Author Topic: Doubleducer II - transducer surgery  (Read 13599 times)

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Offline Rickard

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Doubleducer II - transducer surgery
« on: July 05, 2011, 05:07:20 PM »
Hi,

The second Doubleducer is on it's way, the first is described in the thread 'Longer array and narrower beam'.

One of the SI transducers (XHS 9 SI 160 T) is, I hope, the worst specimen that has ever left the HB factory. Left SI element array is 20 degrees away from the specification. The array touches the copper shield inside the housing causing (luckily harmless, though) short circuit. The two downward discs seem to have been swimming around randomly before the epoxy fill hardened.

The other transducer seems ok. The fill is darker and harder in this transducer so there seems to be changes done to the designs from time to time. I really, really hope that HB has better control on quality now!! A shining outside with a protecting tape signals high quality - where...??

These deficits would have been serious if the transducer had been used for it's original purpose, but the severely displaced left SI array makes it hopeless to make a Doubleducer without dramatic surgery. So I cut of the left part of the transducer without cutting the wires and turned the SI array piece nearly 20 degrees towards the specified inclination. I worked for 12 hours before I was done (damn hard to cut in the resin). The Doubleducer II is soon ready for test on water. A dry test showed it operates well this far.

Rickard


As usual, almost impossible to attach images in this forum.

The patient.
ila_rendered

 
« Last Edit: July 05, 2011, 05:14:13 PM by Rickard »


Offline Bob B

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Re: Doubleducer II - transducer surgery
« Reply #1 on: July 05, 2011, 07:22:56 PM »
Rickard,
I find your discoveries of poor transducer quality control to be far more concerning than many other issues that are posted.
If you assume your disassembly of the transducers to be a valid random sample, the rate of poor quality is very high.

I have wondered for some time if transducer inconsistencies could be as much of an issue as installation variables.  It is not good to wonder if your image quality may not be as good as it should be because of poor transducer construction.

Greg was going to follow up on this when you built your first doubleducer.  I would  really like to see some feedback from HB about this.  :-\
**Looking for the one that makes it all worthwhile**

Offline Rüdiger

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Re: Doubleducer II - transducer surgery
« Reply #2 on: July 06, 2011, 03:41:21 AM »
Hey Rickard

Let us hope, as the transducer was a Monday product, but is HB relay the manufacturer ?
Is it not possible to use a transducer from a other manufacturer ?

mvh
Rüdiger

Offline Rickard

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Re: Doubleducer II - transducer surgery
« Reply #3 on: July 06, 2011, 06:22:11 AM »
Bob,

Yes, the transducer quality is critical for the overall performance, but in defence of HB I must stress that wave theory is rather forgiving and there is no point in wasting resources to reach best achievable internal precision. The downward elements can be allowed to be displaced (different inclinations) up to 2 mm (1/12") without any practical consequences at all. The effect of wrong inclination in my left SI array would, at 455 kHz, be a wide, dark and fuzzy stripe (trajectory of 'the first null') unusually far from the bottom profile in the left SI view. This would have caused some adjustment issues when mounting the transducer. The transducer is probably usable for fishfinding and sidescanning, but with reduced image quality. A beginner would perhaps never discover any deficiencies. That said, I think HB use a risky manufacturing policy if they allow such displacements on purpose.

Rüdiger,

Yes, I'm sure HB build their own SI transducers. It's possible to use any transducer with the appropriate specifications. But the only transducer I'm aware of is the Lowrance LSS-1 and then you need to solve some interfacing problems.

Regards and Vänliga hälsningar
Rickard

Offline abraquelebout

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Re: Doubleducer II - transducer surgery
« Reply #4 on: July 06, 2011, 03:05:42 PM »
hi Rickard
what type of tool are you using to cut your ducer ?
next winter i think that i begin to construct a double ducer, for using in sea, in 455 khz  it's the better solution, in 800 khz there's more noise and the scan is bad
wainting for picture of the RDD2 (Rickard double ducer 2) ;)

Offline Rickard

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Re: Doubleducer II - transducer surgery
« Reply #5 on: July 06, 2011, 07:36:54 PM »
Thanks Abra,
for the RDD2 concept  ;). This doubleducer is actually similar to the one I built this winter. I need a hull mounted ducer for shallow water scanning. The first doubleducer goes with the towfish all the time. I also wanted to test if it's possible to succeed with simpler methods, but as you see the second ducer presented more issues than the first did.

