A normal 3 element 3 band beam may claim 7 DBD gain on 20 metres. If you look at it closely, you will notice, that the beam is a compromise. Its radiator is too short for 20 metres, the director and reflector are too close by, and the rf has to negotiate 12 traps! You can safely subtract 3 dB from the claimed gain, leaving a real gain of 4 DBD. A quarter wave vertical, full size over ideal ground, has a gain of 3 DBD. If you use a shortened (say 0.6 full size) loaded vertical, you might lose 2 dB gain, still giving you 1 DBD. Thus your signal will be 3 dB down when compared to the beam owner's. This is only just noticeable!

Miscellaneous Notes
So far we have covered the Horn antenna, the DDRR, and various shortened verticals. These all serve to comply with the ACT rule, that every non-TV antenna higher than 5 metres needs approval from the local government. To conclude this series, here now some more ideas:
  1. Horizontal antennas can be hung below 5 metres. On wavelengths higher than 10 metres this will direct maximum radiation towards the zenith. This need not be a bad thing; for satellite communications it's actually useful, also on the 80 and 160 metre bands for local traffic.
  2. Sometimes a "Raingutter Antenna" works quite well: A wire attached to your guttering and tuned with an ATU. Contrary to what some antenna-books suggest, you need not insulate the downpipes. I used such an antenna for years at my old QTH in Sydney. The downside is, that it picks up any electrical noise generated in the house, such as computer-hash, very well. Thus a small additional vertical for receiving purposes might be advantageous.
  3. Various antenna books describe methods of concealing antennas, like using thin, coloured wire. Well, if such an antenna is higher than 5 metres, you will still legally require a permit, though it might take longer to catch you, if you haven't got one. Thus we cannot recommend this procedure.
  4. I tried an indoor antenna whilst staying at a Motel in Morwell in VK3 and worked stations from VK2, VK4 and VK5 on 80m in SSB without really trying too hard. Amongst the QSOs was a rag-chew of over an hour's duration! The trick is to run a wire from the antenna end of the ATU as high up as possible, say to a curtain track and drop the end of the wire (possibly rolled up) into a far corner of the room. As counterweight take a similar length wire and clamp the far end to something resembling earth, say a metal window frame. With suitable coupling plugs both wires can be made out of regular coaxial cable. If you find it impossible to couple the antenna to the radio, lengthen it, until you can. Of course this will only work if the motel room does not have a metal roof. If it has, 80m is out, and you must use higher bands. Of course it's all the better if you can install such an antenna at home under the roof!
  5. If all else fails, there is always portable operation. Get out in the bush, install temporary antennas, and have more fun than at home! If you ever have participated in the John Moyle fieldday, you'll love it. For best results on HF look for a site with high groundwater level, say next to a river or lake. For best VHF/UHF results look for mountaintops with little or no vegetation.

VHF Propagation Depending on WX
Bob, ZL3NE writes:
Gentlemen. For the last four years I have carried out an extensive study
on VHF propagation, here are the results. Now before anyone rushes into
print let me ask them to, " try it out for say twelve months", I am sure
they will be surprised.

I kept a record of every opening, the time of day and the weather
pattern applicable when the opening took place. From an area such as
Auckland, propagation can only cover 180 degrees, and during an average
year, openings should occur on 6 meters, 50 days per year. I set out to
do three years, but after 28 months my permit had been cancelled which
slowed things down a bit, still I had recorded enough openings to make a
51-day average per year, without the last eight months.  For the 28
months of the study, the following propagation took place as follows,

6 meters Auckland to         VK2          VK3       VK4        ZL4
Along frontal zones ----------40 -----------6 -------57 ------- --
Across frontal zones --------- 3 -----------3 --------4 --------12
Across anticyclones 1024+ ----36 ----------15 -------42 ---------7
Total number days open--------79-----------24-------103 --------19

It was noted that propagation only took place, when one of the following
weather patterns was active in the propagation path.

Intense anticyclones.
====================
These produced propagation when the pressure exceeds 1024 hPcls in
summer and 1040 hPcls in winter. Signals can vary from very weak to
quite strong, and depending on the air pressure and air temperature
combination, propagation can reach 1296 MHz. The higher the pressure,
and the hotter the average temperature, the higher the frequency of
propagation.

