Date   

Re: PG-502 blowing fuses - PS repair

John Dickens <jake_117_dickens@...>
 

This may be an old subject, but when a tantalum had been ok for 20+ years, is it best to leave it alone or replace it. As I understand it, they don't deteriorate from age, but often fail from over voltage, spikes, trauma. What do you advise?

Jake



On Apr 14, 2016, at 7:43 PM, 'Dennis Tillman' dennis@ridesoft.com [TekScopes] <TekScopes@yahoogroups.com> wrote:

Hi Christoph,
It is not unusual for Tek to design the power supplies where they use one as
a "reference" and use that voltage as the reference for the others. In these
cases you have to first get the "reference" supply to work. Sometimes if
other supplies are shorting out they can drag down this "reference" supply
and make it very hard to troubleshoot the entire power supply section. In
that case the only way to proceed is to remove the load from the other
supplies one at a time until the "reference" pops up to correct voltage.
Then you can narrow down the source of the short or excessive load.

ALWAYS, I can't stress this enough, ALWAYS be suspicious of the tantalum
capacitors. They have a notorious failure rate as everyone on the forum will
tell you. Tek (and everyone else in the industry) used them extensively
before their critical weaknesses were understood. They are used extensively
in the power supply section of every Tek product. Check every one of them
with an ohmmeter. Some people replace them all as a precaution even if they
don't appear to be bad.

-----Original Message-----
Sent: Thursday, April 14, 2016 1:17 AM
Subject: [TekScopes] PG-502 blowing fuses - PS repair

On a PG-502 I had here laying around and had partially repaired such that at
least the pulse train and the levels were workiing - only pulse width was
still defunct - suddenly it blew the 1A fuses F600 and F670.

I measured all transistors, found a few burnt ones, replaces the "normal"
ones with BC546/BC556 and the metal case with BC 161. Still it looks like
the Thyristor 2N4441 plays its role as a crowbar and closes on power up.

I will do another round and check *all* transistors, diodes, zeners etc.

I also tested the thyristor outside the board in a little testcircuit. It
fired on demand and opened as well.

This power supply seems to be a bit tricky because all voltages seems to
depend on other voltages somehow.

Any expert on this modules out there?
Christoph
------------------------------------
Posted by: christophkukulies@me.com
------------------------------------


[Non-text portions of this message have been removed]


Re: TekScopes Moderator

John Dickens <jake_117_dickens@...>
 

I am rather new to this group, impressed with our members, and would very much like to contribute to whatever is necessary to keep this going strong. Jake

On Apr 14, 2016, at 6:58 PM, Dwayne Verhey tekscopes@verhey.org [TekScopes] <TekScopes@yahoogroups.com> wrote:

John,-

I'm using the "PG Offline" software that someone mentioned.

I don't think that Yahoo Groups will die at least until Yahoo is sold,
so we probably have a bit of time. (But to be safe, I grabbed the files
first). I haven't a clue if I get locked out of all groups, but I still
get the Tekscopes e-mails even when locked out of the web interface. And
I don't seem to get locked out of the files or photos at all -- just the
messages. So I'm just grabbing a few thousand at a time. (I'm up to
about 30,000 now; this certainly is a loquacious group! )



On 14/04/2016 6:58 PM, 'John Snyder' Kochcal@earthlink.net [TekScopes]
wrote:

Dwayne

Great:

Are you using and having success with the "Yahoo Message Export" Chrome
plugin?

When it shuts you down, does it cut off only the one you are
downloading, or
all the groups you are joined?

If it looks like you need some help splitting things up to make it in
time,
let me know other wise a single download would seem better

John

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Thursday, April 14, 2016 1:29 PM
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] TekScopes Moderator

On 14/04/2016 12:12 PM, 'John Snyder' Kochcal@earthlink.net [TekScopes]
wrote:


Has anyone used any of the tools and succeeded in getting a text backup?
I am in the process. Up to 2007 now (Yahoo locks me out if I take too
much too fast)

When I have it all, I will put the archive on tecscopes.info, where any
of you can grab a copy.

------------------------------------
Posted by: Dwayne Verhey <tekscopes@verhey.org>
------------------------------------

------------------------------------

Yahoo Groups Links


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Yahoo Groups Links



Re: In praise of crimping BNC's

Brian <brianclarke01@...>
 

Not so fast. Most of the IT cables were 75 Ohm or 95 Ohm. The tooling for the 75 and 95 Ohm BNC connectors is different from that for the 50 Ohm connectors.

Shirley – please note: I removed all the unnecessary tails.

73 de Brian, VK2GCE.

On Friday, April 15, 2016 12:49 PM, Shirley said:


There must be piles of BNC crimping tools languishing in IT departments
around the country. There are probably also bins full of already made up
BNC cables left over from the days of thin Ethernet. The challenge is to
figure out where they are and get them into the hands of people who can use
them.


