Wednesday, February 21, 2018

Locating Sources Of Noise

A Communicator Reprise: September 2011

At one of our Friday breakfast meetings a conversation came up about how some of us have such a high noise level, a great many signals are lost in that noise.  Depending on the frequency or band you listen to, some are experiencing 20db above S9 as their noise floor....  Me? I have to deal with a S7 to S9 noise floor on 80 metres, and a S3-S5 on other bands.

When I started looking into this topic, I was overwhelmed by the books, articles and white papers on the subject.  There is a lot of information on both EMI [Electromagnetic Interference] and RFI [Radio Frequency Interference].  A new term has come into popular use which seems to mix the two into EMC [ElectroMagnetic Compatibility] which is the characteristic of any or all electronic devices to either not emit unwanted signals, and/or not be influenced or interfered with by other devices.

In Ham speak, we can simplify these terms by stating that RFI is interference caused by YOUR station equipment getting into other devices, from TVs, to electronic organs, to your touch controlled paper shredder.  EMI is interference FROM other electronic devices which cause your receiver noise floor to rise. OK, not entirely technically correct, but it serves my purpose here, we can debate later.

As our lives become filled with technology, the likelihood of electronic interference increases. Every lamp dimmer, garage-door opener or other new technical “toy” contributes to the electrical noise around us. Many of these devices also “listen” to that growing noise and may react unpredictably to their electronic neighbours. Whether it’s called EMI, RFI or TVI [Television Interference], unwanted interaction between intentional and unintentional receivers and transmitters has stimulated vigorous growth in the field of electromagnetic compatibility (EMC).

The scope of EMC includes all the ways in which electronic devices interact with each other and their environment. The primary aspect of EMC that concerns amateurs is interference to or from Amateur Radio communications.  Sooner or later, nearly every Amateur Radio operator will have a problem with interference, but temper your dismay. Most cases of interference can be cured!

Since this is a huge subject to deal with, I will cover only the topic of reducing EMI INTO your receiver.  In other words, what can you do to reduce [notice I didn’t say “eliminate”] that S9 noise floor so you can hear the QRP or DX stations… or anyone for that matter. 

All cases of EMI involve a source of electromagnetic energy, a device that responds to this electromagnetic energy (victim) and a transmission path that allows energy to flow from the source to the victim. Sources include radio transmitters, receiver local oscillators, computing devices, electrical noise, lightning and other natural sources. There are three ways that EMI can travel from the source to the victim: radiation, conduction and induction. Radiated EMI propagates by electromagnetic radiation from the source, through space to the victim. A conducted signal travels over wires connected to the source and the victim. Induction occurs when two circuits are magnetically (and in some cases, electrically) coupled. Most EMI occurs via conduction, or some combination of radiation and conduction. For example, a signal is radiated by the source and picked up by a conductor attached to the victim (or directly by the victim’s circuitry) and is then conducted into the victim. EMI from induction is rare.

Look Around — Aside from the brain, the eyes are a trouble shooter’s best tool. Look around. Installation defects contribute to many EMI problems. Look for loose connections, shield breaks in a cable-TV installation or corroded contacts in a telephone installation. Fix these first.

Problems that occur only on harmonics of the fundamental signal usually indicate the transmitter. Harmonics can also be generated in nearby semiconductors, such as an un-powered VHF receiver left connected to an antenna, or a corroded connection in a tower guy wire. Harmonics can also be generated in the front-end components of the TV or radio experiencing interference. Is the wiring connected to the victim equipment resonant on one or more amateur bands?  If so, a common-mode choke placed at the middle of the wiring may be an easy cure.

These are only a few of the questions you might need to ask yourself.  As we discover what devices cause EMI, let’s delve into types of EMI ‘noise.’ First, it is worth keeping a log of exactly when the EMI occurs as this can give a clue to the possible source. Tuning across the affected band or bands can also give some clues about the source of the interference which normally falls into one of the following categories:

Narrow Band
Narrow band interference affects one or more spot frequencies in a band with little or no detectable interference in between these frequencies. On an SSB receiver, a true narrow band source would be heard as a tone, possibly rather rough but narrow enough to be reduced by means of a notch filter.

Broad Band with no peaks
If interference appears right across a band at about the same level with no peaks, it is classed as a broad band source.

Broad band with broad peaks
Some sources such as switch‐mode power supplies and digital electronics produce broad band emissions with regularly spaced broad peaks. The spacing between the peaks indicates the fundamental frequency. The peaks may not be well defined so it is best to note the frequencies of 11 regularly spaced peaks and divide the difference between the highest and lowest by 10.

Broad band with narrow peaks
Some emissions are broad band but also contain narrow band signals as described above. This is characteristic of digital electronic circuitry.

The frequency of a narrow band emission may drift due to temperature changes. The times of these temperature changes can give some clues about the source. If it is crystal controlled, the drift may be very slight but if it uses a ceramic resonator, it may drift up to a few kHz at VHF or a few hundred Hz at HF.

It is worth listening to the interference using FM, SSB and AM modes if possible. You may find one of the following characteristics:

No modulation
This may be a harmonic from a crystal oscillator.
60 or 120 Cycle [Hertz] buzz.
If the audio signal is viewed on an oscilloscope triggered on 'line', the trace stands perfectly still if the interference is synchronized to Hydro’s 60 Hz.

White noise
A steady hiss like the background noise level on the band but at a considerably higher level.

Other modulation
Some sources are modulated with a characteristic sound (see below).

