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Offline Alan HassellTopic starter
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« on: November 27, 2009, 10:14:43 am »
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    FISHER IMPULSE TEST REPORT.

BY ALAN HASSELL

 
Copyright 20/8/94

 
The Fisher Impulse.

Fisher metal detectors, are the oldest manufacturer's of Commercial metal detector's in America and one of the most respected. In 1931 Dr. Gerhard Fisher produced the first Metallscope, a rugged easy to use metal detector. Consisting of two large wooden boxes, containing 5 vacuum valves, assorted batteries and components.

Although primitive and clumsy by today's standards this device soon to become known as the M-Scope captured the imagination of the country. In 1937, Dr. Fisher was granted the first patent for a metal detector in America. His products were much sought after by geologists, for locating ore bodies, utility companies for finding buried pipes and treasure hunters.
During the Second World War and the Korean conflict the company produced metal detectors for the military for detecting mines buried by the enemy. Other manufacturer's began producing similar devices. Fisher's continued research and development in the metal detecting industry assured them of lasting success.

They produced the Aquanaut or 1280X one of the first underwater metal detector's which proved to be a popular addition to their range. In 1985 Fisher Research Laboratories began developing a new Pulse Induction Metal Detector. Unlike Induction Balance detector's Pulse machines are more difficult to manufacture owing to complexities of circuitry. The first prototype was built in 1986, just to convince Jim Lewellen, Fishers boss it worked.

Early Pulse Induction did have their drawbacks and inherent disadvantages. All could be overlooked by the serious user because they know no other type of detector was capable of the depths and penetration advantages that Pulse Induction offered. Early Pulse detectors were slow to respond to targets, and needed constant retuning. All Pulse Induction machines are noted for their high battery drain and loss of depth as power decreased.

Motion pulse detectors needed the coil to be constantly in motion making pinpointing difficult and target recovery a problem. To be competitive in the market place Fisher's research technician's patiently recreated the pulse overcoming these early obstacles.

Released under the name IMPULSE, it is the Worlds first P.I. featuring a liquid Crystal Display for constant monitoring of signal and battery intensity. Fishers radical circuitry gives you over 100 hours use from 8 Alkaline penlight AA cells. Other machines only give 10-12 hours use from Carbide batteries and 40 hours from Alkalines. When a manufacturer makes such a spectacular breakthrough such as this, it is apparent that Pulse has been re-invented.
FIRST IMPRESSIONS.
At first sight you could be forgiven for assuming that it is a 1280X,(AQUANAUT) which it does. Only when you look at the front of the Control Box do you notice the liquid crystal display. The instruction book provided is perhaps one of the most comprehensive well written manuals, I have seen for a long time.

The Impulse comes complete with a lockable high impact (Samsonite) type foam padded carry case. this protects your new detector during transit, from inevitable scratches it would sustain without it. Having saved hard to obtain a new machine, the owner might want to protect and preserve it in pristine condition. Appearances go a long way whenever a person is purchasing either a new or second hand detector.

Keeping your machine in immaculate condition will preserve it's desirability and make a rapid sale later. Fisher could be accused of going to extreme's with the Superb Impulse Presentation, however, it is a top end underwater detector designed for professionals. Justifying its presentation is simple, prevention is better than the cure, detectors are delicate instruments, it pays to look after them.

The Impulse is already assembled, except for the coil, fitting this to the stem is a simple job and your in business to start detecting. Fisher make two coil configurations 8 or 10 and a half inch coils, they are not interchangeable and you have to order either one or other. Personally, I prefer the larger coil it gives you better depth without losing too many small signals.

Both coils are spider and only half an inch thick making them very light and streamlined in the water. The Impulse can be used in three configurations, for diving, wading or shallow water detecting or you can use a special hip mount device to use it on the wet sands. You simply remove the control box from the stem slip a belt through the slot on the rear of the housing and your in business, nothing could be more simple than that.

 Batteries are stored in a separate compartment at the rear of the control box. A custom built, moulded gasket ensures a watertight seal down to 250 feet, more than the average user would ever require. I advise you to use a thin coating of silicon grease before you use it in the water. The actual control box is factory sealed and should only be touched by experienced engineers, tampering with it could not only cause damage but also cancel out your warranty. If you have trouble leave it to the experts.
CONTROLS.
There are only two controls, the combined battery check, tuner on the left volume on the right. The LCD (liquid Crystal Display) is situated between the two controls. Turning the volume control to the right will switch the Impulse on and the bar graph of the LCD appears on the screen. At the same time a loud squeal can be heard from the headphones, you are advised not to put the headphones on your head until after you have turned the unit on. You can do your adjustments once that initial shock wave has gone.

With the headphones over your ears, turn the volume to full, you can adjust it for comfort later. The tuner governs the threshold much the same as it does a VLF. The higher you turn the control the higher the threshold and sensitivity. I should add here, that if you have the threshold tone up too high it could mask out weak or faint signals. As you increase the threshold, the bar graph responds according to how high this control is turned up.

