---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 04/27/14: 18 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:38 AM - Linking 2 coax cables (Carlos Trigo) 2. 05:39 AM - Amp meter jumps when transmitting (rv7a.builder) 3. 06:42 AM - Re: Amp meter jumps when transmitting (Robert L. Nuckolls, III) 4. 06:43 AM - Re: Linking 2 coax cables (Robert L. Nuckolls, III) 5. 07:10 AM - Re: Amp meter jumps when transmitting (rv7a.builder) 6. 07:51 AM - Re: Amp meter jumps when transmitting (Dj Merrill) 7. 07:57 AM - Re: OT: power supply noise (rayj) 8. 08:22 AM - Re: Amp meter jumps when transmitting (rv7a.builder) 9. 10:07 AM - Re: Amp meter jumps when transmitting (Kevin Belue) 10. 10:55 AM - Re: Amp meter jumps when transmitting (Robert L. Nuckolls, III) 11. 11:01 AM - Re: OT: power supply noise (Robert L. Nuckolls, III) 12. 11:28 AM - Re: OT: power supply noise (rayj) 13. 03:53 PM - Re: Amp meter jumps when transmitting (Dj Merrill) 14. 04:04 PM - Re: Linking 2 coax cables (Eric M. Jones) 15. 05:24 PM - Re: Amp meter jumps when transmitting (Henador Titzoff) 16. 05:45 PM - Re: Amp meter jumps when transmitting (Robert L. Nuckolls, III) 17. 06:49 PM - Re: Amp meter jumps when transmitting (Henador Titzoff) 18. 07:51 PM - Re: Amp meter jumps when transmitting (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 04:38:45 AM PST US From: "Carlos Trigo" Subject: AeroElectric-List: Linking 2 coax cables Guys I had to cut and throw away some 2 feet of a Comm antenna cable which I found that had a burnt spot. I don't want to replace all the coax cable, which would be a PIA to do. I also know that I can use a male and a female BNC connectors to make a 2 feet extension, but Is there an elegant and efficient way to connect 2 coax cables to each other, without using a male and a female connectors? Regards Carlos --- Este email est livre de vrus e malware porque a proteo avast! Antivirus est ativa. http://www.avast.com ________________________________ Message 2 _____________________________________ Time: 05:39:17 AM PST US From: "rv7a.builder" Subject: AeroElectric-List: Amp meter jumps when transmitting Hello Group,=0A---- I have a Vans amp meter installed in my RV-7A. When I activate the PTT on the Garmin GNC300XL-the amp meter jumps to ful l scale. I disconnect the antenna coax from back of the radio and hit the P TT and the amp meter needle stays still. I turn off the radio and bring my handheld into the cockpit and hit the transmit button from 2 feet away-an d a very slight movement in the amp meter is detected.-Bringing the handh eld closer to the amp meter will make the needle jump more when the PTT is activated.-I think I have-determined this to be a RF-inference proble m.-My questions are 1) Will the amp meter eventually be damaged by these extreme movements? 2) Is there a fix? 3) Am I alone here or have others exp erience this phenomena?=0A-=0AThanks. John. RV-7A Just about ready to fly ________________________________ Message 3 _____________________________________ Time: 06:42:21 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Amp meter jumps when transmitting At 07:35 AM 4/27/2014, you wrote: Hello Group, I have a Vans amp meter installed in my RV-7A. When I activate the PTT on the Garmin GNC300XL the amp meter jumps to full scale. I disconnect the antenna coax from back of the radio and hit the PTT and the amp meter needle stays still. I turn off the radio and bring my handheld into the cockpit and hit the transmit button from 2 feet away and a very slight movement in the amp meter is detected. Bringing the handheld closer to the amp meter will make the needle jump more when the PTT is activated. I think I have determined this to be a RF inference problem. I bought a Van's ammeter some years ago to explore it's vulnerabilities to strong RF. See pictures here: http://tinyurl.com/mpx8hze I discovered that no only was the instrument devoid of any firewall for RF interference, it was even directionally sensitive!!! See pictures http://tinyurl.com/m4xlj2u http://tinyurl.com/kvo4vwk Just waving the hand-held from side to side would produce behaviors in the pointer error that mimicked the motion of the antenna. My questions are 1) Will the amp meter eventually be damaged by these extreme movements? No 2) Is there a fix? Probably, but labor intensive and clumsy on a finished instrument. It would have been FAR better that the manufacturer demonstrated a knowledge of DO-160 in the first place. 