Date   
Re: SG505 THD issues

EJP
 

Well not really. The specified distortion is <= 0.0008%, 'typically <= 0.0003%', 20-20kHz. So what I am seeing is nearly 3x out of spec. Dennis wrote here a few days ago about seeing his at -98dB THD, which is 6dB better than mine (but still worse than spec (-102dB)). So there is quite a way to go.

Yes it is an AA501 option 01+02, i.e. with IMD, 0-pk/RMS, and 400Hz/80kHz/22-22kHz/CCIR filtering. I always have it in RMS mode.

Re: What calibration items to buy.

Merchison Burke
 

Question. Do you and if you do, how do you calibrate your calibration equipment?



On 2018-Mar-05 8:30 PM, HankC, Boston, WA1HOS via Groups.Io wrote:
Brian,
An ideal cal package is the one I have (all TM500 plugins)TG501 time mark gen
SG503 leveled sig gen up to 250 MHzPG506 Standard amplitude generator + fast-rise output pulse

Beware of the SG504 which goes up to a Ghz; the lowest freq does not go low enough to cover anyfreqs below 250 MHz, which is where the SG503 stops.The ideal setup would be to have both SGs.
HankC, Boston, WA1HOS


---
This email has been checked for viruses by AVG.
http://www.avg.com

Re: SG505 THD issues

Mac Perkins
 

You say you have a 22-22kHz filter, that generally is an option 2 instrument which also changes the response choices to true rms or quasi-peak. The quasi-peak position will give significantly higher readings.
I have not checked my systems recently but your residual numbers seem reasonable from my memory.
That system, with an SC502 to observe the residual, is still my go-to for a quick, accurate test.
-Mac

Re: 2465 Question

Chuck Harris
 

There is no reason you should regret owning a 2465.

I have a 2465, 2465A, 2465B, and 2467, and I find that
I like the 2465 better than the rest for a variety of
reasons:

First, it has a much smoother response to front panel
controls. Turn the vertical position, and the beam
changes immediately. The "A/B" models lag in several modes.

Second, when you have the "A/B's" trigger in the "AUTO LVL"
position, and you a flat trace, the Auto level routine
dances through the different gain settings trying to
find a trigger. This causes the beam to change size
in a repeating pattern that I find annoying. Although
the 2465 has the same feature, the beam change isn't
noticeable on the 2465.

Third, when you touch any button, or switch any switch
on the "A/B" scopes, it will make every light on the
front panel flash. I find this annoying. The 2465 uses
slower logic, and this glitch, I mean feature, isn't as
noticeable.

Fourth, the "A/B" scopes assume that knob positions won't
be moved while the scope is turned off. If you have
the "B" scope in the full intensity position when you
turn it off, and then, while the scope is off, turn the
intensity control to the minimum intensity position,
when the scope is turned back on, the minimum intensity
position will now sport full intensity.

Fifth, I like that the 2465's vertical attenuator switches,
and horizontal timebase switches have pointers and numbers
around them.

There is no reason you should regret owning a 2465. Most
of the added features of the "A" and "B" models are not
all that useful... probably all.

-Chuck Harris

rjv100mailbox-public via Groups.Io wrote:

Hello everyone, I'm new to this group and hope to learn from your discussions. I am learning electronics via books, YouTube, and hands on experimentation. Perhaps a class at a local college in the future. The other day I bought a Teks 2465 Scope , which I now regret after reading the forums. I guess I should have bought a 2465B. The scope should arrive in the next couple of days and would ask what startup procedures other than that listed in the manual would you advise. I have 14 days to return it and want to run it through the mill to ensure it's a good unit. Thanks to all.

Bob

2445B Focus issue

peteq1@...
 

Hi everyone, this is my first post in this group, maybe someone can help?

I bought a Tektronix 2445B (same as a 2465B except bandwith), Serial below 050000, so it has the old-style A5 board without SMD and without the leaking caps.
It looks almost like new, has below 900h of operation, came from a broadcasting station (sfb, Sender Freies Berlin) here in Germany. I did the bandwith "hack" on the A1 board (seems to work very close to my 2465B).