Warm and Cold fronts /Ducts.
===========================
These are found where the isobars are very close together, such as in
the warm winds preceding warm or cold fronts. They quite often coincide
with jet stream winds, and often contain CB (or thunder). They are
prominent on weather maps shown in the daily papers, TV maps, and in
weather fax maps, even ducts have been displayed there. From these
weather maps, you will be able to pick out the paths of propagation and
see the principles I have shown. Signals can be extremely strong with
2-watt stations being able to contact on 2 meters to 2250 km. As with
the previous mode the higher the temperature, the higher the MUF goes.

Across fronts.
=============
With a temperature change of say 10+ degrees. That is, from the warm
side of a front, to the cold side. The angle to cross these fronts is
above 70 degrees, But if the front contains a very active thunderstorm,
then from any angle. Under these conditions, back-scatter is very
prominent with skewed propagation as well.

This year I have been studying, weather types, during which NO
propagation has ever been recorded here. They are: -

1. Anticyclones with air pressures below 1024 hpcls. (Christchurch has
enhancements, which give propagation to 1020 hpcls).
2. Occluded fronts.

Now let us compare this season, Nov, Dec, and January 92 days?

In Auckland, occluded fronts were recorded on 29 days. Openings recorded
Nil.

Weak anticyclones 1024 hPcls and below, were recorded on 44 days,
propagation, Nil.

Intense anticyclones over 1024 hPcls, recorded on 7 days. Propagation on
all 7 days!

Fronts and tropical cyclones were recorded on 12 days; propagation took
place on all 12. If you wondered why Auckland signals were scarce you
now know why.

Propagation seasons are altered by the sun changing, the air temperature
to air pressure, and the relationship / quantity, of frontal activity.
As an example, an anticyclone in summer of 1025 hPcls with an air
temperature of 30c will produce propagation from VK to ZL, in winter
with an air temperatures of 15 c we need an anticyclone of 1040 hpcls!
See the relationship.

Propagation is always evident here on ten meters before showing up on 50
MHz. Therefore 10-meters can be used as an indicator of when the
propagation is going to open to 50 MHz. and higher. The first indicator
to look for in Northern New Zealand, is the VK2RSY beacon on 28.261 MHz,
it is always in first, and when it reaches S7 on my S meter the
six-meter band is open. From VK2, 3, 5, 7 use the ZL3 beacon on 28.228.
From VK2, 4 use ZL6B on 28.200. Another interesting beacon for me is the
JA5 on 28.264 MHz. When this reaches S7+, six is open to Japan. In all
my findings I have always had 10 meters open first, then 6 meters. When
6 meter signals are S9+, I find 2 meters opens, when 2 meters reaches S7
or above, 70 cm opens.

Could I suggest that an approach be made to your local TV channel with a
request that any major CB activity within 1500 km of your area, or in
any propagation path be shown or announced in their weather maps /
reports. I have done that here, they were surprised anyone was
interested, but were willing to co-operate. Repeatedly I am advised of
CB coming before it provides propagation. May I say, always look ahead,
and try to improve your percentage of opening strikes. This is what
Amateur VHF DX is about.

Gentlemen this is a brief run down on the subject. Take the next year,
and see how you go with it. See if you can increase your number of
contacts, good luck. Bob ZL3NE.


