---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 07/06/10: 18 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:30 AM - Matronics.com access? (Robert L. Nuckolls, III) 2. 09:43 AM - Re: stray RF (Robert L. Nuckolls, III) 3. 09:45 AM - Re: Matronics.com access? (Robert L. Nuckolls, III) 4. 09:56 AM - Re: Matronics.com access? (Robert Borger) 5. 10:11 AM - Re: Matronics.com access? (ROGER & JEAN CURTIS) 6. 10:28 AM - Re: stray RF (James Robinson) 7. 11:08 AM - Heat Sink necessary? (jonlaury) 8. 11:41 AM - Z-31B Ground Power Contactor Diode (jonlaury) 9. 12:14 PM - Re: Heat Sink necessary? () 10. 12:15 PM - Re: HLMP-2685 multi-LEDs off LR3C (James Kilford) 11. 12:38 PM - Re: Matronics.com access? (Dale Ellis) 12. 01:07 PM - Re: Microphone levels (B Tomm) 13. 01:08 PM - Re: Heat Sink necessary? (Robert L. Nuckolls, III) 14. 02:29 PM - Re: Z-31B Ground Power Contactor Diode (Robert L. Nuckolls, III) 15. 02:34 PM - Re: Microphone levels (Robert L. Nuckolls, III) 16. 02:48 PM - Re: Microphone levels (Ron Quillin) 17. 04:35 PM - Re: Microphone levels (Robert L. Nuckolls, III) 18. 04:52 PM - Re: Microphone levels (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 09:30:37 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Matronics.com access? Is anyone having trouble accessing http://matronics.com Bob . . . ________________________________ Message 2 _____________________________________ Time: 09:43:54 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: stray RF At 11:18 PM 7/5/2010, you wrote: >Hi Bob >I have recently developed a problem when I transmit my VSI and other >features on my Cheltons goes crazy. I have added a engine monitor >EI MVP-50 recently. Is there a way to isolate the cause. This is a >recent occurance No prior problem for 350 hrs A high-probability possibility is that a feed line shield has become detached at one end or the other on your comm antenna. A simple inspection may suffice. An organized troubleshooting effort suggest you dummy load the transceiver at the back of the tray with a device like this: http://aeroelectric.com/Pictures/Tools/RF_Antenna_Test_Tools/DummyLoad.jpg See if the problem goes away. If so, then move the dummy load to the other end of the feedline. You'll need a male-male adapter, a t-connector can be used too. Try again to see if the problem goes away or is still there. If the problem does not manifest with either dummy load experiment, then it's likely that something has changed in system conditions for the Cheltons. But I'm betting it's a feed line problem. Bob . . . ________________________________ Message 3 _____________________________________ Time: 09:45:01 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Matronics.com access? At 09:26 AM 7/6/2010, you wrote: > > >Is anyone having trouble accessing http://matronics.com > I think the servers were down for a period of time since midnight last night but they seem to be up now. All is right with the world . . . Bob . . . ________________________________ Message 4 _____________________________________ Time: 09:56:38 AM PST US Subject: Re: AeroElectric-List: Matronics.com access? From: Robert Borger Bob, Yup, it was down for a while but seems to be back up now. Bob Borger On Jul 6, 2010, at 9:26, Robert L. Nuckolls, III wrote: > > Is anyone having trouble accessing http://matronics.com > > > > > Bob . . . > > > > ________________________________ Message 5 _____________________________________ Time: 10:11:28 AM PST US From: "ROGER & JEAN CURTIS" Subject: RE: AeroElectric-List: Matronics.com access? Is anyone having trouble accessing http://matronics.com Bob . . . Seems to be OK for me Roger ________________________________ Message 6 _____________________________________ Time: 10:28:28 AM PST US From: James Robinson Subject: Re: AeroElectric-List: stray RF Thanks Bob!!!! James Robinson Glasair lll N79R Spanish Fork UT U77 ________________________________ From: "Robert L. Nuckolls, III" Sent: Tue, July 6, 2010 10:45:17 AM Subject: Re: AeroElectric-List: stray RF At 11:18 PM 7/5/2010, you wrote: > Hi Bob > I have recently developed a problem when I transmit my VSI and other features >on my Cheltons goes crazy. I have added a engine monitor EI MVP-50 recently. >Is there a way to isolate the cause. This is a recent occurance No prior >problem for 350 hrs A high-probability possibility is that a feed line shield has become detached at one end or the other on your comm antenna. A simple inspection may suffice. An organized troubleshooting effort suggest you dummy load the transceiver at the back of