---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 12/20/07: 18 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:52 AM - Re: Battery Contactors (Noel Karppinen) 2. 02:54 AM - Re: Battery Contactors (Noel Karppinen) 3. 05:35 AM - Re: SD-8 Alternator OFF Annunciator? (Robert L. Nuckolls, III) 4. 05:38 AM - Re: Switched hot bus (Robert L. Nuckolls, III) 5. 07:05 AM - Amp 59250 t-head tool (Robert L. Nuckolls, III) 6. 07:28 AM - Re: Amp 59250 t-head tool (BobsV35B@aol.com) 7. 08:24 AM - Alternator whine in audio (wgill10@comcast.net) 8. 08:40 AM - Firewall Placement Of Electrical Components (DaveG601XL) 9. 08:43 AM - Re: Alternator whine in audio (Hinde, Frank George (Corvallis)) 10. 09:52 AM - Re: Alternator whine in audio (Ron Quillin) 11. 10:42 AM - Re: Alternator whine in audio (wgill10@comcast.net) 12. 11:54 AM - RV-List: good warning labe (Charles Brame) 13. 12:11 PM - swapping two radios using 3P/DT switch? (Lincoln Keill) 14. 12:48 PM - Re: swapping two radios using 3P/DT switch? (Rob Turk) 15. 12:48 PM - Re: swapping two radios using 3P/DT switch? (Robert Borger) 16. 01:41 PM - Re: swapping two radios using 3P/DT switch? (jetboy) 17. 02:26 PM - Re: Audio isolation amp questions (nauga@brick.net) 18. 03:34 PM - Re: swapping two radios using 3P/DT switch? (JOHN TIPTON) ________________________________ Message 1 _____________________________________ Time: 02:52:59 AM PST US From: "Noel Karppinen" Subject: AeroElectric-List: Re: Battery Contactors Hi Peter The resistance of mine is 16 Ohms when cold, so it is right in the ball park. Noel ----- Original Message ----- Noel Check the resistance on the coil. A continuous duty contactor will show a resistance of 10 to 18 ohms. An intermittant one will show 3 to 5 ohms Peter ________________________________ Message 2 _____________________________________ Time: 02:54:11 AM PST US From: "Noel Karppinen" Subject: AeroElectric-List: Re: Battery Contactors Thanks for that comprehensive reply, Bob. Now I am completely convinced that there is nothing to worry about. Noel ----- Original Message ----- >"Richard T. Schaefer" ><schaefer@rts-services.com> wrote: > >It's normal for them to be a little too warm to touch. The current is > about right. Look at this at a 10W heater. It will get warm! > Dead on target Richard. In times past that this conversation was conducted, I went to the bench and held one of our stock battery contactors in an energized condition until its temperature stabilized. See: http://www.aeroelectric.com/Pictures/Contactors/Battery_Contactor_Temp s_1.jpg The effects of temperature rise were obvious too in terms of the current draw for the contactor. Room temperature current draw was on the order of 0.8 amps. But after two hours of operation . . . http://www.aeroelectric.com/Pictures/Contactors/Battery_Contactor_Temp s_2.jpg . . . current draw is down to about 0.56 amps. This phenomenon is a function of the positive temperature coefficient of copper wire used to wind the coil. As the device warms up, it's resistance goes up and the current goes down. In terms of a gross test of a contactor's intermittent or continuous duty status, if it's still functioning after 5 minutes of continuous operation then it MUST be a continuous duty device. The intermittent duty devices tailored for starter motor control would have spit out all their smoke after 5 minutes! It's not often that we are physically able to "feel" a piece of operating equipment and find that it's too hot to touch but it can raise concerns when the device is not OBVIOUSLY designed to run hot . . . like engines and exhaust stacks. The contactors that dissipate about 10 watts don't heat up real fast . . . but in still air they'll get pretty toasty. Bob . . . ________________________________ Message 3 _____________________________________ Time: 05:35:09 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: SD-8 Alternator OFF Annunciator? At 07:50 AM 10/2/2007 -0700, you wrote: > >"With Z-13, you leave the SD-8 off until needed when >it is determined that the main alternator is off line >(lv light on). You drop to e-bus loads, open battery >contactor, turn SD-8 on and continue to airport of >intended destination. If the SD-8 is not overloaded, >the lv warning light will go back out." > >With regards to the SD-8 and the lv light, Z-13 has a single lv light on >the diagram. The descripton for the PV/OV crows foot kit available from B >and C states that "The PM/OV was designed to give over voltage protection >to the permanet magnet