EWWA Countries list
A2 BOSTWANA OD LEBANON ZK2 NIUE ISL
A3 TONGA OE AUSTRIA ZK3 TOKELAU ISL.
A4 OMAN OH FINLAND ZL NEW ZEALAND
A5 BUTHAN OK CZECH REPUBLIC ZL7 CHATAM ISL.
A6 UNITED ARAB EMIRATES OM SLOVAK REPUBLIC ZP PARAGUAY
A7 QUATAR ON BELGIUM ZS SOUTH AFRICA
A9 BAHRAIN OX GREENLAND ZS8 PRINCE EDWARD & MARION ISL
AP PAKISTAN OY FAROE ISL. 3A MONACO
BV TAIWAN OZ DENMARK 3B6 AGALEGA ISL.
BY CHINA P2 PAPUA NEW GUINEA 3B7 ST BRANDON ISL
C2 NAURU P4 ARUBA 3B8 MAURITIUS ISL
C3 ANDORRA P5 NORTH KOREA 3B9 RODRIGUEZ ISL.
C5 GAMBIA PA NETHERLANDS 3C EQUATORIAL GUINEA
C6 BAHAMAS PJ2 CURACAO 3C0 PAGALU/ANNOBON ISL.
C9 MOZAMBIQUE PJ4/PJ5/PJ6 SABA/EUSTASIUS/BONAIRE 3D2 FIJI
CE CHILE PJ7 ST.MARTEEN 3D2 ROTUMA
CE0E EASTER ISLAND PY BRAZIL 3DA0 SWAZILAND
CE0X SAN FELIX & AMBROSIO PY0t TRINIDAD & MARTIN VAZ ISL. 3V TUNISIA
CE0Z JUAN FERNANDEZ PZ SURINAME 3W VIETNAM
CN MOROCCO R1FJ FRANZ JOSEF LAND 3X GUINEA
CO CUBA S2 BANGLADESH 4J/4K AZERBAIDJAN
CP BOLIVIA S5 SLOVENIA 4L GEORGIA
CT PORTUGAL S7 SEYCHELLES 4O MONTENEGRO
CT3 MADEIRA S9 SAO TOME 4S SRI LANKA
CU AZORES SM SWEDEN 4U1ITU UNO GENEVA
CX URUGUAY SP POLAND 4U1UN UNO NEW YORK
D2 ANGOLA ST SUDAN 4U1VIC VIENNA
D4 CAPE VERDE ST0 SOUTHERN SUDAN .4X ISRAEL
D6 COMORES SU EGYPT 4W TIMOR EAST
DL GERMANY SV GREECE 5A LIBYA
DU PHILIPPINES T2 TUVALU 5B CYPRUS
E3 ERITREA T30 WEST KIRIBATI 5H TANZANIA
E4 PALESTINIA/Cisjordania/Ramalah T31 CENTRAL KIRIBATI 5N NIGERIA
E4 PALESTINIA/Gaza T32 EAST KIRIBATI 5R MADAGASCAR
EA SPAIN T33 BANABA ISL. 5T MAURITANIA
E7 BOSNIA HERZEGOVINA T5 SOMALIA 5U NIGER
EA8 CANARY ISLANDS T7 SAN MARINO 5V TOGO
EA9 CEUTA T88 BELAU (WEST CAROLINES) 5W WESTERN SAMOA
EA9 MELILLA TA TURKEY 5X UGANDA
EI IRELAND TF ICELAND 5Z KENYA
EK ARMENIA TG GUATEMALA 6W SENEGAL
EL LIBERIA TI COSTA RICA 6Y JAMAICA
EP IRAN TI9 COCOS ISL 7O YEMEN
ER MOLDAVIA TJ CAMEROON 7O SOCOTRA ISL
ES ESTONIA TL CENTRAL AFRICA 7P LESOTHO
ET ETHIOPIA TN CONGO 7Q MALAWI
EU BYELORUSSIA TP COUNCIL OF EUROPE 7X ALGERIA
EX KIRGHIZ TR GABON 8P BARBADOS
EY TADZHIK TT TCHAD 8Q MALDIVES
EZ TURKOMAN TU IVORY COAST 8R GUYANA
F FRANCE TY BENIN 9A CROATIA
FG/FM/FS FRENCH ANTILLES TZ MALI 9G GHANA
FH MAYOTTE UA1 EUROPEAN RUSSIA 9H MALTA
FK NEW CALEDONIA UA2 KALININGRAD 9J ZAMBIA
FO TAHITI UA9/0 ASIATIC RUSSIA 9K KUWAIT
FO MARQUISES ISLANDS .UJ UZBEKISTAN 9L SIERRA LEONE
