Letters2009
Oh3ne
Correspondence from our sisterclub VK5BAR in Adelaide, Austalia Our contacts in Australia :
John Elliott VK5EMI President email: dellio2@bigpond.net.au
Leigh Turner VK3KLT Vice President email: invertech@frontierisp.net.au
11.2.2009 Dear John,
We have read about Australina fires every day in the papers and TV news. When I look map of fires, it seems that Adelaide is quite near fires.
We worried what happens there. Please qive some comments about fires. People seems to be powerless agaist nature.
It there accidents in your area? Is the enough help available for homeless people. Is there anything what we can help?
We have full winter: snow and cold, just opposite of your situation.
My icefishing pictures: http://picasaweb.google.com/oh3gdo/Talvi2008#
Some winterpictures from Finland :
http://images.google.fi/images?q=talvikuvia&oe=utf-8&rls=org.mozilla:fi:official&client=firefox-a&um=1&ie=UTF-8&ei=UxKTSf-ECJXW0gWP2M2nCw&sa=X&oi=image_result_group&resnum=1&ct=title
Pekka OH3GDO
12.2.2009
Pekka,
We are very grateful for your concern for us:
It has been very hot here until recently;
The last 7 days of January averaged a maximum of 40.5C.
The hottest day was 45.7C
The temperature now is much more comfortable, and the nights are cool.
That sort of Wx causes many problems – not only fires.
Our railway system and tram systems were damaged, as the tracks became twisted by the excessive temperatures.
Many cars broke down, and electricity failures were common.
Before the fires in Victoria began, large fires near Port Lincoln (250 Kms west of Adelaide) destroyed some fish processing factories.
Some smaller fires near Adelaide have only caused minor damage.
We have been lucky.
The fires near Melbourne are a long way from us.
Australia is much bigger than many people expect.
Most of the major fires are about 600 Kms east of Adelaide.
My wife and I drove through the area north of Melbourne in November last year. It was very pretty then.
The native bushland will slowly regenerate after the fires. Most Australian trees and bushes will recover naturally.
Some native plant seeds need a fire to make them germinate.
14.2.2009 Hello Pekka,
Following up on John’s note below, the latest bushfire figures have risen to 1800 homes destroyed and death toll expected to rise to 300 when the missing and unaccounted folks are located and identified. Homeless and displaced people now exceed 6000 with a further high number of burns victims in the hospitals. A week later, fires are still burning in some locations and posing high risk of spreading to other communities in Victoria.
The problem with Australian bushlands nearby to town settlements is the large number of Eucalypt / gum trees which are rich in eucalyptus oil which has an extremely high energy value during combustion under such sustained high 45 degree temperatures and high wind conditions. The fuel load and calorific value is massive.
As John said our VK3 counterparts are helping provide the emergency radio communication networks as the power lines and telephone systems have also been destroyed. They are also providing backup communications for the emergency services. All a very depressing disaster for us. Also for the poor native animals who have been the silent sufferers.
Changing the subject I wanted to ask you how are the economic conditions in Finland now, my colleagues at UPM are reporting a lot of lay-offs of jobs and associated hardship as business and forward orders quickly decline during this global economic melt-down; what is the general sentiment around Tampere and the region from your perspective?
I guess we must all try and remain cheerful and optimistic about these terrible events.
73 Leigh VK5KLT
Pekka,
When there are several days in succession of very high 45 deg heatwave conditions like that, the eucalyptus oil from the tree sap and leaves evaporates into the surrounding air and forms a highly combustible vapour cloud that envelopes the whole bushlands areas comprising of high density trees. One spark of ignition from a lightning strike etc. and you have an explosive fireball inferno and wildfire driven by high winds that is unstoppable and anything and everything in its path is completely wiped out. Such dangerous combination of conditions happen in parts of Australia every few decades….but this latest heatwave was unprecedented in severity and duration. Maybe associated with the global warming phenomena.
Pekka,
Thank you for the information about your inventions.
It is very interesting reading. Your wheel looks very special, like something from a space story.
The festival is so different to those that we have here.
My wife and I went to a fair (festival) in a small village in New South Wales in 2007. It was quite warm (about 30C), so the weather was very different to yours. We still enjoy our hot sausages on hot days. The village name is Woolbrook. There is a small creek (brook) which runs through the village. There were no husky sled rides (hi), but there were goat races. Our younger son, the sportsman, plays in-line hockey. There is only one ice rink in Adelaide, but he plays at the local Recreation Centre on in-line (wheel) skates on a wooden floor.
COUNTRY AND WESTERN MUSIC FOR ENTERTAINMENT.
(The favourite music of this band was blues jazz, which they played a little of. Playing Country and Western music in the Australian farming areas, however is what is more popular.)
Thank you also for information about the war against Russia/Soviet Union in WWII. I did not know very much about that war.
You were very lucky that Finland was not occupied by Russia after the war, as Poland, Czechoslovakia and other countries were for many years.
