Discussion:
AC Power line capacitor to chassis
(too old to reply)
o***@tubes.com
2017-04-13 18:48:35 UTC
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Regarding my Hallicrafters SX-99.

It has that capacitor that goes from the AC power line (cord) to the
chassis. It's C56 .01 600v.

I have read articles that call these "death caps". This radio has a
transformer, so it's not a hot chassis. But from what I read, those caps
can become faulty and create a hot chassis.

Some people recommend just removing them, while others say that there is
a special type of cap made just for that purpose. (What is that special
cap, and where does a person get them?).

What do you guys do with these?
I've never really understood why they are there anyhow????

I may put a 3 prong cord on this radio, so it's grounded, but I have not
decided if this is really necessary, and the cord is not bad that is on
it now.
Foxs Mercantile
2017-04-13 21:10:32 UTC
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Post by o***@tubes.com
Regarding my Hallicrafters SX-99.
It has that capacitor that goes from the AC power line (cord) to the
chassis. It's C56 .01 600v.
Another item, not to go too large in value either.
0.01 uF is fine, do not exceed 0.015 uF.
You will occasionally find 0.05 up to 0.1 uF.
Replace those with 0.015 uF.
Post by o***@tubes.com
I have read articles that call these "death caps". This radio has a
transformer, so it's not a hot chassis. But from what I read, those caps
can become faulty and create a hot chassis.
They're called that because th e old caps failed short.
And typically spectacularly. Setting fire to themselves etc.
The new "safety" type fail open.
Post by o***@tubes.com
Some people recommend just removing them, while others say that there is
a special type of cap made just for that purpose. (What is that special
cap, and where does a person get them?)
Some people are just fucking morons.
There ARE special capacitors. X2 types that go across the line, and Y2
types that go from the line to ground or chassis.
<https://en.wikipedia.org/wiki/Film_capacitor#Safety_and_EMI.2FRFI_suppression_film_capacitors>
Post by o***@tubes.com
What do you guys do with these?
I replace them with the correct rated parts.
Post by o***@tubes.com
I've never really understood why they are there anyhow????
They are there for signal or noise purposes. Bringing the AC line to
signal ground for example.
Post by o***@tubes.com
I may put a 3 prong cord on this radio, so it's grounded, but I have not
decided if this is really necessary, and the cord is not bad that is on
it now.
It's a fool's errand to NOT put a 3 wire cord on any radio or test
equipment these days.
--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

---
This email has been checked for viruses by AVG.
http://www.avg.com
o***@tubes.com
2017-04-13 21:00:12 UTC
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Post by Foxs Mercantile
There ARE special capacitors. X2 types that go across the line, and Y2
types that go from the line to ground or chassis.
<https://en.wikipedia.org/wiki/Film_capacitor#Safety_and_EMI.2FRFI_suppression_film_capacitors>
Keeping the size the same is intended.... It's .01 and will stay .01.

Why cant a ceramic cap be used instead?
Jim Mueller
2017-04-14 00:26:57 UTC
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Post by o***@tubes.com
Post by Foxs Mercantile
There ARE special capacitors. X2 types that go across the line, and Y2
types that go from the line to ground or chassis.
<https://en.wikipedia.org/wiki/
Film_capacitor#Safety_and_EMI.2FRFI_suppression_film_capacitors>
Post by o***@tubes.com
Keeping the size the same is intended.... It's .01 and will stay .01.
Why cant a ceramic cap be used instead?
X2 and Y2 capacitors are available in both plastic film and ceramic
types; you can use either. You get them from the regular parts
distributors like Digi-Key or Mouser. They are made to withstand the
rigors (like surge voltages) of the AC power line and to generally not
fail. If they do fail, they are designed to fail open rather than
shorted to prevent a fire or shock hazard. They aren't particularly
expensive so be sure to use them.
--
Jim Mueller ***@nospam.com

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.
o***@tubes.com
2017-04-14 16:08:47 UTC
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Post by Jim Mueller
X2 and Y2 capacitors are available in both plastic film and ceramic
types; you can use either. You get them from the regular parts
distributors like Digi-Key or Mouser. They are made to withstand the
rigors (like surge voltages) of the AC power line and to generally not
fail. If they do fail, they are designed to fail open rather than
shorted to prevent a fire or shock hazard. They aren't particularly
expensive so be sure to use them.
Are these caps actually called X2 and Y2?

If someone would be kind enough to provide a URL to these on one of them
companies (Digikey, Mouser, etc). It's hard enough on dialup and not
knowing exactly what I am looking for can be tough.

Yea, I dont want a cap that will catch fire, but is that even possible
with standard ceramic caps? I mean, why cant I use a standard ceramic?

One other thing, which of these big companies will send out a small
order, (like one or 3 caps), without a big minimum order or raping me on
shipping? I've not dealt with any of these companies, so I am not sure
which would work best for this sort of thing....

Thanks
Jim Mueller
2017-04-15 06:36:03 UTC
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On Fri, 14 Apr 2017 12:08:47 -0400, oldschool wrote:

snip
Post by o***@tubes.com
Are these caps actually called X2 and Y2?
Yes. There are also ones with dual ratings, X2/Y2, that are suitable for
either application.
Post by o***@tubes.com
If someone would be kind enough to provide a URL to these on one of them
companies (Digikey, Mouser, etc). It's hard enough on dialup and not
knowing exactly what I am looking for can be tough.
Digi-Key page: https://www.digikey.com/product-detail/en/kemet/
R413I21004000M/399-11733-ND/5141841
Manufacturer's data sheet: http://www.kemet.com/Lists/ProductCatalog/
Attachments/497/KEM_F3100_R41_Y2_300.pdf

These are for a 0.01uF Y2/X1 capacitor. X1 is a higher rating than X2.
They are $0.49 in lots of 1 or $3.48 for 10. Digi-Key has no minimum
order and doesn't charge for shipping if payment comes with the order
(i.e. send in a paper order with a check or money order enclosed). They
do charge tax so you will have to contact them to find our how much to
include for that.
Post by o***@tubes.com
Yea, I dont want a cap that will catch fire, but is that even possible
with standard ceramic caps? I mean, why cant I use a standard ceramic?
I have seen ceramic capacitors catch fire. The one I saw was a 1KV
capacitor connected across the AC line. The fire started on one edge of
the disk and continued across. I cut the power when about 1/2 was burned
away. In other applications I have seen them where nothing was left but
the leads.

