Digest for sci.electronics.repair@googlegroups.com - 25 updates in 6 topics

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"Danny D." <dannydiamico@gmail.com>: Oct 27 11:16PM

Oren wrote, on Mon, 27 Oct 2014 09:23:28 -0700:
 
> Use this for a pass:
 
> <http://www.centaurforge.com/images/EMERSON50%20100_3471.jpg>
 
I'll betcha they won't (can't) deface that!
Oren <Oren@127.0.0.1>: Oct 27 04:40PM -0700

On Mon, 27 Oct 2014 23:16:08 +0000 (UTC), "Danny D."
 
>> Use this for a pass:
 
>> <http://www.centaurforge.com/images/EMERSON50%20100_3471.jpg>
 
>I'll betcha they won't (can't) deface that!
 
Tell those little heathens, Oren will come to class and teach then how
to make little rocks out of big rocks.
--
Somtimes you just have a bad day at the dungeon
"Danny D." <dannydiamico@gmail.com>: Oct 27 11:48PM

Oren wrote, on Mon, 27 Oct 2014 16:40:21 -0700:
 
> Tell those little heathens, Oren will come to class and teach then how
> to make little rocks out of big rocks.
 
The teacher told me most of the really bad kids have been suspended
by now.
 
I guess there's no way to not leave a child behind when they *want*
to be left behind.
 
I think, in California, they can be emancipated at something like 16,
which is the age these kids are around.
Oren <Oren@127.0.0.1>: Oct 27 05:16PM -0700

On Mon, 27 Oct 2014 23:48:28 +0000 (UTC), "Danny D."
>to be left behind.
 
>I think, in California, they can be emancipated at something like 16,
>which is the age these kids are around.
 
I left school at 16. Quit when I had the earliest chance. It really
wasn't the place for me. I moved out of our home too, went out into
the world and made my bones, retired at age 50 and have no regrets.
IMHO some kids should not be in government mandated skewls, er,
schools.
"Danny D." <dannydiamico@gmail.com>: Oct 28 12:39AM

Oren wrote, on Mon, 27 Oct 2014 17:16:36 -0700:
 
> the world and made my bones, retired at age 50 and have no regrets.
> IMHO some kids should not be in government mandated skewls, er,
> schools.
 
I'm sorry about that Oren. Unless you're happy about it. School isn't
for all kids, especially the kind of kid who likes to do it his own
way, and the ones who don't like sitting down at a desk for 180 days
in a row.
J Burns <burns4@nowhere.com>: Oct 27 09:18PM -0400

On 10/27/14, 8:16 PM, Oren wrote:
 
> the world and made my bones, retired at age 50 and have no regrets.
> IMHO some kids should not be in government mandated skewls, er,
> schools.
 
My best day at school came when I was 15. It was English class. I tore
open a ream of paper and tossed it out the third-floor window. The wind
scattered the sheets like tickertape, all over the huge lawn. It was
the most beautiful sight I'd ever seen.
 
The teacher told me to pick it up. I felt like Br'er Rabbit: "Don't
throw me in the briar patch!" It was great! I wished I'd been allowed
to spend all day every day out picking up papers, from the time I was 5.
 
I had another good day at 17 when I whipped out my toothbrush and
toothpaste and started brushing my teeth in Calculus. The teacher
turned pale and stood over my desk menacing me with karate chops and
karate kicks. Then he took me to The Office.
 
I thought it was turning into a bad day because if the principal
misunderstood the situation, that could tarnish my reputation. When he
sentenced me to 5 days' detention, I saw he was doing his best not to
bust out laughing, so I knew my sterling reputation was safe. I loved
detention. It was the only class where teachers kept their mouths shut.
 
That teacher didn't even know Calculus. Every day, I had to sit and
listen to him talk about how he adored Adolf Hitler.
"Michael A. Terrell" <mike.terrell@earthlink.net>: Oct 27 09:24PM -0400

J Burns wrote:
> detention. It was the only class where teachers kept their mouths shut.
 
> That teacher didn't even know Calculus. Every day, I had to sit and
> listen to him talk about how he adored Adolf Hitler.
 
 
One of mine was walking down the hallway, past open classroom doors
while carrying the front of a wall locker under my arm. The looks were
priceless! The school board's maintenance crew was going to order a new
panel of three doors because of broken spot welds. I told them to let
me take it to the metal shop, to repair it so three kids wouldn't be
without lockers for weeks. I brought it back 15 minutes later, with
some nice burn marks in the ugly brown paint. The other kids gave me
strange looks for months after that. :)
 
 
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
"Danny D." <dannydiamico@gmail.com>: Oct 27 11:24PM

josephkk wrote, on Thu, 23 Oct 2014 18:23:37 -0700:
 
> I see a complete failure to account for wind loads. Wind loads on this
> tree house will be larger than the dead loads. Ask the owner to calculate
> the wind loads as well.
 
