The Presidents Notes and Quotes July/August 2004
From the heading you can see that this addition of Gateway is to cover the next two months, therefore take special care of it because there will be no separate August issue. We have arranged this to allow our editor to concentrate on his business at this time which includes providing some of the electronics needed to allow video coverage of the sailing events in the coming Olympics.

Which reminds me, those of you interested in DX. From June 1st to 15th September Greek amateurs my use SX2004 or SY2004 prefixes in their call signs to commemorate the Olympic and Paralympic Games 2004. (For the uninitiated the normal Greek amateur prefix is SV).

Our clubroom project is progressing well with the outside cladding completed and the inside paneling the focus of the next working bees. Most of the internal electrical wiring has also been completed. It has been encouraging to see the number of different members lending a hand, it really has been a combined effort and with some luck with the WX over the next few weeks our target of having the room on site at Cranbourne during August is a real possibility.

July 17th of course is our club hamfest, final arrangements will be made at the meeting on Friday 16th. As that man in the adds would say BE THERE.

Valerie and Ian Benson are about to set off on an adventure North via the Adelaide to Darwin Railway and then I believe a leisurely drive home. I hope we have a change to contact them "on air" while they are away. I will be away for two weeks in September farm sitting 10th-24th and be on most weekday afternoons at 4pm local on 7.1 +QRM. Also monitor the Ballarat repeater on 146.750. Mike Ide VK3KTO has agreed to chair the September meeting for me. Thanks Mike.

We have engaged the services of a First Aid expert for our August Meeting who will talk on shack safety and first aid in the case of an electric shock situation. This is a must for all concerned families who have any one at home who dabble in electronics.

That's all from me till September issue in the mean time keep using the spectrum.
73's Peter VK3VB.

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GGREC SHACK PROJECT
A progress report by Ian Jackson VK3BUF & Photography by Ross Jackson VK3HDW

WE'RE NEARLY THERE!

(the above pic is a slightly edited version, with the temporary
'gap' in the centre of the building removed to give a true idea of size)

Last Saturday we had yet another Working Bee at the shack prep site at Drouin West. This was the 6th one in the series. Attending were Max 3TMK, Ian 3KSZ, Graeme 3BXG, Ron 3EXJ, Reg 3UK, Jenny, David 3XMF, Mike 3KTO, Paul 3TGX, Myself Ian 3BUF, Ross 3HDW, Dianne 3JDI (Ross & Di had time out for an AOCP exam at Tooradin)

The previous weekend's work session was every bit as busy where much of the ceiling ply and the last of the external cladding was fitted. Saturday focused on insulating the walls and gluing in interior wall lining material. This is a plywood sheet coated in a white 'polyester chequerboard' finish. About 50% of the interior wall lining is now in place and about 30% of the electrical wiring has been terminated. Max 3TMK has been instrumental in cabling and fitting off. Ron 3EXJ painted the two external doors in preparation for the colorbond steel door skins yet to be fitted

Ron had only returned 3 days before from a caravan trip to Mildura.
(Note the temporary GGREC sign that Reg
had erected.)

We will have to think about the kind of signage needed on the finished building. Should it be a discrete GGREC sign near the main door, or big letters a metre high?

After all the insulation was fitted we formed two teams and continued to glue/nail the sheets to the wall with the nail gun. This involved lots of fiddling, cursing and other miscellaneous tasks.

I am under instruction to insert lots of pictures this month. In the pic below you can see part of the frame for the lighting & ventilation bulkhead situated above the intended operating & project benches.

The above picture gives some idea of interior size, with one of the six 'barred' skylights in the foreground. That's me on the left with the gluepot, getting ready for another sheet. Below shows Graeme 3BXG (left) and David 3XMF (right) discussing the merit of tight tolerances in corners.

We will need one more big working sessions to complete the interior of the shack (less plumbing fixtures) This includes mounting the ceiling tiles and the light fittings. That should happen on Saturday the 24th of July, the weekend after the Hamfest Sale. Once that is done, the building will be ready for transport.

This brings us to the next task, which is the preparation of the Guide Hall site. We will have to install a double gate, then prepare foundations for about 8 fencing posts and pour concrete into the six reinforced concrete moulds which will form the final resting place for the building. Once this has set, a crane-truck making two trips, will install the two 5.2 metre halves at the long-awaited site. A local newspaper has shown interest in photographing this landmark event.

Outside, there will be a sealed fluorescent light above each door, plus a movement detector to operate them. A 150W floodlight on the end can illuminate the tower from underneath. We won't be mounting these fittings until the building has been shifted.

Above is Ian, Graeme, David and Max in the plywood 'cutting zone'

A lot of time has been spent on the electrical design of this building. We have dual fluorescent lamps in each of the two operating rooms, plus a pair of recessed down-lights above each workbench. Emergency Stop buttons on the wall of each room will kill the power when pressed, just in case you see a fellow operator, with their hand wrapped around an anode, performing a highland jig. ( I suggest checking their nationality before pressing the red button in case they are inexplicably performing a highland jig) A two speed ventilation fan mounted in the ceiling space above the toilet will draw air from all three rooms via a duct system, and vent it outside. The bulkhead that runs the length of the building also forms part of a distribution system for coaxial cables that lead from the tower to the radio equipment.