The problem is that most ceramic capacitors in this capacitance and
voltage range are Z5U material. This has high losses so they heat up
even when operated on AC well below their apparent voltage rating.
Eventually they can't take it anymore and they burn up. Ceramic X and Y
rated capacitors are made to operate on AC so they don't have this
problem.
--
Jim Mueller ***@nospam.com

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.
o***@tubes.com
2017-04-15 18:26:41 UTC
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Post by Jim Mueller
snip
Post by o***@tubes.com
Are these caps actually called X2 and Y2?
Yes. There are also ones with dual ratings, X2/Y2, that are suitable for
either application.
Post by o***@tubes.com
If someone would be kind enough to provide a URL to these on one of them
companies (Digikey, Mouser, etc). It's hard enough on dialup and not
knowing exactly what I am looking for can be tough.
Digi-Key page: https://www.digikey.com/product-detail/en/kemet/
R413I21004000M/399-11733-ND/5141841
Manufacturer's data sheet: http://www.kemet.com/Lists/ProductCatalog/
Attachments/497/KEM_F3100_R41_Y2_300.pdf
These are for a 0.01uF Y2/X1 capacitor. X1 is a higher rating than X2.
They are $0.49 in lots of 1 or $3.48 for 10. Digi-Key has no minimum
order and doesn't charge for shipping if payment comes with the order
(i.e. send in a paper order with a check or money order enclosed). They
do charge tax so you will have to contact them to find our how much to
include for that.
Post by o***@tubes.com
Yea, I dont want a cap that will catch fire, but is that even possible
with standard ceramic caps? I mean, why cant I use a standard ceramic?
I have seen ceramic capacitors catch fire. The one I saw was a 1KV
capacitor connected across the AC line. The fire started on one edge of
the disk and continued across. I cut the power when about 1/2 was burned
away. In other applications I have seen them where nothing was left but
the leads.
The problem is that most ceramic capacitors in this capacitance and
voltage range are Z5U material. This has high losses so they heat up
even when operated on AC well below their apparent voltage rating.
Eventually they can't take it anymore and they burn up. Ceramic X and Y
rated capacitors are made to operate on AC so they don't have this
problem.
Thanks for the info.

Unfortunately, Digikey is one of the sites that refuse to load on my
computer. Not sure if it's because of my slow dialup connection, or
because the newest browser I can use is Firefox 3.x, or because it's
HTTPS (those secure sites will not load 90% of the time for me).

Guess I'll have to wait till I get to the library to load that site.

By the way, this line cap is .0022, not .01.

I found a .002 cap on ebay rated at 200 KV. I bet that would not burn
up, but I'm not willing to pay $35 for it either.... (Not to mention it
would probably not fit in the chassis).
(Ebay works fine on dialup, just slow).
Peter Wieck
2017-04-15 20:03:14 UTC
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For the record:

I will not, repeat, NOT purchase any sorts of current electronic components or parts from eBay. The potential for counterfeits is far too great.

When searching for obsolete or discontinued parts, needs must when the devil drives. Unhappily.

I need the likes of Digikey, Mouser and Newark out there and their continued existence is worth the few cents I might save otherwise.

Peter Wieck
Melrose Park, PA
o***@tubes.com
2017-04-17 18:01:51 UTC
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Post by Peter Wieck
I will not, repeat, NOT purchase any sorts of current electronic components
or parts from eBay. The potential for counterfeits is far too great.
When searching for obsolete or discontinued parts, needs must when the
devil drives. Unhappily.
I need the likes of Digikey, Mouser and Newark out there and their continued
existence is worth the few cents I might save otherwise.
Peter Wieck
Melrose Park, PA
How can there be counterfeits for packages of small parts? For example I
bought a pack of 300 resistors of assorted values. They are just generic
resistors. When I got them, I tested a dozen or so, and they were within
tolerance, so I was satisfied. If they were not within reason, I would
have complained and gotten a refund.

I also recently spent many hours on ebay, buying packs of 5 or more
common generic connectors. After spending around $40, buying from or 8
sellers, I now have a good selection of plugs, such as RCA male and
female, 1/4" guitar cord plugs, F connectors, and so on... I'd never get
anything accomplished if I had to place an order each time I need a
common plug, or a resistor. I plan to order a selection of caps soon
too.

I buy NOS tubes from ebay. There is no other place to get them unless
you just stumble across someone who has that sort of thing.

I also get vintage equipment from ebay. Unless craigslist has something,
there again, where the heck else would I find that stuff.

About the only way I could see counterfeits for electronic parts would
be if someone sold cheap generic caps and re-labeled them as Sprague or
something like that. That hardly seems worth the effort for low cost
items.

Other stuff from ebay such as jewelery, clothing, watches, and stuff
like that would be more likely to be counterfeits, like a cheap watch
that is labeled as a Rolex. But I dont buy stuff like that on ebay. My
ebay shopping is mostly just electronic parts, vintage electronics, some
tools, and car parts.

I did get screwed several times in the early days of ebay. For example,
I bought a computer that literally went up in smoke when I plugged it
in, and a power saw which was actually cracked in half, and a book that
apparently had gotten soaked. Back then it was hard to get a refund. The
guy with that computer told me to mail it back and I will get a refund.
But the shipping cost to send it back was 80% of the sale price. I ended
up just saving the drives, RAM, mouse and keyboard, and tossing the rest
of it in the trash.

These days, ebay really does protect buyers very well. Last year I
bought a used laptop computer with XP loaded on it. It did not work
properly at all. The seller gave me a refund, and I did not have to mail
it back. Afterwards, I wiped the hard drive, installed XP myself and it
has worked well ever since. The hardware was fine, it was just the OS
that was defective.

I also bought a starter for my tractor, when I got it, it was dead. The
seller sent me another one (which worked), and told me to toss that dead
one in the trash (I saved it in case I ever need parts from it).

I have been quite happy with 99% of the stuff I have gotten from Ebay in
the last 5 years. About the only thing I got lately that was not
satisfactory, was a $2 cable that goes from the 1/8" stereo plug on a
computer (audio) to two RCA jacks. It works, but for some reason, that
1/8" plug seems a little too thin, and dont make a good connection.
Rather than make a big deal out of it, I just chopped off that 1/8"
plug, and soldered on another one.

I'd probably order more stuff from places like Digikey, Mouser and
Newark, if there were not large minimum orders and shipping fees. Not to
mention that I have great difficulty accessing their websites on dialup
(Yea, I know thats my own problem, but if those sites were not
overloaded with java scripts and CSS files, I could proably use them).

If it was not for ebay, I'd not be able to work with electronics at all.
The only electronics store nearby is Radio Shack, (25 miles away), and
they are peobably going out of buisiness real soon.
Peter Wieck
2017-04-17 19:50:35 UTC
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Post by o***@tubes.com
How can there be counterfeits for packages of small parts? For example I
bought a pack of 300 resistors of assorted values. They are just generic
resistors. When I got them, I tested a dozen or so, and they were within
tolerance, so I was satisfied. If they were not within reason, I would
have complained and gotten a refund.
Here is the logic:

The eBay seller has to get his/her parts from somewhere.
Just because a part is tiny and cheap does not make it good.
Even though modern manufacturing of such parts is extremely efficient and generates few defects, 'few' does not equal 'none'.

So, these no-name manufacturers get a run of bad parts - which then then auction off to the highest bidder, dumpster or otherwise dispose of them.
Whereupon they turn up on eBay.

Connectors that failed heat-treating, or the plating is too thin/thick, or toxic (cadmium with contaminants) wind up on eBay.

