---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 01/29/11: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:03 AM - Re: OT-potting with RTV silicone (Charlie England) 2. 06:39 AM - Re: Questions about the 9005 Low Voltage Module (Jared Yates) 3. 07:11 AM - Re: OT-potting with RTV silicone (Robert L. Nuckolls, III) 4. 07:13 AM - Re: Questions about the 9005 Low Voltage Module (Robert L. Nuckolls, III) 5. 07:36 AM - Re: OT-potting with RTV silicone (paul wilson) 6. 07:55 AM - Re: ELT antenna performance (Bill Boyd) 7. 08:13 AM - Re: lan tracer (jonlaury) 8. 08:55 AM - Re: Re: lan tracer (Bob McCallum) 9. 09:01 AM - Re: Comm Antenna & SWR: More Information (kuffel@cyberport.net) 10. 09:50 AM - Conduit and Abrasion (Andy Turner) 11. 08:07 PM - Re: Conduit and Abrasion (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 06:03:45 AM PST US From: Charlie England Subject: Re: AeroElectric-List: OT-potting with RTV silicone On 1/29/2011 1:25 AM, rayj wrote: > > do not archive > > Is RTV silicone acceptable for potting electronics? I know Bob > recommends E6000 or equivalent but I have several 1/2 tubes of RTV I'd > like to use up. The item I'm potting is the "ballast for some cheap > fluorescent fixtures that buzz. I'm hoping I can quiet them down. > > Thanks for all replies. If the label doesn't say 'sensor safe' or something similar, it's likely that it will be corrosive. If you're just potting the transformer, it might not corrode fast enough to matter, but I'd be really leery about using it on a circuit board. Charlie ________________________________ Message 2 _____________________________________ Time: 06:39:36 AM PST US Subject: Re: AeroElectric-List: Questions about the 9005 Low Voltage Module From: Jared Yates Update- my 9005 unit is working now. I replaced the reference diode with ano ther and all is well. I must have damaged the first one somehow. If anyone e lse i planning on making one of these, let me know. I have lots of extra par ts from the digikey order minimums, and a functioning test rig that I can se nd you for a few bucks in shipping. On Jan 4, 2011, at 10:11, "Robert L. Nuckolls, III" wrote: > At 09:28 PM 1/3/2011, you wrote: >> That's great information, thank you for your help! I found the Digikey i nvoice and I think I might have ordered the wrong part. >> >> The national part is the Digikey LM285Z-2.5-ND >> http://www.national.com/ds/LM/LM185-2.5.pdf >> >> The one that I ordered is made by ON Semiconductor, Digikey LM285Z-2.5GOS -ND. >> http://www.onsemi.com/pub_link/Collateral/LM285-D.PDF >> > > I don't think so. The LM series devices are National > Semiconductor originations. All competing manufacturers > have to put out a drop in duplicate of the part. > > If the voltage at U107-3 had been zero or identical > to an adjacent pin, then I would suspect a solder > splash or an ECB defect often called a 'cat hair'. > The fact that your measurement is unique and way out > of whack for what the LM285 should present suggests > that neither event is in force. You might check > markings or color code for the R104 . . . make sure > it.s a 4.7K and not something higher. Also re-flow > the solder joins on R104. It's extremely rare that a > new part is bad out of the box so if the LM285 is > not installed wrong, we need to explore other possible > causes for U107-3 voltage not to be 2.50 volts. > > > Bob . . . > > > ========================== ========= ========================== ========= ========================== ========= ========================== ========= > ________________________________ Message 3 _____________________________________ Time: 07:11:24 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: OT-potting with RTV silicone At 02:25 AM 1/29/2011, you wrote: > >do not archive > >Is RTV silicone acceptable for potting electronics? I know Bob >recommends E6000 or equivalent but I have several 1/2 tubes of RTV >I'd like to use up. The item I'm potting is the "ballast for some >cheap fluorescent fixtures that buzz. I'm hoping I can quiet them down. "Potting" implies a material that will set up in what's called "deep section". Exemplar materials are those that use a catalyst to effect a chemical reaction throughout the mass of potting compound. RTV's I've encountered come in both catalytic and environmentally "set". I think that materials that come in tubes are set up by moisture in the air. E6000 and other cements set up when solvents evaporate. Both will eventually get firm throughout the mass but E6000 can take days, RTV might take months. Rather than "pot", try "coating". The buzzing will be mitigated by adding any dampening mass to the devices that vibrate. Use a thin layer of any non-catalytic material over the offending devices. Let that set up (perhaps a couple days) and apply another coat if the first