Re: In praise of crimping BNC's

Shirley Dulcey KE1L
 

There must be piles of BNC crimping tools languishing in IT departments
around the country. There are probably also bins full of already made up
BNC cables left over from the days of thin Ethernet. The challenge is to
figure out where they are and get them into the hands of people who can use
them.

On Thu, Apr 14, 2016 at 10:05 PM, Peter Gottlieb hpnpilot@gmail.com
[TekScopes] <TekScopes@yahoogroups.com> wrote:



It is quite possible to install the screw-together type really well, but
it
takes some skill and patience. It's not fast but you don't need much in
the way
of special tools.

Buy connectors new, with all the bits and pieces. Get high quality ones; I
like
Kings among others. Make sure the connector is specifically designed for
the
cable you are using. Fudging it doesn't usually work out very well. You
may
need to grind down the thickness of an open end wrench to work with the
flats on
the body.

The cable prep and installation directions are easily found with Google.
Learn
to follow the directions precisely, including tightening torque. It took
me a
while but the ones I do now have the pin in correctly and there is no play
in
the cable, it's gripped nice and solidly. Impedance is as good as it gets
with BNC.

I'd love to have a high quality crimper setup but just can't justify the
cost
for the limited use I'd get from it. Yes, with the prep tool and crimper
you're
done in no time with great results, it's just very costly per connector if
you're doing under 5 connectors a year.


On 4/14/2016 9:51 PM, Bob Albert bob91343@yahoo.com [TekScopes] wrote:

BNC connectors seem to be ubiquitous and so it behooves us to find a
suitable
way of installing those connectors on cables.
I have seen some crimpers but none are cheap. I have also seen some
variety
in connectors that lead me to believe that one crimper won't work for
everything.
I don't mind soldering the center conductor but the issue arises as to
whether
to tin it first and how to get all the strands into the pin. I have
trimmed
off many strands in an effort to insert the center conductor.
Most of my work on the test bench is with RG-58A/U or its equivalents.
If you
know of an inexpensive way of installing inexpensive connectors with
acceptable reliability, please share it. I am one person with a small
laboratory and need to put a BNC on a cable perhaps a few times a year.
If I
have to spend a trifle more it won't matter much but some of the
solutions
appear to be more than a trifle higher in cost.
I also want to know a good procedure for installing all parts of the
connector, the center conductor, the shield, the pin, the funny little
washers
and insulators and all the other stuff that comes in the bag.
Bob


On Thursday, April 14, 2016 2:25 PM, "big_sky_explorer@yahoo.com
[TekScopes]"
<TekScopes@yahoogroups.com> wrote:


I think that we have to separate out the pros and cons of
crimping/soldering
to a finer degree. Not that I disagree with the crimping approach as
Walter
has commented on but there is a certain degree of poor reliability that
I have
witnessed with this approach when employed by the (shall we say) the
“commonly
found” user in the field.

I say “commonly found” because these are the people who are somewhat
unknowledgable about connectors and crimping processes in general since
they
are trained either by OJT or by another who has learned by intuition to
assemble connectors but not investigated the nitty-gritty technical
aspects of
them. Usually these people and/or their employers have had little
exposure to
the subtleties of connector reliability and associated tooling as
affected by
sourcing, manufacturing quality and such.

First, we look at sourcing. Obviously a smaller installing or repair
agency
will consider cost as a fairly important issue. This means that they
will
probably purchase their connectors from a source that offers fairly
inexpensive (<$2) connectors that are a given to be made in China.

Next, given the propensity for tooling to either become lost, damaged or
worn
out, these people will most likely look for the first supplier who
offers
inexpensive crimp tooling. Again the Chinese come to bat with their
offerings.
When we add minimal experience and knowledge to low quality connectors
and
tooling, we can have the setting for a connector installation that could
possibly be unreliable.

I do understand one’s desire for a reliable connection within the
connector.
Having worked on space hardware it was a given that this had to happen.
And,
of course, we had no qualms about multi-hundred $$ tooling and expensive
MIL
qualified connectors at our disposal. But I have to ask how many members
of
this group have access to that type of quality hardware for their home
projects let alone want to spend the money for same?

My experience using inexpensive (Chinese) BNC connectors with
off-the-street
tooling is that the center pin is often made of a fairly brittle alloy
that
tends to crack if the correct crimp pressure is not applied or the crimp
die
is not of the exact dimensions. This has led me to occasionally find
field
installations where the installer had over crimped the center contact
causing
cracking but not to a point where it was obvious when the connector was
assembled. Later, through flexing and movement of the cable, the contact
between the pin and center conductor became erratic and very obvious
when used
at higher frequencies.

When using “cheap” connectors I personally solder the center conductor
into
the pin. I find it easy to do and know that the connection will last and
that
I don’t end up having to throw away a connector should the crimp cause
cracking to occur. A little heat applied from the iron and the job is
done.
And has anyone ever wondered what that tiny hole is for in the side of
the
pin? To accept solder.