Some residential sources of EMI
Television Installations
The line time base frequency of 625 line television systems is 15.625kHz. Harmonics may be heard as narrow band signals on multiples of this frequency, for example, 3500 kHz, 3515.625kHz, 3531.25kHz, etc. As the line frequency is 1MHz divided by 64, harmonics are found on multiples of 125kHz. If the TV is receiving an off‐air program, the harmonic will usually have a sound which changes with picture content when heard on an SSB or CW receiver. To prove that a TV set is the source, try watching another TV set (with low EMI!) and select different channels until you find one where changes in the picture coincide with changes in the sound heard on the radio.
Some large screen plasma TV sets radiate broadband interference mainly in the lower half of the HF band. Because of the large screen area most of the interference comes directly from the screen. Measures such as a mains filters are unlikely to be effective. Fortunately, so far as TV sets, are concerned “plasma” is an obsolete technique so incidences as interference should reduce as equipment is replaced.

Switch‐mode power supplies
A switch‐mode power supply (SMPS) generates a square wave at a frequency of 30 ‐ 90kHz or more. On the LF, MF and lower HF bands, harmonics from an SMPS can produce broad band EMI with broad peaks and 100Hz modulation. The peaks are spaced at multiples of the switching frequency. On the higher HF bands and at VHF, the peaks may merge together.

TV power supplies
When heard on an AM or SSB receiver, the sound form a TV switch‐mode power supply usually changes with picture content (see also TV line time base harmonics above) but is broad band and may peak at a certain frequency such as 14‐18 MHz. The switch mode power supply also runs when in standby mode and its characteristics may change so that interference is only noticeable in standby mode. Emissions in standby mode are normally continuous but in some sets sold since 1999, the noise is modulated at about 8 ‐ 10Hz in standby mode. This produces a 'chuff‐chuff' noise like a fast steam train.  With old Analogue TVs being discarded over the next few years, be prepared for new problems with digital TV.

TV 'set‐top boxes' – the Shaw, Telus, Satellite Boxes & PVR
There are various types of TV 'set‐top box' for satellite TV, cable TV, digital terrestrial TV or video on demand via ADSL (Asymmetric Digital Subscriber Line). These normally have switch‐mode power supplies that run continuously.

If the EMI occurs mainly after dark, does it appear when a certain light or lights are on in a room nearby?

Electronic transformers
For lighting which uses 12 volt halogen spotlights, the transformers may either be a conventional type or an 'electronic transformer' which is a switch‐mode power supply with AC output.

Compact fluorescent and LED lamps (Low energy lamps)
Most types, are electronic and contain a small switch mode power supply. There are also larger non-electronic types such as the Philips SL range which generate less EMI but have a heavy iron‐cored choke.

Computer power supplies
In a desktop computer, the SMPS is normally in a screened box with a mains filter and may therefore produce much less EMI than a computer monitor where the SMPS may be unscreened. Laptop computers have an external AC power supply unit/charger which is normally an SMPS without screening.

Fax machines
The power supply runs 24 hours a day and it almost always a switch‐mode type.

Electric Motors
EMI from an AC or DC electric motor with brushes and a commutator is broad band without peaks. Its pitch varies as the motor speed varies. The variations in speed and the pattern of use can give clues about the source. For example, this might be a washing machine or drier, sewing machine, electric lawn mower, food mixer, electric drill, hair dryer or even a model railway. It is not likely to be a refrigerator as these normally use induction motors which do not produce EMI.

Faulty thermostats can arc for 1 ‐ 30 seconds or more producing broad band EMI with no peaks and 100Hz modulation. This may be heard on a number of HF and/or VHF bands. The most common source is a faulty gas central heating boiler thermostat and it is likely to be worse in winter. The arcing may occur at every 5 ‐ 20 minutes although in some cases it could be as often as two or three times per minute.

Conventional fluorescent lights
EMI from fluorescent lights is broad band with no peaks and is modulated with a 120Hz buzz, mainly on the LF, MF and lower HF bands. Fluorescent lights have been required to include EMI suppression since 1978 although most met the relevant standard long before this date. If the tube is worn out and flickering at 60Hz, this can increase the level of EMI.

Dimmer switches
EMI from dimmer switches is similar to that produced by fluorescent lights and is stronger when the lamp is dimmed than when on full brightness. Dimmer switches sold in the Canada have been required to include EMI suppression since 1978 although most met the relevant standard long before this date. They seldom cause problems to amateur reception unless they are faulty or are a type not designed for the Canadian market – hint hint eBay buyers of Chinese products.

Various oscillators in a computer and its associated components such as the keyboard and mouse can produce narrow band radiated emissions. Some are crystal controlled and generally have no drift or modulation while others use a ceramic resonator which drifts and may have slight frequency modulation which can be heard as a 'warbling' noise on an SSB or CW receiver. Such modulation may sound like someone typing on a keyboard or playing a game. Almost all PCs have a crystal oscillator at or near 14.318MHz although this signal may not be particularly strong. Nevertheless, if it is present at the same time as other signals, this shows that the other signals are likely to come from a computer. In many cases, a computer monitor radiates more EMI than the computer itself. In addition to broad band emissions from the SMPS in a computer monitor, there may be line time base harmonics which are similar to TV line time base harmonics except that the spacing is larger (31 kHz or more). There are numerous different line frequencies depending on the screen resolution and refresh rate. Computer line time base harmonics normally give a very pure crystal‐controlled note and are likely to be strongest on the 1.8 and 3.5MHz bands.

Intruder alarm systems
Intruder alarm systems normally contain a microprocessor and can radiate signals from the wiring to the sensors on the HF and/or VHF bands. As they normally use a ceramic resonator, the harmonics drift slightly and may have slight modulation which can be heard on an SSB receiver. This modulation may change if the alarm ever goes off and may also change when the user presses keys on the control panel.

Other digital electronic devices
Digital electronic circuitry can radiate narrow band signals on certain frequencies such as harmonics of the clock frequency and may also produce broad band signals. Such sources include NICAM decoders and other digital electronics in TV sets, video recorders and satellite receivers/decoders. Many of these devices are connected to long cables which can radiate EMI on HF bands as well as VHF.