FO AUSTRALES UN KAZAKHSTAN 9M2 WEST MALAYSIA
FO RAPA Island UR UKRAINE 9M6 EAST MALAYSIA
FP ST PIERRE & MIQUELON V2 ANTIGUA 9N NEPAL
FR REUNION V3 BELIZE 9Q ZAIRE
FT5W Crozet Is. V4 ST KITTS & NEVIS 9U BURUNDI
FT5X KERGUELEN Is. V5 NAMIBIA 9V SINGAPORE
FT5Z AMSTERDAM & ST PAUL Is V63 MICRONESIA 9X RWANDA
FW WALLIS & FUTUNA V73 MARSHALL ISL. 9Y TRINIDAD & TOBAGO
FY FRENCH GUYANA V8 BRUNEI AT /VU ANTARCTICA
G ENGLAND VE CANADA BY ANTARCTICA
GD ISLE OF MAN VK AUSTRALIA CE9 ANTARCTICA
GJ JERSEY VK0 HEARD ISL. CX ANTARCTICA
.GU GUERNSEY VK0M MACQUARIE ISL. DL-DP0 ANTARCTICA
GI NORTHERN IRELAND VK9C COCOS KEELING ISL. EA ANTARCTICA
GM SCOTLAND VK9L LORD HOWE ISL. UR-EM ANTARCTICA
GW WALES VK9N NORFOLK ISL FT5Y ANTARCTICA
H4 SOLOMON ISL. VK9W WILLIS ISL G-VP8 ANTARCTICA
HA HUNGARY VK9X CHRISTMAS ISL. HC ANTARCTICA
HB SWITZERLAND VP2 ANGUILLA/MONTSERRAT/VIRGIN HF ANTARCTICA
HB0 LIECHTENSTEIN VP5 TURK & CAICOS ISL. HL ANTARCTICA
HC ECUADOR VP6 PITCAIRN I ANTARCTICA
HC8 GALAPAGOS ISL. VP8 FALKLAND ISL. KC4 ANTARCTICA
HH HAITI VP8/LU SOUTH SANDWICH ISL LU ANTARCTICA
HI DOMINICAN REPUBLIC VP8/LU SOUTH. SHETLAND LZ ANTARCTICA
HK COLUMBIA VP8/LU SOUTH GEORGIA OA ANTARCTICA
HKO ST. ANDRES ISL. VP8/LU SOUTH ORKNEY OH ANTARCTICA
HL KOREA VP9 BERMUDA PA ANTARCTICA
HP PANAMA VQ9 CHAGOS ISL. PY ANTARCTICA
HR HONDURAS VU INDIA R1A ANTARCTICA
HS THAILAND VU7 ANDAMAN ISL. SM ANTARCTICA
HV VATICAN W/K/N UNITED STATES VK0 ANTARCTICA
HZ SAUDI ARABIA XE MEXICO ZL ANTARCTICA
I/IS/IT ITALIA XF4 REVILLA GIGEDO ZS ANTARCTICA
J2 DJIBOUTI XT BURKINA FASSO 3Y ANTARCTICA
J3 GRENADA & DEPENDENCIES XU CAMBODIA 8J ANTARCTICA
J5 GUINEA BISSAU XW LAOS
J6 ST LUCIA XZ MYANMAR
J7 DOMINICA YA AFGHANISTAN
J8 ST VINCENT & DEPENDENCIES YB INDONESIA
JA JAPAN YI IRAK
JDm MINAMI TORISHIMA YJ VANUATU
JDo OGASAWARA YK SYRIA
JT MONGOLIA YL LATVIA
JW SWALBARD YN NICARAGUA
JX JAN MAYEN YO ROMANIA
JY JORDAN YS EL SALVADOR
KH0 NORTHERN MARIANAS YU SERBIA
KH2 GUAM YV VENEZUELA
KH4 MIDWAY ISL Z2 ZIMBABWE
KH6 HAWAIIAN ISL Z3 MACEDONIA
KH8 AMERICAN SAMOA ZA ALBANIA
KL7 ALASKA ZB GIBRALTAR
KP2/KP4 US VIRGIN/PUERTO RICO ZD7 ST HELENA ISL
LA NORWAY ZD8 ASCENCION ISL
LU ARGENTINA ZD9 TRISTAN DACUNHA & COUGH
LX LUXEMBURG ZF CAYMAN ISL
LY LITHUANIA ZK1 NORTH COOK
LZ BULGARIA ZK1 SOUTH COOK
OA PERU

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