I believe that an earlier comment was made where the user is tinning the
center contact when assembling a connector. That can create problems as
the
connector sees use. First, the gold strike on the pin is there for a
reason –
to afford a highly reliable, non-oxidizing contact surface. Obviously a
tin
strike contact in many other (non-RF) multi-pin connectors can exhibit
higher
contact resistance, oxidation and, hence, possible intermittents when in
use.

Second, the sliding of the pin into the mating receptacle can deposit
the tin
onto the mating contact surface. If this surface also contains a gold
strike,
the overlay of tin on that surface will reduce the contact reliability
and RF
characteristics of that connector as well.

When working in Colorado, I had the opportunity to attend a seminar at
the
(then) National Bureau of Standards on RF connector reliability. It was
quite
informative to learn about connector contact plating techniques and how
it
affects the reliability of the connector. And it was also a real
eye-opener to
find out how limited the number of mate/un-mate cycles a typical
connector can
go through before the RF characteristics begin to degrade. Of the ones
found
around the lab, N connectors were the most substantial. BNC connectors
were
significantly less.

Greg



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2465A in unusual application...

Bill Sudbrink
 

Hi,

I thought some of you might enjoy this. This is a replica
of the CYCLOPS camera, featured in the February 1975
issue of Popular Electronics. The 2465A is acting as a
display for it.

http://www.swtpc.com/mholley/PopularElectronics/Feb1975/PE_Feb1975.htm

Here are a couple of pictures:

http://wsudbrink.dyndns.org:8080/images/cyclops-latest/P4140003.JPG

http://wsudbrink.dyndns.org:8080/images/cyclops-latest/P4140004.JPG

Test target:
http://wsudbrink.dyndns.org:8080/images/cyclops-latest/P4140005.JPG

Image:
http://wsudbrink.dyndns.org:8080/images/cyclops-latest/P4140008.JPG

Image of hand:
http://wsudbrink.dyndns.org:8080/images/cyclops-latest/P4140009.JPG

This image looks much better "live". The single frame, "frozen"
by the camera, doesn't do it justice. This will be exhibited in
operation at the East Coast Vintage Computer Festival, this
weekend:

http://vcfed.org/wp/wp-content/uploads/2015/12/eastxiflyer.pdf

Bill Sudbrink


Re: - Plug-ins from the 1960s & 70s

Dave Seiter
 

It's too bad that none of them are actual "mil" plugins, then they might be worth something...
-Dave

From: "John Dickens jake_117_dickens@yahoo.com [TekScopes]" <TekScopes@yahoogroups.com>
To: TekScopes@yahoogroups.com
Sent: Thursday, April 14, 2016 12:53 PM
Subject: [TekScopes] - Plug-ins from the 1960s & 70s

 
In case anyone is interested, I just ran across the following Craigslist add selling 23 plug-ins from the 60s and 70s: "These units are plug ins for Tektronix oscilloscopes commonly found on U.S. aircraft carriers in the 60's and 70's. Selling for 20 - 40.00 each or make offer on all 23. I also have an oscilloscope for 40.00. Sold as is untested.”

https://dubuque.craigslist.org/for/5522355104.html <https://dubuque.craigslist.org/for/5522355104.html>

Jake

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Re: New member application blocked

 

Yes, but that isn't the archive of Tekscopes! It's just a file repository
left over from the days when the file storage was very small.

Dave

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: 15 April 2016 02:14
To: TekScopes@yahoogroups.com
Subject: RE: [TekScopes] New member application blocked

Hi Menachem,
The Tekscopes Archive is a different forum. It doesn't have anything to do
with TekScopes so membership in one does not include membership in the
other.

There is no one with Jeff's name that I have rejected. There have only been
4 rejected applications in the past 4 weeks and all were rejected because
they didn't provide any comment at all about why they want to join the
group. The main reason he would be rejected is if he doesn't include a
paragraph explaining his interest in joining the group. This is explained in
the instructions for joining.

Dennis Tillman W7PF

-----Original Message-----
Sent: Thursday, April 14, 2016 3:27 AM
Subject: [TekScopes] New member application blocked

I'm not sure how the best way is to do this, but Jeff Randels, who is a
member on Tekscopes Archive has applied to join this group, and his
application is constantly rejected.

He has a 2467 with some problems. I've helped him through a number of them,
but there are other unsolved issues which need the expertise of those, who
are much more experienced than me, in this area.

He has asked me to intervene to allow him to post on this forum also.

Menahem Yachad
Israel
------------------------------------
Posted by: yachadm@gmail.com
------------------------------------




------------------------------------
Posted by: "Dennis Tillman" <dennis@ridesoft.com>
------------------------------------


------------------------------------

Yahoo Groups Links


Re: groups.io as tekscopes list server

 

I received a reply from Mark Fletcher

Hi Dave,
Right now we support the downloading of the member list and the downloading
of the group archives. We don't have any way of exporting files, databases,
photos or the wiki yet, but it's planned.
Hope this helps.
Mark
So yes, the group archive can be backed up externally today, the rest to
follow.

Dave
-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: 14 April 2016 15:32
To: TekScopes@yahoogroups.com
Subject: RE: [TekScopes] groups.io as tekscopes list server

As a group owner on there I will enquire ...