Cable TV
Many modern cable television systems use vision carriers from 128MHz upwards on multiples of 8MHz up through the 2 metre Ham band. The street cabinets normally contain a switch‐mode power supply which may produce detectable emissions on the HF bands due to common‐mode signals conducted along the coaxial cables.

Telephone equipment
Fax machines contain a microprocessor which runs continuously. If a computer is connected to a modem, this can allow EMI from the computer to be radiated via the telephone line. If the modem can receive fax or voice calls, the owner may leave the computer running all the time. If a telephone subscriber has an ISDN (Integrated Services Digital Network) line, the line carries 90V DC which powers a switch‐mode power supply in the customer's premises. Some types of ISDN equipment at the customer's premises can produce EMI when a call is in progress.  Businesses and even some homes may have their own internal telephone exchange or PABX. Some types can produce EMI on the HF and VHF bands.

Emissions from overhead telephone lines
If the EMI is strongest under telephone lines or close to a telephone pole, the source could be one of the items mentioned above but in many cases, it is something completely unrelated to the telephone system. If anything feeds EMI onto the AC in a house, this can be coupled onto telephone wires via the AC transformer of any Hydro powered telephone equipment such as an answering machine or a cordless phone.

Vehicles - Ignition systems
Although there have been regulations controlling ignition interference since 1952, this can be a problem for weak signal reception near a busy road. Many transceivers contain a noise blanker which is effective against the short impulses from vehicle ignition systems.

Remote keyless entry receivers
Some cars made since mid 1994 use radio keys operating on 433.92MHz. Radio key receivers in some cars contain a local oscillator which runs continuously somewhere in the range 433.275 ‐ 433.475MHz. Other types use a super‐regenerative receiver and some aftermarket alarms sold in 1994 and 1995 can emit broad band noise across the 430‐440MHz band


Touch Lamps
These are table lamps with a touch‐operated switch which turns the lamp on and off and selects several levels of brightness. They contain a sawtooth oscillator which operates continuously and produce emissions which are similar to an SMPS but with a fundamental frequency of around 190kHz. Some models sold before 1996 contain no EMI suppression.

Garage door openers
The super‐regenerative receivers for some 173MHz remote‐controlled garage door openers manufactured in the late 1980s radiate broad band noise on 430‐440MHz. They can also receive VHF radio paging and rebroadcast it at a number of frequencies on the 430‐440 MHz band!

Water conditioners
Electronic water conditioners are claimed to reduce deposition of lime scale. Some types such as the "Water King" and "Water Imp" use a sequence of audio frequency tones which have harmonics up to 28MHz in some cases. The radiated emissions have a very unusual characteristic as the a tone changes about once a second in a sequence which repeats every few minutes.

Electric fences
EMI from an electric fence is a regular clicking noise. The source is likely to be a sparking at a faulty insulator rather than the electric fence unit itself. Try looking for flashovers in the dark (with the landowner's permission).

Overhead power cables
Overhead power cables can radiate broad band noise with 120Hz modulation. High voltage cables always produce a certain amount of EMI due to corona discharge from the cable itself but EMI can be greatly increased due to arcing at a faulty insulator, in which case, the level of EMI may reduce in dry weather.

Radio Paging
This sounds rather like packet radio but usually starts with a tone. Strong signals from nearby radio paging transmitters may be heard on the 2 metre band or other bands but in most cases, such breakthrough is caused by shortcomings in the amateur receiver. Transceivers with extended receive coverage are more likely to be affected than those which only cover amateur bands. Hand‐held transceivers connected to an outdoor aerial can be particularly susceptible.

Power line Adaptors (PLAs)
In recent years these have become a serious source of interference. They are sometimes used for networking computers but the most common use is for video distribution. Generally they minimize emissions in the amateur bands (known as notching) so that interference is most likely to be noticed on the HF broadcast bands.

Your Cell Phone
My phone’s Bluetooth makes a strange rhythmic buzz in one pair of my computer speakers when it communicates with its companion Bluetooth device.  Took me days to figure that out, but just one pair, not any other in my ham shack?  Cheapest solution was to turn the cell phone off!

Searching for the Source 
Basically, the first step is to determine if the noise is household noise or neighbourhood noise or atmospheric noise; the latter we can't do much about except put up high-gain, highly directional arrays to increase your signal to noise ratio.
  1. Start out by recording the noise floor on 80 & 20 meters, either via the S-meter or panadaptor.
  2. Put a 12 volt car battery across the terminals of your power supply, fully charged of course.
  3. Then turn on everything in the house and I mean everything. Best to do this test with the family away for 2-3 hours. Record the result.

Turn off all the circuit breakers so there is no AC coming into the house… the only thing on in your house should be your transceiver, powered by the battery. If the noise goes away, it must be household generated (duh).  Turn the volume up [if you don't have help] and turn on one circuit breaker at a time until the noise returns, then on the breaker that causes the highest return of the noise floor. The next step is to turn off all the others you've turned on so far, then locate what is still on in the house and one-by-one turn it off [or unplug it], until the noise goes away, and hopefully you have located the RF noisy device or devices, before the fridge defrosts. You may need to repeat this to find multiple sources of noise.

Again, look for noise sources in Ryobi battery chargers, Plasma TV's, switching power supplies, electric blankets, electronic bug zappers, electric fences, cell phone chargers, cordless phone chargers, electronic exercise equipment, air ionizers or conditioners, electronic light dimmers, timers, readouts that are multiplexed [scanned], computers made between 2000 and 2007 as the CPU oscillated at some direct or harmonic frequency on various ham bands. One of my main computers generates birdies all up and down the 75/80 meter band – about 3 ‘S’ units of buzzes, clicks and tweeting birdies!  Any computer that doesn't run in the GHz. range is a potential source of HF noise.
Don’t rule out your hot tub motors, timers and heaters too… pumps for the pool and especially as the starter capacitor ages, fridges and freezer with induction motors shouldn’t be an issue, but don’t rule them out.  Run the microwave oven too… they leak no matter how good it is… and the older the unit, the more it leaks RF. We know some florescent fixtures can be noisy, even some of the new energy efficient ones.. they can be the worst offenders and, don't forget the toxic mercury-filled "eco-bulb” we are almost forced to use.