treatment is insufficient. But putting the devices in a potting form and filling it with any non-catalytic material will leave a liquid interior that may take a very long time to firm up. The garden variety RTV's smell like vinegar . . . not sure about the details of their functional chemistry but I do know that the acetic acid is antagonistic to metals during the cure cycle. I observed that fact in a $thousand$ boo-boo at Cessna about 40 years ago! There are RTVs that don't smell like pickles, if that's the variety you have, you can go forward with very little risk. Bob . . . ________________________________ Message 4 _____________________________________ Time: 07:13:40 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Questions about the 9005 Low Voltage Module At 09:33 AM 1/29/2011, you wrote: >Update- my 9005 unit is working now. I replaced the reference diode >with another and all is well. I must have damaged the first one >somehow. If anyone else i planning on making one of these, let me >know. I have lots of extra parts from the digikey order minimums, >and a functioning test rig that I can send you for a few bucks in shipping. Congratulations! You're now much further down the path of a very steep learning curve. I hope this experience encourages you to continue expanding your horizons. I've had an increased interest in the 9005 . . . in fact, I had to order more bare boards. I'd planned to phase it out entirely but it's a good starting point for individuals who want to put their toes in the electronic pond. As you've discovered, the water only seems cold . . . Bob . . . ________________________________ Message 5 _____________________________________ Time: 07:36:58 AM PST US From: paul wilson Subject: Re: AeroElectric-List: OT-potting with RTV silicone Correct and that brand uses an acid . Having said that you can still buy RTV that contaons no acid. The no acid type is what the Kitfox guys use to bond the fiberglass tank to the Al spar. Avoid the acetic acid mentioned on the label. All use moisture as the curing catalyst. PaulW ===== At 06:06 AM 1/29/2011, Robert L. Nuckolls, III wrote: >The garden variety RTV's smell like > vinegar . . ________________________________ Message 6 _____________________________________ Time: 07:55:37 AM PST US Subject: Re: AeroElectric-List: ELT antenna performance From: Bill Boyd Millihertz antennas are impractically long. At least, the resonant ones are. Your mileage won't vary on this one. -Bill B On Fri, Jan 28, 2011 at 7:15 PM, Noel Loveys wrote: > Thanks Dick... I was unaware there even was a millihertz. In English cla ss > many snows ago we were told when it came to abbreviations, the rule was o nly > capitalize measurements which were peoples=92 names. Under that rule mH z > would be correct for either millihertz or megahertz or even gHz...gigaher tz. > > > Noel > > > *From:* owner-aeroelectric-list-server@matronics.com [mailto: > owner-aeroelectric-list-server@matronics.com] *On Behalf Of *Richard > Tasker > *Sent:* January 28, 2011 12:45 PM > > *To:* aeroelectric-list@matronics.com > *Subject:* Re: AeroElectric-List: ELT antenna performance > > > Hey Bob, not to pick nits , but you are the example here after all... ;- ) > > > mHz - millihertz > > MHz - megahertz > > Dick Tasker > > Robert L. Nuckolls, III wrote: > > > > When I first got into electronics as a profession, > I was working for a two-way radio company in Wichita. > We serviced a few systems in the 72 mHz band but > most were in the vicinity of 150 mHz and a few > were up about 450. > > This was all vacuum tube stuff. The 450 mHz > equipment was at the upper fringe of what > was practical. It was harder to develop power, > losses in feedlines was higher, keeping > receiver sensitivity to less than 1 microvolt > was more demanding. All-in-all, higher > cost of ownership. > > You'd think that customers would shy away from > this equipment. On the contrary. Antennas were > more efficient. Terrestrial noise was a small > influence. Signals behaved much better in the > confines of tall buildings. The cab companies > wouldn't have anything different. The police > wanted it but the FCC decreed that public > services will conduct business in the 150 mHz > band. 150 mHz was subject to much more multi- > path nulls and noise. > > 121.5 mHz was picked for the first ELTs > because it was a frequency already serviced > by aviation communication services. Same > with 243 albeit military. > > * > =========== > =========== =========== =========== > > * > > ________________________________ Message 7 _____________________________________ Time: 08:13:22 AM PST US Subject: AeroElectric-List: Re: lan tracer From: "jonlaury" > > PostPosted: Fri Jan 28, 2011 10:41 am Post subject: lan tracer > John; > > Check the link you posted. It leads to a website