'Within tolerance' is momentary. Put 400V on that resistor/connector/whatever and see what that really means.

The virtue of purchasing through an established seller is that they have a vested interest in you getting what you expect, and with no blow-back on them.

Again, things that are obsolete, discontinued and/or non-generic are exceptions, to be purchased where available, when available. eBay can be useful this way.

Mouser will sell me anything that I can fit into a USPS Flat-Rate box for that flat rate, or less. I do kinda-sorta save up my needs so that I typically spend $80-$100 for and order, making shipping relatively lower than the sales tax, if applicable. But they have _no_ minimum order. And, they have knowledgeable people who do answer the phone, and who are very helpful. They are by far, not the only ones.

But, keeping shipping in mind, if you are not paying it on your eBay orders, somebody is - and that cost is coming straight off the top of the quality of the parts you are buying. And, here is the thing: A C Radio is down in South Philadelphia, and has a pretty good selection of electronics parts, components and such. Given my hybrid, and not using the AC, I could get there and back on the battery alone, no need for gas, and I have done so for an acute need. But that is still 5KW of electricity, or about $0.70 worth. And about an hour of my time. So, sometimes shipping is a bargain.
analogdial
2017-04-19 20:09:51 UTC
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Post by Peter Wieck
Post by o***@tubes.com
How can there be counterfeits for packages of small parts? For example I
bought a pack of 300 resistors of assorted values. They are just generic
resistors. When I got them, I tested a dozen or so, and they were within
tolerance, so I was satisfied. If they were not within reason, I would
have complained and gotten a refund.
The eBay seller has to get his/her parts from somewhere.
Just because a part is tiny and cheap does not make it good.
Even though modern manufacturing of such parts is extremely efficient and generates few defects, 'few' does not equal 'none'.
So, these no-name manufacturers get a run of bad parts - which then then auction off to the highest bidder, dumpster or otherwise dispose of them.
Whereupon they turn up on eBay.
Connectors that failed heat-treating, or the plating is too thin/thick, or toxic (cadmium with contaminants) wind up on eBay.
'Within tolerance' is momentary. Put 400V on that resistor/connector/whatever and see what that really means.
The virtue of purchasing through an established seller is that they have a vested interest in you getting what you expect, and with no blow-back on them.
Again, things that are obsolete, discontinued and/or non-generic are exceptions, to be purchased where available, when available. eBay can be useful this way.
But this is nothing new. I've made several purchases from Chinese ebay
vendors for basic electronic parts such as resistors and caps. I have
never recieved a bag of junk. I check the caps for capacitance and
leakage and nearly all are fine. The worst I got was one package in
which a few caps had bubbles and holes in the coating. Probably from a
rejected load. But they weren't leaky.

I test everything and I have found a very few leakers in the caps. If
these are rejected loads, it suggests they are holding a high
standard.

In my admittedly limited expirence, the quality of the parts I've bought
from Chinese ebay vendors is better than the surplus stuff I bought
years ago from Olson and much better than the junk I bought from Poly
Paks.

The prices from the Chinese ebay vendors is low but not low enough to
raise flags. For example, from a major US vendor, an order of 5000 1/2
W carbon film resistors might have a unit cost of just under 1 cent. In
onesies and twosies those resistors are about a dime each. A Chinese
ebay vendor might sell an assortment of resistors for about two cents
each. That doesn't raise my "too good to be true" alarm.
Post by Peter Wieck
Mouser will sell me anything that I can fit into a USPS Flat-Rate box for that flat rate, or less. I do kinda-sorta save up my needs so that I typically spend $80-$100 for and order, making shipping relatively lower than the sales tax, if applicable. But they have _no_ minimum order. And, they have knowledgeable people who do answer the phone, and who are very helpful. They are by far, not the only ones.
But, keeping shipping in mind, if you are not paying it on your eBay orders, somebody is - and that cost is coming straight off the top of the quality of the parts you are buying. And, here is the thing: A C Radio is down in South Philadelphia, and has a pretty good selection of electronics parts, components and such. Given my hybrid, and not using the AC, I could get there and back on the battery alone, no need for gas, and I have done so for an acute need. But that is still 5KW of electricity, or about $0.70 worth. And about an hour of my time. So, sometimes shipping is a bargain.
I've read that the China Post isn't charging the small time vendors
postage. Essentially, it's an export subsidy and an employment subsidy.
I haven't verified that but it makes sense to me. And this is money
going to the USPS.
Jim Mueller
2017-04-18 04:33:26 UTC
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On Mon, 17 Apr 2017 14:01:51 -0400, oldschool wrote:

snip
Post by o***@tubes.com
I buy NOS tubes from ebay. There is no other place to get them unless
you just stumble across someone who has that sort of thing.
As for counterfeit tubes, there is an article about them from July 1956
on page 40 of this magazine, http://www.americanradiohistory.com/Archive-
Radio-News/50s/Radio-News-1956-07.pdf. No doubt some of them are still
around. Back in the day there were also companies who sold used or
factory reject tubes. Rad-Tel, Cornell, and Zaylatron (SP?) come to mind
but there were many others. These definitely still show up; I have
gotten them.

Here is an web site about more recent intentionally mismarked tubes,
https://vacuumtubesinc.com/index.php/hallofshame. International
Components Corporation is a well known supplier of such things.

And then there are the Eastern European and Chinese manufacturers, some
of whom are good and some of whom don't follow the specs very closely at
all.

As for resistors and capacitors, there certainly are counterfeits out
there. Some equipment manufacturers are controlled by the bean counters
and saving 1/10 of a cent on a part is important. Since there is a
market, someone will fill it. If the company then has an excess, it ends
up on the surplus market and may well turn up on ebay.

Ebay is not your friend. The only way to get parts of known quality is
to buy them from the factory authorized distributor. But if you are a
gambler, you can buy your parts where ever you like.

And, at least twice so far I have told you that Digi-Key doesn't have a
minimum order and they don't charge shipping if you include payment with
your order. But if you choose to not pay attention . . .
--
Jim Mueller ***@nospam.com

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.
o***@tubes.com
2017-04-18 07:04:49 UTC
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Post by Jim Mueller
And, at least twice so far I have told you that Digi-Key doesn't have a
minimum order and they don't charge shipping if you include payment with
your order. But if you choose to not pay attention . . .
-
In order to include payment, I would need to place an order by snail
mail and include a check. That is fine with me, but I need a paper
catalog. Do they send them out?

Even if I had high speed internet, I often prefer looking at a paper
catalog, so I can make notes and circle things.

I saw an article one some web forum, and a guy said he went on Mouser's
website and said he felt so overwhelmed with items that he bought his
needs elsewhere. I immediately thought about when I went on their site a
few months ago (at a WIFI spot), and I felt the same way. I just wanted
a few caps and there were so many brands, variations, temperature
ranges, and on and on, I felt lost. I kept thinking "why does it need to
be this complicated:. In the old days, you chose them by axial or radial
leads, picked tubular, ceramic, mica, or electrolytic, and got the
proper capatance and voltage. That was all there was to it.
Peter Wieck
2017-04-18 12:25:44 UTC
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Post by o***@tubes.com
I saw an article one some web forum, and a guy said he went on Mouser's
website and said he felt so overwhelmed with items that he bought his
needs elsewhere.
THAT is when you pick up the phone and speak to a human being. Mouser 'stocks' those as well.

