---------------------------------------------------------- Avionics-List Digest Archive --- Total Messages Posted Fri 02/05/10: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:47 AM - Re: Thermocouple compatible bulkhead connector? (Noel Loveys) 2. 08:07 AM - Re: Thermocouple compatible bulkhead connector? (Ron Quillin) 3. 08:37 AM - Re: Thermocouple compatible bulkhead connector? (Kevin Carey) 4. 10:50 AM - Re: Thermocouple compatible bulkhead connector? (John Loram) 5. 10:55 AM - Re: Thermocouple compatible bulkhead connector? (John Loram) 6. 11:57 AM - Re: Thermocouple compatible bulkhead connector? (rampil) 7. 11:59 AM - Re: Thermocouple compatible bulkhead connector? (Noel Loveys) 8. 01:29 PM - Re: Thermocouple compatible bulkhead connector? () ________________________________ Message 1 _____________________________________ Time: 07:47:51 AM PST US From: "Noel Loveys" Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector? John: My advice would be to just use a grummet. The wires on thermocouples have to be a consistent types of metal from the couple itself to the instrument. Finding a multi pin bulkhead fitting in the exact correct metals may be difficult if not impossible. If your plane is certified be sure to follow AC43 for specs on cable supporting. Noel -----Original Message----- From: owner-avionics-list-server@matronics.com [mailto:owner-avionics-list-server@matronics.com] On Behalf Of John Loram Sent: February 3, 2010 7:33 PM Subject: Avionics-List: Thermocouple compatible bulkhead connector? Does any one know of a source (other than Omega) for multi-pin bulkhead connectors that are compatible with Type J & K thermocouples? I wiring the firewall foreword... thanks, -john- ________________________________ Message 2 _____________________________________ Time: 08:07:13 AM PST US From: Ron Quillin Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector? At 07:47 2/5/2010, you wrote: >The wires on thermocouples have >to be a consistent types of metal from the couple itself to the instrument. I don't believe as stated that's entirely true. A voltage is developed across a junction of differing metals, that's why a TC works, but... If a transition is made from conductor metal type A, to conductor metal type B, we'll assume some voltage +E is developed. However, when transitioning back from conductor metal type B to conductor metal type A, voltage E is again developed, but it is now -E. When both transitions are at the same temperature, the voltages cancel one another out and minimal if any error voltage is generated. We do this all the time in a thermal-vacuum chamber used for NASA satellite/spacecraft verification all the time and it's quite acceptable; assuming the transitions are at a constant or nearly so temperature. While the instrument within the chamber is cycled from ~ +85C to ~ -100C, the transition connector remains near ambient ~ +22C. Errors are minimal and well within acceptable limits. Ron Q. ________________________________ Message 3 _____________________________________ Time: 08:37:41 AM PST US From: "Kevin Carey" Subject: Re: Avionics-List: Thermocouple compatible bulkhead connector? Have you checked with the manufacturer of the EGT/CHT system you're using? I have an EI UBG-16 and when I checked with EI, they didn't have a problem with using a standard multi-pin connector at the bulkhead. There are already two pretty common looking multi-pin connectors in the harness for the EGT and CHT leads installed at the factory. Kevin ----- Original Message ----- From: "Noel Loveys" Sent: Friday, February 05, 2010 10:47 AM Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector? > > John: > > My advice would be to just use a grummet. The wires on thermocouples have > to be a consistent types of metal from the couple itself to the > instrument. > Finding a multi pin bulkhead fitting in the exact correct metals may be > difficult if not impossible. > > If your plane is certified be sure to follow AC43 for specs on cable > supporting. > > Noel > > -----Original Message----- > From: owner-avionics-list-server@matronics.com > [mailto:owner-avionics-list-server@matronics.com] On Behalf Of John Loram > Sent: February 3, 2010 7:33 PM > To: avionics-list@matronics.com > Subject: Avionics-List: Thermocouple compatible bulkhead connector? > > > Does any one know of a source (other than Omega) for multi-pin bulkhead > connectors that are compatible with Type J & K thermocouples? I wiring the > firewall foreword... > > thanks, -john- > > > ________________________________ Message 4 _____________________________________ Time: 10:50:02 AM PST US From: "John Loram" Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector? You're quite correct Ron. Somehow I had failed to notice that I would be creating two, opposite polarity junctions that would be "isothermal"... Now, I just need to find a cheap source for mil spec circular connectors (MIL-C-5015). Anybody have a favorite source? I need a bulkhead and plug connector with 24 pins for the thermocouples. thanks all for comments, -john- _____ From: owner-avionics-list-server@matronics.com [mailto:owner-avionics-list-server@matronics.com] On Behalf Of Ron Quillin Sent: Friday, February 05, 2010 8:07 AM Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector? At 07:47 2/5/2010, you wrote: The wires on thermocouples have to be a consistent types of metal from the couple itself to the instrument. I don't believe as stated that's entirely true. A voltage is developed across a junction of differing metals, that's why a TC works, but... If a transition is made from conductor metal type A, to conductor metal type B, we'll assume some voltage +E is developed. However, when transitioning back from conductor metal type B to conductor metal type A, voltage E is again developed, but it is now -E. When both transitions are at the same temperature, the voltages cancel one another out and minimal if any error voltage is generated. We do this all the time in a thermal-vacuum chamber used for NASA satellite/spacecraft verification all the time and it's quite acceptable; assuming the transitions are at a constant or nearly so temperature. While the instrument within the chamber is cycled from ~ +85C to ~ -100C, the transition connector remains near ambient ~ +22C. Errors are minimal and well within acceptable limits. Ron Q. ________________________________ Message 5 _____________________________________ Time: 10:55:33 AM PST US From: "John