This is a good point so I will mention it to him.
 
We worked on the second floating 16-foot section today, by the way.
https://c4.staticflickr.com/4/3955/15459997077_b22b960f68_b.jpg
 
So now we're suspended 32 feet straight out.
 
Only 60 or so feet to go!
"Danny D." <dannydiamico@gmail.com>: Oct 27 11:31PM

dpb wrote, on Thu, 23 Oct 2014 07:36:12 -0500:
 
> T=W/sin(angle) = (W/2)/sin(11) --> 2500/0.2 --> 12,500 lb
 
Wow. Those were wonderful calculations.
I forwarded it all to my friend, and will reply back with his response.
 
Meanwhile, we worked on the second section today, and we ended up stopping
about 2 feet away from redwoods which we need to squeeze through.
https://c4.staticflickr.com/4/3937/15460483990_09bffcce41_b.jpg
"Danny D." <dannydiamico@gmail.com>: Oct 27 11:34PM

CRNG wrote, on Thu, 23 Oct 2014 12:40:15 -0500:
 
> I don't think they are taking heed. They have been successful with
> their little neighborhood projects, and they are starting to get over
> confident.
 
I think the owner is taking heed, it's just that he's a third party
to this conversation (he doesn't know Usenet). :)
 
BTW, here's a view from below today, when I dropped my glasses
and had to climb down the steep hill to retrieve them.
 
https://c4.staticflickr.com/4/3943/15645979325_89a8481615_b.jpg
"Danny D." <dannydiamico@gmail.com>: Oct 27 11:37PM

dpb wrote, on Thu, 23 Oct 2014 13:35:20 -0500:
 
> Of course, if the droop angles are significantly larger than the assumed
> 10 degree or so, then they gain a fair amount by there being a larger
> vertical component but it's too spooky by far as described and shown
 
I'm sorry I haven't responded in a while. I hurt my back and was laid
up but hopefully I'm better now ...
 
The whole thing is supposed to hang from the cables, but we did anchor
one end because we needed a way for people to get "on" the decking.
 
Here's where we left it today...
https://c4.staticflickr.com/4/3945/15459995717_3722bf0914_b.jpg
"Danny D." <dannydiamico@gmail.com>: Oct 27 11:40PM

CRNG wrote, on Thu, 23 Oct 2014 08:05:45 -0500:
 
> increasing the tension in the cable. I really hope someone convinces
> them to have a engineer look at their exact config and do some simple
> calcs as you have done above.
 
I'm sorry I haven't been able to respond lately.
 
We had to readjust all the cables today, with a set of 5 winches, as
we had to re-balance everything once the second 16-foot section was
planked.
 
Unfortunately, I ruined my clothing, as I hadn't expected the oil
to still be soaking wet ... even though it was drying outside for
a day ...
 
https://c2.staticflickr.com/6/5616/15645979935_55c2665284_b.jpg
"Danny D." <dannydiamico@gmail.com>: Oct 27 11:46PM

VinnyB wrote, on Wed, 22 Oct 2014 05:58:58 -0500:
 
> The lawyers are going to love it. Everyone from the wire rope
> manufacturer to the water-boy will be sued.
 
You forgot the screw manufacturers!
https://c4.staticflickr.com/4/3935/15025811753_8de1cc2650_b.jpg
 
Notice we gave up on the lower screw (the one with the longer thread).
 
It was just too hard to drive into the wood.
 
Even with this nice pile driver thing from Harbor Freight!
https://c4.staticflickr.com/4/3934/15459836048_8f3a566c90_b.jpg
 
The screw on top, with the shorter thread, goes in without pounding!
Ian Malcolm <See.My.Sig.for.email@totally.invalid>: Oct 28 12:21AM

"Danny D." <dannydiamico@gmail.com> wrote in
> https://c4.staticflickr.com/4/3955/15459997077_b22b960f68_b.jpg
 
> So now we're suspended 32 feet straight out.
 
> Only 60 or so feet to go!
 
See <http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)>
The chances of your bridge deck fluttering in a blow are fairly high.
 
--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL
"Danny D." <dannydiamico@gmail.com>: Oct 28 12:42AM

Ian Malcolm wrote, on Tue, 28 Oct 2014 00:21:08 +0000:
 
> See <http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)>
> The chances of your bridge deck fluttering in a blow are fairly high.
 
We actually joked, a few times, about the Tacoma Narrows bridge, and,
yes, I think just about everyone has seen that video of the car on
the bridge and the person getting out and making it just in time.
 