Recommended factory setting is for two bars to be present on the LCD for optimum performance. The tuner gives you greater control over your Impulse, simply because if you go over a large target you can decrease sensitivity. Sometimes you may find a large target is in fact several small targets all bunched together. Because you were able to decrease sensitivity you are able to isolate each and every one.

Something you cannot do with many other PI machines being sold on the open market. It's a great feature especially if your trying to work in a heavily contaminated area. I often wonder how many of those large targets I walked away from, were clusters of smaller targets that I couldn't be bothered to dig. The headphones are completely submersible, and have a special drain plug to enable them to flood when diving. But if you are, you are advised to place the headphones on your head once your under the water, remember equalization or embolism.

The headphones are pietzo electric type with the sound coming out of both sides and are supplied as standard equipment. During use a VCO (voltage controlled oscillator) is used to increase the pitch and tone of the signal as the search coil passes over the target. Pulse Induction machines are not affected by salt water or Black mineralized sands. Salt water is conductive, as such it enhances the depth and magnetic fields given off by the coil.

As a point of interest voltages in excess of 450 volts are developed within search coils of Pulse Induction machines. The Impulse is a non motion pulse detector, this means that you simply find the loudest part of the signal and you should be right over the centre of the target. Fisher state that target response is fast, they are being highly modest, conservative and unpretentious, it has the fastest response time of any PI on the market.

In one test with my good buddy and detecting partner Mick Killeen present we moved a gold ring back and forth across the width of the coil as fast as we could possibly make our hands move, The Impulse responded every time never missing a beat. Now that's what we call fast. This means that if your in the water and go over a target you will get your response if there's a target present. Putting my name and reputation on the line, I'd go as far as to say the response time is just as fast as any VLF detector.

Motion PI detectors are fast, but you have to keep the coil moving to pinpoint. Slow responding PIs can miss targets simply because the user is moving the coil too fast over a target. There is simply no way this can happen with the Impulse, remembering of course that the coil puts out a decreasing cone shaped pattern. Provided, your coil goes over a buried object it will respond.

IMPULSE ON TEST

Through my own choice I live almost next to Port Phillip Bay in Melbourne. For myself it's ideal living so close to the beach, five minutes and I'm in the car park already kitted up and ready to get into the water. July and August are our coldest months, and the chill factor when a southerlies blowing is enough to force you out of the water despite having a nice thick wet/dry suit on.

Testing new machines, or any U/W machine takes a great deal of concentration and time.
P.I. detectors are a special breed of wildcat that takes time to train. Like dogs, you have to familiarize yourself with the animal, patiently training it until it becomes obedient and responds to your commands. Detectors are the same, you just don't get the best out of a machine the first time you use it.

There's the element of excitement, who doesn't get excited the first time you get into the water with a new machine. As luck would have it, the day I received my Impulse, the sun came out and the wind was blowing off shore. Conditions were ideal, the Bay was flat as a mill pond. Despite the cold, I had travelled to one of my favourite places that has not only been very kind to myself but many others now involved in shallow water metal detecting.

This particular beach had produced the largest ring ever to come out of Australian water's weighing 42.5 gram's of 22 carat gold. It only takes a few seconds to connect the coil to the search rod with the nylon nut and bolt and I was ready to get into the water. Once in the water, I first turned on the tuner before turning on the volume on/off switch. I had read the book and didn't want to get my ears blasted when doing the battery check.

As I ventured into deeper water, I was continually retuning the tuner control trying to keep it on the two bars recommended by Fishers. Although manufacturers recommend this setting, I felt the signal was up too high and would mask out faint or deep targets. I say this because I held the coil on the bottom as I tuned the machine but when I raised the coil off of the bottom to start scanning the threshold increased.

The instruction book states quite emphatically in several places that the threshold tone will go up and down in tone as you sweep the coil back and forth. this is a perfectly normal response since the distance between the coil and the bottom varies as you sweep your coil back and forth. I experienced this whilst going over tidal ripples that you sometimes get on the bottom. The manual states you can adjust the threshold to maintain a conformable average.

Once I got into the deepest part of the channel I reduced the threshold tone down so that it was only just audible with only one bar showing on the LCD. I found I was able to grid the channel once I had reduced the threshold and it wasn't long before I started to recover some decent targets such as coins.
Once a target is detected under the coil, the signal can be described as a growl, near surface targets sound like a screaming banshee.
I was amazed how sensitive the coil is, I had to drag my scoop further behind me that I would normally do with other machines. If my scoop came too close to the coil the Impulse would let me know about it. The Impulse is slightly buoyant which means it floats beside you while your digging your target out of the hole.

Although the coil is buoyant, no effort is required to keep the coil on the bottom and effortless searching can be experienced. Diver's can use a special clip on weight to stop the Impulse floating away whilst on the bottom, this accessory is available from Fishers. You will not need it for shallow water work though. Reducing the tuner on large targets works fine leaving a sharp single sound in the case of aluminium can bottoms of which there are many on every beach owing to youths taking cans into the water on a hot sunny day.