3) Am I alone here or have others experience this phenomena? No doubt there are many others. Since it's a transient event that affects the display only while talking, it's a cosmetic behavior. You might consider just 'living' with it. With one caveat . . . make sure that your coax connectors are good at both ends of the feedline . . . it wouldn't hurt to do an SWR check. The phenomenon you're observing MIGHT be the result of a very RF-Hot cockpit due to loss of shield ground on either end of the coax. But it your antenna system is golden, then there are no risks for just ignoring it. I wrote to Van's about this condition . . . never heard back from them. It no doubt affects their entire line of instruments with electronic signal conditioning. Bob . . . ________________________________ Message 4 _____________________________________ Time: 06:43:06 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Linking 2 coax cables At 06:37 AM 4/27/2014, you wrote: > > >Guys > >I had to cut and throw away some 2 feet of a Comm antenna cable which I >found that had a burnt spot. >I don't want to replace all the coax cable, which would be a PIA to do. >I also know that I can use a male and a female BNC connectors to make a 2 >feet extension, but >Is there an elegant and efficient way to connect 2 coax cables to each >other, without using a male and a female connectors? Yeah, sort of but it's pretty process sensitive. I'd vote for the connectors. Bob . . . ________________________________ Message 5 _____________________________________ Time: 07:10:25 AM PST US From: "rv7a.builder" Subject: Re: AeroElectric-List: Amp meter jumps when transmitting Thanks Bob for that great analysis. John.=0AOn Sunday, April 27, 2014 6:57 AM, "Robert L. Nuckolls, III" wrote:=0A olls.bob@aeroelectric.com>=0A=0AAt 07:35 AM 4/27/2014, you wrote:=0AHello G roup,=0A- - - I have a Vans amp meter installed in my RV-7A. When I a ctivate =0Athe PTT on the Garmin GNC300XL the amp meter jumps to full scale . I =0Adisconnect the antenna coax from back of the radio and hit the PTT =0Aand the amp meter needle stays still. I turn off the radio and bring =0A my handheld into the cockpit and hit the transmit button from 2 feet =0Aawa y and a very slight movement in the amp meter is detected. =0ABringing the handheld closer to the amp meter will make the needle =0Ajump more when the PTT is activated. I think I have determined this =0Ato be a RF inference p roblem.=0A=0A- - I bought a Van's ammeter some years ago to=0A- - e xplore it's vulnerabilities to strong RF.=0A=0A- - See pictures here: =0A=0Ahttp://tinyurl.com/mpx8hze=0A=0A- - I discovered that no only was the instrument=0A- - devoid of any firewall for RF interference,=0A- - it was even directionally sensitive!!! See=0A- - pictures=0A=0Ahtt p://tinyurl.com/m4xlj2u=0A=0Ahttp://tinyurl.com/kvo4vwk=0A=0A- - Just w aving the hand-held from side to side=0A- - would produce behaviors in the pointer error=0A- - that mimicked the motion of the antenna.=0A=0A =0AMy questions are 1) Will the amp meter eventually be damaged by these =0Aextreme movements?=0A=0A- - No=0A=0A- 2) Is there a fix?=0A=0A- - Probably, but labor intensive and clumsy on=0A- - a finished instru ment. It would have been FAR=0A- - better that the manufacturer demonst rated=0A- - a knowledge of DO-160 in the first place.=0A=0A- 3) Am I alone here or have others experience this phenomena?=0A=0A=0A- - No dou bt there are many others. Since it's=0A- - a transient event that affec ts the display=0A- - only while talking, it's a cosmetic behavior.=0A - - You might consider just 'living' with it.=0A=0A- - With one cav eat . . . make sure that your coax=0A- - connectors are good at both en ds of the feedline . . .=0A- - it wouldn't hurt to do an SWR check.- The=0A- - phenomenon you're observing MIGHT be the=0A- - result of a very RF-Hot cockpit due to loss=0A- - of shield ground on either end of the coax.=0A=0A- - But it your antenna system is golden, then=0A- - there are no risks for just ignoring it.