Other wiring includes security, telephone, PC network cables and earthing points for transceivers. Each operating bench has four double power points. Above the inside of each of the two external doors are battery-backed emergency 'Exit' signs and lights which will operate in times of mains power failure.

(Left) David VK3XMF putting coloured
silicone around the steel-framed doorway.

We must give some thought to how the building is to be used once completed. We want to give maximum flexibility and access to members who want to 'drop in' and do some operating, while maintaining a reasonable level of security. One such system being examined is an electronic keyfob that could be made available for a small supply cost of around $10. The key would un-latch the solenoid at the front door permitting entry by simply waving it near a sensor. It would then be placed near a second 'park station' inside to activate building power lighting and (when present) air conditioning. A simple PC system would data-log all of these events.

Either way, we shall finish up with a first class operating facility that should serve the club for many years to come. Not withstanding the hard work of a large portion of our Club members, we must also thank the Casey Shire Council who has contributed a significant amount of monetary assistance to bring the project to completion.

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AMSAT Echo Satellite Launched Successfully
At 0630UTC on the 28th of June the http://www.amsat.org/amsat-new/echo AMSAT Echo amateur radio satellite was successfully launched from the Baikonur Cosmodrome in Kazakhstan. Telemetry from the satellite can be received on 435.150MHz FM. The 10-inch-square microsat, equipped with a transmitter capable of up to 7 watts output, will allow voice communications using handheld FM transceivers. However, AMSAT requests that amateurs do not transmit to Echo until checkout and commissioning has been completed and the satellite is made available for general use.

There will be a presentation on Echo at the http://www.uk.amsat.org\t AMSAT-UK Space Symposium which is being held from the 30th of July to 1st of August at the University of Surrey, Guildford. This event is open to all radio amateurs and SWLs and for further information on it please contact the AMSAT-UK secretary, Jim Heck, G3WGM, on 01 258 453 959 or e-mail: g3wgm@amsat.org

Astronaut and Cosmonaut Operate Simultaneously from ISS
Staying in space and - for the first time - an astronaut and a cosmonaut have been on the air simultaneously from both of the ARISS operating positions on the Space Station. Astronaut Mike Fincke, KE5AIT, operating as NA1SS, made about 60 contacts on 2 metres during the ARRL Field Day last weekend, while Expedition 9 Commander Gennady Padalka, RN3DT, operated on 70-centimetres as RS0ISS. Thanks to the http://www.arrl.org ARRL for this news story.

Actor and radio amateur Marlon Brando is a Silent Key
One of the best-known names in cinematic as well as amateur radio circles, actor Marlon Brando, died on the 1st of July at the age of 80. Known to hams world-wide as KE6PZH and FO5GJ, Brando is listed on the FCC database as Martin Brandeaux. He was on the air occasionally through the years with his FO5 callsign from his private island in French Polynesia. In an interview with Larry King on CNN recorded in 1994 and shown again this week, Brando confirmed his continued interest in amateur radio. In response to a caller's question, he said amateur radio provided him with the opportunity to "just be himself".
From RSGB
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YAESU FT897

Recently, with my plans to buy a caravan, and go camping etc, thoughts turned to what radio equipment I should install in my new 'toy'

After much tooing and throwing between the Yaesu FT897 and the Icom 706 mk3G, I decided to go for the Yaesu rig. In Yaesu's line up of portable multi-band sets there is the FT817, FT857, and this, the FT897. I was originally interested in the little FT817 rig as you could carry it on your side and go foot portable with it, however when I was finally allowed onto the HF bands, I tried to work a bloke running one of these up in Queensland, and the 10W output just didn't cut it. As I was not impressed by the styling of the FT857 (also 100W on HF) I skipped it and went for the '897, which I bought from G&C comms in Cranbourne, along with the optional DTMF mike.

The FT897 covers from the 160m HF band, up to 70cm UHF, all modes. On receive it covers a lot more ground, from long wave to above the 70cm band, including the commercial broadcast bands on AM & FM. On almost all frequencies the radio will operate in all modes, with the exception of the broadcast FM band where the set is locked to wideband FM, a mode not available anywhere else.
On transmit you get 100W on HF, on up to the 6M band, then 50W on 2M, & 20W on 70cm. Of course the radio will not allow you to transmit out of band, it also knows to limit transmit modes in some places.
If your antenna is not quite rite and you present the radio with a bad mismatch then the output power is automatically turned down to save the output devices, although it is probably not a good idea to rely on this feature.

Due to the FT897 being a smallish transportable rig, front panel room is at a premium, and most controls have double functions, this even includes the power switch, which doubles as a tuning speed selector. As such, all functions that missed out on a dedicated control are either selectable via a menu system, or can be allocated to one of three 'soft' buttons under the main display.