Loram" Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector? Turns out that such connectors do exist in several different version. You buy the pins separately to match the thermocouple wire. Pins cost about $20 each. However, I've finally realized that it won't be necessary to use a special connector. (see other posts on same subject). I'm determined not to have to disconnect 24 wires for thermocouples every time I want to pull the engine. -john- > -----Original Message----- > From: owner-avionics-list-server@matronics.com > [mailto:owner-avionics-list-server@matronics.com] On Behalf > Of Noel Loveys > Sent: Friday, February 05, 2010 7:47 AM > To: avionics-list@matronics.com > Subject: RE: Avionics-List: Thermocouple compatible bulkhead > connector? > > > > John: > > My advice would be to just use a grummet. The wires on > thermocouples have to be a consistent types of metal from the > couple itself to the instrument. > Finding a multi pin bulkhead fitting in the exact correct > metals may be difficult if not impossible. > > If your plane is certified be sure to follow AC43 for specs > on cable supporting. > > Noel > > -----Original Message----- > From: owner-avionics-list-server@matronics.com > [mailto:owner-avionics-list-server@matronics.com] On Behalf > Of John Loram > Sent: February 3, 2010 7:33 PM > To: avionics-list@matronics.com > Subject: Avionics-List: Thermocouple compatible bulkhead connector? > > > Does any one know of a source (other than Omega) for > multi-pin bulkhead connectors that are compatible with Type J > & K thermocouples? I wiring the firewall foreword... > > thanks, -john- > > > > > > > > Photoshare, and much much more: > > > > ________________________________ Message 6 _____________________________________ Time: 11:57:56 AM PST US Subject: Avionics-List: Re: Thermocouple compatible bulkhead connector? From: "rampil" Amphenol certainly makes TC compatible pins for J & K combos. You might be able to request samples. These pins are usually not stocked at Digikey or Newark, etc, but that does not mean they are not potentially available. Check the Amphenol catalogs for your choice in metal or plastic circular connectors. -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=284991#284991 ________________________________ Message 7 _____________________________________ Time: 11:59:34 AM PST US From: "Noel Loveys" Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector? As far as i know for certification the metals have to be consistant... If the plane is not certified that is not a requirement. Noel From: owner-avionics-list-server@matronics.com [mailto:owner-avionics-list-server@matronics.com] On Behalf Of Ron Quillin Sent: February 5, 2010 12:37 PM Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector? At 07:47 2/5/2010, you wrote: The wires on thermocouples have to be a consistent types of metal from the couple itself to the instrument. I don't believe as stated that's entirely true. A voltage is developed across a junction of differing metals, that's why a TC works, but... If a transition is made from conductor metal type A, to conductor metal type B, we'll assume some voltage +E is developed. However, when transitioning back from conductor metal type B to conductor metal type A, voltage E is again developed, but it is now -E. When both transitions are at the same temperature, the voltages cancel one another out and minimal if any error voltage is generated. We do this all the time in a thermal-vacuum chamber used for NASA satellite/spacecraft verification all the time and it's quite acceptable; assuming the transitions are at a constant or nearly so temperature. While the instrument within the chamber is cycled from ~ +85C to ~ -100C, the transition connector remains near ambient ~ +22C. Errors are minimal and well within acceptable limits. Ron Q. ________________________________ Message 8 _____________________________________ Time: 01:29:23 PM PST US From: Subject: Re: Avionics-List: Thermocouple compatible bulkhead connector? I've used the 38999 series Mil connectors (with std gold pins) with great success for all kinds of firewall connections - including K and J type thermos. Flame Enterprises as a distributor for Mil-everything. http://www.flamecorp.com/ The CPC Series 2 connectors are also good, but they are plastic - not recommended for use on the firewall. You can get those from all the usual suspects - Mouser, Digi-Key, Allied, etc. I have not used them, but they may come in a metal form factor...dunno. James Redmon Berkut #013/Race 13 www.berkut13.com ----- Original Message ----- From: John Loram To: avionics-list@matronics.com Sent: Friday, February 05, 2010 10:48 AM Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector? You're quite correct Ron. Somehow I had failed to notice that I would be creating two, opposite polarity junctions that would be "isothermal"... Now, I just need to find a cheap source for mil spec circular connectors (MIL-C-5015). Anybody have a favorite source? I need a bulkhead and plug connector with 24 pins for the thermocouples. thanks all for comments, -john- ------------------------------------------------------------------------- --- From: owner-avionics-list-server@matronics.com [mailto:owner-avionics-list-server@matronics.com] On Behalf Of Ron Quillin Sent: Friday, February 05, 2010 8:07 AM To: avionics-list@matronics.com Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector? At 07:47 2/5/2010, you wrote: The wires on thermocouples have to be a consistent types of metal from the couple itself to the instrument. I don't believe as stated that's entirely true. A voltage is developed across a junction of differing metals, that's why a TC works, but... If a transition is made from conductor metal type A, to conductor metal type B, we'll assume some voltage +E is developed. However, when transitioning back from conductor metal type B to conductor metal type A, voltage E is again developed, but it is now -E. When both transitions are at the same temperature, the voltages cancel one another out and minimal if any error voltage is generated. We do this all the time in a thermal-vacuum chamber used for NASA satellite/spacecraft verification all the time and it's quite acceptable; assuming the transitions are at a constant or nearly so temperature. While the instrument within the chamber is cycled from ~ +85C to ~ -100C, the transition connector remains near ambient ~ +22C. Errors are minimal and well within acceptable limits. 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