=0A=0A- - I wrote to Van's about this condition . . . never=0A- - heard back from them. It no doub t affects=0A- - their entire line of instruments with=0A- - electro =============== ________________________________ Message 6 _____________________________________ Time: 07:51:14 AM PST US Subject: Re: AeroElectric-List: Amp meter jumps when transmitting From: Dj Merrill On 4/27/2014 8:35 AM, rv7a.builder wrote: > I disconnect the antenna coax from back of the radio and hit the PTT > and the amp meter needle stays still. Just as an aside, it is generally a bad idea to activate a transmitter with no antenna attached. There is a good chance of damaging the transmitter by doing this. fyi -Dj -- Dj Merrill - N1JOV - VP EAA Chapter 87 Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/ Glastar Flyer N866RH - http://deej.net/glastar/ ________________________________ Message 7 _____________________________________ Time: 07:57:43 AM PST US From: rayj Subject: Re: AeroElectric-List: OT: power supply noise The parts were part of the CNC kit I bought years ago. It is the power supply for the stepper motors. The output is in the neighborhood of 5 amps at 38Vdc The kit specified an UNregulated power supply because of problems associated with back emf from the stepper motors as they decelerate, as I understand it. The motor drivers derive the required 5Vdc internally from the power supply hookup. My main concern was about radiated noise being picked up because they are both inside an old metal computer case. Thanks for the reply. Raymond Julian Kettle River, MN The things we admire in men, kindness and generosity, openness, honesty, understanding and feeling are the concomitants of failure in our system. And those traits we detest, sharpness, greed, acquisitiveness, meanness, egotism and self-interest are the traits of success. And while men admire the quality of the first they love the produce of the second. -John Steinbeck, novelist, Nobel laureate (1902-1968) On 04/26/2014 10:56 PM, Robert L. Nuckolls, III wrote: > > > At 03:10 PM 4/26/2014, you wrote: >> >> Greetings, >> >> I'm considering putting an unregulated power supply (transformers, >> diodes, and a condenser) in an old computer box along with the >> electronics to run several stepper motors for a CNC system. >> >> I'm wondering if noise radiated from the power supply will cause >> problems for the stepper motor drivers. > > Probably not. Do you have these parts already in hand? > Regulated, clean power supplies up to 350W are pretty > cheap on eBay. I seldom build a supply any more, the labor > alone is more than the cost of an off-the-shelf, plug-n-play > device. > > > Bob . . . > > ________________________________ Message 8 _____________________________________ Time: 08:22:00 AM PST US From: "rv7a.builder" Subject: Re: AeroElectric-List: Amp meter jumps when transmitting Thanks for telling me that. I won't try that again. What actually happens t hat could damage the transmitter? Thanks. John=0AOn Sunday, April 27, 2014 8:10 AM, Dj Merrill wrote:=0A =0A--> AeroElectric-List mes sage posted by: Dj Merrill =0A=0AOn 4/27/2014 8:35 AM, rv7a. builder wrote:=0A> I disconnect the antenna coax from back of the radio and hit the PTT =0A> and the amp meter needle stays still.=0A=0AJust as an asi de, it is generally a bad idea to activate a transmitter =0Awith no antenna attached.- There is a good chance of damaging the =0Atransmitter by doin g this.=0A=0Afyi=0A=0A-Dj=0A=0A-- =0ADj Merrill - N1JOV - VP EAA Chapter 87 =0ASportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/=0AGlasta ________________________________ Message 9 _____________________________________ Time: 10:07:08 AM PST US Subject: Re: AeroElectric-List: Amp meter jumps when transmitting From: Kevin Belue I saw this problem years ago also. Their electronic manifold pressure gauge has same issue. I replaced the MP with a non-electric version. The rest of my instruments are from an EFIS. No problems with this configuration. K. Belue RV-10 Sent from my iPhone On Apr 27, 2014, at 8:41 AM, "Robert L. Nuckolls, III" wrote: > > At 07:35 AM 4/27/2014, you wrote: > Hello Group, > I have a Vans amp meter installed in my RV-7A. When I activate the PTT on the Garmin GNC300XL the amp meter jumps to full scale. I disconnect the antenna coax from back of the radio and hit the PTT and the amp meter needle stays still. I turn off the radio and bring my handheld into the cockpit and hit the