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EGT probe/gauge help please.
by
jackbombay
on 15 Oct, 2007 08:29
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I recall a discussion here about different EGT probes and how some are really sensitive (K type I'm pretty sure) to any changes in the wire that runs from the probe to the gauge, but there is also another type that is far less picky about the wire length.
I need to install an EGT gauge in my westfalia and the longest set of wires that autometer makes for their EGT gauge is 10.5', not long enough. So what other options are there?
Thanks!
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#1
by
KTZed
on 15 Oct, 2007 09:05
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#2
by
jackbombay
on 15 Oct, 2007 09:05
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Ah ha! I found
this,
this, and
this, but that combo costs about $100 more than the autometer version I have purchased :-/
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#3
by
jackbombay
on 15 Oct, 2007 09:11
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Here ya go
http://aircraftspruce.com/catalog/inpages/micro10egt.php
Thats a lot cheaper than the ISSPRO bits and pieces!
When I talked with autometer they were actually fairly rude about the fact that there is no way to make the leads longer tat they would stand behind. I already have the autometer though asI figured longer leads would be no big deal. I can sell the autometer to a friend that needs one for his sprinter, so thats not a big deal.
If the gauge reads 50* off I wouldn't care much, but I'll have no way of knowing if its reading 50* off or 200* off :-/
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#4
by
saurkraut
on 15 Oct, 2007 09:21
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Libbybapa had a couple of miles of this lead wire on ebay a while back. Try sending him an IM.
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#5
by
TD_Bunny
on 15 Oct, 2007 10:16
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Just curious if you have looked at Dakota Digital for EGT gauge/Probe? they seem to have decent prices with a reasonable product but i dont know how they match up with the spruce or autometer.
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#6
by
jackbombay
on 15 Oct, 2007 11:05
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Ah ha! I found this, this, and this, but that combo costs about $100 more than the autometer version I have purchased :-/
Ahh, the amplified gauges can use regular old copper wire :-)
And according to David Marshal the difference in resistance is so small between the official lead wire and plain old copper wire that its irrelevant, I'll measure the resistance between the 8.5' of lead wire I have an 20' of plain old copper wire and go from there.
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#7
by
Baxter
on 15 Oct, 2007 12:54
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I think the jist of it was..
So long as you used EXACTLY the same wire and EXACTLY the same connectors and the wires were EXACTLY the same length, and when crimping the wires didn't protrude from the terminal and tough the toher wires then you are pretty much okay.
It's something to do with how the thermocouple works, junction of 2 metals? and basically if you solder, thats a big no no, but using the same crimps is okay as they cancel each other out, or something.
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#8
by
Baxter
on 15 Oct, 2007 12:58
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Oh, and the UK's Aircraft Spruce type place is Airworld UK, they just send you any old electrical flex as an extension for their thermocouples.
just to add to the conundrum.
:lol:
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#9
by
Baxter
on 15 Oct, 2007 13:03
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:lol:
I think I'll just buy a fast car, already done!
All this is making my head hurt!
:lol:
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#10
by
jackbombay
on 15 Oct, 2007 21:57
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Well, I checked the resistance of copper wire to the resistance of the 2 wires that came with the EGT gauge and they were way different, which is completely meaningless, but it was enough to make me order the ISSPRO gauge so I don't have to worry about it at all, accurate for sure, $50 more than the autometer and I can sell the autometer one easily enough.
Thanks for the advice guys!
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#11
by
jauguston
on 10 Nov, 2007 21:39
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The Isspro gauge doesn't care how long the wire is. I have 48' of wire to the sender on my motorhome. I called them and they said just use 18ga copper wire and you are good to go.
Jim
New member installing a 1.6 TD in my '87 Samurai.
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#12
by
jauguston
on 11 Nov, 2007 08:12
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What research would be more reliable than the telephone discussion I had with the tech support person at Isspro?? Please don't tell me to see some opinion of a self-appointed internet expert.
Jim
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#13
by
jauguston
on 11 Nov, 2007 09:05
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Andrew,
I am a little bit confused by your response. Are you trying to say that the tech support person at Isspro gave me wrong information? Some long class A motorhomes have Isspro thermocouple wires up to 55' long and they work fine. I have three of their pyrometers each with different length wires to the thermocouple and all work fine. I consider Isspro to be a very good product and have quite a few of there instruments.
I am always willing to learn.
Jim
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#14
by
Vincent Waldon
on 11 Nov, 2007 10:37
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Are you trying to say that the tech support person at Isspro gave me wrong information?
If they told you to use any old 18ga wire as an extension, then yes, IMHO, they are wrong.... assuming they were talking about extending between the thermocouple and the amplifier (my ISSPRO has an amplifier). If they were talking about between the amplifier and the gauge (the four wires) then they are correct.
Here's what a typical manufacturer of thermocouples has to say on this subject;
If you need to increase the length of the leads from your thermocouple, you must use the correct type of thermocouple extension wire (eg type K for type K thermocouples). Using any other type of wire will introduce a thermocouple junction. Any connectors used must be made of the correct thermocouple material and correct polarity must be observed.
(taken from
http://www.picotech.com/applications/thermocouple.html which is a great one-page primer on how thermocouples work and design considerations when using them).
Perhaps the guy on the phone was thinking about the amplifier wires, or perhaps was misinformed, or uninformed.... after all, he's in the gauge business rather than the thermocouple business.
Vince