When I hear again from Gunnar, I will remind him of Tampere. My wife and leave for New Zealand on Friday, so I will not be answering emails after Wednesday. Your honorary member will be happy to receive your emails then! I will write again to you once we are home (April 18++) Best wishes, John Elliott VK5EMI President and Web Master AHARS
[[Letter from Leigh VK5KLT] 11.6.2009]
Dear Pekka,
It’s been quite a while now since we last exchanged e-mails; trust that all is going well with you and your family there in Tampere. I imagine you’re enjoying the wonderful Finnish summer time and getting outdoors and soaking up the sun as often as possible. Perhaps some radio field days.
I have not come to Finland for many months now so we’ve not had an opportunity to catch up! Most of my travels this year have been to USA.
The week after next I’m very briefly in Helsinki for just 2 days for some business meetings. Not enough time to visit Tampere and say “Hello” to my good friends this time.
Sisällysluettelo |
[muokkaa] ======
I do have a few hours to spare after my meetings and wanted to ask you are there any good amateur radio stores / radio surplus shops in Helsinki that I could visit?
I’m staying at the Scandic Hotel Simonkentta, Simonkatu 9, Helsinki on Sunday 21, 22 June.
What’s new from your side?
73
Leigh VK5KLT
P.S. Forwarded below is some humour you might also enjoy!
Attached is a recent photo of my daughter and granddaughter plus a recent homebrew project for testing my HF amplifiers. I’ve also recently updated my qrz.com webpage with a few pics.
More:
[ http://www.qrz.com/hampages/t/l/vk5klt/GU84B_photo.jpg Tubes5 ]
[muokkaa] Humor from Leigh
On his 74th birthday, a man got a gift certificate from his wife.
The certificate paid for a visit to a medicine man living on a nearby reservation who was rumoured to have a wonderful cure for erectile dysfunction.
After being persuaded, the man drove to the reservation, handed his ticket to the medicine man while wondering just exactly what he was in for.
The old Indian slowly and methodically produced a potion, handed it to him, and with a grip on his shoulder, warned, "This is powerful
medicine and it must be respected. You take only a teaspoonful and then you say, '1-2-3 '. When you do that, you will become more manly than
you have ever been in your life, and you can perform as long as you want."
The man was encouraged. As he walks away, he turned and asked, "How do I stop the medicine from working?" "Your partner must say '1-2-3-4,' the medicine man responded. "But, when she does, the medicine will not work again until the next full moon." The man was very eager to see if it worked so he went home, showered, shaved, took a spoonful of the medicine, and invited his wife to join him in the bedroom. When she came in, he took off his clothes and said, "1-2-3!" Immediately, he was the manliest of men. His wife was excited and began throwing off her clothes. And then she asked, "What was the 1-2-3 for?" And that, boys and girls, is why we should never end our sentences with a preposition because we could end up with a dangling participle. :-)
Jim
VK5JST / VK5TR
[muokkaa] Pictures from Leigh
Leigh's grandchilden
Leigh's dummyload
[muokkaa] ==========================
Hi Pekka,
Following up on my earlier email last week, here are a few brief technical details of that QRO dry-dummy load:
The HF dummy load uses an array of 16 x 50 Ω 100W non-inductive resistors (3/4 inch x 5 inch) in a series/ parallel combination. All the rugged ceramic body resistors are mounted on a sheet of thick 1/8 inch FR4 fibreglass PCB with etched copper tracks interconnecting all the spring clips to provide 50 Ω microstrip connections to maintain the proper impedance match right throughout. Adjusting the height of the resistor bodies above the upper ground plane achieves a distributed characteristic impedance ZO of 50 Ω so the composite load maintains a decent resistive 50 +/− j0 impedance up to and beyond the 30 MHz HF band.
The PCB assembly attaches via metal stand-off spacers to an aluminium sub-chassis that drops into a 3U 19 inch rack cabinet (matt black) that has a pair of powerful 105 CFM Etri Muffin fans on the rear panel to circulate copious volumes of air to keep the resistor array cool. Unlike any known commercial dummy loads on the ham-radio market, this genuinely QRO load is good to at least 3 kW for reasonably long duty cycles. This power handling estimate is based on the continuous free-air rating of 16 x 100W = 1600 Watt RMS, and then applying a modest 2:1 power dissipation over-rating factor due to the fan-forced air cooling!
For precise power measurement I use an external Bird 4431 Wattmeter that has a variable sampling port built in for monitoring the modulated RF envelope on an oscilloscope or spectrum analyzer while doing two-tone IMD and linearity testing of my HF linear amplifiers, or for operational tune-up.
I know it was a one-off homebrew project but I tend to apply full professional construction techniques even to my hobby projects and firmly believe if any job’s worth doing, then it’s worth doing thoroughly with attention to detail. I’ve even gone to the extra trouble of pantograph engraving the text labelling of the 3mm black anodized aluminium front panel on the 3U 19 inch rack enclosure box so the Dummy Load unit looks as good as or better than any commercially available product.
