---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 06/20/07: 14 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:34 AM - Re: RTV sealants (Dale Ensing) 2. 06:03 AM - Re: RTV sealants (Robert L. Nuckolls, III) 3. 06:27 AM - Re: VOR/GS Antenna (Robert L. Nuckolls, III) 4. 08:15 AM - Re: VOR/GS Antenna (Robert L. Nuckolls, III) 5. 08:55 AM - Re: VOR/GS Antenna () 6. 09:15 AM - Re: Re: VOR/GS Antenna (BobsV35B@aol.com) 7. 09:46 AM - Re: Re: VOR/GS Antenna (Robert L. Nuckolls, III) 8. 11:19 AM - Re: Low Voltage plus Alt Loadmeter (Robert L. Nuckolls, III) 9. 12:44 PM - Re: Re: MB antennnas (John Morgensen) 10. 01:00 PM - Re: RTV sealants (Neil Clayton) 11. 01:39 PM - Re: RTV sealants (Matt Prather) 12. 02:03 PM - Re: RTV sealants (Alan Adamson) 13. 02:23 PM - Radios squawk ...literally (Jerry2DT@aol.com) 14. 02:56 PM - Re: Radios squawk ...literally (Peter Pengilly) ________________________________ Message 1 _____________________________________ Time: 04:34:42 AM PST US From: "Dale Ensing" Subject: Re: AeroElectric-List: RTV sealants While it is important to be aware of the side effects of the acidic acid cured RTVs on electrical contacts/components and use the neutral cured RTVs, especially in a confined area, there is no problem using them on the airframe. (Have you ever used self etching primers on your new winged creation?) The acetic acid cured RTVs provide a stronger adhesion to the metal substrate, if that is desirable, without the proper primer which may be required with the neutral cured RTV's. A strong adhesion is not usually necessary in an electrical/electronic applications. Dale Ensing many years silicone RTV experience with aerospace/aviation industry > > > As far as sealants are concerned, wouldn't shoe goo, Plumbers Goop or RV > Goop from eclectic products work as well? I remember Bob talking about > Shoe Goo and some other similar products. These I believe are all from > eclecti products in LA. I purchased mine at Home Depot...seem to work > well. > Harold > ----- Original Message ----- > From: "bob mackey" > To: > Sent: Monday, June 18, 2007 9:51 PM > Subject: AeroElectric-List: RTV sealants > > >> >> There were several recent recommendations for the use of >> RTV (room temperature vulcanizing) elastic sealants. >> Before putting this stuff near your airframe or avionics, >> you should know that there are many different types of RTV, >> and most of them are somewhat corrosive as a result of the >> acetic-acid curing chemistry (smells like vinegar). >> >> For mounting antennas to aluminum airframes, consider using an >> alcohol-cure RTV such as clear or gray Dow Corning 3145, white >> General Electric RTV 162 or gray high strength RTV 167, or clear >> Loctite 5140. >> >> These alcohol-cure RTVs are more expensive. >> Instead of a buck or three, McMaster sells the GE 162 for $12.66 >> per 2.8 oz tube. >> http://www.mcmaster.com (part number 74935A65, page 3305) >> The Dow 3145 is quite a bit more expensive than that. >> >> references: >> http://www.logwell.com/tech/servtips/RTV.html >> http://www.mgchemicals.com/downloads/appguide/appguide0205-1.pdf >> http://www.mgchemicals.com/products/silicones/cureguide-1part.html >> ... and of course Google... >> >> >> >> >> > > > ________________________________ Message 2 _____________________________________ Time: 06:03:27 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: RTV sealants At 07:30 AM 6/20/2007 -0400, you wrote: Good point Dale. With respect to Shoe Goo (E6000) and close cousins. I've found that these adhesives have excellent adhesion to clean surfaces and are relatively inexpensive and readily available. They do not have the high temperature operating characteristics of silicones and I'm not sure what the long term characteristics are with respect to ageing and in particular, attacks by the byproducts of combustion and the inevitable constituents of oil that will end up on the belly of your airplane. RTV is not as aggressive as an adhesive and has a lower tensile strength but it's resistance to evils of the environment and performance at temperature extremes is inarguable. But if you ever have to open a joint, it's harder to clean up than E6000 