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
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Subject: | Re: 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
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Subject: | Re: Questions about the 9005 Low Voltage Module |
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" <nuckolls.bob@aeroelectr
ic.com> 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 . . .
>
>
>
==========================
=========
==========================
=========
==========================
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=========
>
Message 3
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Subject: | Re: 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
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Subject: | Re: 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
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Subject: | Re: 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
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Subject: | Re: ELT antenna performance |
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 <noelloveys@yahoo.ca> 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:
>
> <snip>
>
> 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
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>
> 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
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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
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Subject: | 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
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Subject: | Conduit and Abrasion |
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
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Subject: | Re: 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.
Bob . . .
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