Finally with a few dollars in my goodie bag, no rings this time but a nice gold plated bangle and small silver Scorpio medallion and chain the cold overcame me and I was forced to retreat to warmer area's. Day two started off with a visit to Mick Killeen, I took the Impulse along to let him have a butchers hook (look).
Mick was suitably impressed and he went over it with a fine tooth comb so to speak. I have to agree with him, it was his words not mine, that it is no Micky Mouse toy dolled up to be something it's not. It pay's to have second opinions because writer's can be accused of being biased.

I attempt to judge any product in an unbiased manner, I firmly believe that one should report the good as well as the faults of a product even if the manufacturer or retailers who are only interested in profit might disagree with me. After several hours and a few beers together I left Mick full of envy, he has now got to try to convince his wife she needs a new birthday present. Something like giving her an electric drill as a xmas present I suppose.

So it was down to the beach and back into the water. Long beaches are not the easiest to search, I went a long way trying to find a channel or hollow that had been scoured out by the currents. So I went to another area and bingo started to get targets. The light was fading, so I decided to just dig out as many targets as I could and leave them in my sieve.
They wouldn't go away and there were so many targets I had to make hay while the sun shone so to speak. Coin after coin after coin appeared in my sieve as I placed another scoopful of sand into the sieve. Then all of a sudden, a glint of gold appeared, it's an unmistakable sight you never forget.

I had to stop detecting and took hold of it, you little beauty, a fine 18 carat gold ring sporting a huge 2 carat sapphire stone. Later valued at $2000, no time to stop, I put the ring in my neck pouch and continued to find target after target. There was no way known you miss one, I had turned the tuner down so much I was working in silent mode, the way I work with my Gold scan. If there's a target the Impulse will detect it.

My sieve was at this stage so overcrowded with stones the weight was beginning to drag it under. There were too many coins to even count the gold started to appear, first a tiny religious medallion then 2 nice wedding bands shone through an earring, an el-cheepo dress ring and finally the tiniest little girls ring I have ever found.

The sun was setting on the horizon, I didn't have a torch and I didn't like leaving a productive area. I had done well and had been invited to a BBQ at Micks that night so you can imagine his reaction when he saw my finds for the few hours I'd been in the water. Whilst we were together we did some tests against other PI detectors we both had and I hate to say this but the Impulse does have the edge over the other machines which was the reason for my success that day.

I reasoned that the extra depth plus high speed target response was the main reason for my success that day. It is also reasonable to state that no matter how your machine is, you will not find gold if the sand is too deep in the first place. One should remember in the beginning we had the wheel, then the steam engine, finally the car.

Without technology, we would all be driving around in steam engines. The same principle applies to metal detector's, if they had there might not be anymore goodies to find. The Impulse is without doubt the most amazing machine available today. Fisher have re-invented Pulse Induction it will improve your find rate. It's guaranteed for five years and is the best investment you could make, one that will return it's initial investment with pleasure, leisure and TREASURE.

I spent 3 years bashing the bush chasing gold. Since I got into the water in 1980, I have never looked back. It's the one place where gold deposits continue to be made year after year after year. You don't even need a miner's right. The magic of the Impulse is not in it's name but it's fast response time and power it develops. If you have not got one then I'm sorry, you'll be missing those golden targets.

The above article was published in Australian Gold, Gem & Treasure Hunting Shortly after this appeared a well known writer wrote a test report for a Treasure Hunting Magazine in the UK. He claimed he had tested the Impulse against several other machines by digging a hole in the ground, burying a coin and then detected the coins. Whilst this might sound like a good idea it's not so practicable.

The moment anyone digs a hole they disturb the natural mineralization of the ground. It is physically impossible to return the area as the same before it was disturbed. Objects buried in the ground for a long time tend to have what's known as a halo effect, this allows objects to be detected deeper. I also have in my collection the same detector this writer used for his test as a comparison. This mans test were inconclusive and did not give a fair representation of what the Impulse could do.
I found out later from John Castle of Joan Allen metal detectors in the UK that this Man who writes under the name of Willie the Wizard had asked them to give him a machine and he would write a favourable report.

This request was refused so the man wrote an article favouring another machine. I personally challenged the individual to a dual in the Water, I would use the Impulse, he could use whatever machine he had used to do his tests with. This offer was declined.
As I have stated in articles before, it doesn't really pay to make test comparisons against other machines. There is always someone around the corner just waiting to shoot you down in flames.
That writer's name and credibility is now questionable. Each individual product put onto the market available for the buying public took time to develop before finally going into production.

Manufacturer's do their own tests to be competitive in the market place. The Impulse is a very popular machine in Australia, the people who own and use them found the Impulse to recover more targets that any machine that was available. Ask an Impulse owner what he thinks, don't rely on my writings, maybe they know something I don't, one thing is for sure, they wouldn't be using an Impulse, if they were not finding goodies. happy hunting

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Offline marks231
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« Reply #1 on: December 14, 2009, 07:41:48 am »
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Thank you for a great reveiw.

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« Reply #2 on: January 10, 2010, 02:09:41 pm »
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Good reveiw.

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