This bridge isn't nearly as long.

It's only about 100 feet long, by 10 feet wide, supported on one end
on the ground and on the far end about 40 or 50 feet up in a tree on
a (very) steep slope.
 
Here's what the first two 16-foot-long sections looked like today,
when we ran out of oiled wood:
https://c4.staticflickr.com/4/3945/15459995717_3722bf0914_b.jpg
 
I'm currently learning how to wash good clothes to get the oil
out! :(
Ricardo Abreu <ricardo.matos.abreu@gmail.com>: Oct 27 04:08PM -0700

Had a little time to check the microwave oven again.
 
1) First, I checked if a short was developing in the magnetron between cathode and anode (case) when the filament gets hot, but it doesn't. If you are wondering how I did it, I disconnected HV and connected a resistor from one of the filament's terminal to case, and checked for voltage across the resistor. Repeated this for the other filament's terminal;
 
2) Took the magnetron off. There were no cracks in the magnets (visible, at least) as Sam suggested;
 
3) Connected the filament (always HV disconnected) and powered the oven with lights off. The filaments clearly glows;
 
4) Checked HV transformer for signs of arcing or shorts, but none visible. Also, windings are not superimposed, they are placed side by side in the same leg, which somewhat reduces chances of arcing between windings;
 
5) Changed the HV diode for a new one (the cheapest part), but to no avail;
 
 
 
Now I'm stuck, and it seems my only option (unless you have a better idea) is to start replacing parts until the thing gets alive again. HV cap is still inexpensive.
 
By your experience, which one fails the most: transformer or magnetron?
"Maynard A. Philbrook Jr." <jamie_ka1lpa@charter.net>: Oct 27 07:55PM -0500

In article <a25935d9-03bf-4cfe-ba8d-fb0a20a5aa33@googlegroups.com>,
ricardo.matos.abreu@gmail.com says...
 
> 5) Changed the HV diode for a new one (the cheapest part), but to no avail;
 
> Now I'm stuck, and it seems my only option (unless you have a better idea) is to start replacing parts until the thing gets alive again. HV cap is still inexpensive.
 
> By your experience, which one fails the most: transformer or magnetron?
 
You don't have a HV probe to test for the - voltage at the diode?

Jamie
Helmut Wabnig <hwabnig@.- --- -.dotat>: Oct 27 10:22PM +0100

>Lots of Din connectors connecting tuner to preamp and amp, power ,
>signal and control connections. Any advice on improving contacts other
>than needle insertion to tension up the socket yokes a bit.
 
 
Contact spray
http://www.youtube.com/watch?v=q1BxYWlT2yc
 
w.
dave <ricketzz@earthlink.net>: Oct 27 11:21AM -0700

On 10/27/2014 09:32 AM, micky wrote:
> etc. although WAMU is on a 5 or 10 second delay most of the time.
> Because the topic and the voices can be the same it means I can't tell
> for a while if I've gotten 88.5 or just another 'instance' of 88.1.
 
Wild Ass Guess here; you are hearing a Translator station rebroadcasting
the main station's programming. These mini-stations fill in nulls or
shadows. check fccinfo.com
dave <ricketzz@earthlink.net>: Oct 27 11:25AM -0700

On 10/27/2014 09:32 AM, micky wrote:
> etc. although WAMU is on a 5 or 10 second delay most of the time.
> Because the topic and the voices can be the same it means I can't tell
> for a while if I've gotten 88.5 or just another 'instance' of 88.1.
 
Here's a list of FM licenses. Translators have a 3 digit number in the
callsign. If it's a flaky receiver you may be interfering with aircraft.
 
http://fccinfo.com/CMDProFacLookup.php?sCurrentService=FM&tabSearchType=Within+Search&ArchiveRecords=N&sKilometers=100&sLatitude=39-17-25&sLongitude=76-36-45&sPlace=Baltimore
Steve Crow <otaku!scrow+nntp@sdf.lonestar.org>: Oct 27 02:21PM -0400

On Mon, 27 Oct 2014, micky wrote:
 
> How can the same FM station appear at two different spots on the dial?
 
--snip--
 
> 88.5 to what I'd estimate is 88.6 or .7 or .8 I get 88.1 again.
 
> How is that happening? I know about harmonics, but that doesn't apply,
> does it?
 