which is easily dissolved with mild solvents. In the case of antenna base sealing on the bottom of the aircraft, I think RTV has "the edge" . . . but it's likely that an E6000 sealing job will be just fine too. Bob . . . > > >While it is important to be aware of the side effects of the acidic acid >cured RTVs on electrical contacts/components and use the neutral cured >RTVs, especially in a confined area, there is no problem using them on the >airframe. (Have you ever used self etching primers on your new winged >creation?) The acetic acid cured RTVs provide a stronger adhesion to the >metal substrate, if that is desirable, without the proper primer which may >be required with the neutral cured RTV's. A strong adhesion is not usually >necessary in an electrical/electronic applications. >Dale Ensing >many years silicone RTV experience with aerospace/aviation industry > > >> >> >>As far as sealants are concerned, wouldn't shoe goo, Plumbers Goop or RV >>Goop from eclectic products work as well? I remember Bob talking about >>Shoe Goo and some other similar products. These I believe are all from >>eclecti products in LA. I purchased mine at Home Depot...seem to work well. >>Harold > >>----- Original Message ----- From: "bob mackey" >>To: >>Sent: Monday, June 18, 2007 9:51 PM >>Subject: AeroElectric-List: RTV sealants >> >> >>> >>>There were several recent recommendations for the use of >>>RTV (room temperature vulcanizing) elastic sealants. >>>Before putting this stuff near your airframe or avionics, >>>you should know that there are many different types of RTV, >>>and most of them are somewhat corrosive as a result of the >>>acetic-acid curing chemistry (smells like vinegar). >>> >>>For mounting antennas to aluminum airframes, consider using an >>>alcohol-cure RTV such as clear or gray Dow Corning 3145, white >>>General Electric RTV 162 or gray high strength RTV 167, or clear >>>Loctite 5140. >>> >>>These alcohol-cure RTVs are more expensive. >>>Instead of a buck or three, McMaster sells the GE 162 for $12.66 >>>per 2.8 oz tube. >>>http://www.mcmaster.com (part number 74935A65, page 3305) >>>The Dow 3145 is quite a bit more expensive than that. >>> >>>references: >>>http://www.logwell.com/tech/servtips/RTV.html >>>http://www.mgchemicals.com/downloads/appguide/appguide0205-1.pdf >>>http://www.mgchemicals.com/products/silicones/cureguide-1part.html >>>... and of course Google... >>> >>> >>> >>> >> >> >> > > >-- >269.9.1/854 - Release Date: 6/19/2007 1:12 PM > > >incoming mail is certified Virus Free. >Checked by AVG. Bob . . . ---------------------------------------- ( "Physics is like sex: sure, it may ) ( give some practical results, but ) ( that's not why we do it." ) ( ) ( Richard P. Feynman ) ---------------------------------------- ________________________________ Message 3 _____________________________________ Time: 06:27:05 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: VOR/GS Antenna At 05:49 PM 6/19/2007 +0000, you wrote: Distorting the classic linear dipole antenna by moving the ends forward or aft on the aircraft will have two significant effects. See: http://www.tpub.com/content/neets/14182/css/14182_186.htm The straight dipole in free space will exhibit strong and equal responses to the broad sides of the dipole and very sharp nulls (near zero response) to the ends. Obviously, the "ideal" antenna would have equal and super responses all the way around the compass . . . but we don't live in a perfect world. Besides, in aircraft, we're MOST interested in VOR stations that lie on our path of flight. As soon as you distort the classic shape, the responses to the broad sides will change . . . one gets weaker while the other one gets stronger. This doesn't continue without bounds . . . if you keep moving the free ends of the antenna closer together, the antenna morphs from an effective radiator/receptor of energy to a poorly terminated transmission line with exceedingly high SWR. At the same time the braodside responses are distorting, the nulls at the ends become less than "perfect" so your ability to utilize VOR stations that lie off your heading is improved. Whether there is advantage to bringing the tips