phishing for cell phone > numbers. Bob, After fixing my typo "allelectroIncs", http://www.allelectronics.com/ pops the website right up for me. Sorry about the Part #... should have been CT-28. I put it in the search box and it goes right to it ready to buy and check out. Do not Archive Read this topic online here: http://forums.matronics.com/viewtopic.php?p=328920#328920 ________________________________ Message 8 _____________________________________ Time: 08:55:48 AM PST US From: Bob McCallum Subject: RE: AeroElectric-List: Re: lan tracer Thanks John; The missing "CT" was the last part of the puzzle. The URL typo was fairly easy to surmise. Bob McC Do not archive > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list- > server@matronics.com] On Behalf Of jonlaury > Sent: Saturday, January 29, 2011 11:09 AM > To: aeroelectric-list@matronics.com > Subject: AeroElectric-List: Re: lan tracer > > > > > > > PostPosted: Fri Jan 28, 2011 10:41 am Post subject: lan tracer > > John; > > > > Check the link you posted. It leads to a website phishing for cell phone > > numbers. > > > Bob, > After fixing my typo "allelectroIncs", http://www.allelectronics.com/ pops the > website right up for me. Sorry about the Part #... should have been CT-28. I put it in > the search box and it goes right to it ready to buy and check out. > > Do not Archive > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=328920#328920 > > > > > > > > _- > ==================================================== > ====== > _- > ==================================================== > ====== > _- > ==================================================== > ====== > _- > ==================================================== > ====== > > ________________________________ Message 9 _____________________________________ Time: 09:01:20 AM PST US From: "kuffel@cyberport.net" Subject: RE: AeroElectric-List: Comm Antenna & SWR: More Information Noel said: << The new units are programmed to a specific aircraft. The first problem I see with this is as soon as a signal is received it can be identified as a single seat something or the other and not all the resources that could be put in the field will be used. This is selective response and I for one am against it. >> Different response is news to me. "Don't know how they do it Outside" but up in Alaska my direct experience was the effort was the same for one or multiple people down. Now when two congressmen go down, including the House Majority Leader, then you get extra resources (can you spell SR-71?). Tom Kuffel ________________________________ Message 10 ____________________________________ Time: 09:50:41 AM PST US Subject: AeroElectric-List: Conduit and Abrasion From: "Andy Turner" Well, this is one of those "making decisions when working late at night and then waking up the next morning and feeling bad about it" situations. I ran Van's 3/4" conduit under the baggage compartment of my RV-10, and then riveted floors into place. I fabricated aluminum supports which attach to the floor ribs as shown below. Due to the corrugations, you have to open up the hole to the point that the conduit rattles around in there. So I put some RTV on the conduit and support (I know, E6000 would have been better), and buttoned everything up. Almost immediately had visions of the support wearing a hole in the conduit and shorting out the battery main feed. On the right side I did it right, with snap bushings or grommet protecting conduit from aluminum. Question is, is the left side setup shown below a short waiting to happen? How resistant is this conduit to abrasion? The aluminum support is 0.32, well polished. -------- Andy Turner Read this topic online here: http://forums.matronics.com/viewtopic.php?p=328926#328926 ________________________________ Message 11 ____________________________________ Time: 08:07:47 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Conduit and Abrasion >On the right side I did it right, with snap bushings or grommet >protecting conduit from aluminum. Question is, is the left side >setup shown below a short waiting to happen? How resistant is this >conduit to abrasion? The aluminum support is 0.32, well polished. Legacy design practice avoids having any material carrying any commodity free to "ride loose" on the edge of a sheet. Consider caterpillar grommets for your problem holes. http://tinyurl.com/4kj3ak4 http://www.surplussales.com/rubber-plastic/plastic-2.html http://www.aircraftspruce.com/catalog/appages/grommetedging.php There are many other sources for similar products. These will soften the edges while widening them to the extent that they do not produce wearing pressure on the conduit or wires. The cool thing is that it can be added over an existing conduit installation. 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