alternator. The yellow light will annunciate if the >alternator switch is left off, or the crowbar over voltage protection has >been tripped. " > >So, will the single lv light depicted on Z-13 light if either the main alt >or the SD-8 are off line? > >If the SD-8 has its own unique lv light as described on the B and C site, >does it light if the aux alt selection switch is OFF? Or, does it only >light if the aux alt selector switch is ON AND the SD-8 is off line? If >the first case is true, during normal operation, the aux lv light will >alway remain lit which would not be an ideal situation. I don't think I've ever suggested the ALL OFF warning light for the SD-8 as used in Z-13/8. The warning light is useful when the SD-8 is a sole-source of engine driven power in simple systems where there is no real LV monitoring and warning system. I've written many times in the past that the most important electrical "instrument" in the electrical system is the calibrated LOW VOLTS warning light set to illuminate when the bus is below 13.0 volts. Figure Z-13/8 suggests the AEC9005-101 LV Warning module (or equivalent) and does not show the SD-8 ALT OFF light which is included in the B&C SD-8 installation kit. This indicator is not useful in the Z-13/8 architecture. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 4 _____________________________________ Time: 05:38:03 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Switched hot bus At 03:36 PM 10/3/2007 +0000, you wrote: >All > > >I am currently working on my wiring diagram for my FADEC equipped >plane. I will be using a slightly modified version of the Z-14 >diagram. I found a fellow builder with the same setup as me and got a >hold of his wiring diagram. Attached is a snippet of that diagram. My >question pertains to the guarded switch for FADEC bus #1 (there is a >similar setup for FADEC bus #2). The diagram is showing 4 AWG wire >between the battery and guarded switch. Shouldn t there be a relay or >something here? > > >Thanks, > > >Jason > > >image001.png I would rather see the FADEC equipment drive from the Main Battery Bus with switching for each feeder supplied downstream of the fuses as appropriate. Without having detailed data on the functionality of your FADEC system and its failure modes, it's not possible to offer a well considered recommendation. If your system demands an architecture like you've illustrated, then the switch should be a relay (solid state perhaps?) right at the battery. The 4AWG wire cited can probably be MUCH smaller. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 5 _____________________________________ Time: 07:05:40 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Amp 59250 t-head tool See item 150197086208 on ebay Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 6 _____________________________________ Time: 07:28:20 AM PST US From: BobsV35B@aol.com Subject: Re: AeroElectric-List: Amp 59250 t-head tool Good Morning 'Lectric Bob, You mentioned once that you had sent your T head crimper in for a rebuild. Do you know if such a service is still available? If so, where and how much ? Happy Skies, Old Bob AKA Bob Siegfried Ancient Aviator Stearman N3977A Brookeridge Air Park LL22 Downers Grove, IL 60516 630 985-8503 In a message dated 12/20/2007 9:08:28 A.M. Central Standard Time, nuckolls.bob@cox.net writes: See item 150197086208 on ebay Bob . . . **************************************See AOL's top rated recipes (http://food.aol.com/top-rated-recipes?NCID=aoltop00030000000004) ________________________________ Message 7 _____________________________________ Time: 08:24:01 AM PST US From: wgill10@comcast.net Subject: AeroElectric-List: Alternator whine in audio Hello All, I have a PlanePower alternator and have noticed a whine noise in the David Clark headset audio. It is really noisy if the headset volume is high; however, if I turn the headset volume down low and turn the comm radio volume up to compensate, the whine is barely detectable. Can anyone explain this and/or provide possible solutions? I called PlanePower to inquire about filter and they informed me that their product has internal noise filtering and that I must have an audio ground problem. When the alternator is switched off-line, the audio is crystal clear. If there was an audio grounding issue I would expect to hear ignition noise too, but thats not the case. Can additional filtering be installed external to the alternator? Suggestions please. Happy holidays, Bill Gill RV-7 Lee's Summit, MO