Here you can see the radio is in "-" negative repeater offset, "TEN" Tone enabled, 13.7V power, "M-002" memory 2, "FM" mode. Memory channels can optionally be given alpha names (that can be toggled to frequency display instead) .
Then follows the bar graph display that is a receive "S" meter here. On transmit it can display TX power, modulation, or SWR.. Under this is usually 3 labels for the 3 buttons immediately under the display, Button "B" in this case is unassigned.
If you don't like the display colour, this can also be changed, or you can allocate the colour changes to a rig function, ie different colours for each band etc.
On the back of the rig are two antenna connections, a SO239 for HF through to 6M, and an N connector for 2 and 70. I though this was a good idea as it makes getting your antenna leads mixed up a lot harder - not to mention SO239 connectors being somewhat inefficient on 70cm. There is also a connection for running packet radio and other digital modes without having to hack into the microphone connection on the front of the radio. I will have to make up some leads and try it out on slow scan TV. On the back you there is also a 'CAT' connector, which is Yaesu talk for a computer connection allowing a PC to take control, however this connector is lost if you want to use either the optional antenna tuner, or linear amp. though if you are desperate for this function, it can also be done via the front panel mic socket. The mic socket by the way, is one of those newfangled RJ45 computer LAN type sockets.
On the bottom of the set is a large compartment that can either house an optional 240V power supply, or 2 rechargeable batteries, however when you run the radio from the internal battery you are limited to 20W TX power.
On air I received good comments about my audio, the only thing that caused trouble was my long wire antenna that was too much for my old Kenwood tuner to completely tune in on 3.620MHz, and as such the radio started to throttle back the TX power making quite a mess of my side band transmissions to Graeme VK3XTA on his recent trip to Swan Hill - also equipped with a Yaesu FT897.
I found I had to limit the radio to 30W TX power, then troubles mostly went away.

Paul VK3TGX
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What's this tool for?

HAMMER: Originally employed as a weapon of war, the hammer nowadays is used as a kind of divining rod to locate expensive parts not far from the object we are trying to hit.

MECHANIC'S KNIFE: Used to open and slice through the contents of cardboard cartons delivered to your front door; works particularly well on boxes containing seats and motorcycle jackets.

ELECTRIC HAND DRILL: Normally used for spinning steel Pop rivets in their holes until you die of old age, but it also works great for drilling mounting holes in fenders just above the brake line that goes to the rear wheel.

PLIERS: Used to round off bolt heads.

HACKSAW: One of a family of cutting tools built on the Ouija board principle. It transforms human energy into a crooked, unpredictable motion, and the more you attempt to influence its course, the more dismal your future becomes.

VICE- GRIPS: Used to round off bolt heads. If nothing else is available, they can also be used to transfer intense welding heat to the palm of your hand.

OXYACETYLENE TORCH: Used almost entirely for lighting various flammable objects in your garage on fire. Also handy for igniting the grease inside a brake drum you're trying to get the bearing grease out of.

WHITWORTH SOCKETS: Once used for working on older British cars and motorcycles, they are now used mainly for impersonating that 9/16 or 1/2 socket you've been searching for, the last 15 minutes.

DRILL PRESS: A tall upright machine useful for suddenly snatching flat metal bar stock out of your hands so that it smacks you in the chest and flings your beer across the room, splattering it against that freshly painted part you were drying.

WIRE WHEEL: Cleans rust off old bolts and then throws them somewhere under the workbench with the speed of light. Also removes fingerprint whorls and hard-earned guitar calluses in about the time it takes you to say, "Ouc...."

HYDRAULIC FLOOR JACK: Used for lowering a motorcycle to the ground after you have installed your new front disk brake set-up, trapping the jack handle firmly under the front fender.

TWEEZERS: A tool for removing wood splinters.

PHONE: Tool for calling your neighbor to see if he has another hydraulic floor jack.

SNAP-ON GASKET SCRAPER: Theoretically useful as a sandwich tool for spreading mayonnaise; used mainly for getting dog-doo off your boot.

E-Z OUT BOLT AND STUD EXTRACTOR: A tool that snaps off in bolt holes and is ten times harder than any known drill bit.

TIMING LIGHT: A stroboscopic instrument for illuminating grease build up.

TWO-TON HYDRAULIC ENGINE HOIST: A handy tool for testing the tensile strength of ground straps and brake lines you may have forgotten to disconnect.

CRAFTSMAN 1/2 x 16-INCH SCREWDRIVER: A large motor mount prying tool that inexplicably has an accurately machined screwdriver tip on the end without the handle.

BATTERY ELECTROLYTE TESTER: A handy tool for transferring sulphuric acid from a car battery to the inside of your tool box after determining that your battery is dead as a door nail, just as you thought.

TROUBLE LIGHT: The mechanic's own tanning booth. Sometimes called a drop light, it is a good source of vitamin D, "the sunshine vitamin," which is not otherwise found under motorcycles at night. Health benefits aside, its main purpose is to consume 40-watt light bulbs at about the same rate that 105-mm howitzer shells might be used during, say, the first few hours of the Battle of the Bulge. More often dark than light, its name is somewhat misleading.