the tray with a device like this: http://aeroelectric.com/Pictures/Tools/RF_Antenna_Test_Tools/DummyLoad.jpg See if the problem goes away. If so, then move the dummy load to the other end of the feedline. You'll need a male-male adapter, a t-connector can be used too. Try again to see if the problem goes away or is still there. If the problem does not manifest with either dummy load experiment, then it's likely that something has changed in system conditions for the Cheltons. But I'm betting it's a feed line problem. Bob . . . ________________________________ Message 7 _____________________________________ Time: 11:08:56 AM PST US Subject: AeroElectric-List: Heat Sink necessary? From: "jonlaury" Using a 25a bridge rectifier for dual power sources for EFI. The injectors might pull 10a, worst case. For normal ops, 6a. Is heat sinking necessary for the rectifer? Thanks, J Read this topic online here: http://forums.matronics.com/viewtopic.php?p=303922#303922 ________________________________ Message 8 _____________________________________ Time: 11:41:06 AM PST US Subject: AeroElectric-List: Z-31B Ground Power Contactor Diode From: "jonlaury" In Z-31B, I'm using a continuous duty contactor with one coil post, like the one shown in the diagram and labled"Existing Battery Contactor", for a Grd. Pwr. Contactor. I'm unsure about where to place and how to orient the diode for a GP jack when using the CD contactor. Thanks for any help, J Read this topic online here: http://forums.matronics.com/viewtopic.php?p=303931#303931 ________________________________ Message 9 _____________________________________ Time: 12:14:48 PM PST US Subject: RE: AeroElectric-List: Heat Sink necessary? From: Jon, You are mixing supply and demand (but that's ok). Normally it is suggested a heat sink be used for a sink load of 20A or more. Since your hardware is bigger than your load you could try it without. If it is continuous load you may want to monitor the rectifier temperature to be sure you're in limits. The manufacturer should publish that. If you're at all concerned about temperature, just add a heat sink. If the heat sink sets you back wait till you see the price at the gas pump. Wow! The poor man's option is to mount it on a piece phenolic block which you'll find does little for heat dissipation but is virtually indestructible should your diode take to glowing in flight. You can cut some grooves in the top of the block to allow air to travel underneath the rectifier. You can also buy one of those computer fans and a frame for about a $1.00 to point in the general direction. I have a variety pack of those stick on thermometers that lets one visualize surface temps. Could be handy for something like this. Most of this is much more fuss than just installing the heat sink. Hey, what kind of injectors pull 10A? I suppose you mean the ignition module. Enjoy, Glenn E. Long -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of jonlaury Sent: Tuesday, July 06, 2010 2:08 PM Subject: AeroElectric-List: Heat Sink necessary? Using a 25a bridge rectifier for dual power sources for EFI. The injectors might pull 10a, worst case. For normal ops, 6a. Is heat sinking necessary for the rectifer? Thanks, J Read this topic online here: http://forums.matronics.com/viewtopic.php?p=303922#303922 ________________________________ Message 10 ____________________________________ Time: 12:15:30 PM PST US Subject: Re: AeroElectric-List: HLMP-2685 multi-LEDs off LR3C From: James Kilford Bob, Just to feed back to you and anyone on the list who might fancy using the HLMP-2685 as a snazzy LED alt. warn. light for the LR3C regulator, I'd like to report the following: It works quite well putting the 8 LEDs of the HLMP in two parallel banks of 4 resistors in series, i.e. four LEDs on one side, in series, put in parallel with the other four LEDs on the other side, those also put in series. I put a current-limiting resistor of 440 ohms works well. In fact, it was two 220 ohm resistors in series, but then I don't have much of a resistor selection... This arrangement seems to check out okay, and looks to be about the right brightness. I might tweak it a little bit at some point. When the warning light is "off", I can't discern any light from the HLMP, and indeed on the bench I can discern no light from it at 6.0V. For day time it looks good, though it might also be too bright for night time use. FWIW! Thanks for your guidance on this matter. James On Sun, Apr 11, 2010 at 12:28 PM, James Kilford wrote: > Bob, > > That's great, thank you. It gives me a good place from which