Hello All,

 I have a PlanePower alternator and have noticed a whine noise in the David Clark headset audio. It is really noisy if the headset volume is high; however, if I turn the headset volume down low and turn the comm radio volume up to compensate, the whine is barely detectable. Can anyone explain this and/or provide possible solutions? I called PlanePower to inquire about filter and they informed me that their product has internal noise filtering and that I must have an audio ground problem. When the alternator is switched off-line, the audio is crystal clear. If there was an audio grounding issue I would expect to hear ignition noise too, but thats not the case. Can additional filtering be installed external to the alternator? Suggestions please.

 

Happy holidays,

Bill Gill

RV-7   Lee's Summit, MO




________________________________ Message 8 _____________________________________ Time: 08:40:27 AM PST US Subject: AeroElectric-List: Firewall Placement Of Electrical Components From: "DaveG601XL" I am building a Zenith 601 and using a variation of the Z16 drawing. I am currently working on placing my regulator, S704-1 OV relay and capacitor. The B&C instructions are pretty clear that this stuff should be mounted on the cockpit side of the firewall and away from engine heat. In this configuration, the Z16 would have me running a 12GA from the capacitor, through the firewall, and out to the up-leg screw on the starter relay. I would also have a 12GA going from the down-leg screw of the battery relay, through the firewall, and to the main distribution bus. My question is two-fold: 1. Is it critical that these electrical parts be on the backside of the firewall. I have seen photos of this stuff on the engine side on other airplanes. 2. If I follow B&C's recommendation on placement, can I run the alternator lead from the capacitor straight to the main distribution bus? This would only require one 12GA wire firewall penetration from the bus to the battery relay. Thanks, -------- David Gallagher 601 XL, tail and wings completed, fueslage almost done. Working engine and electrical systems. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=153287#153287 ________________________________ Message 9 _____________________________________ Time: 08:43:27 AM PST US From: "Hinde, Frank George (Corvallis)" Subject: RE: AeroElectric-List: Alternator whine in audio Have you got a good connection between the alternator case and the engine b lock?....I had kinds of noise issues before i realised that painting the al ternator bracket is a very bad idea and is provides a hi resistance path... Ooops. My plane power alt has been trouble free...no noise. Frank RV 7a IO360 ________________________________ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectr ic-list-server@matronics.com] On Behalf Of wgill10@comcast.net Sent: Thursday, December 20, 2007 8:21 AM Subject: AeroElectric-List: Alternator whine in audio Hello All, I have a PlanePower alternator and have noticed a whine noise in the David Clark headset audio. It is really noisy if the headset volume is high; how ever, if I turn the headset volume down low and turn the comm radio volume up to compensate, the whine is barely detectable. Can anyone explain this a nd/or provide possible solutions? I called PlanePower to inquire about filt er and they informed me that their product has internal noise filtering and that I must have an audio ground problem. When the alternator is switched off-line, the audio is crystal clear. If there was an audio grounding issue I would expect to hear ignition noise too, but that's not the case. Can ad ditional filtering be installed external to the alternator? Suggestions ple ase. Happy holidays, Bill Gill RV-7 Lee's Summit, MO ________________________________ Message 10 ____________________________________ Time: 09:52:25 AM PST US Subject: Re: AeroElectric-List: Alternator whine in audio From: Ron Quillin At 08:20 12/20/2007, you wrote: > I have a PlanePower alternator and have noticed a whine noise in > the David Clark headset audio. It is really noisy if the headset > volume is high; however, if I turn the headset volume down low and > turn the comm radio volume up to compensate, the whine is barely > detectable. Can anyone explain this and/or provide possible solutions? Is this something new, and if so, what has changed? Only your headset, or also pax headsets? You don't mention what you have for an audio/intercom system.... A question. Is each and every headset audio and microphone jack ground bushing insulated from and do not rely on an airframe connection for the 'return' to the source equipment? That is, are there dedicated ground returns for the microphone and headset from each and every jack returning to the audio source, be it radio, audio panel or intercom? Your audio source to the headset will amplify whatever signal it sees between its' input and input common, generally audio lo, chassis or some other airframe referenced ground connection. Likewise, what ever is connected to its' output will hear whatever voltage is seen between the hot or high connection and lo, return, chassis or whatever you wish to call it. Should some