forward or aft is mostly a matter of style. When you're flying the Victor Airways, the charts depict nav aid changeover points where it's recommended that you stop navigating on the station behind you and change to the station in front of you. This may or may not be at the half-way point. There are folks that spend many $killo$ of your tax money to survey these routes with the goal of optimizing performance based on signal strengths from the various facilities. These surveys account for intermediate obstructions and other effects of terrain. Bottom line is that for 99.9% of the way YOUR airplane is going to be used, the VOR antenna configuration is not going to be a key component of your recipe for success in completing the mission of the moment. I think I'd base antenna selection on cost and appearance in that order. Bob archer's wing tip antennas are strong contenders in this market. Only if Bob's product proves inadequate to YOUR tasks would I consider expanding the field of consideration for which antenna to use. Obviously, the v-whiskers are inexpensive and easy to install and attach to a feed line. Consider using a BALUN to improve on the interface between dipole and coax. See: http://aeroelectric.com/articles/BALUN/Balun_Fabrication.html For those members of the List interested in some of the more esoteric aspect of our craft, cruise the website I cited above. Stoke the Next/Back links for a broad and well explained dissertation on antenna science. The same site has a wealth of other data of interest for the curious and motivated reader. Bob . . . ________________________________ Message 4 _____________________________________ Time: 08:15:16 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: VOR/GS Antenna At 08:25 AM 6/20/2007 -0600, you wrote: > > >At 05:49 PM 6/19/2007 +0000, you wrote: > > > Distorting the classic linear dipole antenna by moving the ends > forward or aft on the aircraft will have two significant effects. > See: > >http://www.tpub.com/content/neets/14182/css/14182_186.htm I thought I recognized some of the stuff in the link I cited. The Navy's Electricity and Electronics Training Series are available from the a variety of websites including my own. They are part of the downloadable CD materials which you can access at: http://www.aeroelectric.com/CD/ You'll need a high-speed internet connection to get these documents with any reasonable dispatch. They are big. But you can't beat the price for acquiring some excellent texts on matters electronics. I taught out of earlier versions of these documents at Great Lakes about 40 years ago. If push comes to shove, you can order the CD from us . . . or better yet, attend one of the seminars. You get the CD for free. If you DO have a way to conveniently download the CD, please duplicate and share with your local aviation enthusiasts. Our charge for the CD is a nuisance-fee. It's not our goal to turn a profit on the activity. The goal is to maximize availability of the offered materials to any folks who have an interest. You can get the individual Modules for this series of documents at: http://www.phy.davidson.edu/instrumentation/NEETS.htm Download, share, learn and enjoy . . . Bob . . . ________________________________ Message 5 _____________________________________ Time: 08:55:31 AM PST US From: Subject: AeroElectric-List: Re: VOR/GS Antenna Thanks for the suggestion Bob. One question though. I see the Comant CI-120 blade set for VOR/GS Navigation sells for approx. $800. Do you know of any priced closer to the "cat whisker' style? Thanks, Tom Packard Super Rebel 90%(you know what that means!) --- http://USFamily.Net/dialup.html - $8.25/mo! -- http://www.usfamily.net/dsl.html - $19.99/mo! --- ________________________________ Message 6 _____________________________________ Time: 09:15:43 AM PST US From: BobsV35B@aol.com Subject: Re: AeroElectric-List: Re: VOR/GS Antenna Good Morning Tom, No, I do not. The price is a major detriment. I was using Dorne Margolin units until they raised their price into the stratosphere. I then went to Comants and just last year installed a set of Sensor Systems blades. They have a stainless steel insert in the leading edge which MAY be helpful on unimproved strips. Don't know yet. Those were mounted below the stabilizer on a model E18S Twin Beech which frequents many out of the way landing strips. The cost factor IS terrible, but they work great! The "hidden in the wing tip" solution sounds great if it will work! If that is not an option, I would pop for the blades. 