I use simple tools like a wood saw and a hacksaw. The large downward elements were closer to the edge than I expected, so I had to cut through a section of one of them. It was possible to do with the hacksaw, but it took some time. The piezos feel like brick or tile when when I cut them, they seem very brittle. The most time consuming part has to do with adjustments. It was very difficult, and I still don't know if I succeeded, to carve in the left array piece to correct inclination and position.

First test in/on water is tomorrow, I'll be back  :)!

Regards,
Rickard

Offline Rickard

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Fraud??
« Reply #6 on: July 07, 2011, 05:19:36 PM »
I tested Doubleducer II on water today and found that right SI channel in the ducer that seemed ok for the eye doesn't work at all. There is a short circuit between ground and the plus wire which causes no image at all in the left view in the Doubleducer. At first I thought this was my fault, but very thorough search for the explanation, involving break up of the doubleducer and cutting of the transducer wire and control of resistance between all electric components inside the ducer, shows that the fault was there from the beginning. UNFORTUNATELY I didn't check for short circuits in that transducer before I cut off the rear part so I can't claim the warranty. But, since this check is simple I take for granted that this was done on routine at the HB factory and that the specimen was discarded, still this transducer was sent by someone (probably by an individual, not the HB company, but packed in original boxes) to the market.............???? :-\ :-\ :-\

Now I'm sitting with two deficient SI transducers without any chance to claim any warranty and feel I will be much more careful before I buy HB components from an American eBay dealer again. I will get these things to work in the end because I know how to do it, but what about the regular customer, he/she will have to take the uncomfortable fight with the transatlantic seller or just resign and look for better brands?

I have notified the dealer about my experiences and my suspicions.

Rickard
« Last Edit: July 07, 2011, 06:32:00 PM by Rickard »

Offline Bob B

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Re: Doubleducer II - transducer surgery
« Reply #7 on: July 07, 2011, 08:49:17 PM »
That is really bad luck Rickard....Sorry to hear about your lost time and expense.

I have had issues with E-bay items myself and have stopped shopping there unless I am looking for something that can't be found somewhere else.
**Looking for the one that makes it all worthwhile**

Offline Rüdiger

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Re: Doubleducer II - transducer surgery
« Reply #8 on: July 08, 2011, 04:48:29 AM »
Hey Rickard

Very pity :-X, i hope HB may be obliging.

mvh
Rüdiger

Offline abraquelebout

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Re: Doubleducer II - transducer surgery
« Reply #9 on: July 08, 2011, 05:43:57 PM »
 ::) hi rickard
your experience tel me one thing
in first, before cutting the ducer i must test int in the normal condition...
a good news for me
i search a wreck of a 1924 four masted steel ship, i find it, i dive on it past week...intence emotion
nobody know where is these wreek since 1924 beautifull...yes whe scan
i join picture the wreek measure 90 m...
ila_rendered

Offline Roddy

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Re: Doubleducer II - transducer surgery
« Reply #10 on: July 08, 2011, 06:53:29 PM »
Abra; Nice job!! As allways your work is wonderfull. Roddy
Scan,Scan and Rescan Roddy

Offline Rickard

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Re: Doubleducer II - transducer surgery
« Reply #11 on: July 09, 2011, 06:09:47 AM »
Fantastic, Abra! Which frequency did you use? How deep is it at the location?

Rickard

Offline abraquelebout

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Re: Doubleducer II - transducer surgery
« Reply #12 on: July 09, 2011, 08:12:00 AM »
hi rickard
i use towfish, 60m lengh cable, 455 khz and the deep is ....10 m
the wreek is on rocks, it sunk in  2 dec 1924 on storm, it full of 4000 tons nitrate from chille
at 6 at noon he goes on rocks and the 3 dec there's no trace of it
this ship is wreek legend on my country and nobody as seen it before.
if you go on with a normal sounder you don't see anything exept rock
the towfich make difference like these wreek find in 2009
ila_rendered
picture take in 2010
deep 20 m towfish, 85 m cable, 455 kz
nobody find this because there's rock and you can't make difference between wreek an rock
towfish made it  ;)

Offline PT

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Re: Doubleducer II - transducer surgery
« Reply #13 on: July 10, 2011, 01:06:14 AM »
Abra,

Excellent work.

We have just located the wreck of a small coastal steamer that disappeared off the coast of Victoria (Australia) in 1934. All crew were lost. The families of the crew have been in contact and are most appreciative in knowing where they now rest. See us at: http://www.southernoceanexploration.com/

Also Rickard,

Would a double-ducer work with a 797?

I would like to improve the images that I'm getting by making another 30 metre extension.