unwanted voltage also get stuck in there, it too will be heard. As you turn up the comm audio and the offending noise is not increased, it would be safe to assume the offending signal is after the volume control you are adjusting. In a similar manner, you adjust headset volume and the noise changes; the source is before the control. Your headphones may well just be hearing some voltage drop caused by airframe currents between the jack where you connect them and the piece of gear at the other end of the wire to the jack. >I called PlanePower to inquire about filter and they informed me >that their product has internal noise filtering and that I must have >an audio ground problem. When the alternator is switched off-line, >the audio is crystal clear. So the offending source would seem to be the alternator; it's off, no noise. But how is the alternator noise getting into the headset? Even a good alternator is going to make some noise when under load. It's our duty to minimize how that noise can make it into unwanted places. >If there was an audio grounding issue I would expect to hear >ignition noise too, but that's not the case. Generally ignition noise is radiated noise, not noise in the form of airframe current, so you could easily have (or not) ignition noise (generally) totally unrelated to stray currents causing unwanted voltage drops in audio circuits. >Can additional filtering be installed external to the alternator? >Suggestions please. Generally, additional filtering can be added and may help. But is that just a band aid covering up some other undiscovered issue that, if corrected, would yield an even better solution... Ron Q. ________________________________ Message 11 ____________________________________ Time: 10:42:56 AM PST US From: wgill10@comcast.net Subject: Re: AeroElectric-List: Alternator whine in audio Thanks Ron. This is a new RV-7 aircraft and installation...been there since day one on both audio jacks . I have a Garmin 347 audio panel with an SL-40 comm...both prewired by Stark's. I do have the insulating washers on the jacks with a dedicated ground (unshielded) wired to a central ground. I also have a KX 155 navcomm w/glideslope -- the noise is there with either comm. Bill -------------- Original message -------------- From: Ron Quillin At 08:20 12/20/2007, you wrote: I have a PlanePower alternator and have noticed a whine noise in the David Clark headset audio. It is really noisy if the headset volume is high; however, if I turn the headset volume down low and turn the comm radio volume up to compensate, the whine is barely detectable. Can anyone explain this and/or provide possible solutions? Is this something new, and if so, what has changed? Only your headset, or also pax headsets? You don't mention what you have for an audio/intercom system.... A question. Is each and every headset audio and microphone jack ground bushing insulated from and do not rely on an airframe connection for the 'return' to the source equipment? That is, are there dedicated ground returns for the microphone and headset from each and every jack returning to the audio source, be it radio, audio panel or intercom? Your audio source to the headset will amplify whatever signal it sees between its' input and input common, generally audio lo, chassis or some other airframe referenced ground connection. Likewise, what ever is connected to its' output will hear whatever voltage is seen between the hot or high connection and lo, return, chassis or whatever you wish to call it. Should some unwanted voltage also get stuck in there, it too will be heard. As you turn up the comm audio and the offending noise is not increased, it would be safe to assume the offending signal is after the volume control you are adjusting. In a similar manner, you adjust headset volume and the noise changes; the source is before the control. Your headphones may well just be hearing some voltage drop caused by airframe currents between the jack where you connect them and the piece of gear at the other end of the wire to the jack. I called PlanePower to inquire about filter and they informed me that their product has internal noise filtering and that I must have an audio ground problem. When the alternator is switched off-line, the audio is crystal clear. So the offending source would seem to be the alternator; it's off, no noise. But how is the alternator noise getting into the headset? Even a good alternator is going to make some noise when under load. It's our duty to minimize how that noise can make it into unwanted places. If there was an audio grounding issue I would expect to hear ignition noise too, but thats not the case. Generally ignition noise is radiated noise, not noise in the form of airframe current, so you could easily have (or not) ignition noise (generally) totally unrelated to stray currents causing unwanted voltage drops in audio circuits. Can additional filtering be installed external to the alternator? Suggestions please. Generally, additional filtering can be added and may help. But is that just a band aid covering up some other undiscovered issue that, if corrected, would yield an even better solution... Ron Q.
Thanks Ron.
 