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 6/20/2007 10:57:56 A.M. Central Daylight Time, jtpackard@usfamily.net writes: --> AeroElectric-List message posted by: Thanks for the suggestion Bob. One question though. I see the Comant CI-120 blade set for VOR/GS Navigation sells for approx. $800. Do you know of any priced closer to the "cat whisker' style? Thanks, Tom Packard Super Rebel 90%(you know what that means!) ************************************** See what's free at http://www.aol.com. ________________________________ Message 7 _____________________________________ Time: 09:46:55 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: VOR/GS Antenna At 10:51 AM 6/20/2007 -0500, you wrote: > >Thanks for the suggestion Bob. >One question though. I see the Comant CI-120 blade set for VOR/GS >Navigation sells for approx. $800. Do you know of any priced closer to >the "cat whisker' style? >Thanks, >Tom Packard >Super Rebel 90%(you know what that means!) No, blade antennas are relatively simple with respect to the antenna part . . . Bob archer could easily fabricate a suitable pattern on a piece of copper clad but a couple of 1/16th inch thick, fiberglas "flappers" bolted to each side of your vertical fin would not draw much praise for style. The expensive part of building a blade antenna is to mold a stylistic, robust but LIGHT enclosure around it. The tooling is not cheap, the process not trivial. Hence, demand for such antennas has been decidedly low in spite of the fact that they work well and look good. A set of blades would also be heavier than a v-whisker and this weight sets waaaayyy back on the moment arm for your C.G. calculations. Finally, given the inexorable fade of VOR as a primary mode of navigation, it's my suggestion that you figure out a way to get SOME VOR capability on board with a minimum of expense and effort. I.e. don't bust yer buns to achieve an optimized capability. VOR no longer figures in the best-we-know-how-to-do. The v-whisker is a mild compromise over blades in terms of performance. The wing tip antennas are a bit more compromised yet but sales of those devices is strong. I've not heard of any one replacing them with another technology 'cause it doesn't perform well enough to accommodate the mission. Since I bought my first hand-held GPS in 1995, I've not turned on a VOR receiver for any purpose other than to demonstrate it to someone who is along for the ride or to fiddle with while watching the ground go by. Bob . . . ---------------------------------------- ( "Physics is like sex: sure, it may ) ( give some practical results, but ) ( that's not why we do it." ) ( ) ( Richard P. Feynman ) ---------------------------------------- ________________________________ Message 8 _____________________________________ Time: 11:19:26 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Low Voltage plus Alt Loadmeter At 10:12 AM 6/19/2007 -0700, you wrote: > >THANK YOU sooo much for responding and for the additional information, >I've replied where appropriate below and asked an additional question for >some clarification. >> >I have the LR-3's from B&C which drive/include Low Voltage indicators. That covers the "essentials" . . . >>If you add anything on top of that, I'd recommend >> an expanded scale voltmeter on the e-bus and/or alternator >> loadmeter(s) . . . but both of those are only small peeks at a variety >> of test points you'll need to look at for diagnosis. Ammeters >> and voltmeters are poor monitoring tools. And as diagnostic >> tools, they are only a part of what's necessary for troubleshooting. >> >>>However, I'm stumped as to where to locate the Shunts in the Z-14 so as >>>to be able to connect Battery ammeters. >> >> What kind of panel displays are you considering? >I have dual glass panels (EFIS) w a glass back-up. The Engine