My initial thought was that perhaps the station is operating a
"translator" (repeater) on 88.7-ish, but a search of the FCC database
doesn't turn up anything. There are two translators licensed to Maryland
on 88.7 MHz: W204BA in Oakland and W204CL in Lexington Park. Both belong
to Grace Missionary Church (d/b/a Grace Christian School). Some Googling
shows those affiliated with a small religious radio network, but it's
possible they could be re-transmitting 88.1 for some reason. Both
transmitters are fairly low power, as is typical of translators (250 and
55 watts, respectively), and given the distance (2-3 hours away) I doubt
there would be much overlap in coverage area, if any.
 
So... that possibility fairly well eliminated, I think the best bet is to
zip off an e-mail to the station and ask what's going on. Looks like
those are public radio stations, and my experience has been that the
engineers at those types of facilities are typically pretty helpful when
it comes to resolving reception concerns and addressing technical
questions. If you do that, I'd be curious what you dig up.
 
Since you are able to reproduce the behavior on multiple radios, I doubt
it's a problem with the receivers.
dplatt@coop.radagast.org (David Platt): Oct 27 12:01PM -0700

In article <v7ss4allgf4oosl9rud3hpt3g3rmr6m58a@4ax.com>,
>88.5 to what I'd estimate is 88.6 or .7 or .8 I get 88.1 again.
 
>How is that happening? I know about harmonics, but that doesn't apply,
>does it?
 
There are at least three ways in which you can end up with a strong FM station
at two locations on the dial.
 
(1) As somebody else suggested, it might be a "translator" - a second
transmitter carrying the same program material on a different
channel. Translators are sometimes used to "fill in" a station's
service footprint - e.g. to provide service to an area on the far
side of a mountain from the primary transmitter.
 
(2) Image. FM receivers are almost always superheterodyne
receiver... they have a local oscillator which is tuned either
above, or below, the station's frequency by a fixed amount (most
commonly 10.7 MHz). "Mixing" of the station frequency and the
local oscillator create an "intermediate frequency" signal at
(e.g.) 10.7 MHz which is then filtered, amplified, and decoded.
 
This architecture can cause a station to "reappear" on the dial,
if you're tuned away from it by twice the intermediate frequency
(e.g. by 21.4 MHz) - a second "image" of the station appears on
the dial. Good FM receivers have enough selectivity built into
their "front end" to keep this problem to a minimum - the tuner
"filters out" the station at the image frequency efficiently
enough, before mixing with the local oscillator, to keep it from
"reappearing" or interfering with a desired station (image
rejection is often 90-100 decibels, if I recall correctly).
 
(3) Intermodulation. If you have two strong stations nearby, their
signals can mix (either in the receiver front end, or elsewhere)
and create "spurious" signals located on either side of their true
locations on the dial. These spur signals will often be noisy and
distorted.
 
What you're describing doesn't sound like an image problem (#2)
because the second "copy" of 88.1 is so close to it on the dial. It
might be intermodulation, or the 88.1 station may have a translator
off in the distance.
 
Due to recent consolidation of radio-station ownership (both
commercial service and "noncommercial" FM), the signal at 88.7/88.8
might be a formerly-independent station in another market, which has
been "bought up" by the ownership of 88.1 and is now simply
rebroadcasting its signal.
whit3rd <whit3rd@gmail.com>: Oct 27 01:48PM -0700

On Monday, October 27, 2014 12:01:45 PM UTC-7, David Platt wrote:
> and create "spurious" signals located on either side of their true
> locations on the dial. These spur signals will often be noisy and
> distorted.
 
This sounds very likely; if it is due to front-end nonlinearity, it's
possible to test/treat it by inserting an attenuator between the FM antenna
and the receiver (assuming the receiver has a plug-in antenna).
Lower the signal level, and the spurious response should go away.
 
Alternately, one can attenuate (filter) either the interfering FM station or the (presumably
AM) difference-frequency station: this can be done with a lossy antenna+load
placed near your radio, so can apply without access to antenna terminals.
micky <NONONOmisc07@bigfoot.com>: Oct 27 12:46PM -0400

On Sat, 25 Oct 2014 13:48:42 +0100, "Arfa Daily"
>exclusion and inclusion operators in the Google search field to weed out
>irrelevant crap
 
>Arfa
 
Alas, the exclusion operator - still works fine, but the required
inclusion operator + seems to have been abandoned by Google. Not just
seems. I read on some google page what + does and insist on inclusion
is not it.
 
I don't know what's wrong with them sometimes. They should have known
not to get rid of it.
c4urs11 <c4urs11@domain.hidden>: Oct 27 08:05PM

On Mon, 27 Oct 2014 12:46:12 -0400, micky wrote:
> Alas, the exclusion operator - still works fine, but the required
> inclusion operator + seems to have been abandoned by Google.
 
You can enhance inclusion by repeating a keyword three times.
Not the same as a + but definitely improving the results.
 
Cheers!
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