This is a new RV-7 aircraft and installation...been there since day one on both audio jacks . I have a Garmin 347 audio panel with an SL-40 comm...both prewired by Stark's. I do have the insulating washers on the jacks with a dedicated ground (unshielded) wired to a central ground. I also have a KX 155 navcomm w/glideslope -- the noise is there with either comm.
 
Bill
 
-------------- Original message --------------
From: Ron Quillin <rjquillin@gmail.com>
At 08:20 12/20/2007, you wrote:
 I have a PlanePower alternator and have noticed a whine noise in the David Clark headset audio. It is really noisy if the headset volume is high; however, if I turn the headset volume down low and turn the comm radio volume up to compensate, the whine is barely detectable. Can anyone explain this and/or provide possible solutions?

Is this something new, and if so, what has changed?
Only your headset, or also pax headsets?
You don't mention what you have for an audio/intercom system....

A question.
Is each and every headset audio and microphone jack ground bushing insulated from and do not rely on an airframe connection for the 'return' to the source equipment?  That is, are there dedicated ground returns for the microphone and headset from each and every jack returning to the audio source, be it radio, audio panel or intercom?

Your audio source to the headset will ampli fy whatever signal it sees between its' input and input common, generally audio lo, chassis or some other airframe referenced ground connection.  Likewise, what ever is connected to its' output will hear whatever voltage is seen between the hot or high connection and lo, return, chassis or whatever you wish to call it.  Should some unwanted voltage also get stuck in there, it too will be heard.  As you turn up the comm audio and the offending noise is not increased, it would be safe to assume the offending signal is after the volume control you are adjusting.  In a similar manner, you adjust headset volume and the noise changes; the source is before the control. 

Your headphones may well just be hearing some voltage drop caused by airframe currents between the jack where you connect them and the piece of gear at the other end of the wire to the jack.

I called PlanePower to inquire about filter and they informed me that their product has internal noise filtering and that I must have an audio ground problem. When the alternator is switched off-line, the audio is crystal clear.

So the offending source would seem to be the alternator; it's off, no noise. But how is the alternator noise getting into the headset?  Even a good alternator is going to make some noise when under load. It's our duty to minimize how that noise can make it into unwanted places.

If there was an audio grounding issue I would expect to hear ignition noise too, but thats not the case.

Generally ignition noise is radiated noise, not noise in the form of airframe current, so you could easily have (or not) ignition noise (generally) totally unrelated to stray currents causing unwanted voltage drops in audio circuits.

Can additional filtering be installed external to the alternator? Suggestions please.

Generally, additional filtering can be added and may help. But is that just a band aid covering up some other undiscovered issue that, if corrected, would yield an even better solution...

Ron Q.