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: 14 April 2016 14:36
To: TekScopes@yahoogroups.com
Subject: [TekScopes] groups.io as tekscopes list server

On 04/14/2016 07:44 AM, Peter Gottlieb hpnpilot@gmail.com [TekScopes] wrote:
> If we have an operational backup at least the historical content will be
preserved. There is never a guarantee but the chances of > a loss drop to
close to zero when there are backups.

So, "Is the groups.io service easy to backup?", (after using their
auto-slurp transferring program)?






------------------------------------
Posted by: John Griessen <john@ecosensory.com>
------------------------------------


------------------------------------

Yahoo Groups Links





------------------------------------
Posted by: "David C. Partridge" <david.partridge@perdrix.co.uk>
------------------------------------


------------------------------------

Yahoo Groups Links


Re: In praise of crimping BNC's

Peter Gottlieb
 

It is quite possible to install the screw-together type really well, but it takes some skill and patience. It's not fast but you don't need much in the way of special tools.

Buy connectors new, with all the bits and pieces. Get high quality ones; I like Kings among others. Make sure the connector is specifically designed for the cable you are using. Fudging it doesn't usually work out very well. You may need to grind down the thickness of an open end wrench to work with the flats on the body.

The cable prep and installation directions are easily found with Google. Learn to follow the directions precisely, including tightening torque. It took me a while but the ones I do now have the pin in correctly and there is no play in the cable, it's gripped nice and solidly. Impedance is as good as it gets with BNC.

I'd love to have a high quality crimper setup but just can't justify the cost for the limited use I'd get from it. Yes, with the prep tool and crimper you're done in no time with great results, it's just very costly per connector if you're doing under 5 connectors a year.

On 4/14/2016 9:51 PM, Bob Albert bob91343@yahoo.com [TekScopes] wrote:

BNC connectors seem to be ubiquitous and so it behooves us to find a suitable way of installing those connectors on cables.
I have seen some crimpers but none are cheap. I have also seen some variety in connectors that lead me to believe that one crimper won't work for everything.
I don't mind soldering the center conductor but the issue arises as to whether to tin it first and how to get all the strands into the pin. I have trimmed off many strands in an effort to insert the center conductor.
Most of my work on the test bench is with RG-58A/U or its equivalents. If you know of an inexpensive way of installing inexpensive connectors with acceptable reliability, please share it. I am one person with a small laboratory and need to put a BNC on a cable perhaps a few times a year. If I have to spend a trifle more it won't matter much but some of the solutions appear to be more than a trifle higher in cost.
I also want to know a good procedure for installing all parts of the connector, the center conductor, the shield, the pin, the funny little washers and insulators and all the other stuff that comes in the bag.
Bob


On Thursday, April 14, 2016 2:25 PM, "big_sky_explorer@yahoo.com [TekScopes]" <TekScopes@yahoogroups.com> wrote:


I think that we have to separate out the pros and cons of crimping/soldering to a finer degree. Not that I disagree with the crimping approach as Walter has commented on but there is a certain degree of poor reliability that I have witnessed with this approach when employed by the (shall we say) the “commonly found” user in the field.

I say “commonly found” because these are the people who are somewhat unknowledgable about connectors and crimping processes in general since they are trained either by OJT or by another who has learned by intuition to assemble connectors but not investigated the nitty-gritty technical aspects of them. Usually these people and/or their employers have had little exposure to the subtleties of connector reliability and associated tooling as affected by sourcing, manufacturing quality and such.

First, we look at sourcing. Obviously a smaller installing or repair agency will consider cost as a fairly important issue. This means that they will probably purchase their connectors from a source that offers fairly inexpensive (<$2) connectors that are a given to be made in China.

Next, given the propensity for tooling to either become lost, damaged or worn out, these people will most likely look for the first supplier who offers inexpensive crimp tooling. Again the Chinese come to bat with their offerings. When we add minimal experience and knowledge to low quality connectors and tooling, we can have the setting for a connector installation that could possibly be unreliable.

I do understand one’s desire for a reliable connection within the connector. Having worked on space hardware it was a given that this had to happen. And, of course, we had no qualms about multi-hundred $$ tooling and expensive MIL qualified connectors at our disposal. But I have to ask how many members of this group have access to that type of quality hardware for their home projects let alone want to spend the money for same?

My experience using inexpensive (Chinese) BNC connectors with off-the-street tooling is that the center pin is often made of a fairly brittle alloy that tends to crack if the correct crimp pressure is not applied or the crimp die is not of the exact dimensions. This has led me to occasionally find field installations where the installer had over crimped the center contact causing cracking but not to a point where it was obvious when the connector was assembled. Later, through flexing and movement of the cable, the contact between the pin and center conductor became erratic and very obvious when used at higher frequencies.

When using “cheap” connectors I personally solder the center conductor into the pin. I find it easy to do and know that the connection will last and that I don’t end up having to throw away a connector should the crimp cause cracking to occur. A little heat applied from the iron and the job is done. And has anyone ever wondered what that tiny hole is for in the side of the pin? To accept solder.