transmit button from 2 feet away and a very slight movement in the amp meter is detected. Bringing the handheld closer to the amp meter will make the needle jump more when the PTT is activated. I think I have determined this to be a RF inference problem. > > I bought a Van's ammeter some years ago to > explore it's vulnerabilities to strong RF. > > See pictures here: > > http://tinyurl.com/mpx8hze > > I discovered that no only was the instrument > devoid of any firewall for RF interference, > it was even directionally sensitive!!! See > pictures > > http://tinyurl.com/m4xlj2u > > http://tinyurl.com/kvo4vwk > > Just waving the hand-held from side to side > would produce behaviors in the pointer error > that mimicked the motion of the antenna. > > > My questions are 1) Will the amp meter eventually be damaged by these extreme movements? > > No > > 2) Is there a fix? > > Probably, but labor intensive and clumsy on > a finished instrument. It would have been FAR > better that the manufacturer demonstrated > a knowledge of DO-160 in the first place. > > 3) Am I alone here or have others experience this phenomena? > > > No doubt there are many others. Since it's > a transient event that affects the display > only while talking, it's a cosmetic behavior. > You might consider just 'living' with it. > > With one caveat . . . make sure that your coax > connectors are good at both ends of the feedline . . . > it wouldn't hurt to do an SWR check. The > phenomenon you're observing MIGHT be the > result of a very RF-Hot cockpit due to loss > of shield ground on either end of the coax. > > But it your antenna system is golden, then > there are no risks for just ignoring it. > > I wrote to Van's about this condition . . . never > heard back from them. It no doubt affects > their entire line of instruments with > electronic signal conditioning. > > > > > > Bob . . . > > > > ________________________________ Message 10 ____________________________________ Time: 10:55:42 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Amp meter jumps when transmitting At 09:50 AM 4/27/2014, you wrote: > >On 4/27/2014 8:35 AM, rv7a.builder wrote: >>I disconnect the antenna coax from back of the radio and hit the >>PTT and the amp meter needle stays still. > >Just as an aside, it is generally a bad idea to activate a >transmitter with no antenna attached. There is a good chance of >damaging the transmitter by doing this. Back in the days of germanium output transistors (yes Martha, there WERE germanium devices capable of several watts at VHF) it was considered poor form if not instant death to one's output transistors to key a transmitter into an open circuit. Modern output devices are much more rugged. Further, transmitters at-risk for high SWR damage are fitted with automatic shut-down circuits for protection. Bob . . . ________________________________ Message 11 ____________________________________ Time: 11:01:36 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: OT: power supply noise At 09:56 AM 4/27/2014, you wrote: > >The parts were part of the CNC kit I bought years ago. It is the >power supply for the stepper motors. The output is in the >neighborhood of 5 amps at 38Vdc The kit specified an UNregulated >power supply because of problems associated with back emf from the >stepper motors as they decelerate, as I understand it. Steppers don't generate back emf based on motion of the moving parts. For the fastest possible response time, steppers like to be driven from high resistance if not purely constant current power sources. It's all about that t=L/R thingy. The first stepper systems I crafted used banks of power resistors to raise power source impedance. Modern designs will use constant current output stages in the drivers if they're seeking high accuracy positioning along with fast response. >The motor drivers derive the required 5Vdc internally from the power >supply hookup. > >My main concern was about radiated noise being picked up because >they are both inside an old metal computer case. Your application would run quite well from unregulated, full wave rectified AC as long as the 'relaxed' voltage is not so high as to place output transistors at risk in their OFF state. Bob . . . ________________________________ Message 12 ____________________________________ Time: 11:28:40 AM PST US From: rayj Subject: Re: AeroElectric-List: OT: power supply noise Thanks. Now out to the shop! do not archive Raymond Julian Kettle River, MN The things we admire in men, kindness and generosity, openness, honesty, understanding and feeling are the concomitants of failure in our system. And those traits we detest, sharpness, greed, acquisitiveness, meanness, egotism and self-interest are the traits of success. And while men admire the quality of the first they love the produce of the second. -John Steinbeck, novelist, Nobel laureate (1902-1968) On 04/27/2014 01:00 PM, Robert L. Nuckolls, III wrote: > > > At 09:56 AM 4/27/2014, you wrote: >> >> The parts were part of the CNC kit I bought years ago. It is the >> power supply for the stepper motors. The output is in the >> neighborhood of 5 amps at 38Vdc The kit specified an UNregulated power >> supply because of problems associated with back emf from the stepper >> motors as they decelerate, as I understand it. > > Steppers don't generate back emf based on > motion of the moving parts. For the fastest > possible response time, steppers like to be > driven from high resistance if not purely constant > current power sources. It's all about that > t=L/R thingy. > > The first stepper systems I crafted used banks > of power resistors to raise power source impedance. > Modern designs will use constant current output > stages in the drivers if they're seeking high > accuracy positioning along with fast response. > >> The motor drivers derive the required 5Vdc internally from the power >> supply hookup. >> >> My main concern was about radiated noise being picked up because they >> are both inside an old metal computer case. > > Your application would run quite well from unregulated, > full wave rectified AC as long as the 'relaxed' voltage > is not so high as to place output transistors at risk > in their OFF state. > > > Bob . . . > > ________________________________ Message 13 ____________________________________ Time: 03:53:48 PM PST US Subject: Re: AeroElectric-List: Amp meter jumps when transmitting From: Dj Merrill On 4/27/2014 11:21 AM, rv7a.builder wrote: > Thanks for telling me that. I won't try that again. What actually > happens that could damage the transmitter? Thanks. John Hi John, I am sure someone else on here can explain the technical details better than I, but the simple version is that if the transmitter does not have circuitry built in to protect against it, it can blow some of the parts in the final amplifier stage of the transmitter. Hopefully someone else can chime in with more details of exactly how and why. There is probably a good chance that a modern solid state radio has this protection built in, but unless one knows for sure, there is no reason to take the expensive chance that it doesn't. I'd be more concerned with the older radios, but in general it is just good practice to make sure that you have an antenna or a dummy load attached to the antenna port before keying up the transmitter. My personal choice is to make sure there is an antenna attached before even powering a radio on, regardless of whether I am going to key the transmitter part. -Dj -- Dj Merrill - N1JOV - VP EAA Chapter 87 Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/ Glastar Flyer N866RH - http://deej.net/glastar/ ________________________________ Message 14 ____________________________________ Time: 04:04:13 PM PST US Subject: AeroElectric-List: Re: Linking 2 coax cables From: "Eric M. Jones" Install a new cable or connectors. No other reasonable solution exists. Read my article attached. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones(at)charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=422475#422475 Attachments: http://forums.matronics.com//files/dabbling_with_electricity_179.pdf ________________________________ Message 15 ____________________________________ Time: 05:24:54 PM PST US From: Henador Titzoff Subject: Re: AeroElectric-List: Amp meter jumps when transmitting Dj, John,=0A=0AHere's what happens when a transmitter hurls RF energy down a transmission line.- First, the transmission line has a characteristic i mpedance.- Impedance is almost like a resistance except it's comprised of a mixture of capacitor reactance, inductive reactance and resistance.