Check the house ground rod connection, and any device that has a ground connection.  Don't just tighten, take it off, burnish it, add some anti corrosion compound and re-attach.

Neighbourhood Noise
Sodium & Mercury Street lights, their ballast noise, Shaw cable boxes not properly grounded (they use the 2 metre ham band as a signal carrier)  If it's not grounded properly or the box is left open, your RF signal interferes with cable and vice versa (in VHF).

Landscape Wiring
Including electric fences, electronic pet barriers, solar panel inverters are very RF dirty. Only one or two of the more expensive ones are RF suppressed, all others radiate like an unprotected spark-gap transmitter!

Bad Pole Insulators
And old pole transformers (or loose connections as Fred VE7IO was telling us about at breakfast that morning.)  Just about any motor with brushes and spark plugs.
On the HF bands, interference can enter your home via the AC [Hydro] supply whether underground or overhead and can be radiated by your wiring.  In such cases, switching off a double pole main switch at the fuse box will probably reduce it, although this depends on the exact layout of your Hydro wiring.  Pickup of AC‐borne interference on the HF bands can often be reduced by moving your aerial further from the AC wiring [if possible], or by using a balanced aerial such as a dipole instead of an end‐fed aerial.  Aerial and Antenna – the same thing.

If it is not in your own home, the next step is to go out and search for it using a portable transceiver or receiver, or get someone to help you if you are unable to do this yourself.
In the case of HF Hydro borne interference, the source is likely to be on the same phase as your own main supply.  In a street of houses, every third house is normally on the same phase. On VHF, if you have an aerial on a rotator then it should be possible to get some indication of the direction of the source. EMI which occurs continuously or frequently can often be located without a directional aerial, simply by going around searching for the strongest signal.

For EMI which only occurs intermittently such as an arcing thermostat, a portable directional aerial is very useful. In either case, the receiver should have an 'S' meter, preferably a moving coil type. It is also useful to have an attenuator to reduce the sensitivity when you get closer to the source.

One possible problem is that EMI which is quite strong when using your main station aerial cannot be heard at ground level on a portable receiver. For a narrow band source, the maximum sensitivity is achieved by using CW mode with the narrowest possible bandwidth such as 500 Hz. For broad band sources such as arcing, greater sensitivity is achieved by using a receiver with the widest possible bandwidth. The first thing to establish is whether the source of the EMI source is nearby (within about one hundred metres for example) or further afield such as the next street or even the next town. Getting someone to drive you around the local roads in a car with a portable receiver connected to the car aerial may show a clear peak at a certain point which is not apparent when walking. If interference is being conducted along telephone wiring or Hydro wiring, there may be a number of peaks which coincide with telephone poles, overhead power lines or lamp posts.

Lower HF bands
If interference affects the 1.8MHz amateur band, it may also be audible on an MW broadcast receiver. Alternatively, a ferrite rod aerial with an MW coil can be tuned to the 1.8 MHz amateur band and connected to a portable HF receiver using a 2 turn coupling winding to match into a 50Ω receiver input. For 3.5MHz, the main winding on the ferrite rod should be about 20 turns tuned with a 200 pF variable capacitor. A 1 or 2 turn coupling winding should be used. A ferrite rod aerial is recommended for D/F-ing EMI on the 1.8 and 3.5MHz bands because it can be held right down on the ground to detect the magnetic field from EMI propagating along underground cables as a common mode signal (that is, on all conductors together relative to earth). If properly balanced, a ferrite rod aerial gives a minimum signal when the rod is pointing towards or away from the source but this direction finding property can give misleading results in built‐up areas or near overhead cables because MF/HF interference can travel for hundreds or thousands of metres along Hydro wiring or telephone wiring (particularly if overhead).

Standing waves can cause the signal strength to rise and fall at intervals along the line. With any EMI from overhead cables, it is best to search for it on the highest frequency possible, moving higher as you get closer. If you want to follow overhead power cables across land without a public right of way, permission should be obtained from the landowner before entering. If you can identify which pole is responsible, make a note of its number and report it to BC Hydro.  Do it well or contact the right person and they won’t laugh at you.  After all they use the word “Authority” in their advertising.

Higher HF bands
The tendency for interference to travel along wiring decreases as frequency increases so it is better to search for interference on the highest frequency on which it can be heard. In practice, it will probably be necessary to listen on a frequency above the MUF where the HF bands are quiet. The 28MHz band is a good band to use and a direction finding loop can be made for the task.  Such a loop may not be sensitive enough without a pre‐amplifier however. When you get closer to the source, try to find it on a VHF band but check that the VHF signals have the same characteristics as the HF signals and are not coming from a completely different source!

VHF bands
On 144MHz, it is possible to use a horizontal half wavelength dipole with a balun for direction finding. This gives a minimum signal when pointing towards or away from the source although it can give misleading results if the source happens to be vertically polarized. It is also possible to use a yagi aerial which gives an unambiguous direction bearing. If the source appears to be vertically polarized, the yagi can be used vertically, otherwise horizontal polarization is preferable because the aerial has a narrower beamwidth when used horizontally. A 4 or 5 element yagi is about the largest which is reasonably portable at 144MHz. An HB9CV is of some use but the main lobe is very wide and the directional bearings can 'squint' due to the unbalanced feed. To correct for 'squint', turn the aerial over, take another bearing then average the two.