PHILLIPS SCREWDRIVER: Normally used to stab the lids of old-style paper-and-tin oil cans and splash oil on your shirt; can also be used, as the name implies, to round off Phillips screw heads and can double as oil filter removal wrench by stabbing through stubborn oil filters.

AIR COMPRESSOR: A machine that takes energy produced in a coal-burning power plant 200 miles away and transforms it into compressed air that travels by hose to a Pneumatic impact wrench that grips rusty bolts last tightened 60 years ago by someone in Springfield, and rounds them off.

PRY BAR: A tool used to crumple the metal surrounding that clip or bracket you needed to remove in order to replace a 50 cent part.

HOSE CUTTER: A tool used to cut hoses 1/2 inch too short.
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CB RIDES AGAIN
The other day a mate sent me this email detailing his CB radio modifications and the 'fun' he has had afterwards - no wonder we amateurs get a bad look when we want to put up the new HF beam on top of a 15 meter tower.


Hi All,
As the neighbourhood all found out that my CB has magically been able to get it self into just about any electrical & non electrical equipment for at least a few hundred metres all around.

We are talking
- All amplifiers and Stereos
- TV sets
- Portable FM AM radios
- Record players
- You name it .. I have even heard shower reports.

My CB is interfering will all of these appliances and even more.
Did I mention Baby monitors ?

Amazing what happens when you boost the signal from your rig.

Well, I have actually found a use for it.
We regularly have a dinner at my house on a Friday night and, all I do to call the neighbours over for tea ... yep you guesses it .. get on the CB and yell out.

DINNER IS READY COME AND GET IT.
Channel 34 works best.

Sure enough ... they slowly wonder over, and we begin tea.

I'm making a switch on my rig (CB) that forces the machine into overdrive and now I have direct contact to all electrical appliances all around.

Who says you need a phone ?
Hey baby ......... I don't need a phone ......... I can even use a toaster to communicate if I have to.

Looks like Homer Simpson was on a good thing.

Bloody ripper .. Good neighbours though !
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Retired people
Working people frequently ask retired people what they do to make their days
interesting. Thought you'd like to see what happened to one senior last
week:

I went to the store the other day. I was only in there for about 5 minutes.
When I came out there was a city cop writing out a parking ticket.

I went up to him and said, "Come on, buddy, how about giving a senior a
break?" He ignored me and continued writing the ticket. I called him a Nazi.

He glared at me and started writing another ticket for having worn tires.

So I called him some names.

He finished the second ticket and put it on the windshield with the first.

Then he started writing a third ticket.

This went on for about 20 minutes...the more I abused him, the more tickets
he wrote.

I didn't care...my car was parked around the corner.

I have a little fun each day. It's important at my age.

Tooth Pulling
A man and his wife entered a dentist's office.
The wife said, "I want a tooth pulled. I don't want gas or Novocain because I'm in a terrible hurry. Just pull the tooth as quickly as possible."

"You're a brave woman," said the dentist. "Now, show me which tooth it is."

The wife turns to her husband and says: "Open your mouth and show the dentist which tooth it is, dear."
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Broadband over Power Line threat
The WIA has recently stated its position on BPL, also known as PLC or power line communications. WIA National President Michael Owen VK3KI says while access to broadband capability is important to Australia, it must not cause interference to legitimate users of high frequency radio spectrum.
The WIA is encouraged that the ACA is continuing to develop policies to address the issues arising out of BPL PLC.
The WIA notes that BPL PLC does not provide sufficiently large bandwidth that is obtainable from fibre optic cabling, and may have less attraction in the market place in the long term. The WIA says limited trials which may be conducted from time to time by promoters of BPL PLC are not a good indication of what can be expected with a large scale roll out of the technology.
WIA National Director, Phil Wait VK2DKN is now heading a WIA team that will develop further responses and strategies to counter the threat to amateur radio of BPL PLC in Australia.
The WIA is not the only group with an interest in HF communications that is taking a stand against the technology. A number of other HF users share the WIA's concerns and see it as a threat to their use of that part of the spectrum.

The BPL PLC trial in Hobart
The main energy company in Tasmania, Aurora has completed a small pilot of BPL PLC that provided Internet access to four homes and two floors of its office building in Hobart. Electronics firm Mitsubishi supplied the hardware for the trial that involved seven online users and ran for about two months.
The system uses multiple discreet carriers approximately every 1.1 kHz between about 1.6 MHz and 30 MHz. The WIA in Tasmania monitored the trial that was confined in area and did not use overhead mains power cabling as its transmission medium. Strong multiple carriers of the system and a click every second were received in the vicinity of the trial site.
The ACA was also invited to witness the BPL PLC trial. The ACA recognises BPL is an emerging technology with the potential to play a significant role in delivery improved broadband access to the general public. It is monitoring the debate and studies underway in Europe and the United States.
In the mean time, the ACA is seeking to establish regulatory arrangements that do not unnecessarily block the use of BPL PLC, but at the same time provide reasonable measures to adequately protect radiocommunications reception.
From WIA