Mouser does send out a paper catalog, as does Newark, as do others. Pick up the phone. I also have a 1980 vintage semi-conductor catalog that fits nicely with my solid-state inventory. I can look up contemporary substitutions and have many more options thereby when I search for an obsolete part.

Good old fashioned customer-service is not dead. That you choose not to avail yourself of these services is your issue, not that of the provider. You have been on the planet for a number of years - I expect that by now you should have learned to adapt services available to your specific needs.

As to NOS tubes - How many do you want of what type, vintage, lot number and manufacturer? Do you want the boxes 'fresh' or 'oldened'? This is a cottage industry with many participants.

Peter Wieck
Melrose Park, PA
o***@gmail.com
2017-04-19 15:19:05 UTC
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On Tuesday, April 18, 2017 at 4:06:58 AM UTC-4, ***@tubes.com wrote:
I just wanted
Post by o***@tubes.com
a few caps and there were so many brands, variations, temperature
ranges, and on and on, I felt lost. I kept thinking "why does it need to
be this complicated:.
For hobbyists, maybe it is a bit complicated. But I love the diversity of components. I repair electronics for a living, and often that entails redesigning or a re-spec of the components installed either for performance/durability reasons or obsolescence considerations.

That I can input my own parameters and have the website pare down a part from tens of thousands to a few dozen has saved me many times over.
Peter Wieck
2017-04-19 17:08:12 UTC
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Post by o***@gmail.com
That I can input my own parameters and have the website pare down a part from tens of thousands to a few dozen has saved me many times over.
That would be the point! Choices may be screened. Lack of choice cannot be screened.

Peter Wieck
Melrose Park, PA
o***@tubes.com
2017-04-19 19:38:05 UTC
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Post by Peter Wieck
Post by o***@gmail.com
That I can input my own parameters and have the website pare down a part from
tens of thousands to a few dozen has saved me many times over.
That would be the point! Choices may be screened. Lack of choice cannot be screened.
Peter Wieck
Melrose Park, PA
That is probably true, but that is not going to happen on my dialup
internet.

As soon as I get to a WIFI place, so I can get the phone numbers of
these three companies, I will call them for paper catalogs. I can get
thru a paper catalog a lot faster than having to wait 15 minutes for
each page to load, and I am not willing to spend half a week at the
library or restaurants using their wifi service.

When I moved to a rural area, I had to accept the fact that the internet
service is horrible. It's just something we accept for the peace of mind
of living in the country. I'm not complaining, I would not have it any
other way. There IS life beyond the internet. Paper catalogs worked fine
for decades. The internet worked fine for one decade, then the websites
became all driven by scripts and CSS, and they no longer work for anyone
who does not have high speed internet and a ton of RAM on a high end
computer. Personally, I'll go back to the traditional catalog method....
I'm tired of trying to keep up with the Microsoft upgrade game, and
having to spend tons of money for high speed internet service (If its
even available), to satisfy the web designers who dont know how to write
simple (and usable) websites. Seems that the name of the game today is
to make websites that are as bloated as possible, and consume as much
resources as possible to even function. And the latest trend to turn all
sites to httpS (secured), had resulted in someone like myself unable to
use them at all anymore. Why I need a SECURE website, to simply read the
site, makes no sense at all.
Neon John
2017-04-19 22:28:14 UTC
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Post by o***@tubes.com
That is probably true, but that is not going to happen on my dialup
internet.
<more of the same old whining deleted>

Your whining has become intolerable so welcome to my kill file.

But before you go let me tell you this little story about a wise man.
This man got tired of all the hassles of city life so he moved into a
cabin inside the Cherokee National Forest at the end of a 25 mile long
mountain road. Paradise on earth. Electricity and the demise of the
party line came in the early and late 70s respectively so life is
good.

Going days without seeing a car is good.

Having wonderful neighbors - all 8 of 'em - is good.

Broadband is good.

How did this wise man get broadband so far away from civilization?
Why, though the magic of satellite internet, that's how. All that is
required to get broadband is a shot at the southern sky.

There are two competing companies - Hughsnet and Exede (aka Wild
Blue). Exede is far better but in this case, the mountains obstructed
the shot to that bird so Hughsnet it is. A neighbor who DOES have a
shot at the bird gets Exede. The speed is almost as good as wired
broadband.

Oh, almost forgot. That guy is me. Did I mention that I run an
internet-based business from up here? And before I forget, I looked -
Exede currently offers their service starting at $39/month.

John
John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address
o***@tubes.com
2017-04-19 22:17:26 UTC
Permalink
Raw Message
Post by Neon John
Post by o***@tubes.com
That is probably true, but that is not going to happen on my dialup
internet.
<more of the same old whining deleted>
Your whining has become intolerable so welcome to my kill file.
Thank you for the kill file. At least I wont have to listen to YOUR
whining about me saying what I have available to work with, and my
limitations. NOT whining on my part, just fact.
Post by Neon John
But before you go let me tell you this little story about a wise man.
This man got tired of all the hassles of city life so he moved into a
cabin inside the Cherokee National Forest at the end of a 25 mile long
mountain road. Paradise on earth. Electricity and the demise of the
party line came in the early and late 70s respectively so life is
good.
Going days without seeing a car is good.
Having wonderful neighbors - all 8 of 'em - is good.
Broadband is good.
How did this wise man get broadband so far away from civilization?
Why, though the magic of satellite internet, that's how. All that is
required to get broadband is a shot at the southern sky.
There are two competing companies - Hughsnet and Exede (aka Wild
Blue). Exede is far better but in this case, the mountains obstructed
the shot to that bird so Hughsnet it is. A neighbor who DOES have a
shot at the bird gets Exede. The speed is almost as good as wired
broadband.
Oh, almost forgot. That guy is me. Did I mention that I run an
internet-based business from up here? And before I forget, I looked -
Exede currently offers their service starting at $39/month.
I have thoroughly checked what is available around here. There is ZIP.
Every state or part of the country is different.....
I dont even get a cellphone signal unless I drive to the top of the
hill. Abour the only other option is Direct TV, all they sell is a
packaged deal with TV. (I dont want the tv part), and at a cost of well
over $100 per month. Sorry, I am retired and on Social Security, I cant
afford that.

Of course I suppose I am whining when I say I am on Social Security and
your next remark will be to tell me to quite being retired and get a
fucking job.

Goodbye
Post by Neon John
John
John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address
o***@gmail.com
2017-04-20 15:52:19 UTC
Permalink
Raw Message
Post by o***@tubes.com
As soon as I get to a WIFI place, so I can get the phone numbers of
these three companies, I will call them for paper catalogs.
I'm not sure they print paper catalogues anymore, but you can ask. Even so, a quick look at DigiKey shows something like 600 thousand capacitors alone. Add in the rest of the resistors, diodes, transistors (of all types), ICs (of all types) and I don't see how they could print such a behemoth or have it be of much use if they could.