But it has a focus problem: When cold, it is extremely out of focus (and astig as well), it takes 5 to 10 minutes to get a sharp image. My other 2465BDV is perfect from the first second. I can adjust the focus when cold,
but then I have to re-adjust it while warming up.

I did replace all caps in the power supply. But I am not sure if this problem was there before the re-cap, because this was one of the first things to do after getting the scope.

Any suggestions? I did check the supply voltages of the power supply (J119 on Board A1), all stable from the beginning.

I did check all input voltages to the HV board, and even took the HV board from my other 2465B and put it into this one, same result.

I checked all voltages around Q1851 and Q1852, all very stable from the beginning. -300V is stable. Focus can also be bad if other voltages of the tube are wrong, so I have to look elsewhere.

I checked the Output of the High Voltage Module U1830, pin 4, which should be -900V, according to the schematics. It is only -617V.
The Output of the High Voltage Module U1830, pin 4 is also 617V on my other 2465B, so I think 900V is an error in the schematics.

Someone said it could be a "gassy" CRT. But it is bright, and sharp after warm up.

Thanks
Peter

TDS640A problems and headaches.....

Arty
 

Hi,

I am the lucky owner of the TDS640A scope for the last several years. It worked fine until now. Suddenly, the picture on the main display became totally unreadable. It looks like TV with no horizontal sync, more or less. No more nice grid with traces and menus. I opened up the scope and using troubleshooting included in the Service Manual, checked the signals on J18 on A11 (DRAM Processor/Display module) board (page 6-73). Pins 1 and 2 look OK to me, that is, horizontal and vertical syncs. However, pin 3 with video signal looks different from the Figure 6-39. There are no negative blanking levels. The scope passes power on self check, no problem. I know that because, fortunately, I can display the correct picture using the external monitor connected to the 15 pin D-sub connector on the back panel. What to do next?

1. I know, I know, the caps.... Change them all... I have to do that yet. Trying to buy the right type for right price. I guess all of decoupling capacitors are 33uF 10V, right? I don't want to use any questionable quality electrolytic capacitors (Ebay), so I think I will buy some from Digi-Key.
2. Is it possible to find the schematic somewhere? Searched the internet to no avail. The Tektronix web site provides only User and Service Manuals, with no schematics at all. Anybody has them in PDF?
3. In addition to the video problems, the ON/STBY switch on the front panel stopped working. However, the S1 round button switch on the A11 board works the same way as the front panel one should.

If anybody has any idea how to fix the problems please let me know. Any input appreciated. Thanks.

Re: SHOULD THE SCALE ILLUM. ADJUST THE TRIG HOLDOFF ON A 2246? i DONT THINK SO...

fmmech_24@...
 

Hello, same problem on a 2245A, will try tomorow and reply.

Re: Ceramic strip soldering tek video

RalphJ
 

Good morning, aficionados of Tektronix Oscilloscopes;

Back in the 1960s and 1970s when I was actively working with the 500 series of Tektronix oscilloscopes, one admonition found in the operation and service manual was to use "two percent silver bearing solder" when working on the ceramic terminal strips.

The most common solder alloy used generally for electronics was the 60%-40% Sn-Pb (Tin-Lead) alloy form with a melting point of 370 degrees F. The "eutectic" alloy of 63%-37% Sn-Pb did have a lower melting point of 363 degrees F. which was a advantage, yes, but it also did not have a "plastic" state while it cooled, so it did not develop a poor solder connection if the parts were moved while the solder joint was cooling. This "eutectic" quality was helpful.

I need to divert for a moment to make a comment about the degradation of the English language used in electronics in recent years. The lack of attention to how words are used in electronics is impressive. If we do not take the time to learn the language of the discipline and how to write so that you can describe the work that you have done, then your work may just die with you and be lost, if you are not able to record your work in a way that people later will be able to learn what you have done. This includes the somewhat more common misspelling of "solder" with the variant of "soder" being seen more often now. This is a case where many people are not studying the English language and know nothing of the etymology or history and origin of the words that they are using. They are just making up words that they think sound like the words that they hear. I wonder if they are reading the textbooks with any intent for learning and comprehension of what is in the book.