- R eactances have currents and voltages that are 90 degrees out of phase.- T his means they don't "burn" up any of the energy, whereas resistance has vo ltage and current in phase and does burn up energy.- Check out the attach ed picture from Wiki, which shows how the capacitance, inductance and resis tances are modeled as lumped components. Ideally, the series and parallel r esistances are zero.- In practice they're not but designers try to minimi ze them to decrease attenuation.=0A=0A=0AWhen this energy traveling down th e transmission line reaches the end, what happens?- If there's a resistor there that is equal to the transmission line's characteristic impedance, t hen ideally all of the energy is dissipated in that resistor as heat, since the voltage and current waves are in phase.- If an antenna that is match ed to the line is there, the power is magically transferred to the atmosphe re, because the antenna's job is to match the impedance of the cable to fre e space impedance, which is 376 Ohms.- It isn't really magic, at least ma thematically, but one has to understand Maxwell's and Gaussian's laws to kn ow how this happens and why free space impedance is 376 Ohms.=0A=0A=0ASo le t's say the end of the transmission line is open or doesn't match the imped ance.- In the open case, the energy has nowhere to go except to be transm itted right back to where it came from.- Let's say the transmitter's tran sistors are generating voltage waves that are 10V peak to peak.- This mea ns that the designer has to choose components that can handle this voltage plus some, say another 10V, in order to provide longevity and reliability. - When the reflected energy arrives at the transmitter output, the two wa ves (one going and one coming) can add up to a worst case number of 20V pea k to peak if the phasing is correct. This comes very close to exceeding the design limitation of the transmitter transistors.- If the designer specs the transistors to less than 20V, then the two added waves' peak voltage c ould very well destroy the transistors and/or other components.- The desi gner could add transorbers or some other devices designed to limit the voltage build up at the transmitter to keep it from malfunctioning, but it 's up to the designer and his design specs.=0A=0AAlso, the transmitter has an impedance of its own, and for maximum power transfer it should equal the line's impedance.- When the reflected wave comes back, if there is a sli ght mismatch between the transmitter and line impedances, there will be som e power dissipation at the transmitter but some of the power (wave) will re flect back to the end of the line.- This means there are several waves on the line, but each reflection decreases in amplitude because of losses alo ng the line and at the ends.- All of these waves have to be added or subt racted to find the real voltages at the ends.=0A=0ASo the bottom line is ca n the transmitter handle the reflected waves such that when they add up, th e end voltage doesn't damage the transmitter components, which of course ha ve maximum voltage and power limits.- I add power in there because power causes heat and components can only handle so much maximum temperature.=0A =0AHope this helps.=0A-=0AHenador Titzoff=0A=0A=0A>______________________ __________=0A> From: Dj Merrill =0A>To: aeroelectric-list@ma tronics.com =0A>Sent: Sunday, April 27, 2014 6:52 PM=0A>Subject: Re: AeroEl ectric-List: Amp meter jumps when transmitting=0A> =0A>=0A>--> AeroElectric -List message posted by: Dj Merrill =0A>=0A>On 4/27/2014 11: 21 AM, rv7a.builder wrote:=0A>> Thanks for telling me that. I won't try tha t again. What actually =0A>> happens that could damage the transmitter? Tha nks. John=0A>=0A>Hi John,=0A>- - I am sure someone else on here can ex plain the technical details =0A>better than I, but the simple version is th at if the transmitter does =0A>not have circuitry built in to protect again st it, it can blow some of =0A>the parts in the final amplifier stage of th e transmitter. Hopefully =0A>someone else can chime in with more details of exactly how and why.=0A>=0A>- - There is probably a good chance that a modern solid state radio has =0A>this protection built in, but unless one knows for sure, there is no =0A>reason to take the expensive chance that i t doesn't.