to experiment. > > James > > On Thu, Apr 8, 2010 at 2:04 PM, Robert L. Nuckolls, III > wrote: >> >> >> >>> >>> >>> http://parts.digikey.com/1/parts/681506-led-lt-bar-hi-eff-red-8led-dip-hlmp2685.html >>> >>> I'd like to hook one of these to the LR3C regulator instead of the >>> supplied filament lamp, so that it can go into the annunciator panel >>> too. >>> >>> I've been trying to trace a schematic of Bob's, which I'm sure I've >>> seen, of how to use an LED instead of a filament lamp with the LR3C, >>> as a starting point. I can't find it, and the resistor values would >>> be different in any case, so can anyone throw any light on to how to >>> use one of these 8-LED devices with the LR3C? >> >> The schematic I published is at: >> >> http://aeroelectric.com/Pictures/Schematics/LR3_LV_Led_1.jpg >> >> Your application will take some experimentation. >> You can try paralleling all the LEDs and seeing how >> well you can excite the array and still have uniform >> illumination. You may find that you need to treat >> them as separate LEDs. >> >> Just be aware that LR3 lamp driver is never completely >> "OFF". The off current is too low to get any light >> from a bulb but it will cause an LED to glow at a >> reduced intensity. Hence the paralleling resistor to >> get the LED to mimic a lamp more closely. >> >> Bob . . . >> >> ________________________________ Message 11 ____________________________________ Time: 12:38:11 PM PST US Subject: Re: AeroElectric-List: Matronics.com access? From: Dale Ellis No problem from here no not archive On Tue, Jul 6, 2010 at 10:26 AM, Robert L. Nuckolls, III wrote: > > > Is anyone having trouble accessing http://matronics.com > > > Bob . . . > > ________________________________ Message 12 ____________________________________ Time: 01:07:47 PM PST US From: "B Tomm" Subject: RE: AeroElectric-List: Microphone levels Bob, My interface circuit which brings a line level output through an impedance matching transformer to the mic input of the aircraft radio may need to go through a capacitor to block the DC bias voltage coming from the radio from getting to the output of the matching transformer. Do you agree with this method and can you recommend a value for this cap? Bevan -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Monday, July 05, 2010 3:26 PM Subject: Re: AeroElectric-List: Microphone levels --> At 03:04 PM 7/5/2010, you wrote: >--> > > Bob, > >Would you expect that the microphone output level from a standard >Aviation headset to be similar/ or even the same as a standard handheld >audio microphone as used with a professional sound board? No. Aircraft microphones are victim to legacy compatibility standards that emulate the original carbon granule microphones (like those in telephones through the 70s). http://en.wikipedia.org/wiki/Carbon_microphone The audio output is not only very high (as much as 1 vrms) it is generated with a power supply delivered by the transmitter. Hence, most aircraft microphones have active electronics so that modern TINY voltage microphones can dress up like a carbon mic. > I don't own an audio >meter but just need to be close for a non-aircraft related project. Sound boards are generally set up to accept 100 mV pk-pk (30 mV rms) output from dynamic mics delivered on twisted pairs. Bob . . . ________________________________ Message 13 ____________________________________ Time: 01:08:41 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Heat Sink necessary? At 01:07 PM 7/6/2010, you wrote: > >Using a 25a bridge rectifier for dual power sources for EFI. The >injectors might pull 10a, worst case. For normal ops, 6a. >Is heat sinking necessary for the rectifer? yes . . . but simply mounting it to a metallic surface on the airplane will be sufficient. 10A on any one leg of the device will dissipate about 7 watts of heat that is easily managed by most metal surface mounting situations. Doing in-situ temperature measurements on the molded bridge rectifier is VERY difficult. There's no thermally integral metal surface available for sampling. You'd need to bury a tiny-wire thermocouple in the mounting under the rectifier assembly. You can measure the temperature of the sheet metal directly opposite the rectifier and make some assumptions about thermal resistance of the mounting . . . but it's more fuss than you'd probably want to experience. 