For the record, I hate schematics in .pdf and I hate E-Books. The more a schematic is enlarged the less info you have. Going from one page back to another is cumbersome. Of course, with .pdf schematics I can at least find most of them and have them in front of me in minutes rather than having a printed schematic shipped to me by ground mail.

But when culling tens of thousands of transistors down to a few candidates, a smart site is the only way that will save me time. When looking for an IGBT for example, I can input one, several, or many parameters into the filters, parameters that are critical to my application requirement. The website then selects and cross matches from the many thousands of possibilities based on my filters to a few that I can quickly select. I can even filter in price or immediate availability in real time, something catalogues can't do.

If you're looking for some standard caps or resistors for hobby work, a catalogue will do fine. But for me, time is money. A smart site will cross match with split second efficiency and accuracy. If I had a time machine, I'd go back to the previous century and sit on the front porch with my Sears catalogue and listen to a ballgame on my old AM radio and enjoy every minute of it.
Jim Mueller
2017-04-21 00:36:00 UTC
Permalink
Raw Message
Post by o***@gmail.com
Post by o***@tubes.com
As soon as I get to a WIFI place, so I can get the phone numbers of
these three companies, I will call them for paper catalogs.
I'm not sure they print paper catalogues anymore, but you can ask. Even
so, a quick look at DigiKey shows something like 600 thousand capacitors
alone. Add in the rest of the resistors, diodes, transistors (of all
types), ICs (of all types) and I don't see how they could print such a
behemoth or have it be of much use if they could.
For the record, I hate schematics in .pdf and I hate E-Books. The more
a schematic is enlarged the less info you have. Going from one page
back to another is cumbersome. Of course, with .pdf schematics I can at
least find most of them and have them in front of me in minutes rather
than having a printed schematic shipped to me by ground mail.
But when culling tens of thousands of transistors down to a few
candidates, a smart site is the only way that will save me time. When
looking for an IGBT for example, I can input one, several, or many
parameters into the filters, parameters that are critical to my
application requirement. The website then selects and cross matches
from the many thousands of possibilities based on my filters to a few
that I can quickly select. I can even filter in price or immediate
availability in real time, something catalogues can't do.
If you're looking for some standard caps or resistors for hobby work, a
catalogue will do fine. But for me, time is money. A smart site will
cross match with split second efficiency and accuracy. If I had a time
machine, I'd go back to the previous century and sit on the front porch
with my Sears catalogue and listen to a ballgame on my old AM radio and
enjoy every minute of it.
The one thing that I have noticed that these sites don't allow you to
filter for is lead length. Many parts now have short pins for PCB
mounting but many are also available with longer leads. The only way to
know is to look up the manufacturer's part number on the manufacturer's
data sheet, something that is far easier to do online. I doubt that the
distributor's catalogs list that parameter so there will be several parts
with the same description differing only by the manufacturer's number.
Since these parts have different numbers, they are, indeed, different,
but knowing what the difference is can be challenging without the
manufacturer's data sheet.
--
Jim Mueller ***@nospam.com

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.
g***@gmail.com
2017-04-21 01:10:18 UTC
Permalink
Raw Message
Post by o***@gmail.com
Post by o***@tubes.com
As soon as I get to a WIFI place, so I can get the phone numbers of
these three companies, I will call them for paper catalogs.
I'm not sure they print paper catalogues anymore, but you can ask. Even so, a quick look at DigiKey shows something like 600 thousand capacitors alone. Add in the rest of the resistors, diodes, transistors (of all types), ICs (of all types) and I don't see how they could print such a behemoth or have it be of much use if they could.
For the record, I hate schematics in .pdf and I hate E-Books. The more a schematic is enlarged the less info you have. Going from one page back to another is cumbersome. Of course, with .pdf schematics I can at least find most of them and have them in front of me in minutes rather than having a printed schematic shipped to me by ground mail.
But when culling tens of thousands of transistors down to a few candidates, a smart site is the only way that will save me time. When looking for an IGBT for example, I can input one, several, or many parameters into the filters, parameters that are critical to my application requirement. The website then selects and cross matches from the many thousands of possibilities based on my filters to a few that I can quickly select. I can even filter in price or immediate availability in real time, something catalogues can't do.
If you're looking for some standard caps or resistors for hobby work, a catalogue will do fine. But for me, time is money. A smart site will cross match with split second efficiency and accuracy. If I had a time machine, I'd go back to the previous century and sit on the front porch with my Sears catalogue and listen to a ballgame on my old AM radio and enjoy every minute of it.
"When looking for an IGBT for example,..."
Hate to show my ignorance, but what is an "IGBT"?
o***@gmail.com
2017-04-21 11:21:26 UTC
Permalink
Raw Message
Post by g***@gmail.com
Post by o***@gmail.com
Post by o***@tubes.com
As soon as I get to a WIFI place, so I can get the phone numbers of
these three companies, I will call them for paper catalogs.
I'm not sure they print paper catalogues anymore, but you can ask. Even so, a quick look at DigiKey shows something like 600 thousand capacitors alone. Add in the rest of the resistors, diodes, transistors (of all types), ICs (of all types) and I don't see how they could print such a behemoth or have it be of much use if they could.
For the record, I hate schematics in .pdf and I hate E-Books. The more a schematic is enlarged the less info you have. Going from one page back to another is cumbersome. Of course, with .pdf schematics I can at least find most of them and have them in front of me in minutes rather than having a printed schematic shipped to me by ground mail.
But when culling tens of thousands of transistors down to a few candidates, a smart site is the only way that will save me time. When looking for an IGBT for example, I can input one, several, or many parameters into the filters, parameters that are critical to my application requirement. The website then selects and cross matches from the many thousands of possibilities based on my filters to a few that I can quickly select. I can even filter in price or immediate availability in real time, something catalogues can't do.
If you're looking for some standard caps or resistors for hobby work, a catalogue will do fine. But for me, time is money. A smart site will cross match with split second efficiency and accuracy. If I had a time machine, I'd go back to the previous century and sit on the front porch with my Sears catalogue and listen to a ballgame on my old AM radio and enjoy every minute of it.
"When looking for an IGBT for example,..."
Hate to show my ignorance, but what is an "IGBT"?
Insulated Gate Bipolar Transistor.

Fairly recent development in transistors. Take a look here:

http://www.electronics-tutorials.ws/power/insulated-gate-bipolar-transistor.html
Terry S
2017-04-21 12:37:29 UTC
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Raw Message
I guess "recent" is relative, I've been using these in motor controls since the late 80's or early 90's.