- I'd be more =0A>concerned with the older radios, but in gener al it is just good practice =0A>to make sure=0A that you have an antenna or a dummy load attached to the =0A>antenna port before keying up the transmi tter.- My personal choice is to =0A>make sure there is an antenna attache d before even powering a radio on, =0A>regardless of whether I am going to key the transmitter part.=0A>=0A>-Dj=0A>=0A>-- =0A>Dj Merrill - N1JOV - VP EAA Chapter 87=0A>Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/spor ========================0A> =0A>=0A>=0A>=0A>=0A> ________________________________ Message 16 ____________________________________ Time: 05:45:18 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Amp meter jumps when transmitting >So the bottom line is can the transmitter handle the reflected waves >such that when they add up, the end voltage doesn't damage the >transmitter components, which of course have maximum voltage and >power limits. I add power in there because power causes heat and >components can only handle so much maximum temperature. I'm aware of no supplier to aviation that does not consider the rare but possible failure of a coax connection . . . it's common practice to build in protection, robustness or a combination of the two. Bob . . . ________________________________ Message 17 ____________________________________ Time: 06:49:47 PM PST US From: Henador Titzoff Subject: Re: AeroElectric-List: Amp meter jumps when transmitting This is very true, Bob, but I would also like to add that the possibility o f an open in the connectors and coax is more common than "rare."- Most of these failures occur during build, which are accidental, corrosion or fail ure to tighten down connectors correctly.=0A=0A=0AWhile aviation suppliers will consider the rare but possible failure you mention below, there are se veral scenarios where this is not true.- One scenario is the supplier rec eiving counterfeit parts that do not meet specs.- Another scenario is a s hady buyer ordering the wrong parts and a faulty lot is manufactured and sh ipped.- Manufactured lots vary from lot to lot, and some lots may sneak t hrough that do not meet specifications but work well until "something happe ns."- In particular, this business of counterfeit parts has been plaguing manufacturing for at least two decades now.=0A=0A-=0AHenador Titzoff=0A =0A=0A>________________________________=0A> From: "Robert L. Nuckolls, III" =0A>To: aeroelectric-list@matronics.com =0A >Sent: Sunday, April 27, 2014 8:44 PM=0A>Subject: Re: AeroElectric-List: Am p meter jumps when transmitting=0A> =0A>=0A>--> AeroElectric-List message p osted by: "Robert L. Nuckolls, III" =0A>=0A> =0A>>So the bottom line is can the transmitter handle the reflected waves =0A>>such that when they add up, the end voltage doesn't damage the =0A>>tr ansmitter components, which of course have maximum voltage and =0A>>power l imits.- I add power in there because power causes heat and =0A>>component s can only handle so much maximum temperature.=0A>=0A>- - I'm aware of no supplier to aviation that does not=0A>- - consider the rare but poss ible failure of a coax=0A>- - connection . . . it's common practice to build=0A>- - in protection, robustness or a combination of the=0A>- ==================0A>=0A>=0A>=0A>=0A>=0A> ________________________________ Message 18 ____________________________________ Time: 07:51:48 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Amp meter jumps when transmitting > >Manufactured lots vary from lot to lot, and some lots may sneak > through that do not meet specifications but work well until > "something happens." In >particular, this business of counterfeit > parts has been plaguing manufacturing for at least two decades now. Forgive me my friend but we're reaching WAAaaayyyy down into the worry bucket with this line of reasoning. Once you open that door . . . where do the caveats end? Cracked magneto rotors? Contaminated fuel? Bogus rivets? The world is indeed fraught with risks. Nonetheless, the vast majority of misadventures in every venue have nothing to do with parts that fail to meet published requirements. Adding such worries to the knowledge base is potential misdirection of valuable attention from much greater risks. 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