The use of microstrip interconnect wiring is undoubtedly overkill in the HF range, but I wanted the composite load to be an accurate as possible 50Ω / very low VSWR as seen looking into the input coax connector. High power/ high RF current often does funny things when it meets impedance discontinuities. Making the whole distributed physical structure look like 50Ω by adjusting the resistor diameter / height above ground plane ratio, then any stray L and parasitic C will be absorbed into the characteristic impedance ZO of the symmetrical structure so the undesired reactance of the distributed network is minimal and essentially looks like 50 Ω resistive. The QRO load holds up its resistive 50 +/− j0 impedance right through to the 6m band. I’ve used a high-quality silver plated / Teflon insulation SO-239 socket and RG-142 Teflon dielectric / silver double braid coax to ensure low losses.
The return loss is over 25 dB and the VSWR under 1.12 up to 30 MHz as measured on a HP Network Analyzer.
I find homebrew project construction terrific fun and besides it’s good to do my modest bit to keep the homebrew spirit alive and well and flourishing in our VK amateur community!
I was fortunate to find the big resistors on eBay last year at a reasonable price from a USA vendor in Ohio called Bizarre Surplus.
73
Leigh
Letter from John Elliot 12.8.2009 Pekka, Many thanks to Leigh for forwarding your email to him. The links to the many things that you have been doing are all most interesting. It seems to me that you have no time to sleep, hi.
I hope that Leigh doesn’t get too many ideas for club events from those things that you do. Leigh has a big ambition for his 160 metre loop!!
I may also use Picasa for our photos of our trip to New Zealand.
At the moment, I can only find about 2 hours per week to edit our photos, so we may all be old men (>> OM ) by the time I am finished!
In the meantime, here are a few photos from that trip that may be of interest to you:
All these photos were taken in the South Island.
Christchurch, New Zealand.
John VK5EMI with John, VK5BJE, who is also from Adelaide.
(You may have seen this photo in our website newsletter).
BJE is the tall person!
Our little campervan – “home” for 18 days while we toured the South Island.
(Toyota Hi Top). Not comfortable for fat people!
Mount Cook. Highest mountain in New Zealand. (3754 metres).
My XYL, Deidre, visits the Christchurch Spinners and Weavers Guild.
Deidre is very active in the Spinning and Weaving Guild in Adelaide.
Note the large mural on the wall.
I note some more recent emails from you.
I have many other emails to reply to first, but I’m looking forward to catching up again with you (via emails) soon!
John Elliott
VK5EMI
President and Web Master
AHARS
[muokkaa] Old memories from Leigh
Hi Pekka,
Thanks for this additional infomation on the old glass plate and bellows focus camera. Yes it was amazing how we used to improvise and make-do when we were young kids and made best use of the few hard-to-find items we had to experiment with and build things with; and make them into something useful! Sadly few young folks today are motivated enough to get deeply interested in technical things and build experimental apparatus and hardware any more; most just prefer to mess with computers and software instead :-(
When I was 12 years old I obtained a used Vidicon tube from the local television station and built a TV camera with it. The project won the 1965 Science Prize at school. The project was quite daunting as I had to calculate the required A/m magnetic flux densities and Gauss field strengths and wound all the horizontal and vertical saddle deflection coils and the focus coil by hand. I used a C-mount 16mm lens from an old WWII era movie film camera for the optics. When I was 14 I was more ambitious and built another television camera using a large 3-inch Image Orthicon tube. It was so sensitive it could view scenes in dim moonlight as the tube had an in-built photo-multiplier. I used the lens from a Praktica 35mm reflex camera.
That's how I subsequently got interested in ATV and eventually built a complete PAL colour television transmitter once I obtained my ham radio licence.
I remember the Philips Aristona mantle radio as it was also sold here in Australia in that era. I recall it had very good fidelity of sound! Philips radios and TVs were always well designed and well built.
Philips set up an Australian manufacturing plant here in Adelaide at a suburb called Hendon. It produced radios, televisions, valves, and passive components. Later it produced semiconductors. One of our AHARS committee members Jim Tregellas VK5JST / VK5TR used to be factory manager at the semiconductor plant.
73
[muokkaa] Chrismas Letter from Australia 13.12.3009
Many thanks for this Pekka; I have this morning forwarded your message and photo gallery pics to our AHARS club committee members and John will further distribute to all.
A very Merry Christmas to you and family, and all of our good friends at OH3NE.
I always enjoy your sketches!
Cheers,
Leigh == Merry Christmas and Happy 2010 New Yea
Dear Hannu and Pekka,
Just a short note to extend to you and all OH3NE club members and OH friends a very Merry Christmas and Happy 2010 New Year from all of us at AHARS / VK5BAR. Our congenial information exchanges amateur radio comradeship and cooperation over the past 2009 year has been very enjoyable.
Best wishes,
Leigh Turner VK5KLT Vice President AHARS