Interface >unit is a JPI product (black box) which captures information from probes >and sensors, it relies on Shunts for AMP meter input. The information >from the EIU black box is interpreted and displayed on graphic indicators >on a display page with the EFIS units. You use the plural version of shunt. Does the system have more than one input for monitoring a current? Or is there one input that can be switched to one of mulitple shunts? >OK, so I've got the low voltage indicators, and If I go ahead and install >the shunts per the Z-14 to supply Alternator loadmeters, I'm not sure I >understand how to interpret the information that I receive from the >Alternator loadmeters. What would this information be telling me? If I >understand it correctly (?) it would display the current that is being >output from the Alternator, correct? But if I understand correctly it >doesn't tell me that the battery is charging, (Is this what you mean when >you say that items 3 and higher have little or no significance in >Operations? can you illuminate? IF the bus is being supported at the design set point (i.e. 13.8 to 14.6 volts with 14.2 being nominal) AND assuming further that the battery is in good shape and capable of accepting a charge, then it IS being charged. There is no value in having a minus-zero-plus indicator (battery ammeter) to confirm this. I'm presuming that you intend to MAINTAIN the battery with respect to KNOWING that its capacity is sufficient to your endurance needs, then knowing that the bus voltage is where it should be is sufficient. Alternator loadmeters are generally set up to display percent of full load. See: https://matronics.com/aeroelectric/Catalog/9007-120-1_Loadmeter.jpg The instrument is then paired with shunt(s) that are sized for the capability of the device being monitored. E.g. a 55A alternator should get a 55A shunt, a 20A alternator is fitted with a 20A shunt. This allows one to switch a single instrument to as many devices as you wish and know what PERCENTAGE of that device's capabilities are in demand at any given time. As to operations . . . if the low volts warning light is OUT (and the engine monitor confirms the bus at an acceptable voltage) of what value is it as a pilot to know what ANY current is? You have designed your system to carry all the loads required for operation. Knowing what those loads are at any given moment are incidental to piloting the airplane. If the low voltage warning light is ON, of what value is it to know what any current is? You have designed your Plan-B operations and KNOW that the battery will support Plan-B for x number of hours with loads you've already decided to support. My assertion is that every load situation for both normal and alternator-out operations are known in advance and knowing a reading only validates your Plan-B design . . . it adds no value for comfortable completion of flight. Once you're on the ground, you're going to find that you need a LOT more data to interpret the failure and deduce needs for repair. So unless you're going to install a LOT of shunts and voltage sample points for the purpose of diagnosing the failure from the pilot's seat, the classic choices for instrumentation beyond a low-volts warning and an e-bus voltmeter are a toss up. Bob . . . ________________________________ Message 9 _____________________________________ Time: 12:44:47 PM PST US From: John Morgensen Subject: Re: AeroElectric-List: re: MB antennnas Robert L. Nuckolls, III wrote: > I don't need the antenna . . . but if you could > get me the dimensions I asked about earlier, it > would be helpful. > > Bob . . . > Down 6" from the belly and then 88" long. In addition, there is a copper wire coil about 6" long in the middle of the antenna. Hope this helps. John Morgensen RV-9A ________________________________ Message 10 ____________________________________ Time: 01:00:07 PM PST US From: Neil Clayton Subject: Re: AeroElectric-List: RTV sealants Another sealant question; Does anyone know of a sealant-like product that could be used for the gap between the canopy and body as a weather seal? I There are no off-the-shelf weather seals I can find that will fit exactly. Perhaps