It is important to remember that at 144MHz, direction finding in a built up area can give misleading results due to reflected signals from buildings, lamp posts, cars, etc. It is therefore necessary to take a number of bearings from different locations as no single direction bearing can be regarded as reliable. If D/F‐ing from a car, remove any 144MHz mobile aerial before taking a directional bearing as this can reflect signals. It should be noted that Time Difference Of Arrival (TDOA) and ring Doppler direction finding techniques are only suitable for D/F‐ing a coherent carrier and cannot be used on random noise from motors or thermostats.

The 50MHz band is less prone to reflections than 144MHz but the only reasonably portable direction finding aerial is likely to be a loop. Another possibility is to use an 88‐108MHz FM broadcast receiver tuned between stations with a 3 element FM aerial.

UHF bands
If EMI can be heard up to the 70cm band, a 10 element 70cm band yagi makes a good direction finding aerial but at UHF, more care is required to avoid misleading results due to reflected signals.

Finding thermostats
A thermostat which arcs for perhaps 20 seconds every 10 minutes can be most annoying but difficult to find. If it is very close (less than about 30 metres), it may be possible to detect it using a UHF portable TV set with a 10 element UHF TV aerial. The wide TV IF bandwidth is an advantage when searching for a broad band source. The TV set should be tuned to a channel where there is no signal. It is important to make sure that the channel is free of any digital television signals as these look like noise on the screen but with a coarser 'snow' than true white noise. As arcing thermostats are modulated at 100Hz, they produce two darker bands of noise on the TV screen which are darkest when the aerial is pointing at the source. If your portable TV receiver has a video output via a SCART or phono connector, it can be used for locating broad band UHF sources of EMI by tuning it to a channel where there is no signal and listening to the video output via an audio amplifier or crystal earphone. An arcing thermostat produces a distinctive rasping sound which is clearly distinguishable from the background noise. If a suspect gas furnace has a flue which is near the street or near your property, it should be possible to hear when it lights up and switches off, particularly with a fan‐assisted [forced-air] system. If you listen on a portable receiver at the same time, an arcing thermostat will produce a burst of EMI lasting for a few seconds or more each time the furnace turns off and possibly when it turns on.  Going from an old mercury switch to a solid state thermostat “may” fix the problem, or create an new one!

Residential property
If you decide to approach the occupier of a house or flat where you think the source of the interference is, bear in mind that the occupier will probably want to be sure of your identity and your motive before letting you in. It is a good idea to write or telephone first to gain their confidence and arrange a convenient time for a visit. Remember that the source may not actually be where you think it is so you should say that there may be something in the house or flat which is causing interference. In most cases, the only way to prove what is causing the EMI is to ask the owner to switch off various electrical equipment until the source is found. In most cases, there is no fault in the equipment in question and only amateur bands are affected.

A diplomatic approach is therefore essential as the owner of the equipment is under no obligation to do anything about the EMI so it can only be reduced with their cooperation. Any EMI reduction should be restricted to measures which can be fitted by the owner without the need for you to touch or dismantle the equipment in question. In some cases, for example a faulty thermostat, the EMI is likely to interfere with the owner's broadcast radio or TV reception and may affect neighbours.

Commercial or industrial premises
If EMI appears to be coming from an office, shop, factory or other commercial premises, some effort may be required to make contact with the right person. In the case of a large company, there is probably an office services manager, building services manager or technical manager whom you could contact. If you are lucky, there may be a licensed radio amateur working on the site somewhere and he or she could be a very useful contact.

In any case, it is best to write or telephone first and ask to make an appointment to see the appropriate person. With luck and a diplomatic approach, they may be prepared to take you around the site to look for the source. You will need to take a portable receiver as it probably won't be possible for equipment to be turned off.

Reducing the EMI
If you prove conclusively that a certain piece of equipment is producing EMI, it is worth trying to find out full details of the make, model number and date of purchase so that a complaint can be made directly to the manufacturer or importer. A polite and technically well‐informed approach is recommended when dealing with manufacturers. The equipment probably met all necessary standards at the date of manufacture so the only way forward is on a good will basis. The best approach when dealing with manufacturers is usually to phone first and find out the name of the person responsible for EMC then follow up the phone call with a letter, fax or e‐mail. It is also worth finding out whether a newer model is available with reduced EMI. In some cases, the manufacturer may be prepared to provide a filter or exchange the equipment in question for a newer model at a reduced price.

Of course, if none of this works, and you still have an S9 noise floor, you can always move to the country.  A good friend has an “impressive” radio shack out beyond 200th among the cow paddies and he has a S-0 [that’s zero] noise floor, yeah… no noise, none, nada, zilch! And there are so many more stations on his radio than mine. He hears the world – I hear Californian and Texan Kilowatts and OH8X with the world’s largest Amateur Radio antenna!

The original article was written by Gary Skett and appeared in The SARC Communicator in September 2011. 

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Saturday, February 17, 2018

The Ultimate Transmatch

The Communicator Revisited: September 2011

A few participants have asked me about the “Ultimate Transmatch” used at Field Day in conjunction with our “vee beam”.  

This device would today be called an “antenna tuner” which is really a misnomer because the device does not tune the antenna, rather it provides the transmitter with a 50 ohm resistive load by compensating for capacitive and inductive reactance present in the transmission line and antenna.  The SWR protection circuits in modern transceivers require an SWR of 2: 1 or less if they are to deliver the full rated power of the transmitter section. If the forward power is all radiated from the antenna and none of it is reflected, the SWR will be 1:1 which is ideal, but seldom achieved.  