I believe that an earlier comment was made where the user is tinning the center contact when assembling a connector. That can create problems as the connector sees use. First, the gold strike on the pin is there for a reason – to afford a highly reliable, non-oxidizing contact surface. Obviously a tin strike contact in many other (non-RF) multi-pin connectors can exhibit higher contact resistance, oxidation and, hence, possible intermittents when in use.

Second, the sliding of the pin into the mating receptacle can deposit the tin onto the mating contact surface. If this surface also contains a gold strike, the overlay of tin on that surface will reduce the contact reliability and RF characteristics of that connector as well.

When working in Colorado, I had the opportunity to attend a seminar at the (then) National Bureau of Standards on RF connector reliability. It was quite informative to learn about connector contact plating techniques and how it affects the reliability of the connector. And it was also a real eye-opener to find out how limited the number of mate/un-mate cycles a typical connector can go through before the RF characteristics begin to degrade. Of the ones found around the lab, N connectors were the most substantial. BNC connectors were significantly less.

Greg


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Re: In praise of crimping BNC's

Bob Albert
 

BNC connectors seem to be ubiquitous and so it behooves us to find a suitable way of installing those connectors on cables.
I have seen some crimpers but none are cheap.  I have also seen some variety in connectors that lead me to believe that one crimper won't work for everything.
I don't mind soldering the center conductor but the issue arises as to whether to tin it first and how to get all the strands into the pin.  I have trimmed off many strands in an effort to insert the center conductor.
Most of my work on the test bench is with RG-58A/U or its equivalents.  If you know of an inexpensive way of installing inexpensive connectors with acceptable reliability, please share it.  I am one person with a small laboratory and need to put a BNC on a cable perhaps a few times a year.  If I have to spend a trifle more it won't matter much but some of the solutions appear to be more than a trifle higher in cost.
I also want to know a good procedure for installing all parts of the connector, the center conductor, the shield, the pin, the funny little washers and insulators and all the other stuff that comes in the bag.
Bob

On Thursday, April 14, 2016 2:25 PM, "big_sky_explorer@yahoo.com [TekScopes]" <TekScopes@yahoogroups.com> wrote:


  I think that we have to separate out the pros and cons of crimping/soldering to a finer degree. Not that I disagree with the crimping approach as Walter has commented on but there is a certain degree of poor reliability that I have witnessed with this approach when employed by the (shall we say) the “commonly found” user in the field.

I say “commonly found” because these are the people who are somewhat unknowledgable about connectors and crimping processes in general since they are trained either by OJT or by another who has learned by intuition to assemble connectors but not investigated the nitty-gritty technical aspects of them. Usually these people and/or their employers have had little exposure to the subtleties of connector reliability and associated tooling as affected by sourcing, manufacturing quality and such.

First, we look at sourcing. Obviously a smaller installing or repair agency will consider cost as a fairly important issue. This means that they will probably purchase their connectors from a source that offers fairly inexpensive (<$2) connectors that are a given to be made in China.

Next, given the propensity for tooling to either become lost, damaged or worn out, these people will most likely look for the first supplier who offers inexpensive crimp tooling. Again the Chinese come to bat with their offerings. When we add minimal experience and knowledge to low quality connectors and tooling, we can have the setting for a connector installation that could possibly be unreliable.

I do understand one’s desire for a reliable connection within the connector. Having worked on space hardware it was a given that this had to happen. And, of course, we had no qualms about multi-hundred $$ tooling and expensive MIL qualified connectors at our disposal. But I have to ask how many members of this group have access to that type of quality hardware for their home projects let alone want to spend the money for same?

My experience using inexpensive (Chinese) BNC connectors with off-the-street tooling is that the center pin is often made of a fairly brittle alloy that tends to crack if the correct crimp pressure is not applied or the crimp die is not of the exact dimensions. This has led me to occasionally find field installations where the installer had over crimped the center contact causing cracking but not to a point where it was obvious when the connector was assembled. Later, through flexing and movement of the cable, the contact between the pin and center conductor became erratic and very obvious when used at higher frequencies.

When using “cheap” connectors I personally solder the center conductor into the pin. I find it easy to do and know that the connection will last and that I don’t end up having to throw away a connector should the crimp cause cracking to occur. A little heat applied from the iron and the job is done. And has anyone ever wondered what that tiny hole is for in the side of the pin? To accept solder.

I believe that an earlier comment was made where the user is tinning the center contact when assembling a connector. That can create problems as the connector sees use. First, the gold strike on the pin is there for a reason – to afford a highly reliable, non-oxidizing contact surface. Obviously a tin strike contact in many other (non-RF) multi-pin connectors can exhibit higher contact resistance, oxidation and, hence, possible intermittents when in use.

Second, the sliding of the pin into the mating receptacle can deposit the tin onto the mating contact surface. If this surface also contains a gold strike, the overlay of tin on that surface will reduce the contact reliability and RF characteristics of that connector as well.