there's a liquid sealant that can be extruded into the gap and will mould to the right shape? Thanks Neil At 01:37 PM 6/19/2007, you wrote: > > >As far as sealants are concerned, wouldn't shoe goo, Plumbers Goop >or RV Goop from eclectic products work as well? I remember Bob >talking about Shoe Goo and some other similar products. These I >believe are all from eclecti products in LA. I purchased mine at >Home Depot...seem to work well. >Harold >----- Original Message ----- From: "bob mackey" >To: >Sent: Monday, June 18, 2007 9:51 PM >Subject: AeroElectric-List: RTV sealants > > >> >>There were several recent recommendations for the use of >>RTV (room temperature vulcanizing) elastic sealants. >>Before putting this stuff near your airframe or avionics, >>you should know that there are many different types of RTV, >>and most of them are somewhat corrosive as a result of the >>acetic-acid curing chemistry (smells like vinegar). >> >>For mounting antennas to aluminum airframes, consider using an >>alcohol-cure RTV such as clear or gray Dow Corning 3145, white >>General Electric RTV 162 or gray high strength RTV 167, or clear >>Loctite 5140. >> >>These alcohol-cure RTVs are more expensive. >>Instead of a buck or three, McMaster sells the GE 162 for $12.66 >>per 2.8 oz tube. >>http://www.mcmaster.com (part number 74935A65, page 3305) >>The Dow 3145 is quite a bit more expensive than that. >> >>references: >>http://www.logwell.com/tech/servtips/RTV.html >>http://www.mgchemicals.com/downloads/appguide/appguide0205-1.pdf >>http://www.mgchemicals.com/products/silicones/cureguide-1part.html >>... and of course Google... >> >> >> >> > > >-- >269.9.0/853 - Release Date: 6/18/2007 3:02 PM ________________________________ Message 11 ____________________________________ Time: 01:39:58 PM PST US Subject: Re: AeroElectric-List: RTV sealants From: "Matt Prather" There was an article a while back in Sport Aviation that was written by a fellow that used automotive urethane windshield adhesive to install the canopy on his RV-4 (I think).. As I recall, he used a product like this: http://www.levineautoparts.com/3murwiad10fl.html Regards, Matt- > > > Another sealant question; > > Does anyone know of a sealant-like product that could be used for the > gap between the canopy and body as a weather seal? > I There are no off-the-shelf weather seals I can find that will fit > exactly. Perhaps there's a liquid sealant that can be extruded into > the gap and will mould to the right shape? > > Thanks > Neil > > > At 01:37 PM 6/19/2007, you wrote: >> >> >>As far as sealants are concerned, wouldn't shoe goo, Plumbers Goop >>or RV Goop from eclectic products work as well? I remember Bob >>talking about Shoe Goo and some other similar products. These I >>believe are all from eclecti products in LA. I purchased mine at >>Home Depot...seem to work well. >>Harold >>----- Original Message ----- From: "bob mackey" >>To: >>Sent: Monday, June 18, 2007 9:51 PM >>Subject: AeroElectric-List: RTV sealants >> >> >>> >>>There were several recent recommendations for the use of >>>RTV (room temperature vulcanizing) elastic sealants. >>>Before putting this stuff near your airframe or avionics, >>>you should know that there are many different types of RTV, >>>and most of them are somewhat corrosive as a result of the >>>acetic-acid curing chemistry (smells like vinegar). >>> >>>For mounting antennas to aluminum airframes, consider using an >>>alcohol-cure RTV such as clear or gray Dow Corning 3145, white >>>General Electric RTV 162 or gray high strength RTV 167, or clear >>>Loctite 5140. >>> >>>These alcohol-cure RTVs are more expensive. >>>Instead of a buck or three, McMaster sells the GE 162 for $12.66 >>>per 2.8 oz tube. >>>http://www.mcmaster.com (part number 74935A65, page 3305) >>>The Dow 3145 is quite a bit more expensive than that. >>> >>>references: >>>http://www.logwell.com/tech/servtips/RTV.html >>>http://www.mgchemicals.com/downloads/appguide/appguide0205-1.pdf >>>http://www.mgchemicals.com/products/silicones/cureguide-1part.html >>>... and of course Google... >>> >>> >>> >>> >> >> >> >> >> >> >> >>-- >>269.9.0/853 - Release Date: 6/18/2007 3:02 PM > > ________________________________ Message 12 ____________________________________ Time: 02:03:56 PM PST US From: "Alan Adamson" Subject: RE: AeroElectric-List: RTV sealants Lancair sells a "d" seal that would probably work or it looks like you can get the same stuff from mcmaster carr. Look for silicone seals and you'll find it, it's 5/8" wide by 3/8" tall and has a flat back. You put in on with clear silicone. Actually McMaster has tons of that kind of stuff. Makes good edge protection stuff as well. Alan -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Neil Clayton Sent: Wednesday, June 20, 2007 3:59 PM Subject: Re: AeroElectric-List: RTV sealants --> Another sealant question; Does anyone know of a sealant-like product that could be used for the gap between the canopy and body as a weather seal? I There are no off-the-shelf weather seals I can find that will fit exactly. Perhaps there's a liquid sealant that can be extruded into the gap and will mould to the right shape? Thanks Neil At 01:37 PM 6/19/2007, you wrote: > > >As far as sealants are concerned, wouldn't shoe goo, Plumbers Goop or >RV Goop from eclectic products work as well? I remember Bob talking >about Shoe Goo and some other similar products. These I believe are all >from eclecti products in LA. I purchased mine at Home Depot...seem to >work well. >Harold >----- Original Message ----- From: "bob mackey" >To: >Sent: Monday, June 18, 2007 9:51 PM >Subject: AeroElectric-List: RTV sealants > > >>--> >> >>There were several recent recommendations for the use of RTV (room >>temperature vulcanizing) elastic sealants. >>Before putting this stuff near your airframe or avionics, you should >>know that there are many different types of RTV, and most of them are >>somewhat corrosive as a result of the acetic-acid curing chemistry >>(smells like vinegar). >> >>For mounting antennas to aluminum airframes, consider using an >>alcohol-cure RTV such as clear or gray Dow Corning 3145, white General >>Electric RTV 162 or gray high strength RTV 167, or clear Loctite 5140. >> >>These alcohol-cure RTVs are more expensive. >>Instead of a buck or three, McMaster sells the GE 162 for $12.66 per >>2.8 oz tube. >>http://www.mcmaster.com (part number 74935A65, page 3305) The Dow 3145 >>is quite a bit more expensive than that. >> >>references: >>http://www.logwell.com/tech/servtips/RTV.html >>http://www.mgchemicals.com/downloads/appguide/appguide0205-1.pdf >>http://www.mgchemicals.com/products/silicones/cureguide-1part.html >>... and of course Google... >> >> >> >> > > >-- >269.9.0/853 - Release Date: 6/18/2007 3:02 PM ________________________________ Message 13 ____________________________________ Time: 02:23:02 PM PST US From: Jerry2DT@aol.com Subject: AeroElectric-List: Radios squawk ...literally Folks, Away from home with very annoying problem... Dual Icom's, dual antennas,same problem either one. Hit transmit and I send out a squeal with voice. other pilots say it is LOUD!! Before I borrow tools and tear things apart, any suggestions? Only one PTT switch wired in at present. Sound like a bad ground somewheres? Any and all help very appreciated. Jerry Cochran ************************************** See what's free at http://www.aol.com. ________________________________ Message 14 ____________________________________ Time: 02:56:52 PM PST US From: "Peter Pengilly" Subject: RE: AeroElectric-List: Radios squawk ...literally Have you tried a different headset? Could be a microphone feedback problem? Pete -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Jerry2DT@aol.com Sent: 20 June 2007 22:20 Subject: AeroElectric-List: Radios squawk ...literally Folks, Away from home with very annoying problem... Dual Icom's, dual antennas,same problem either one. Hit transmit and I send out a squeal with voice. other pilots say it is LOUD!! Before I borrow tools and tear things apart, any suggestions? Only one PTT switch wired in at present. Sound like a bad ground somewheres? Any and all help very appreciated. Jerry Cochran _____ See what's free at AOL.com . ------------------------------------------------------------------------------------- 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.