The recommended "two percent silver bearing solder" or 62%-36%-2% Sn-Pb-Ag alloy has a melting point down to 354 degrees F. which is about 15 degrees lower than the common 60%-40% Sn-Pb alloy, and that could be significant, but the major advantage in this case is that the addition of the silver to the alloy will reduce the tendency to leach silver out of the metalized ceramic terminal, and make the terminal more reliable over a longer time period.

Tek had a lot of really good talented people working for it. Not just electronics engineers, but chemists, physicists, and others also. Between Tektronix, Hewlett-Packard, and General Radio, they provided most of the instruments that we used to design the systems that put men on the moon.

Enjoy;

Ralph, N7KGA
Latte Land, Washington

Re: Re-introduction to the group

 

WTF……………..?

On Feb 26, 2018, at 6:58 PM, jafinch78 . <jafinch78@...> wrote:

On Mon, Feb 26, 2018 at 03:11 pm, Tom Gardner wrote:


There are many ways to skin a cat; TENS is one designed specifically to skin
cats, rather than a mere side side-effect.
Definitely keep skinning the aliens and enemies of the U.S. Jurisdiction... including with internal affairs operations when required when enemies are found. Wonder what Trump's announcement regarding death sentencing Edwards, Schriever, Malmstrom and the other cocaine pedos higher up will result in... then I see lately F.E. Warren is in the mix as the scapegoat? At least the Navy and Air Force comes clean at lower ranks, though like CIA DEA and their NOC's... higher up is all sorts of shady. Even worse I'm sure is the Army that comes out gets their family murdered and the informant gets pinned wrongfully like Ted Gunderson noted with one case that comes to mind.

OK... emotionally magnified moment... Here are some sites with more info for those interested:
https://distrowatch.com/table.php?distribution=tens
https://en.wikipedia.org/wiki/Lightweight_Portable_Security

The AF site makes me think Transcutaneous Electrical Nerve Stimulation (TENS) Therapy

Then there is the site: https://www.spi.dod.mil/lipose.htm

I'm thinking after seeing both sites... is the TENS Therapy performing liposuction or something to cause less fat? jk ;-)


Re: P6058 vs P6058A

RalphJ
 

Where is Russ Fillinger, W7LXR, when you really need him?

He could answer that question just from memory.

Ralph, N7KGA
Latte Land, Washington

Re: Cheap differential probe ?

Peter Brown
 

Jim Williams tackled this

https://books.google.com/books?id=H9rAU4Rf--YC&pg=PA270&lpg=PA270&dq#v=onepage&q&f=false



On Thu, Mar 1, 2018 at 9:54 PM, Dennis Tillman W7PF <@Dennis_Tillman_W7PF>
wrote:

There is no such thing as a cheap differential probe. They have to be
matched across a wide frequency range to have good CMRR. If you want a
cheap CMRR the solution may be on your scope. All dual trace scopes have an
ADD function for both traces. They all haave a way to invert a trace on one
of the channels. So switch to Add, Invert one channel, and use the gain
knob of one channel to adjust the trace to a straight line when you put a
signal in through two same number probes - any two will do as long as they
are the same (two P6109 probes for example).

Voila, a poor man's Differential probe.

As long as there isn't too much of a voltage difference between the two
channels the waveform will stay on the screen where this will work OK. It
isn't much but that is probably the best you are going to get when you
require "cheap"

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David
Slipper
Sent: Thursday, March 01, 2018 6:45 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Cheap differential probe ?


Sadly, nothing under £100 on fleaBay :-(

Anything in the DIY arena ??

Dave




--
Dennis Tillman W7PF
TekScopes Moderator



Tek 2445B Focus Problem

peteq1@...
 

Hi everyone, this is my first post in this group, maybe someone can help?