When working in Colorado, I had the opportunity to attend a seminar at the (then) National Bureau of Standards on RF connector reliability. It was quite informative to learn about connector contact plating techniques and how it affects the reliability of the connector. And it was also a real eye-opener to find out how limited the number of mate/un-mate cycles a typical connector can go through before the RF characteristics begin to degrade. Of the ones found around the lab, N connectors were the most substantial. BNC connectors were significantly less.

Greg

[Non-text portions of this message have been removed]

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Re: New member application blocked

 

Hi Menachem,
The Tekscopes Archive is a different forum. It doesn't have anything to do
with TekScopes so membership in one does not include membership in the
other.

There is no one with Jeff's name that I have rejected. There have only been
4 rejected applications in the past 4 weeks and all were rejected because
they didn't provide any comment at all about why they want to join the
group. The main reason he would be rejected is if he doesn't include a
paragraph explaining his interest in joining the group. This is explained in
the instructions for joining.

Dennis Tillman W7PF

-----Original Message-----
Sent: Thursday, April 14, 2016 3:27 AM
Subject: [TekScopes] New member application blocked

I'm not sure how the best way is to do this, but Jeff Randels, who is a
member on Tekscopes Archive has applied to join this group, and his
application is constantly rejected.

He has a 2467 with some problems. I've helped him through a number of them,
but there are other unsolved issues which need the expertise of those, who
are much more experienced than me, in this area.

He has asked me to intervene to allow him to post on this forum also.

Menahem Yachad
Israel
------------------------------------
Posted by: yachadm@gmail.com
------------------------------------


Re: PG-502 blowing fuses - PS repair

 

Hi Christoph,
It is not unusual for Tek to design the power supplies where they use one as
a "reference" and use that voltage as the reference for the others. In these
cases you have to first get the "reference" supply to work. Sometimes if
other supplies are shorting out they can drag down this "reference" supply
and make it very hard to troubleshoot the entire power supply section. In
that case the only way to proceed is to remove the load from the other
supplies one at a time until the "reference" pops up to correct voltage.
Then you can narrow down the source of the short or excessive load.

ALWAYS, I can't stress this enough, ALWAYS be suspicious of the tantalum
capacitors. They have a notorious failure rate as everyone on the forum will
tell you. Tek (and everyone else in the industry) used them extensively
before their critical weaknesses were understood. They are used extensively
in the power supply section of every Tek product. Check every one of them
with an ohmmeter. Some people replace them all as a precaution even if they
don't appear to be bad.

-----Original Message-----
Sent: Thursday, April 14, 2016 1:17 AM
Subject: [TekScopes] PG-502 blowing fuses - PS repair

On a PG-502 I had here laying around and had partially repaired such that at
least the pulse train and the levels were workiing - only pulse width was
still defunct - suddenly it blew the 1A fuses F600 and F670.

I measured all transistors, found a few burnt ones, replaces the "normal"
ones with BC546/BC556 and the metal case with BC 161. Still it looks like
the Thyristor 2N4441 plays its role as a crowbar and closes on power up.

I will do another round and check *all* transistors, diodes, zeners etc.

I also tested the thyristor outside the board in a little testcircuit. It
fired on demand and opened as well.

This power supply seems to be a bit tricky because all voltages seems to
depend on other voltages somehow.

Any expert on this modules out there?
Christoph
------------------------------------
Posted by: christophkukulies@me.com
------------------------------------


Re: TekScopes Moderator

Torch
 

John,-

I'm using the "PG Offline" software that someone mentioned.

I don't think that Yahoo Groups will die at least until Yahoo is sold,
so we probably have a bit of time. (But to be safe, I grabbed the files
first). I haven't a clue if I get locked out of all groups, but I still
get the Tekscopes e-mails even when locked out of the web interface. And
I don't seem to get locked out of the files or photos at all -- just the
messages. So I'm just grabbing a few thousand at a time. (I'm up to
about 30,000 now; this certainly is a loquacious group! )



On 14/04/2016 6:58 PM, 'John Snyder' Kochcal@earthlink.net [TekScopes]
wrote:

Dwayne

Great:

Are you using and having success with the "Yahoo Message Export" Chrome
plugin?

When it shuts you down, does it cut off only the one you are
downloading, or
all the groups you are joined?

If it looks like you need some help splitting things up to make it in
time,
let me know other wise a single download would seem better

John

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Thursday, April 14, 2016 1:29 PM
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] TekScopes Moderator

On 14/04/2016 12:12 PM, 'John Snyder' Kochcal@earthlink.net [TekScopes]
wrote:


Has anyone used any of the tools and succeeded in getting a text backup?

I am in the process. Up to 2007 now (Yahoo locks me out if I take too
much too fast)

When I have it all, I will put the archive on tecscopes.info, where any
of you can grab a copy.

------------------------------------
Posted by: Dwayne Verhey <tekscopes@verhey.org>
------------------------------------

------------------------------------

Yahoo Groups Links


Re: TekScopes Moderator

ykochcal
 

Dwayne

Great:

Are you using and having success with the "Yahoo Message Export" Chrome
plugin?