Best regards to all

Peter

Offline Rickard

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Re: Doubleducer II - transducer surgery
« Reply #14 on: July 10, 2011, 03:33:42 AM »
Peter,
Yes, it should be possible to make a Doubleducer for the 797. However, as Greg wrote, the 797 lacks 262 kHz capability so the best choice would be to join two XHS 9 HDSI 180 T transducers for best image at 455 kHz. You can't expect to see much difference at the unit display while on water, but there will be a visible improvement as you replay on a computer (e g HumViewer). (Don't forget to check the transducers as thoroughly as you can before any abuse... ::) ). A 30 m extension should work fine.

I took a quick look on you projects, do you use the 797 in your searches?

Rickard
Modified with change of recommended transducer to XHS 9 HDSI 180 T.
« Last Edit: August 13, 2011, 04:04:01 AM by Rickard »

Offline PT

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Re: Doubleducer II - transducer surgery
« Reply #15 on: July 11, 2011, 05:47:53 AM »
Rickard,

We use a variety of remote sensing equipment, which include a magnetometer, Deep Vision sidescan, Burton sidescan, and for shallow water work my 797.
The most important part is the research conducted before we head out. The last site took about eight years to find, and about 15 square kilometres of seabed covered. We can now look for our next target: a small paddle steamer.

Regards

Peter

Offline Rickard

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Re: Doubleducer II - transducer surgery
« Reply #16 on: July 19, 2011, 05:46:08 PM »
I have carved out the wires close the front of the right SI element and located the short circuit. It was caused by contact between the plus wire and the foil shield a few mm before the element. I removed the foil and joined the tranducers into a Doubleducer for the second time. No sign of short circuits so far. The short circuit was intermittent so HB may have missed it when testing before delivery. I have to wait a few days for the second (final?) test on water.

Rickard

Offline Jolly Roger

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Re: Doubleducer II - transducer surgery
« Reply #17 on: July 20, 2011, 06:46:40 AM »
Nice job Rickard!

Keep us posted about the results.

Regards from the sandbox / Harry
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Offline Rickard

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Re: Doubleducer II - transducer surgery
« Reply #18 on: July 21, 2011, 01:48:32 PM »
Thanks Harry,

I tested Doubleducer II on water today and the results appear to be as with the first Doubleducer (whew...). It may be my imagination, but the left side, the side that took most of the surgery, seems to have a bit better resolution than the right side. The change of impedance due to the increase of element mass reduces the signal level at 455 kHz, but there is no visible reduction at 262 kHz. I can test such things with the new Doubleducer because I can connect them individually.

The image shows the cured patient.

Rickard

ila_rendered
« Last Edit: July 21, 2011, 02:46:04 PM by Rickard »

Offline Roddy

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Re: Doubleducer II - transducer surgery
« Reply #19 on: July 21, 2011, 02:44:17 PM »
Nice! :)
Scan,Scan and Rescan Roddy

Offline Rickard

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Re: Doubleducer II - transducer surgery
« Reply #20 on: August 11, 2011, 01:31:55 PM »
After solving the data loss issue by using an older memory card I could do a controlled test of the poor Doubleducer. I think the patient has recovered very well. I scanned over the same area with the Doubleducer and a standard transducer at 262 and 455 kHz using the same settings in the unit. The images from Humviewer are as they came out without any adjustments.

To me it's rather easy to see which one is best...

Rickard

The conditions are indicated in the file names. One must open the image files to really see the differences in resolution.
« Last Edit: August 11, 2011, 01:35:57 PM by Rickard »

Offline Rüdiger

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Re: Doubleducer II - transducer surgery
« Reply #21 on: August 11, 2011, 02:12:09 PM »
Hi Rickard

Very good results, but unfortunately not option for everyone, we can only hope that HB developed its transducer.

mvh
Rüdiger

Offline Rickard

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Re: Doubleducer II - transducer surgery
« Reply #22 on: August 11, 2011, 02:48:23 PM »
Thanks Rüdiger,

But I disagree, anyone with a bit of patience (and better luck with quality than I had), and of course a wallet that allows for the costs can do this.

Hälsningar
Rickard

Offline abraquelebout

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Re: Doubleducer II - transducer surgery
« Reply #23 on: August 12, 2011, 12:34:55 PM »
hi rickard (the ducer doctor)
nice work, i'm waiting this winter, and money for my future double ducer
now i'm scaning in salt water,
if 800 khz is not practicable in salt water because more noise etc on depht, the double at 455 may be the solution
now i'm on holidays, and the program is scaning, diving for archeology and surfing.
in 4 weeks whe close the search for this year in salt water archeology......may be the super wreck ;)


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