I bought a Tektronix 2445B (same as a 2465B except bandwith), Serial below 050000, so it has the old-style A5 board without SMD and without the leaking caps.
It looks almost like new, has below 900h of operation, came from a broadcasting station (sfb, Sender Freies Berlin) here in Germany. I did the bandwith "hack" on the A1 board (seems to work very close to my 2465B).

But it has a focus problem: When cold, it is extremely out of focus (and astig as well), it takes 5 to 10 minutes to get a sharp image. My other 2465BDV is perfect from the first second.

I did replace all caps in the power supply. But I am not sure if this problem was there before the re-cap, because this was one of the first things to do after getting the scope.

Any suggestions? I did check the supply voltages (J119 on Board A1), all stable from the beginning.

I did check all input voltages to the HV board, and even took the HV board from my other 2465B and put it into this one, same result.

I checked all voltages around Q1851 and Q1852, all very stable from the beginning. -300V is stable. Focus can also be bad if other voltages of the tube are wrong, so I have to look elsewhere.

I checked the Output of the High Voltage Module U1830, pin 4, which should be -900V, according to the schematics. It is only -617V.
The Output of the High Voltage Module U1830, pin 4 is also 617V on my other 2465B, so I think 900V is an error in the schematics.

Someone said it could be a "gassy" CRT. But it is bright, and sharp after warm up.

Thanks
Peter
from Germany (-12 °C at the moment)

2465 Question

rjv100mailbox-public@...
 

Hello everyone, I'm new to this group and hope to learn from your discussions. I am learning electronics via books, YouTube, and hands on experimentation. Perhaps a class at a local college in the future. The other day I bought a Teks 2465 Scope , which I now regret after reading the forums. I guess I should have bought a 2465B. The scope should arrive in the next couple of days and would ask what startup procedures other than that listed in the manual would you advise. I have 14 days to return it and want to run it through the mill to ensure it's a good unit. Thanks to all.

Bob

SG505 THD issues

EJP
 

I've owned two SG505s for several years and never really achieved the specified performance from either of them.

#1 has .0030% THD into AA501 unfiltered at 0dBm 1KHz. It improves to .0020% with 22-22kHz filter in. I acquired this one about ten years ago, not working, with shorted C1201 or C1210: I replaced both with aluminium electro to fix this. Last week I remembered they were originally tantalum and got curious as to whether they needed to be, so I replaced again with 100uF 20V tantalum: no improvement; if anything, 0.0001-2% worse. THD improves after 20 minutes or so to 0.0023% unfiltered, .0015% filtered as above. Every now and again it comes up from power-on at .0012% THD filtered, which I cannot explain or reproduce on demand. The distortion is mostly 3HD with a little kink at the bottom of each cycle. This one is cohoused in a TM515 with the AA501/01. AA501 has been calibrated for minimum THD and correct V and dB readings.

#2 has 0.0038% THD unfiltered as above, improves to 0.0022% with 22-22kHz filter. This one has a frequency instability when first powered up for a few seconds, something like 10kHz superimposed on 1kHz which dies down and locks after 3-4 seconds. #2 is the later one with the extra circuitry around the BAL/COMP pins of the NE5534s and also has the IMD option 01, but it has always been slightly worse than #1 for THD. This one is housed in a separate TM515 along with an AF501 and two FGs.

SNR for #1 is -100dBm, #2 -90dBm which I had never noticed (i.e. measured) before today, rather a big difference.

Both have been recapped as far as electrolytics go, and calibrated for output level: nothing else done to them at all apart from replacing C1601, a 6u8F 10Hz range capacitor, in #1. In this one I also did briefly try LME49710s in the three critical positions (U1401/1520: the two with BAL/COMP circuits; and U1510 the initial oscillator) but if anything it got slightly worse again, which is interesting.

All these THD figures are 3-4x too high. Should I be looking into these SG505s? and if so where? or should I take another look at the AA501? and if so ditto.

TIA

EJP

Re: What calibration items to buy.

Brendan
 

Im looking at an agilent 33220a for timebase calibration? and a tek attenuator set off of the auction site.Thank you for the link to the pulser.