10A doesn't present much of a challenge to a device with a metal heat-sink interface. Use a little 'heat sink' grease under it when mounting. http://www.radioshack.com/product/index.jsp?productId=2102858 Bob . . . ________________________________ Message 14 ____________________________________ Time: 02:29:46 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Z-31B Ground Power Contactor Diode At 01:39 PM 7/6/2010, you wrote: > >In Z-31B, I'm using a continuous duty contactor with one coil post, >like the one shown in the diagram and labled"Existing Battery >Contactor", for a Grd. Pwr. Contactor. > >I'm unsure about where to place and how to orient the diode for a GP >jack when using the CD contactor. The banded end of the diode connects to the "BAT" terminal of the contactor which in turn faces incoming power from the ground power connector. The other end of the diode goes to the small coil terminal which is switched to ground to energize the contactor and bring ground power onto the bus. Bob . . . ________________________________ Message 15 ____________________________________ Time: 02:34:01 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Microphone levels At 02:58 PM 7/6/2010, you wrote: > >Bob, > >My interface circuit which brings a line level output through an impedance >matching transformer to the mic input of the aircraft radio may need to go >through a capacitor to block the DC bias voltage coming from the radio from >getting to the output of the matching transformer. Do you agree with this >method and can you recommend a value for this cap? Some experimentation is probably called for. You need to find a resistor value that becomes a 'dummy microphone'. The resistor probably wants to have 2-3 volts dropped across it while the transmitter is 'talking'. Then make sure the effective output impedance and signal level of your transmit audio source can drive the necessary signal into this load . . . 3 v pk-pk is probably a good upper bound to strive for. Then pick a capacitor who's reactance at say 100Hz is about 1/10 that of the sum of dummy load resistor + source output impedance. Bob . . . ________________________________ Message 16 ____________________________________ Time: 02:48:32 PM PST US From: Ron Quillin Subject: RE: AeroElectric-List: Microphone levels At 14:36 7/6/2010, you wrote: >signal level of your transmit audio source can > drive the necessary signal into this load . . . > 3 v pk-pk is probably a good upper bound to > strive for. Without grabbing my scope, 3Vpp --sounds-- a bit hot for a mic input. Is that value a typo? Ron Q. ________________________________ Message 17 ____________________________________ Time: 04:35:49 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Microphone levels At 04:46 PM 7/6/2010, you wrote: >At 14:36 7/6/2010, you wrote: >>signal level of your transmit audio source can >> drive the necessary signal into this load . . . >> 3 v pk-pk is probably a good upper bound to >> strive for. > >Without grabbing my scope, 3Vpp --sounds-- a bit hot for a mic input. Nope. That's what can come out of an aircraft microphone the emulates the legacy carbon mic. Of course, REAL carbon microphones are exceedingly rare in service now. Just for grins, put your scope on the mic line of a headset and see what kinds of signals can be seen there. They may have migrated down over the years . . . Bob . . . ________________________________ Message 18 ____________________________________ Time: 04:52:46 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Microphone levels At 04:46 PM 7/6/2010, you wrote: >At 14:36 7/6/2010, you wrote: >>signal level of your transmit audio source can >> drive the necessary signal into this load . . . >> 3 v pk-pk is probably a good upper bound to >> strive for. > >Without grabbing my scope, 3Vpp --sounds-- a bit hot for a mic input. Nope. That's what can come out of an aircraft microphone the emulates the legacy carbon mic. Of course, REAL carbon microphones are exceedingly rare in service now. Just for grins, put your scope on the mic line of a headset and see what kinds of signals can be seen there. They may have migrated down over the years . . . P.s. Just checked some links as follows: http://www.capitalavionics.com/tip_0909.asp http://tinyurl.com/24g4wjf and a number of others that 'specd' aircraft mics for sensitivity, current draw, bias voltage but failed to call out the output voltage present when those specs are being satisfied. I think it was DO170 that talks industry specifics. I did see an anecdotal reference to 100-500 mv which would translate to 300-1500 mv pk-pk. Same ball park. We used to design for 3v pk-pk to have zero risk of clipping . . . at least in THAT part of the circuit! 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