The Ultimate Transmatch became popular nearly 40 years ago when it was introduced by Lew McCoy in QST of July 1970.  It is mainly renowned for its ability to match a wide range of impedances, far greater than the average “tuner”.  In conjunction with the use of open wire feeder which is close to “lossless” compared with any transmission line you can name, it is an extremely useful device particularly when the antenna (in the case the vee beam) is non-resonant, i.e not cut for any particular band or frequency.  I used it at home for several years to match my transmitter to an 80 m inverted vee fed with ladder line, on bands in which the SWR likely exceeded 50:1.  Try that with your average tuner.  The high SWR doesn’t much matter if the transmission line losses are low.   I used the 80 m vee successfully on 80, 40, 20 and 15 m to work the world with 100 watts despite an SWR that was off-scale on my meter.  If my feedline was coax instead of ladder line, the losses would have consumed most of the power and very little would have radiated.  

Alas, the Ultimate Transmatch is no longer considered “ultimate” as the circuit has been supplanted with other variations that are considered superior.  Modification of my unit to a more modern version would be a simple matter, and I intend to do it one of these days.  The figure shows the basic circuit which is a basic T-network with an additional shunt capacitor placed across the transmitter terminals and ganged to the transmitter-side capacitor in such a way that the two capacitors move together.  Its chief disadvantage is that the T configuration is that of a high pass filter, which means that it does little to suppress harmonics or spurious signals that are higher than the desired frequency.  Although not a perfect device, it saved the day for us at Field Day when the MFJ auto-tuner could not do the job.  

Here’s what David Knight G3YNH and Nigel Williams G3GFC say about the Ultimate Transmatch in Impedance Matching. Part 2: Popular Matching Networks: 
"An inauspicious fate awaits anything which presumes to call itself 'The Ultimate'; although to be fair, it was probably so called because of its enormous matching range in comparison to the then-prevalent networks intended for use with co-ax fed antennas. The Ultimate transmatch must now be regarded as an obsolete circuit; but to those who still own and use such units, it should be obvious where to put the wire cutters. With the offending C3 removed from circuit, it should still be possible to match any impedance with occasional recourse to a dual-capacitor matching strategy; and by connecting the spare C3 across C2 it should be possible to increase the efficiency still further, provided that the minimum capacitance does not become too large for matching high-impedance (high |Z|) loads at high frequencies."

VA7XB’s home-built Ultimate Transmatch using roller inductor and two high-voltage variable capacitors, with  SWR meter at left rear and 4:1 balun at right rear.

The original article was written by John Brodie VA7XB and appeared in The SARC Communicator in September 2011. 

Read the entire newsletter at:

Wednesday, January 31, 2018

The February 2018 Communicator

Here is the latest Communicator. In this edition you will find:

Over 50 pages of Amateur Radio News from the South West corner of Canada. This issue focuses on Amateur Radio satellites, especially for beginners. Yes, you too can listen, or work Low Earth Orbit satellites with a homemade antenna and a cheap handheld transceiver.

We'll show you several antenna projects, programming tips and How-To's

You can read or download the SARC February 2018 Communicator
Your feedback is always welcome. My deadline for the March edition is February 20th. If you have news from your Vancouver area club, events or other items of interest please email them to the

Saturday, January 27, 2018

An Ounce Of Prevention

A Communicator Reprise: May 2011

Take a good look around every room in your home, your ham shack as well as outside in your garage, shed and car. Consider all the things you would be sorry to lose or find hard to replace - then mark them.  Particularly as Amateurs, we may have thousands of dollars worth of equipment in our car or home. 

Remember that anything remotely useful or attractive is resalable. For instance, all your electrical and mechanical goods, household appliances, furniture, pictures, ornaments, antiques and silver, in fact anything can be a target of thieves. Garages and gardens sheds are also at risk. Protect your lawn mower and keep your tools locked up. They may well be used by an intruder to force his way into your home! Finally, always lock your car no matter where it is parked and remove any valuables from sight. 

Marking is easy 

Property  Marking  is  a  quick,  easy  Do-It-Yourself job, and it costs so little. For an outlay of only a few dollars and an hour or so of your time you could be saving yourself a great deal of money, inconvenience and personal anguish. 

Permanent Marking 

Engraving and punching identifies your property for good. Inexpensive tools and kits for the job can be bought from DIY  and hardware stores. Improvising by scratching to save yourself the outlay is acceptable but might need a little extra care. 

Invisible Marking 

For antiques or other valuable property which might be devalued or spoiled by visible marking, there's an invisible ultra-violet marker. Burglars cannot see it, but if something marked is stolen police can identify it with a special ultra-violet lamp. UV markers are available from most good DIY stores and stationers at around five dollars. It's important to remember that UV marking fades and will need to be renewed every so often. 

There are three ways of marking

  1. Engraving with an electric engraving tool, fine drill or other sharp-pointed tool. Use a template or stencil or simply do it freehand.  
  2. UV marking the invisible method using an ultra-violet pen. Simple to use - but needs renewing periodically. 
  3. Punching With a hammer and a set of punches bearing marking information.  Use  only  on heavier metal, items such as bicycles, mowers or engines.
Note that aluminum is easily damaged by punching and should not be marked in this way.

What to engrave 

At one time it was suggested that you mark your property with your SIN number. This is no longer the case. Police cannot readily trace SIN numbers, complicating the return of your property. Drivers License (DL) numbers however, can be tracked from any mobile police terminal in seconds! In most cases, police who find property in the hands of suspicious characters will attempt to verify it immediately via the  Canadian  Police  Information  Centre (CPIC) [NCIC in the United States]. Stolen property from across Canada is entered on this system and it can be accessed in seconds. Engraving the DL Province of issue before the number will assist police, for example: BC DL 1234567 

In the case of a business or organization, police agencies in some jurisdictions will issue an ‘Operation Provident’ number. This Program is meant to provide an easily traced number to identify ownership where it is not the property of a single individual. 

Where to mark your property 

Where you mark your property matters, particularly if you are using the engraving method. If you prefer the mark to remain out of sight, you'll obviously choose somewhere behind or underneath the article. 