The new HF band
Access to the 60-metre band in a number of countries is proving to be a boon to amateur radio with the new band providing international contacts. Some radio amateurs in the United States are reporting having worked all mainland states and into Britain on as little as 20 watts on frequencies around 5.4 MHz.
The United States has a number of channels on the band available to the Amateur Service on a secondary basis - that is that they do no cause interference to others uses of that spectrum.
A number of other countries have also given restricted access to their radio amateurs while others are allowing beacon or short-term test transmissions.
For example, the Marconi Radio Club of Newfoundland VO1MRC recently conducted experiments using a CW beacon alternately into a low-angle aerial vertical antenna and a high-angle inverted V. The WIA recognises the potential of gaining access to spectrum around 5MHz and is now negotiating with the ACA on this issue.
Aussie schools prepare for chats with space station
At least five Australian school listed to speak via amateur radio with crew on board the International Space Station. The Amateur Radio ISS coordinator Tony Hutchison VK5ZAI says the waiting list for schools is currently around 18 months and a number Australian schools will get their turn in the next 12 months.

Stealth wallpaper to combat eavesdropping
A British defence manufacturer has developed a "wallpaper" to block electronic eavesdropping on wireless LANs used indoors. The material is made in a similar way to flexible printed circuit boards using copper strips on a plastic substrate. Its use prevent outsiders from listening in on in-building wireless LAN traffic, while letting through other signals such as broadcast radio and mobile phone calls. Info: http://networks.silicon.com/lans/0,39024663,39121501,00.htm

From WIA

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GGREC HAMFEST
Saturday 17TH July 2004

At our LARGE venue,
The CRANBOURNE PUBLIC HALL,
On the corner of Clarendon St and High St,
Melways 133 K4
(High Street forms part of the South Gippsland highway in Cranbourne)

40 tables of new and used Electrical,
Electronic and Amateur Radio equipment


* Everything is under cover
* Free Tea & Coffee available all day.
* A selection of food will also be available.
* A 12 channel Hand Held GPS will be drawn as a Door Prize
* Doors open to sellers at 8.30 am & buyers at 10.00 am
* Buyers can gain entry for $5.00
* Sellers will pay $20.00 per table, which includes entry for two.
* All proceeds from the sale will go towards the Gippsland Gate Radio & Electronics Club (GGREC). Club Shack project.

Persons wishing to reserve a table position must Contact
Dianne Jackson VK3JDI before the event on 03 5625 2545
to obtain a Stall Holder information sheet.
(Book early, positions are limited!)
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T Shirt Slogans

1. I CHILDPROOFED MY HOUSE, BUT THEY STILL GET IN.

2. On the front . . .60 IS NOT OLD. On the back. . .IF YOU'RE A TREE.

3. I'M STILL HOT... IT JUST COMES IN FLASHES.

4. AT MY AGE, "GETTING LUCKY" MEANS FINDING MY CAR IN THE PARKING LOT.

5. MY REALITY CHECK JUST BOUNCED.

6. LIFE IS SHORT. MAKE FUN OF IT.

7. I'M NOT 50. I'M $49.95 PLUS TAX.

8. ANNAPOLIS - A DRINKING TOWN WITH A SAILOR PROBLEM.

9. I NEED SOMEBODY BAD... ARE YOU BAD?

10. PHYSICALLY PFFFFFT!

11. BUCKLE UP. IT MAKES IT HARDER FOR THE ALIENS TO SNATCH YOU
FROM YOUR CAR.

12. I'M NOT A SNOB. I'M JUST BETTER THAN YOU ARE.

13. IT'S MY CAT'S WORLD. I'M JUST HERE TO OPEN CANS.

14. EARTH IS THE INSANE ASYLUM OF THE UNIVERSE.

15. KEEP STARING....I MAY DO A TRICK.

16. WE GOT RID OF THE KIDS. THE CAT WAS ALLERGIC.

17. DANGEROUSLY UNDER-MEDICATED.

18. MY MIND WORKS LIKE LIGHTNING. ONE BRILLIANT FLASH AND IT'S GONE.

19. EVERY TIME I HEAR THE DIRTY WORD "EXERCISE", I WASH MY MOUTH OUT WITH CHOCOLATE.

20. CATS REGARD PEOPLE AS WARM-BLOODED FURNITURE.

21. LIVE YOUR LIFE SO THAT WHEN YOU DIE, THE PREACHER WILL NOT HAVE TO TELL LIES AT YOUR FUNERAL.

22. IN GOD WE TRUST. ALL OTHERS WE POLYGRAPH.
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Grounding is key to good reception
From: jpd@space.mit.edu (John Doty)
Newsgroups: rec.radio.shortwave