________________________________ Message 12 ____________________________________ Time: 11:54:30 AM PST US Subject: AeroElectric-List: RV-List: good warning labe From: Charles Brame I got some beautiful braided steel lines from Earl's Indy. Purchased via the telephone. Great service. However, I failed to specify 37=B0 fittings. Auto use 45=B0 fittings. I had to reorder which was an expensive lesson. Earl's Indy did stock the 37=B0 fittings and didn't blanch when I said it was for an experimental airplane. Earl's Indy =BB 1-800-331-INDY Earl's Indy, Your one stop for Earl's Performance Parts. www.earlsindy.com/ - 5k - Cached - Similar pages Charlie Brame RV-6A N11CB San Antonio ------------------------------------------- Time: 03:10:44 PM PST US From: "Don Hall" Subject: RV-List: good warning label. Your ironic humor for today: I'm adding the matco parking brake and needed to order some shorter brake lines. Found some 20" steel braided straight an4 lines from an online auto/performance website. They came with the label: "Warning: Competition/Off Road Use Only. Not approved for highway use." Hmmm. Well. I do hope to go "off road", so I'm thinking I should be good. ****************************************** Don Hall N517DG (registered) rv7 finishing ****************************************** ________________________________ Message 13 ____________________________________ Time: 12:11:20 PM PST US From: Lincoln Keill Subject: AeroElectric-List: swapping two radios using 3P/DT switch? Bob and/or other electronics gurus-- I'm using revision 11 and looking at chapter 11 (switches) and also the FAQ's...I have attached an excerpt from the FAQ's that I think applies to my question as well...it's a gentleman inquiring about using either a "3PDT" switch (I think numerically this is a "3-3 switch"?) to change between two comm radios. If I have a panel mount comm radio (with it's own antenna) and a portable comm radio (an SP-200 with it's own antenna) and a simple two-place intercom system (i.e. PM 3000), I believe I need the above referenced three-pole double-throw (3-3) switch to swap between the two radios: a pole for the wire going to the headset earphones, a pole for the wire coming from the headset microphone, and a pole to swap the PTT line. By doing this, I can swap radios without having to go through the intercom system which is in-line with your philosophy (which I agree with) of minimizing knob-twisting distractions. I don't see any examples of triple pole switches in the book and I can't find any in the Spruce catalog, but if I'm thinking correctly, do you have a suggested resource for obtaining one? Otherwise is there another switching logic I should consider? Once again, everyone please feel free to shoot holes in my ideas. Thanks. Lincoln Keill Sacramento, CA My plane is equipped with an old King KX170B, Microair 720, with a Sigtronics SPA 400 intercom. I have interconnected them with a simple switching arrangement that allows selecting comm1 (King), comm 2, (MicroAir), both (audio only), nav (audio for ident). My problem is, I've describe my circuitry to a good A&P, and I think I've improperly wired the switches for comm selection. I've used a DPDT miniature toggle to switch the Mic audio and Headset audio to either comm1, or comm 2, with a SPST miniature toggle to either connect or remain open across the headset audio switch lugs of the DPDT switch. The configuration works, and communications are clear, according to all reports I've received during the last year. My A&P tells me that I should have also included the transmitter key line in the switch, using a 3PDT switch, so as to key up the proper transmitter. My gut tells me he's right, but now I'm curious to know why the simpler circuit I've used hasn't caused problems during the last year. Many times I've had both radios tuned to the same frequency, and keying the mike has never created the squeal normally associated with two transmitters using the same frequency at the same time. In fact, the radio not selected will receive the information transmitted by the other. I've used a hand-held radio to double check, and can not detect any keying of the transmitter section of the non-selected radio when the PTT switch is keyed, and I know that the transmit key line is connected to both radios directly. What am I missing? A If you have confirmed that the non-selected transmitter is indeed passive then you're probably okay. I'm at a loss to explain why you are not having problems . . . the standard practice since day one has been to switch both mic-audio and PTT lines for the selected transmitter. The only thing I can think of is that some modern transmitters I've seen don't need the PTT line to make the transfer from receive to transmit. Microphones should break both the PTT and Mic-Audio lines when the PTT button is relaxed. This allows different microphones to share the same input to the transmitter without interfering with each other. Many modern amateur transmitters sense the microphone power current draw when a microphone is connected to the audio circuit via the PTT switch and use this to deduce the need to transfer from receive to transmit. ________________________________ Message 14 ____________________________________ Time: 12:48:33 PM PST US From: "Rob Turk" Subject: Re: AeroElectric-List: swapping two radios using 3P/DT switch? 