If you purchase a used item that has been marked, engrave a single line through the previous marking and place your DL number above or below it. The really important thing to remember is to select a surface that can't be removed without spoiling the basic appearance or performance of the article. 

Keep  a  record  of  your property 

You  can  protect  items  that can’t be marked, and those that can, by keeping a record of them. A simple and effective way of doing this is to photograph each item, preferably in colour, paying special attention to any distinguishing marks such as initials or crests which may be used to identify the item. Take the photograph against a plain background and include a ruler to give an idea of size. 

Use the record form to keep a list  of  the  items  you have marked and where the marks are. It’s a good idea to give a second copy of the list and the photographs to someone you trust for them to look after. If you have property stolen, be prepared to provide copies of serial numbers and photos to police. 

Do not advertise your absence 

We all chat on the various repeaters but we do not always know who is listening in. There is no expectation of privacy and the AR bands are open to monitoring by many people including unscrupulous ones with scanners. Mention of your intended absence on holidays may be advertising for those with criminal intentions to pay you a visit. As you know, the licensing database is readily available to anyone with an Internet connection and it takes only minutes to look up your call-sign for your address unless you have asked for it to be withheld. 

For more advice on marking or  protecting  your  property, contact your local police station. 

Monday, January 22, 2018

Amateur Radio: A 21st Century Hobby

Youth Involvement

Surrey Amateur Radio Club Field Day

Getting youth involved in Amateur Radio is one of our most important challenges for the long-term viability of our hobby. There is a great video from the Radio Society of Great Britain (RSGB) that illustrates the exciting aspects of modern Amateur Radio.
Amateur Radio: A 21st Century Hobby

SARC is offering our Basic Licensing course starting April 3rd

Thursday, January 18, 2018

A Long Lasting Battery Backup For Your HT

A Communicator Reprise: April 2011

This is day five of a SEPAR callout and you're at home. Your hand-held radio (HT) battery is out of juice and you have no means of charging it. What you now wish you had is a substantial, fully charged battery to keep your HT operational for the couple of weeks that Hydro is going to take to restore the power.

Where Can I Get One Real Cheap?

Organizations which replace all their Uninterruptible Power Supply (UPS) batteries on a scheduled basis will often give them away. These batteries are typically the Sealed Lead Acid (SLA) type which means no gases escape them (provided you don't overcharge them) and so no particular safety precautions are required re: handling or ventilation as well as no need to add water from time to time. Clubs are often given a number of these batteries which are then made available to members.

What Does It Cost To Keep My HT Going For A Couple Of Weeks?

The battery has to have sufficient capacity. Battery capacity is specified in Ampere-hours, abbreviated Ah. A very common UPS battery is rated at 12 Volts and 7 Ah. What this means is that, theoretically, the battery will be able to deliver: The battery voltage has to match the voltage expected by your HT. Most HTs will work fine with a 12 Volt battery but you will need to check your HT documentation to be sure. For example, some iCom HTs cannot be powered from an external source. Charged - Yes. Powered - No.

How Does This 7 Amp-Hours Translate Into Operating Time?

Let's suppose that in order to ration your battery current consumption you listen for a total of 5 hours per day and that your total transmit time in a day is 1/4 hour.
For my old Kenwood TH28A, the current drain would be as follows:

  • Receiver current drain is 0.075 A (75 mA), loud so others can hear;
  • Transmit current drain is 0.100 A (100 mA), Low power;
To calculate the total ampere hours used in one day:
  • Receive amp hours per day = 0.075 A x 5.00 hrs = 0.375 Ah;
  • Transmit amp hours per day = 0.1 A x 0.25 hrs = 0.025 Ah; 
  • Total amp hours per day = 0.400 Ah

So, number of days you'll be able to use your HT using one of these 7 amp-hour batteries is 7 Ah / 0.400 Ah per day = 17.5 days. If you were to listen and transmit for twice as many hours in the day the battery would last for about 9 days. This is based on the Kenwood TH-28A. The current drains for your HT will undoubtedly be different. Still, this shows that one of these batteries can run an HT for quite a number of days.

OK, I'm Convinced I Need One Of These... What Else Do I Need?

  • A means of charging the battery (BEFORE the power goes off);
  • A cable with a fuse in the middle and appropriate connectors on the ends for connecting the battery to your HT.
The Battery Charger — Doesn't have to be expensive. You will encounter two different types, Trickle charger and "Smart" charger. The very inexpensive trickle chargers will continue to supply a small amount of current to the battery even when it is fully charged. As this is typically more current than needed to keep the battery fully charged, the battery lifetime will be reduced. For this reason, once the battery is fully charged it should be disconnected from the charger. As batteries lose their charge over a period of time, even when not used, the battery should be reconnected to the charger after three months.
The Smart chargers will supply charging current to the battery until the battery is fully charged. At this point, the Smart charger reduces its output voltage so as to supply just enough current to keep the battery fully charged. Consequently, there is no need to disconnect the charger and it will maintain the battery in the fully charged state indefinitely without overcharging it. RP Electronics in Vancouver sells a very suitable Smart charger for about $30. Part # FC-1212B. It charges 6 and 12V batteries. Charging current is selectable. 