With grounds the most common experience is "the more the merrier". As you add more, however, you usually reach a diminishing returns (no pun intended) situation where there is no *observable* improvement: that's usually a good place to stop. There are also exceptional circumstances where grounding increases noise problems, but these, in my experience, are much rarer than the pundits who preach against "ground loops" seem to think.
Even a semi-quantitative theoretical treatment of grounding in oversimplified situations requires heavy math at RF. Experimentation is thus required even if one has done elaborate calculations. It's often easier to use the theory as a guide to what to try, and then experiment.
What's ground? If connect the shield of my coax (which is grounded outside) to the antenna input of my R8, I hear lots of junk, indicating that there is an RF voltage difference between the coax shield and the R8 chassis. Last night this measured about S5.5, which is about -93 dBm (preamp off, 6KHz bandwidth). That's a lot of noise: it was 18 dB above my antenna's "noise floor", and 26 dB above the receiver's noise floor.
This sort of disagreement about ground potential is characteristic of electrically noisy environments. The receiver will, of course, respond to any voltage input that differs from its chassis ground. The antenna, on the other hand, is in a very different environment, and will have its own idea of what ground potential is. If you want to avoid noise pickup, you need to deliver a signal, referenced at the antenna to whatever its ground potential is, in such a way that when it arrives at the receiver, the reference potential is now the receiver's chassis potential.
Coaxial cable represents one way to do this. Coax has two key properties:
1. The voltage between the inner conductor and the shield depends only on the state of the electromagnetic field within the shield.
2. The shield prevents the external electromagnetic field from influencing the internal electromagnetic field (but watch out at the ends of the cable!).
So, it's easy, right? Run coax from the antenna to the receiver. Ground at the antenna end will be whatever the antenna thinks it is, while ground at the receiver end will be whatever the receiver thinks it is. The antenna will produce the appropriate voltage difference at the input side, and the receiver will see that voltage difference uncontaminated by external fields, according to the properties given above.
Unfortunately, it doesn't quite work that way. It's all true as far as it goes, but it neglects the fact that the coax can also guide noise from your house to your antenna, where it can couple back into the cable and into your receiver. To see how this works, let me first describe how this noise gets around.

The noise I'm talking about here is more properly called "broadband electromagnetic interference" (EMI). It's made by computers, lamp dimmers, televisions, motors and other modern gadgets. I have all these things. In many cases, I can't get them turned off, because it would provoke intrafamilal rebellion. However, even when I turn them off, the noise in the house doesn't go down very much, because my neighbors all have them too. In any case, one of the worst offenders is my computer, which is such a handy radio companion I'm not about to turn *it* off.
Some of this noise is radiated, but the more troublesome component of this is conducted noise that follows utility wires. Any sort of cable supports a "common mode" of electromagnetic energy transport in which all of the conductors in the cable are at the some potential, but that potential differs from the potential of other nearby conductors ("ground"). The noise sources of concern generate common mode waves on power, telephone, and CATV cables which then distribute these waves around your neighborhood. They also generate "differential" mode waves, but simple filters can block these so they aren't normally a problem.

So, let's say you have a longwire antenna attached to a coaxial cable through an MLB ("Magnetic Longwire Balun" [sic]). Suppose your next door neighbor turns on a dimmer switch. The resulting RF interference travels out his power lines, in through yours, through your receiver's power cord to its chassis, and out your coaxial cable to your MLB. Now on coax, a common mode wave is associated with a current on the shield only, while the mode we want the signal to be in, the "differential" mode, has equal but opposite currents flowing on shield and inner conductor. The MLB works by coupling energy from a current flowing between the antenna wire and the coax shield into into the differential mode. But wait a second: the current from the antenna flows on the coax shield just like the common mode current does. Does this mean that the antenna mode is contaminated with the noise from your neighbor's dimmer?

The answer is a resounding (and unpleasant) yes! The way wire receiving antennas work is by first moving energy from free space into a common mode moving along the antenna wire, and then picking some of that off and coupling it into a mode on the feedline. In this case, the common mode current moving along the antenna wire flows into the common mode of the coax, and vice versa. The coax is not just feedline: it's an intimate part of the antenna! Furthermore, as we've seen, it's connected back through your electrical wiring to your neighbor's dimmer switch. You have a circuitous but electrically direct connection to this infernal noise source. No wonder it's such a nuisance!

The solution is to somehow isolate the antenna from the common mode currents on the feedline. One common way to do this is with a balanced "dipole" antenna. Instead of connecting the feedline to the wire at the end, connect it to the middle. Now the antenna current can flow from one side of the antenna to the other, without having to involve the coax shield. Unfortunately, removing the necessity of having the coax be part of the antenna doesn't automatically isolate it: a coax-fed dipole is often only slightly quieter than an end-fed longwire. A "balun", a device which blocks common mode currents from the feedline, is often employed. This can improve the situation considerably. Note that this is not the same device as the miscalled "Magnetic Longwire Balun".

Another way is to ground the coaxial shield, "short circuiting" the common mode. Antenna currents flow into such a ground freely, in principle not interacting with noise currents. The best ground for such a purpose will be a earth ground near the antenna and far from utility lines.