When it shuts you down, does it cut off only the one you are downloading, or
all the groups you are joined?


If it looks like you need some help splitting things up to make it in time,
let me know other wise a single download would seem better

John

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Thursday, April 14, 2016 1:29 PM
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] TekScopes Moderator

On 14/04/2016 12:12 PM, 'John Snyder' Kochcal@earthlink.net [TekScopes]
wrote:


Has anyone used any of the tools and succeeded in getting a text backup?

I am in the process. Up to 2007 now (Yahoo locks me out if I take too
much too fast)

When I have it all, I will put the archive on tecscopes.info, where any
of you can grab a copy.




------------------------------------
Posted by: Dwayne Verhey <tekscopes@verhey.org>
------------------------------------


------------------------------------

Yahoo Groups Links


Re: - Plug-ins from the 1960s & 70s

Artek Manuals <manuals@...>
 

I predict that tube merchants are going to find themselves in the same predicament that the manual business is in i.e a shrinking market The people (like us) who keep this old stuff going are becoming fewer and fewer as the ranks die off and the gear gets to antique collector fodder versus the poor-mans lab equipment of 10 years ago. The Audiophile demand for tubes is likely not growing either. I think in the next 5 years these guys are going to wonder what to do with all the "pulls". I know there was a large lot on evil-bay (10,000 + tubes) and as I recall he had a real struggle getting his money out of them

Dave

On 4/14/2016 6:02 PM, Jerome Leach jerome_leach@yahoo.com [TekScopes] wrote:
Yup, tubes all gone. Thought about emailing the guy to inform him that
without the tubes, the dump is most likely the next stop for them. Scrap
is way down, so there is hardly enough aluminum to make it worthwhile to
go to the junkyard with them.

From: "Richard Solomon dickw1ksz@gmail.com [TekScopes]"
<TekScopes@yahoogroups.com>
To: TekScopes <TekScopes@yahoogroups.com>
Sent: Thursday, April 14, 2016 4:47 PM
Subject: Re: [TekScopes] - Plug-ins from the 1960s & 70s

From what I can see, some "tube merchant"
has already plundered them.

Pity,

73, Dick, W1KSZ
--
Dave
Manuals@ArtekManuals.com
www.ArtekManuals.com


Re: - Plug-ins from the 1960s & 70s

cmjones01
 

Some of those plugins, like the 1A4s, only have one tube in anyway so it's
no great shakes to replace...

Chris

On 14 Apr 2016 11:06 pm, "Jerome Leach jerome_leach@yahoo.com [TekScopes]" <
TekScopes@yahoogroups.com> wrote:



Yup, tubes all gone. Thought about emailing the guy to inform him that
without the tubes, the dump is most likely the next stop for them. Scrap is
way down, so there is hardly enough aluminum to make it worthwhile to go to
the junkyard with them.

From: "Richard Solomon dickw1ksz@gmail.com [TekScopes]" <
TekScopes@yahoogroups.com>
To: TekScopes <TekScopes@yahoogroups.com>
Sent: Thursday, April 14, 2016 4:47 PM
Subject: Re: [TekScopes] - Plug-ins from the 1960s & 70s


From what I can see, some "tube merchant"
has already plundered them.

Pity,

73, Dick, W1KSZ

On Thu, Apr 14, 2016 at 12:53 PM, John Dickens jake_117_dickens@yahoo.com
[TekScopes] <TekScopes@yahoogroups.com> wrote:




In case anyone is interested, I just ran across the following Craigslist
add selling 23 plug-ins from the 60s and 70s: "These units are plug ins
for
Tektronix oscilloscopes commonly found on U.S. aircraft carriers in the
60's and 70's. Selling for 20 - 40.00 each or make offer on all 23. I
also
have an oscilloscope for 40.00. Sold as is untested.”

https://dubuque.craigslist.org/for/5522355104.html <
https://dubuque.craigslist.org/for/5522355104.html>

Jake


[Non-text portions of this message have been removed]


Re: - Plug-ins from the 1960s & 70s

 

Yup, tubes all gone. Thought about emailing the guy to inform him that without the tubes, the dump is most likely the next stop for them. Scrap is way down, so there is hardly enough aluminum to make it worthwhile to go to the junkyard with them.

From: "Richard Solomon dickw1ksz@gmail.com [TekScopes]" <TekScopes@yahoogroups.com>
To: TekScopes <TekScopes@yahoogroups.com>
Sent: Thursday, April 14, 2016 4:47 PM
Subject: Re: [TekScopes] - Plug-ins from the 1960s & 70s

  From what I can see, some "tube merchant"
has already plundered them.