Terry
Post by o***@gmail.com
Insulated Gate Bipolar Transistor.
http://www.electronics-tutorials.ws/power/insulated-gate-bipolar-transistor.html
o***@gmail.com
2017-04-21 14:02:39 UTC
Permalink
Raw Message
Post by Terry S
I guess "recent" is relative, I've been using these in motor controls since the late 80's or early 90's.
Terry
The word "recent" is imprecise (which is why I chose it), and the qualifier "fairly" that I used kind of makes it more so, and given the long history of semiconductors, it's not actually inaccurate. In any case, lots of old timers haven't heard of them. Most know the transition of si and ge bipolars to darlingtons and mosfets etc., but many don't know what an IBGT is. I called it a fairly recent development in order to be sure it wasn't insulting to the poster who didn't know what one was.
Post by Terry S
Post by o***@gmail.com
Insulated Gate Bipolar Transistor.
http://www.electronics-tutorials.ws/power/insulated-gate-bipolar-transistor.html
The word "recent" is imprecise (which is why I chose it), and the qualifier "fairly" that I used kind of makes it more so. In any case, lots of old timers haven't heard of them. Most know the transition of si and ge bipolars to darlingtons and mosfets etc., but many don't know what an IBGT is. I called it a fairly recent development in order to be sure it wasn't insulting to the poster who didn't know what one was.
g***@gmail.com
2017-04-22 02:13:07 UTC
Permalink
Raw Message
Post by o***@gmail.com
Post by Terry S
I guess "recent" is relative, I've been using these in motor controls since the late 80's or early 90's.
Terry
The word "recent" is imprecise (which is why I chose it), and the qualifier "fairly" that I used kind of makes it more so, and given the long history of semiconductors, it's not actually inaccurate. In any case, lots of old timers haven't heard of them. Most know the transition of si and ge bipolars to darlingtons and mosfets etc., but many don't know what an IBGT is. I called it a fairly recent development in order to be sure it wasn't insulting to the poster who didn't know what one was.
Post by Terry S
Post by o***@gmail.com
Insulated Gate Bipolar Transistor.
http://www.electronics-tutorials.ws/power/insulated-gate-bipolar-transistor.html
The word "recent" is imprecise (which is why I chose it), and the qualifier "fairly" that I used kind of makes it more so. In any case, lots of old timers haven't heard of them. Most know the transition of si and ge bipolars to darlingtons and mosfets etc., but many don't know what an IBGT is. I called it a fairly recent development in order to be sure it wasn't insulting to the poster who didn't know what one was.
Not insulting in the least and thanks for the link that explained the thing well.

Garrett

Peter Wieck
2017-04-14 11:13:17 UTC
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Raw Message
Post by Foxs Mercantile
It's a fool's errand to NOT put a 3 wire cord on any radio or test
equipment these days.
Being as this is a radio newsgroup, the above sentiment needs some clarification.

AA5 radios (transformerless devices) should not have a 3-wire cord as the chassis is either hot when the radio is on, or at all times depending on how the plug is installed. For these sorts of radios, a polarized plug to insure that (at least) when "OFF" the radios is not hot is advisable. Of course, this depends on whether or not your household wiring is correct. Generally, they should be treated as Hot Chassis devices at all times, much as all guns are loaded even when they are not.

Many sorts of audio equipment become problematic if a 3-wire plug is used, even those with transformers. Many of these use the chassis as the ground plane, adding the third wire can (and often does) cause hum-loops as the system ground hitherto connected to the mains-neutral may be at a different level than the mains ground - HUmmmmmmmmmmmm. How does this happen? A bit of understanding of the National Electrical Code (NEC) is useful. Up until well into the 1970s, a ground wire was permitted to be one gauge less than the hot and neutral wires. For longer than that, MC (metallic conduit) cable, AKA BX, was permitted to use the case as the ground. More than a few individuals here, I am sure, have wiring that predates the code changes.

In general, and if the chassis is *not* used as the ground plane, converting to a 3-wire grounded cord is a good thing. But with care and understanding, not willy-nilly.

Peter Wieck
Melrose Park, PA
Foxs Mercantile
2017-04-14 12:01:36 UTC
Permalink
Raw Message
Post by Peter Wieck
Post by Foxs Mercantile
It's a fool's errand to NOT put a 3 wire cord on any radio or test
equipment these days.
Being as this is a radio newsgroup, the above sentiment needs some clarification.
AA5 radios (transformerless devices) should not have a 3-wire cord
as the chassis is either hot when the radio is on, or at all times
depending on how the plug is installed. For these sorts of radios,
a polarized plug to insure that (at least) when "OFF" the radios is
not hot is advisable. Of course, this depends on whether or not your
household wiring is correct. Generally, they should be treated as
Hot Chassis devices at all times, much as all guns are loaded even
when they are not.
Actually, no, the chassis are not "hot" as far as directly connected
to the AC mains.

The common "supply return" bus is hot to the AC mains, and is usually
capacitively coupled to the chassis so that the chassis is a the
supply return potential as far as the signals are concerned.
Post by Peter Wieck
Many sorts of audio equipment become problematic if a 3-wire plug is
used, even those with transformers. Many of these use the chassis as
the ground plane, adding the third wire can (and often does) cause
hum-loops as the system ground hitherto connected to the mains-neutral
may be at a different level than the mains ground - HUmmmmmmmmmmmm.
How does this happen? A bit of understanding of the National Electrical
Code (NEC) is useful. Up until well into the 1970s, a ground wire was
permitted to be one gauge less than the hot and neutral wires. For
longer than that, MC (metallic conduit) cable, AKA BX, was permitted to
use the case as the ground. More than a few individuals here, I am sure,
have wiring that predates the code changes.
Having all of the chassis at the same potential will NOT cause ground
loops unless there is a reason that one chassis is trying to be above
that common potential. That is a design fault, NOT a default condition.
Post by Peter Wieck
In general, and if the chassis is *not* used as the ground plane,
converting to a 3-wire grounded cord is a good thing. But with care
and understanding, not willy-nilly.
ANY piece of test equipment, and ANY piece of equipment with a connector
one it where one side is common. For example, 1/4" phone jack, RCA, BNC
Amphenol, UHF etc requires a safety ground to the chassis to preclude
any chance of electrocution.
--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

---
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http://www.avg.com
Peter Wieck
2017-04-14 13:04:32 UTC
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Raw Message
http://www.nostalgiaair.org/pagesbymodel/158/M0012158.pdf
________________________________________________________________________

Actually, no, the chassis are not "hot" as far as directly connected
to the AC mains.

The common "supply return" bus is hot to the AC mains, and is usually
capacitively coupled to the chassis so that the chassis is a the
supply return potential as far as the signals are concerned.
________________________________________________________________________
Note the direct mains connection to the common ground. Not uncommon for AA5 radios. Makes the chassis at line-potential 100% of the time if plugged in one way, when-on if plugged in the other way. Grounding this chassis via a 3-wire cord could be spectacular. Remember, you cannot count on household wiring to be correct 100% of the time.