3PDT and 4PDT switches are easy to get at online electronics stores like Digikey. ----- Original Message ----- From: Lincoln Keill To: aeroelectric-list@matronics.com Sent: Thursday, December 20, 2007 9:09 PM Subject: AeroElectric-List: swapping two radios using 3P/DT switch? Bob and/or other electronics gurus-- I'm using revision 11 and looking at chapter 11 (switches) and also the FAQ's...I have attached an excerpt from the FAQ's that I think applies to my question as well...it's a gentleman inquiring about using either a "3PDT" switch (I think numerically this is a "3-3 switch"?) to change between two comm radios. If I have a panel mount comm radio (with it's own antenna) and a portable comm radio (an SP-200 with it's own antenna) and a simple two-place intercom system (i.e. PM 3000), I believe I need the above referenced three-pole double-throw (3-3) switch to swap between the two radios: a pole for the wire going to the headset earphones, a pole for the wire coming from the headset microphone, and a pole to swap the PTT line. By doing this, I can swap radios without having to go through the intercom system which is in-line with your philosophy (which I agree with) of minimizing knob-twisting distractions. I don't see any examples of triple pole switches in the book and I can't find any in the Spruce catalog, but if I'm thinking correctly, do you have a suggested resource for obtaining one? Otherwise is there another switching logic I should consider? Once again, everyone please feel free to shoot holes in my ideas. Thanks. Lincoln Keill Sacramento, CA ________________________________ Message 15 ____________________________________ Time: 12:48:35 PM PST US From: Robert Borger Subject: Re: AeroElectric-List: swapping two radios using 3P/DT switch? Lincoln, Check ebay Item number: 180195626322 They seem to be primarily used in audio (musical instruments, guitar parts) circuits. It's a push-button (foot operated) switch but might could be adapted to your use. I just found a 3PDT toggle switch available from MPJA (Marlin P. Jones & Associates) online http://www.MPJA.com/ ( http://www.mpja.com/prodinfo.asp?number=16075+SW ) Try to search 3PDT switch in Google for more options. Good building and great flying, Bob Borger On Thursday, December 20, 2007, at 02:26PM, "Lincoln Keill" wrote: >Bob and/or other electronics gurus-- > > I'm using revision 11 and looking at chapter 11 (switches) and also the FAQ's...I have attached an excerpt from the FAQ's that I think applies to my question as well...it's a gentleman inquiring about using either a "3PDT" switch (I think numerically this is a "3-3 switch"?) to change between two comm radios. > > If I have a panel mount comm radio (with it's own antenna) and a portable comm radio (an SP-200 with it's own antenna) and a simple two-place intercom system (i.e. PM 3000), I believe I need the above referenced three-pole double-throw (3-3) switch to swap between the two radios: a pole for the wire going to the headset earphones, a pole for the wire coming from the headset microphone, and a pole to swap the PTT line. By doing this, I can swap radios without having to go through the intercom system which is in-line with your philosophy (which I agree with) of minimizing knob-twisting distractions. I don't see any examples of triple pole switches in the book and I can't find any in the Spruce catalog, but if I'm thinking correctly, do you have a suggested resource for obtaining one? Otherwise is there another switching logic I should consider? Once again, everyone please feel free to shoot holes in my ideas. Thanks. > > Lincoln Keill > Sacramento, CA ________________________________ Message 16 ____________________________________ Time: 01:41:01 PM PST US Subject: AeroElectric-List: Re: swapping two radios using 3P/DT switch? From: "jetboy" wouldnt you want to leave both audios available? This can be done by joining the audio lines or through series resistors of around 100 ohms if you dont use an audio panel. Just turn the volume down on the radio not being used. Most GA aircraft use a DPDT toggle switch (C150) or DP rotary switch (C152/C172-182) to select the transmitter for the mic / PTT. Ralph -------- Ralph - CH701 / 2200a Read this topic online here: http://forums.matronics.com/viewtopic.php?p=153361#153361 ________________________________ Message 17 ____________________________________ Time: 02:26:05 PM PST US From: "nauga@brick.net" Subject: AeroElectric-List: Re: Audio isolation amp questions Thanks for the response, Bob. I did a little more thorough search of the archives and found answers to everything in there (don't know why I couldn't find them for the past few days), but thanks for taking the time anyway. Dave Hyde ________________________________ Message 18 ____________________________________ Time: 03:34:25 PM PST US From: "JOHN TIPTON" Subject: Re: AeroElectric-List: swapping two radios using 3P/DT switch? Steinair have a selection, which they say are used for audio switching etc ----- Original Message ----- From: Rob Turk To: aeroelectric-list@matronics.com Sent: Thursday, December 20, 2007 8:46 PM Subject: Re: AeroElectric-List: swapping two radios using 3P/DT switch? 3PDT and 4PDT switches are easy to get at online electronics stores like Digikey. ----- Original Message ----- From: Lincoln Keill To: aeroelectric-list@matronics.com Sent: Thursday, December 20, 2007 9:09 PM Subject: AeroElectric-List: swapping two radios using 3P/DT switch? Bob and/or other electronics gurus-- I'm using revision 11 and looking at chapter 11 (switches) and also the FAQ's...I have attached an excerpt from the FAQ's that I think applies to my question as well...it's a gentleman inquiring about using either a "3PDT" switch (I think numerically this is a "3-3 switch"?) to change between two comm radios. If I have a panel mount comm radio (with it's own antenna) and a portable comm radio (an SP-200 with it's own antenna) and a simple two-place intercom system (i.e. PM 3000), I believe I need the above referenced three-pole double-throw (3-3) switch to swap between the two radios: a pole for the wire going to the headset earphones, a pole for the wire coming from the headset microphone, and a pole to swap the PTT line. By doing this, I can swap radios without having to go through the intercom system which is in-line with your philosophy (which I agree with) of minimizing knob-twisting distractions. I don't see any examples of triple pole switches in the book and I can't find any in the Spruce catalog, but if I'm thinking correctly, do you have a suggested resource for obtaining one? Otherwise is there another switching logic I should consider? Once again, everyone please feel free to shoot holes in my ideas. Thanks. Lincoln Keill Sacramento, CA ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.