Still another way is to block common mode waves by burying the cable. Soil is a very effective absorber of RF energy at close range.

Unfortunately, none of these methods is generally adequate by itself in the toughest cases. Baluns are not perfectly effective at blocking common mode currents. Even the best balun can be partially defeated if there's any other unsymmetrical coupling between the antenna and feedline. Such coupling can occur if the feedline doesn't come away from the antenna at a right angle. Grounds are not perfect either. Cable burial generally lets some energy leak through. A combination of methods is usually required, both encouraging the common mode currents to take harmless paths (grounding) and blocking them from the harmful paths (baluns and/or burial).

The required isolation to reach the true reception potential of the site can be large. According to the measurements I quoted above, for my site the antenna noise floor is 18 dB below the conducted noise level at 10 MHz. 18 dB of isolation would thus make the levels equal, but we want to do better than that: we want the pickup of common mode EMI to be insignificant, at least 5 dB down from the antenna's floor. In my location the situation gets worse at higher frequencies as the natural noise level drops and therefore I become more sensitive: even 30 dB of isolation isn't enough to completely silence the common mode noise (but 36 dB *is* enough, except at my computer's CPU clock frequency of 25 MHz).

Getting rid of the conducted noise can make a huge difference in the number and kinds of stations you can pick up: the 18 dB difference between the conducted and natural noise levels in the case above corresponds to the power difference between a 300 kW major world broadcaster and a modest 5 kW regional station.

The method I use is to ground the cable shield at two ground stakes and bury the cable in between. The scheme of alternating blocking methods with grounds will generally be the most effective. The ground stake near the house provides a place for the common mode noise current to go, far from the antenna where it cannot couple significantly. The ground stake at the base of my inverted-L antenna provides a place for the antenna current to flow, at a true ground potential relative to the antenna potential. The buried coax between these two points blocks noise currents.

I'm no expert on electrical codes, and codes differ in different countries. However, I believe that any such requirement must refer only to grounds used for safety in an electric power distribution system: I do not believe this applies to RF grounds.

Remember that proper grounding practice for electrical wiring has very little to do with RF grounding. The purpose of an electrical ground is to be at a safe potential (a few volts) relative to non-electrical grounded objects like plumbing. At an operating frequency of 50/60 Hz, it needs to have a low enough impedance (a fraction of an ohm) that in case of a short circuit a fuse or breaker will blow immediately.

At RF such low impedances are essentially impossible: even a few centimeters of thick wire is likely to exhibit an inductive impedance in the ohm range at 10 MHz (depends sensitively on the locations and connections of nearby conductors). Actual ground connections to real soil may exhibit resistive impedances in the tens of ohms. Despite this, a quiet RF ground needs to be within a fraction of a microvolt of the potential of the surrounding soil. This is difficult, and that's why a single ground is often not enough.

If you have a "ground loop". It's harmless. In case of a nearby lightning strike it may actually save your receiver. My R8 isn't grounded like that, so I had to take steps to prevent the coax ground potential from getting wildly out of kilter with the line potential and arcing through the power supply. I'm using a surge supressor designed to protect video equipment: it has both AC outlets and feedthroughs with varistor or gas tube clamps to keep the various relative voltages in check. Of course the best lightning protection is to disconnect the receiver, but I'm a bit absent minded so I need a backup.

I suspect part of the reason I see so much noise from neighbors' appliances on my electric lines may be that my house's main ground wire is quite long. The electrical service comes in at the south corner of the house (which is where the breaker box is), while the water (to which the ground wire is clamped) enters at the east corner. All perfectly up to code and okay at 60 Hz, but lousy at RF: if it was shorter, presumably more of the noise current would want to go that way, and stay away from my receiver.

If you try to get maximum signal transfer with a short loaded (resonant) vertical antenna with a radiation resistance of, say, 10 ohms, 20 ohms of ground resistance is going to be a big deal. If you're transmitting 50 kW, your ground resistance had better be *really* tiny or things are going to smoke, melt or arc.

On the other hand, a ground with a resistance of 20 ohms is going to be fairly effective at grounding a cable with a common mode characteristic impedance of a few hundred ohms (the characteristic impedance printed on the cable is for the differential mode; the common mode characteristic impedance depends somewhat on the distance of the cable from other conductors, but is usually in the range of hundreds of ohms). Of course, if it was lower a single ground might do the whole job (but watch out for mutual inductance coupling separate conductors as they approach your single ground).

In addition, a ground with a resistance of 20 ohms is fine for an unbalanced antenna fed with a high impedance transformer to supress resonance. Such a nonresonant antenna isn't particularly efficient, but high efficiency is not required for good reception at HF and below (not true for VHF and especially microwave frequencies).