Having all of the chassis at the same potential will NOT cause ground
loops unless there is a reason that one chassis is trying to be above
that common potential. That is a design fault, NOT a default condition.
__________________________________________________________________________
Sure. If the system ground is connected to the Mains neutral – most two-wire installations – all is well. Now, take one component in a chain and connect the system ground to the mains ground. If the mains ground is not *exactly* the same as the mains neutral – HUMMMmmmmmmmmm. And even in the best-installed systems, the mains ground and neutral are seldom at the same potential – and hence why Isolated Ground requirements exist for medical equipment and other critical applications.

Adding 3-wire cords to audio equipment designed against a 2-wire configuration must be done exceedingly carefully. Writing for myself, I prefer installing an external ground to all components to a high-quality ground. What is dangerous is if the mains ground is ‘above’ the mains neutral – which is very, very, common.

Peter Wieck
Melrose Park, PA
Foxs Mercantile
2017-04-14 14:44:23 UTC
Permalink
Raw Message
Post by Peter Wieck
http://www.nostalgiaair.org/pagesbymodel/158/M0012158.pdf
________________________________________________________________________
Actually, no, the chassis are not "hot" as far as directly connected
to the AC mains.
Fine, you found the exception.
A good many more of them do NOT directly connect to the chassis.
Post by Peter Wieck
Sure. If the system ground is connected to the Mains neutral – most
two-wire installations – all is well. Now, take one component in a
chain and connect the system ground to the mains ground. If the mains
ground is not *exactly* the same as the mains neutral – HUMMMmmmmmmmmm.
And even in the best-installed systems, the mains ground and neutral
are seldom at the same potential – and hence why Isolated Ground
requirements exist for medical equipment and other critical applications.
Isolated ground are NOT floating grounds, the are referenced back to a
single common ground point, typically separate (at the point of use)
from the distribution ground. I.e., conduit and such.
Post by Peter Wieck
Adding 3-wire cords to audio equipment designed against a 2-wire
configuration must be done exceedingly carefully. Writing for myself,
I prefer installing an external ground to all components to a high-
quality ground. What is dangerous is if the mains ground is ‘above’
the mains neutral – which is very, very, common.
A second ground is a violation of the electrical code.
You get one ground, and that is the one tied to neutral at the meter
panel.
--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

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Jim Mueller
2017-04-15 06:04:15 UTC
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To clarify one of the issues, AC/DC radios (some of which are AA5s) made
before the late '30s generally had some part of the circuit tied to the
chassis. This could be one side of the AC line or part of the bias
circuitry. Grounding the chassis of one of these would cause major
problems. Most, but not all, AA5s made after the early '40s had a
"floating ground" which was not connected to the chassis (sets with PC
boards didn't even have a chassis). Grounding the chassis of one of
these would not cause any spectacular problems but may cause operational
problems since they weren't designed to be operated that way. However,
these sets are generally well insulated so there is no need to ground
them if the cabinet and knobs are intact.

Hot chassis sets generally do not have one side of the AC line connected
directly to the chassis. The connection is through the power switch.
This means that if the switch is on, one side of the line is connected to
the chassis. But if the switch is off, the other side of the line is
connected to the chassis through the tube heaters (which have a low
resistance when cold). As a result, there is no "safe" way to plug it
in; both ways are wrong depending on if the set is on or off. If the
cabinet doesn't provide adequate insulation, the only way to make them
safe is to use an isolation transformer.
--
Jim Mueller ***@nospam.com

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.
o***@tubes.com
2017-04-15 18:11:49 UTC
Permalink
Raw Message
Post by Jim Mueller
To clarify one of the issues, AC/DC radios (some of which are AA5s) made
before the late '30s generally had some part of the circuit tied to the
chassis. This could be one side of the AC line or part of the bias
circuitry. Grounding the chassis of one of these would cause major
problems. Most, but not all, AA5s made after the early '40s had a
"floating ground" which was not connected to the chassis (sets with PC
boards didn't even have a chassis). Grounding the chassis of one of
these would not cause any spectacular problems but may cause operational
problems since they weren't designed to be operated that way. However,
these sets are generally well insulated so there is no need to ground
them if the cabinet and knobs are intact.
Hot chassis sets generally do not have one side of the AC line connected
directly to the chassis. The connection is through the power switch.
This means that if the switch is on, one side of the line is connected to
the chassis. But if the switch is off, the other side of the line is
connected to the chassis through the tube heaters (which have a low
resistance when cold). As a result, there is no "safe" way to plug it
in; both ways are wrong depending on if the set is on or off. If the
cabinet doesn't provide adequate insulation, the only way to make them
safe is to use an isolation transformer.
I posted this before on here, but in brief, my Hallicrafters S41 SW
radio had a live chassis. Worse yet, it had a metal cabinet, which was
isolated by rubber grommets, but when the grommets dried up from age,
the whole radio was live. I was young when I got that radio, and I
learned the hard way to respect that thing, but I also got badly burned
when I hooked some thin wire from the chassis ground to the center screw
on the wall outlet cover plate, to ground it for antenna / reception
needs. When I turned the radio on, that thin wire started burning, fell
on my hand and burned deep into my fingers, as well as leaving burns on
the floor, before the wire finally burned away, or did it blow the house
fuse??? (I cant remember). But I do remember the painful burn with
insulation embedded in my skin, and going to the hospital. And I recall
my father wanting to toss that radio in the garbage, until a
professional radio person said it needed an isolation transformer, and
my father paid him for transformer..

I still have that radio and the isolation xformer. Lots of memories in
that thing. But I will say that was one dangerous radio as it came from
the factory. It was also a very popular radio since it sold cheap, and
had fairly good reception.

Then again, I also remember a lot of those old power tools from the same
era. The ones with the metal housing, and the two prong plugs that
seemed to like to shock people.

Some of the modern electrical codes seem excessive at times, but it sure
beats those dangerous things they made in the 40s and 50s. I also recall
some sort of kitchen mixer (mix master), that my mother had, and got a
bad shock from. I was very young, but I remember seeing my father
throwing it in the garbage and taking mom to the store for a new one,
after hearing my mother act as if she was going to die long after the
thing was unplugged.
Sofa Slug
2017-04-15 20:25:26 UTC
Permalink
Raw Message
Post by o***@tubes.com
Post by Jim Mueller
To clarify one of the issues, AC/DC radios (some of which are AA5s) made
before the late '30s generally had some part of the circuit tied to the
chassis. This could be one side of the AC line or part of the bias
circuitry. Grounding the chassis of one of these would cause major
problems. Most, but not all, AA5s made after the early '40s had a
"floating ground" which was not connected to the chassis (sets with PC
boards didn't even have a chassis). Grounding the chassis of one of
these would not cause any spectacular problems but may cause operational
problems since they weren't designed to be operated that way. However,
these sets are generally well insulated so there is no need to ground
them if the cabinet and knobs are intact.
Hot chassis sets generally do not have one side of the AC line connected
directly to the chassis. The connection is through the power switch.
This means that if the switch is on, one side of the line is connected to
the chassis. But if the switch is off, the other side of the line is
connected to the chassis through the tube heaters (which have a low
resistance when cold). As a result, there is no "safe" way to plug it
in; both ways are wrong depending on if the set is on or off. If the
cabinet doesn't provide adequate insulation, the only way to make them
safe is to use an isolation transformer.
I posted this before on here, but in brief, my Hallicrafters S41 SW
radio had a live chassis. Worse yet, it had a metal cabinet, which was
isolated by rubber grommets, but when the grommets dried up from age,
the whole radio was live. I was young when I got that radio, and I
learned the hard way to respect that thing, but I also got badly burned
when I hooked some thin wire from the chassis ground to the center screw
on the wall outlet cover plate, to ground it for antenna / reception
needs. When I turned the radio on, that thin wire started burning, fell
on my hand and burned deep into my fingers, as well as leaving burns on
the floor, before the wire finally burned away, or did it blow the house
fuse??? (I cant remember). But I do remember the painful burn with
insulation embedded in my skin, and going to the hospital. And I recall
my father wanting to toss that radio in the garbage, until a
professional radio person said it needed an isolation transformer, and
my father paid him for transformer..
I still have that radio and the isolation xformer. Lots of memories in
that thing. But I will say that was one dangerous radio as it came from
the factory. It was also a very popular radio since it sold cheap, and
had fairly good reception.
<...snipped>
"Hot chassis" sets can be made safer by installing a polarized plug and
then rewiring the AC switch so it switches the "hot" side of the AC line
instead of the neutral. The neutral is then connected to chassis ground.