Cable - Wire size and type - #18 AWG 2 conductor stranded wire. One red conductor and one black, max 20 feet
Fuse holder - you want an in-line fuse holder with a 5 amp fuse. Put this in series with the red conductor. The fuse is necessary to protect the wire and battery from short circuits. These batteries store a lot of energy so if you short circuit the terminals there's a good chance the battery will blow up and spray sulfuric acid all over the place. So... don't leave out the fuse.
Battery connector - Different batteries have different style terminals so it depends on what battery you get. Most of the ones SARC gets have two metal tabs 1/4" wide and about 3/8" long. A very suitable connector for this is the Pico fully insulated female Quick Connect #1765. It does a good job of covering the metal tab so that if you drop a screwdriver across the tabs it won't short circuit the battery and melt a hole in the screwdriver shaft.
HT DC power connector - Different HTs also have different style power connectors. You will probably need to take the HT with you when purchasing this connector. Some suppliers sell the power connectors with leads attached. This is very desirable as it means you don't have to solder the leads on yourself. As these connectors are quite small, soldering to them is a bit tricky. You MUST make sure that you know which wire is to go to the positive (Red) terminal of the battery and which to the negative (Black) terminal. If you get this wrong you will probably cause serious damage to your HT.
Once your cable is assembled (complete with fuse), you connect it to the battery. Make sure you don’t mix up the positive (RED) and negative (BLACK) connections, plug the other end into the DC In socket of your HT, and you're in business.

How To make This Even More Useful

It would be nice if this same battery/cable combination could be used with another HT or if your HT could be plugged into a different battery. There is a way to do this using Anderson Power Pole connectors. These connectors are used by emergency communicators all over North America so that any radio can be connected to any power source, regardless of what kind of connector is on the radio or power source. To modify your cable to do this, simply cut it in half, install Power Pole (PP) connectors on the free ends and plug them into each other. 

For installation instructions see NOTE The red and black connectors MUST be oriented with respect to each other as shown in the instructions. If you orient yours differently, they won't mate with anyone else's gear. 
To operate your radio from a different power source, separate  the PP connectors on your cable from each other and plug the radio end into the PP connector of the new source. Similarly, to use your battery with a different radio, unplug the PP connectors on your cable and plug the battery end into the PP connector of the new radio.

What If I Don't Have The Necessary Skills Or Tools To Do This?

If there's enough interest, SARC can put on a workshop session during which you make your cable.

Battery Disposal

At some point, your battery won't hold a charge anymore. Any recycler which accepts standard lead-acid batteries (like the one in your car) should accept it - You may even get some money back for it but you shouldn't just chuck it into the garbage.

Additional Information

Technical overview of the batteries we typically get:

Local Parts Suppliers

  • Battery charger - RP Electronics
  • Wire - RP Electronics, Main Electronics
  • Connectors - Canadian Tire, RP Electronics, Main Electronics, Lee‘s Electronics
  • Fuse holders - Canadian Tire, RP Electronics, Main Electronics, Lee‘s Electronics
  • Power Poles - MRO Electrical Supply

 eBay and Amazon have these parts on-line.

Wednesday, January 17, 2018

SARC Pioneers Profiled

Mike Heritage VE7CLE (SK)

The initial Surrey Amateur Radio Club meeting, chaired by Doug Moore, VE7CBM, was held in September 1975 in a classroom at the North Surrey Senior High School. Doug was a teacher at the school and had graduated many new, young Hams from his annual courses. In attendance at this meeting were the founding member VE7's: Doug Moore CBM, Fred Orsetti CJG (now IO), Carl Bertholm CLC, Mike Heritage CLE, Mike Holley AVM, Cary MillerCFC (SK) Vic Medway CON (SK), Cecil Bogies YM (SK), Cory Galbraith CGR, Ken Clarke EZV (now BC), Ron Davies CBT, Ray Sims AXF, Bill Moore BGA, Wayne Horne CNJ, Bob Searle CHB, John Buchanan CTJ (SK), Jim Johnson CSJ (now VA7ET), Al Neufeld CDC, Bill Driscole ARL, Bren McCullough BGM, Lee Hopwood BDZ, Len TAM, and George Cruikshank (SK). Doug Moore was elected President. Mike became Secretary/Treasurer in 1977 and he remained in this position until 1980 he was a very active member of SARC. 

Mike's dad was an amateur radio operator and Mike and his dad spent many hours enjoying contacts on CW and SSB. Ham radio was something Mike thoroughly enjoyed especially the Field Day outings on top of McKee (Monkey) Mountain. The club purchased a generator, a 204BA monoband antenna, and went after first place in Field Day. In addition to finding time to operate the radios, Mike and his buddy Carl VE7CLC, became well known for their ability to provide the Field Day team with excellent food . I'm sure it was the food that helped move SARC into first place in Canada for several years. Mike always provided much fun, laughter and camaraderie during these outings. It was always a pleasure to work alongside Mike on the radio or setting up antennas. He consistently provided a positive approach. Mike was also an accomplished Harmonica player and provided entertainment at several SARC Christmas parties. Mike continued as an active member of SARC and was always ready to help with club projects or help any member who needed a hand.

In the 90's Mike was diagnosed with Parkinson's disease and was forced to retire from his job. On his QSL card he proudly displayed the Parkinson's Logo and he became a very active member of the Parkinson's Society. This was typical of Mike, always helping others needing a helping hand. During the last few years Mike found it very difficult to operate his radio as his hands were not steady enough to handle the  microphone. Not to be deterred, Mike advanced to operating PSK-31 where he made many contacts, but eventually it became very difficult for Mike to continue with any type of radio communication. Mike was a close personal friend who freely gave his time whenever it was needed. 

His Parkinson's made it very difficult for him but he never gave up and for that I will always admire his endurance. Mike spent many hours discussing Parkinson's with my wife, who is also affected, providing her with information and support. My wife and I miss Mike very much and we both feel privileged to have known him for almost 40 years through the good and the difficult times.

I believe all who knew Mike and shared his love of life, the outdoors and amateur radio will agree he was a special person. Mike passed in May 2011 and at Mike's celebration of life memorial many guests paid tribute to his generosity and his warm personality. We take some comfort in knowing that Mike is at peace and free of the stresses associated with Parkinson's.

~ Fred Orsetti VE7IO


Locating Sources Of Noise

A Communicator Reprise: September 2011 At one of our Friday breakfast meetings a conversation came up about how some of us have such a ...