Much antenna lore comes from folks with transmitters who, armed with the "reciprocity" principle, assume that reception is the same problem. The reciprocity principle says that an antenna's transmission and reception properties are closely related: it's good physics, but it ignores the fact that the virtues required of a transmitting and receiving antenna are somewhat different. Inefficiency in a transmitting antenna has a direct, proportional effect on the received signal to noise ratio. On the other hand, moderate inefficiency in an HF receiving antenna usually has a negligible effect on the final result. A few picowatts of excess noise on a transmitting antenna has no effect on its function, but is a big deal if you're receiving (of course, one might not want to have transmitter power going out via unintended paths like utility lines: this is indeed the "reciprocal" of the conducted noise problem, and has similar solutions).

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General Meeting Minutes
Date: 18 June 2004
Start time: 08:00 PM.
Location: Guide Hall Cranbourne
Chairperson: Peter Pavey VK3VB
Minute Taker: Bruno Tonizzo VK3BFT

Present: As per attendance sheet

Visitors and Guests: John Woodland
Apologies: Colin VK3CLS, Graeme & Susan Coleman VK3YCG, Dorothy & Helmut Inhoven VK3DHI, Ivan Blezard VK3ARV, Jan Oncken VK3NOV, Warren Mansfield.

Correspondence Received:
WIA - June Amateur Radio Magazine
FAMPARC News letters for June 2004.
VK3BJA Amateur Licence 18/05/2004 to 17/05/2005
Treasurer's Report: As Tabled
Read by: Andrew Clinkaberry VK3HFA, Moved: Andrew Clinkaberry VK3HFA Seconded by: Colin Bishop VK3HR Carried: Yes
New Callsigns: Nil
Previous Minutes: As published and read. Moved: Peter Pavey VK3VB
Seconded : Mike Ide VK3KTO

Business Arising from Previous Minutes:
Andrew moved a motion to transfer money from our investment account to our savings account. Seconded by John Whittingham, Carried - yes.
Building Update - Cladding has been placed on one side, Volunteers are in good numbers. Have applied for a Grant from a fund to assist volunteers. $5900 has been allocated from Council to supply goods & services.
Next working bee - 20th June & 3rd July.
We have offered an article "How we built our shack" for AR magazine - waiting reply.
Hamfest - 13 tables left promotional emails are not getting through to AR editor.
IRLP - Email from another Node administrator telling us that our repeater is "pulsing". Email reply sent off for clarification. Peter Pavey asked if we needed to set up a roster to monitor IRLP to speak to overseas amateurs.
JOTA - Dave Campbell to co-ordinate. Contact has been made with the guides.

General Business:
Naree has negotiated a dinner for two, valued at $75.00, for Trio's restaurant. Motion was moved by VK3VB to sell tickets over two nights and was carried. Tickets on sale at June GM to be drawn at the Mid Year Dinner.
Pub night - 28th August Names & $5:00 deposit required.
Club Antennas - Phil Pavey to organise a team to replace the Dipole and HF Beam.
Membership Fees - reminder to be placed into the next magazine.
Mid Year Dinner - 26th June 2004 6:00 PM start time.

Meeting Closed at around 08:40 PM.
Guest Speaker : John Woodland Subject South East Water Sewerage treatment plant.

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Gippsland Gate Radio and Electronics Club Inc.
Incorporation Number A0016893M

Club Meetings are held on the third Friday of each month at the Cranbourne Girl Guide Hall in Grant Street. Prac nights are held on the first Friday night at the same location. Both nights commence at 8:00 PM.
Visitors will be made most welcome.
Committee Members 2004 - 2005
President Peter Pavey VK3VB (5998 3533)
Secretary Bruno Tonizzo VK3BFT (9700 4526)
Treasurer Andrew Clinkaberry VK3HFA
Committee Members Mike Ide VK3KTO
Ian Jackson VK3BUF
Reg Goddard VK3UK
Peter Woodland VK3KCG
Magazine Editor John Whittingham VK3XJW

Club Station VK3BJA located at the Guide Hall
6M Repeater VK3RDD : Freq. In 52.575, out 53.575 MHz
70cm Repeater VK3RLP Freq. In 434.475, out 439.475MHz
CTCSS 88.5Hz IRLP Node Number- 6794 (Using VK3RLP)
Call in Frequencies are: HF on 28.325 MHz, USB VHF on 146.225 MHz, FM and UHF on 438.850 MHz, FMClub nets are held on the second and fourth Sunday nights on 146.225 MHz
Visit our internet site at: http://www.ggrec.org.au
Current GGREC Inc. Membership Fee Schedule
Full Member $37.00, Pensioner Member $22.00
Junior Member $22.00, Extra Family Member $17.00
Fees due after each April Annual General Meeting.

The deadline for submitting gateway articles is EIGHT DAYS before each General meeting.

Please direct magazine correspondence to:
John Whittingham 82 Mc Mahons Rd Frankston 3199
Phone: 9781 3682 or Email johnwhittingham@optushome.com.au

All other club correspondence to P.O. Box 1098, Cranbourne 3977
or Email :secretary@ggrec.org.au

It costs 90 cents to produce and send each copy of Gateway.

Disclaimer- The opinions expressed in this publication do not necessarlly reflect the official view of the GGREC inc and the GGREC inc cannot be held responsible for incorrect information published.

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