For a write-up on how to do this - as well as some info on using
transformers with an unmodified radio - see:

<http://www.geojohn.org/Radios/MyRadios/Safety.html>
o***@tubes.com
2017-04-16 07:21:40 UTC
Permalink
Raw Message
Post by Sofa Slug
Post by o***@tubes.com
Post by Jim Mueller
To clarify one of the issues, AC/DC radios (some of which are AA5s) made
before the late '30s generally had some part of the circuit tied to the
chassis. This could be one side of the AC line or part of the bias
circuitry. Grounding the chassis of one of these would cause major
problems. Most, but not all, AA5s made after the early '40s had a
"floating ground" which was not connected to the chassis (sets with PC
boards didn't even have a chassis). Grounding the chassis of one of
these would not cause any spectacular problems but may cause operational
problems since they weren't designed to be operated that way. However,
these sets are generally well insulated so there is no need to ground
them if the cabinet and knobs are intact.
Hot chassis sets generally do not have one side of the AC line connected
directly to the chassis. The connection is through the power switch.
This means that if the switch is on, one side of the line is connected to
the chassis. But if the switch is off, the other side of the line is
connected to the chassis through the tube heaters (which have a low
resistance when cold). As a result, there is no "safe" way to plug it
in; both ways are wrong depending on if the set is on or off. If the
cabinet doesn't provide adequate insulation, the only way to make them
safe is to use an isolation transformer.
I posted this before on here, but in brief, my Hallicrafters S41 SW
radio had a live chassis. Worse yet, it had a metal cabinet, which was
isolated by rubber grommets, but when the grommets dried up from age,
the whole radio was live. I was young when I got that radio, and I
learned the hard way to respect that thing, but I also got badly burned
when I hooked some thin wire from the chassis ground to the center screw
on the wall outlet cover plate, to ground it for antenna / reception
needs. When I turned the radio on, that thin wire started burning, fell
on my hand and burned deep into my fingers, as well as leaving burns on
the floor, before the wire finally burned away, or did it blow the house
fuse??? (I cant remember). But I do remember the painful burn with
insulation embedded in my skin, and going to the hospital. And I recall
my father wanting to toss that radio in the garbage, until a
professional radio person said it needed an isolation transformer, and
my father paid him for transformer..
I still have that radio and the isolation xformer. Lots of memories in
that thing. But I will say that was one dangerous radio as it came from
the factory. It was also a very popular radio since it sold cheap, and
had fairly good reception.
<...snipped>
"Hot chassis" sets can be made safer by installing a polarized plug and
then rewiring the AC switch so it switches the "hot" side of the AC line
instead of the neutral. The neutral is then connected to chassis ground.
For a write-up on how to do this - as well as some info on using
<http://www.geojohn.org/Radios/MyRadios/Safety.html>
Funny thing, this article mentions the Hallicrafters S-38. THe S-38 is
electrically the same as the S-41 that I mentioned caused me a lot of
problems. The only difference is the look of the case between these
models. The S-38 also has a metal case isolatated from the chassis by
rubber grommets, which decay over time and then the entire radio can be
live to the 120 V AC line.

Altrhough there were other AA5 radios with hot chassis, these
Hallicrafters S-38 and S-41 were some of the most dangerous radios ever
made, because of their metal case, and those grommets that do decay
after not all that many years.

I already knew the way to modify them, but having it in schematic form
is a good reminder and should be real helpful for those who are not as
familiar with AC wiring as I am. (I worked for an electrician for many
years).
J.B. Wood
2017-04-17 10:41:43 UTC
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Post by Peter Wieck
Post by Foxs Mercantile
It's a fool's errand to NOT put a 3 wire cord on any radio or test
equipment these days.
Being as this is a radio newsgroup, the above sentiment needs some clarification.
AA5 radios (transformerless devices) should not have a 3-wire cord as
the chassis is either hot when the radio is on, or at all times
depending on how the plug is installed. For these sorts of radios, a
polarized plug to insure that (at least) when "OFF" the radios is not
hot is advisable. Of course, this depends on whether or not your
household wiring is correct. Generally, they should be treated as Hot
Chassis devices at all times, much as all guns are loaded even when
they are not.
Many sorts of audio equipment become problematic if a 3-wire plug is
used, even those with transformers. Many of these use the chassis as
the ground plane, adding the third wire can (and often does) cause
hum-loops as the system ground hitherto connected to the
mains-neutral may be at a different level than the mains ground -
HUmmmmmmmmmmmm. How does this happen? A bit of understanding of the
National Electrical Code (NEC) is useful. Up until well into the
1970s, a ground wire was permitted to be one gauge less than the hot
and neutral wires. For longer than that, MC (metallic conduit) cable,
AKA BX, was permitted to use the case as the ground. More than a few
individuals here, I am sure, have wiring that predates the code
changes.
In general, and if the chassis is *not* used as the ground plane,
converting to a 3-wire grounded cord is a good thing. But with care
and understanding, not willy-nilly.
Peter Wieck Melrose Park, PA
Excellent points, Peter. You know your stuff. BTW, I have a 4-tube
(35Z5-12SA7-12SQ7-50L6) Sears Silvertone AM table radio (manufactured by
Arvin) that has a hot chassis via a capacitor connection to the AC line.
Rather than the usual loop antenna, the radio has a hank of wire that
is extended to serve as antenna. This radio was purchased way back when
by my dad and I remember as a kid getting shocked holding the bare end
of the antenna while inadvertently touching the refrigerator door. Too
bad the RF design engineers ignored basic electrical safety. Probably
one reason we now have polarized plugs and receptacles. Sincerely,
--
J. B. Wood e-mail: ***@hotmail.com
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