Pity,

73, Dick, W1KSZ

On Thu, Apr 14, 2016 at 12:53 PM, John Dickens jake_117_dickens@yahoo.com
[TekScopes] <TekScopes@yahoogroups.com> wrote:




In case anyone is interested, I just ran across the following Craigslist
add selling 23 plug-ins from the 60s and 70s: "These units are plug ins for
Tektronix oscilloscopes commonly found on U.S. aircraft carriers in the
60's and 70's. Selling for 20 - 40.00 each or make offer on all 23. I also
have an oscilloscope for 40.00. Sold as is untested.”

https://dubuque.craigslist.org/for/5522355104.html <
https://dubuque.craigslist.org/for/5522355104.html>

Jake




[Non-text portions of this message have been removed]

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Re: In praise of crimping BNC's

Greg Muir
 

I think that we have to separate out the pros and cons of crimping/soldering to a finer degree. Not that I disagree with the crimping approach as Walter has commented on but there is a certain degree of poor reliability that I have witnessed with this approach when employed by the (shall we say) the “commonly found” user in the field.

I say “commonly found” because these are the people who are somewhat unknowledgable about connectors and crimping processes in general since they are trained either by OJT or by another who has learned by intuition to assemble connectors but not investigated the nitty-gritty technical aspects of them. Usually these people and/or their employers have had little exposure to the subtleties of connector reliability and associated tooling as affected by sourcing, manufacturing quality and such.

First, we look at sourcing. Obviously a smaller installing or repair agency will consider cost as a fairly important issue. This means that they will probably purchase their connectors from a source that offers fairly inexpensive (<$2) connectors that are a given to be made in China.

Next, given the propensity for tooling to either become lost, damaged or worn out, these people will most likely look for the first supplier who offers inexpensive crimp tooling. Again the Chinese come to bat with their offerings. When we add minimal experience and knowledge to low quality connectors and tooling, we can have the setting for a connector installation that could possibly be unreliable.

I do understand one’s desire for a reliable connection within the connector. Having worked on space hardware it was a given that this had to happen. And, of course, we had no qualms about multi-hundred $$ tooling and expensive MIL qualified connectors at our disposal. But I have to ask how many members of this group have access to that type of quality hardware for their home projects let alone want to spend the money for same?

My experience using inexpensive (Chinese) BNC connectors with off-the-street tooling is that the center pin is often made of a fairly brittle alloy that tends to crack if the correct crimp pressure is not applied or the crimp die is not of the exact dimensions. This has led me to occasionally find field installations where the installer had over crimped the center contact causing cracking but not to a point where it was obvious when the connector was assembled. Later, through flexing and movement of the cable, the contact between the pin and center conductor became erratic and very obvious when used at higher frequencies.

When using “cheap” connectors I personally solder the center conductor into the pin. I find it easy to do and know that the connection will last and that I don’t end up having to throw away a connector should the crimp cause cracking to occur. A little heat applied from the iron and the job is done. And has anyone ever wondered what that tiny hole is for in the side of the pin? To accept solder.

I believe that an earlier comment was made where the user is tinning the center contact when assembling a connector. That can create problems as the connector sees use. First, the gold strike on the pin is there for a reason – to afford a highly reliable, non-oxidizing contact surface. Obviously a tin strike contact in many other (non-RF) multi-pin connectors can exhibit higher contact resistance, oxidation and, hence, possible intermittents when in use.

Second, the sliding of the pin into the mating receptacle can deposit the tin onto the mating contact surface. If this surface also contains a gold strike, the overlay of tin on that surface will reduce the contact reliability and RF characteristics of that connector as well.

When working in Colorado, I had the opportunity to attend a seminar at the (then) National Bureau of Standards on RF connector reliability. It was quite informative to learn about connector contact plating techniques and how it affects the reliability of the connector. And it was also a real eye-opener to find out how limited the number of mate/un-mate cycles a typical connector can go through before the RF characteristics begin to degrade. Of the ones found around the lab, N connectors were the most substantial. BNC connectors were significantly less.

Greg


Re: In praise of crimping BNC's

John Ferguson
 

There's another aspect to compression BNC connectors and that is their
length. Judging from the photographs, I can see the chance of bumping
against one of these things and its length giving it enough leverage to
ruin the jack. If all the enthusiasm I read on the sites selling
compression tools is about doing type F connectors, then it doesn't have
much to do with the sort of things I want, namely a really well made BNC
crimp.

I don;t need weatherproof either - or at least I hope I don't.

On 04/14/2016 04:37 PM, Dwayne Verhey tekscopes@verhey.org [TekScopes]
wrote:

On 14/04/2016 3:29 PM, David DiGiacomo telists@davmar.org [TekScopes]
wrote:



OK, but this doesn't explain why CATV has switched over to compression
connectors. Does anyone know?

_
If you are referring to F type 75 ohm co-ax connectors, they don't use a
centre pin. The solid centre conductor acts as the pin. The compression
only has to deal with the outer shield.


Re: TekScopes Moderator

John Griessen
 

On 04/14/2016 01:26 PM, Stefan Trethan stefan_trethan@gmx.at [TekScopes] wrote:
Portola Valley, CA
It's a residential area near Palo Alto.
Silicon valley kingpin territory...

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