---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 12/28/10: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:51 AM - Re: Re: Voltage Regulator Output (Robert L. Nuckolls, III) 2. 07:55 AM - Re: Re: Voltage Regulator Output (Robert L. Nuckolls, III) 3. 08:02 AM - SD-8 Performance (Robert L. Nuckolls, III) 4. 03:43 PM - faulty push to talk (bob noffs) 5. 06:45 PM - Re: faulty push to talk (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 07:51:22 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Voltage Regulator Output At 01:23 PM 12/27/2010, you wrote: > > > . . . .Since I have battery backup up on my EFIS and GPS, I'm not > that concerned. I can still land safely, which is all I'm really looking for. > >The EIS should give me ample visual and audio warning if I set it >for a little lower threshold value, say 13.8V. Michael, It's not clear to me that you've acquired an understanding of the simple-ideas that go into a recipe for success for your airplane's electrical system. There's a recommended library of information but in particular, a chapter on system reliability published in the AeroElectric Connection. You can get printed/bound copies for a nominal fee or download it and print yourself at no cost other than printer expenses. You're correct that OV conditions are rare and one of the least concerns for reducing risk . . . which is why chapter 17 goes to some length attempting to order various system frailties and failures in order of criticality. The architecture diagrams offered in appendix Z strive to bring the best legacy design goals from TC aviation into the new "kitchen". Owner Built and Maintained aviation is crafting new recipes specific to what the builder wants/needs . . . not what the FAA or program managers dictate. At the same time, we strive to drive risks to still lower numbers. If you've not taken advantage of the resources cited, I would encourage you to do so. It goes toward increasing your comfort and confidence in the operation of your airplane. Happy new year! Bob . . . ________________________________ Message 2 _____________________________________ Time: 07:55:04 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Voltage Regulator Output At 01:23 PM 12/27/2010, you wrote: > P.S. Here's some alternator noise signatures for PM and WF3P (wound-field/three-phase) alternators: http://www.aeroelectric.com/Pictures/Curves/Safari_Bus_Noise_1.gif http://www.aeroelectric.com/Pictures/Curves/Safari_Bus_Noise_2.gif http://www.aeroelectric.com/Pictures/Curves/SD-8_Noise_Data.pdf The SD-8 (and similar PM alternators) does not present an unusually severe problem with respect to noise. Bob . . . ________________________________ Message 3 _____________________________________ Time: 08:02:43 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: SD-8 Performance I'd forgotten about this plot we crafted for B&C 6 years ago . . . http://www.aeroelectric.com/Reference_Docs/Alternator_Data/SD8-Performance.pdf This data was gathered on the test bench and then plotted against engine RPM for the two common drive pad ratios: Lycoming 1:1.3 and Continental 1:1.5 There are two curves. One that predicts usable output at minimum battery maintenance voltage of 13.8. The second curve shows output available if the bus is pulled down to 12.5 volts . . . not so low as to begin discharging the battery but also not high enough to push energy back into the battery. It was this data gathering exercise that suggested one could plan to load the SD-8 to as much as 10A under some circumstances. Bob . . . ________________________________ Message 4 _____________________________________ Time: 03:43:52 PM PST US Subject: AeroElectric-List: faulty push to talk From: bob noffs hi all, my friend bought a kitfox and when the ptt button is pressed the rotax tach. goes to far right and so does the gas gauge. the intercom and radio all continue to work normally. any hints where he should look first? he isolated the power to the ptt by jumping at the battery but no change. bob noffs ________________________________ Message 5 _____________________________________ Time: 06:45:29 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: faulty push to talk At 05:39 PM 12/28/2010, you wrote: >hi all, > my friend bought a kitfox and when the ptt button is pressed the > rotax tach. goes to far right and so does the gas gauge. the > intercom and radio all continue to work normally. any hints where > he should look first? he isolated the power to the ptt by jumping > at the battery but no change. Does it do it with the radio turned off? This has the flavor of an RF interference problem. You need to dummy load the transceiver's antenna line . . . http://aeroelectric.com/Pictures/Tools/RF_Antenna_Test_Tools/DummyLoad.jpg and see if the problem goes away. Are these perchance Van's instruments? I've had two of them in my shop, an ammeter and a fuel gauge as I recall. Both were extraordinarily vulnerable to strong RF in the cockpit. 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