Re: What calibration items to buy.

 

Brian,
An ideal cal package is the one I have (all TM500 plugins)TG501 time mark gen
SG503 leveled sig gen up to 250 MHzPG506 Standard amplitude generator + fast-rise output pulse

Beware of the SG504 which goes up to a Ghz; the lowest freq does not go low enough to cover anyfreqs below 250 MHz, which is where the SG503 stops.The ideal setup would be to have both SGs.
HankC, Boston, WA1HOS

Re: Tekmate floppy setup problem.

Fabio Trevisan
 

Hi Szabolcs...
It may be a long shot but, have you considered that the very first disk, or
one of the first that you tried, could have been contaminated by fungae,
mold, etc... And that it could have made the drives head dirty?
Have you tried to clean the heads using a cleaning floppy disk and IPA, or
using a cotton swab?
In the begginig of the years 2000 when floppy disks were already on their
way out, but lots of people still had large sets of years past backups, it
was very common for my customers to trash a lot of floppies, thinking they
were bad, just to find out that there was only one bad disk, which
eventually clogged the heads of the reader, rendering all other disks
unreadable.
Fungae love the kind of lubricant that used to be used back then, to
protect the disks from abrasion.
Brgrds,
Fabio

On Mar 5, 2018 11:34 AM, "Szabolcs Szigeti" <szigiszabolcs@...> wrote:

Hi,

Thanks, but I doubt it. I have tried a number of disks, even one from an
original packaging. I'm able to use them in a notebook. The imteresting
thing is that if I try to format them in in the Tekmate, then format stops
with unusable track 0, but it formats that track. or at least does
something with that, because then I have to reformat the disk to use it
again. This is why i suspect that there is some discrepancy in what
bios/dos thinks about the drives and what they are really. But, I do not
see anything else other than the bios setup to change the floppy type.
I can still not beleive that I have 3 equally faulty floppy drives, but
I'll try and get hol of a fourth one or try them in a PC. I'll also try
cleaning them, to make sure that that is not the problem.

Szabolcs


2018-03-05 4:04 GMT+01:00 battyhugh <@Hugh>:

It might surprise you, but your floppys are corrupt. I would suggest
getting a tube of disk cleaner (10%alcohol and a drop of detergent) - and
using a nice clean tissue - I recommend toilet paper - open the shutter
and
clean the disk carefully on both sides. I have to do this to recover old
disks with files.

Good luck

Hugh @Hugh



Re: How to Use this Forum ..... ????

tinkera123
 

Thanks for all the responses ... some via PM .... I now have a couple of solutions to suit my needs.

Cheers,
Ian

Re: How to Use this Forum ..... ????

Richard Knoppow
 

If you get messages via e-mail the address of the original poster is included in the header. Some add their e-mail address to their signature (as I do). One has only to copy that address and paste it into the To field without the list address or you can send a new e-mail. Lists vary as to what shows up on the reply choices so you must check to see which addresses the particular list uses. Some have a "Reply all" and also a "Reply" choice, however, they do not always go the same places. This list sends to both list and original sender when you click "reply all" but only to the list for "Reply". To send to the original poster only one has to edit the To field or cut and paste.
The archive for messages is automatic. If you post to the list the message will go into the archive. Some lists also have a place on their web sites to put pictures, documents, etc. Yahoo lists will notify subscribers when this is done, not sure about IO.

On 3/5/2018 1:54 PM, David DiGiacomo wrote:
On Sun, Mar 4, 2018 at 7:04 PM, tinkera123 <@tinkera123> wrote:
I cannot find anywhere, including in "Help", as to how to do the following. Can some either explain how it works .... or point to somewhere I can read it myself ....?????
1. How do I Private Message another Member of this Group ??
2. How do I 'archive' Topics that I feel I will need to refer to in the future ?? I am aware of the "Search" function.
Both of these are extremely easy on groups.io:
1. Starting from the message page or topic page, click on Reply, then Private.
2. Go to the topic page, then save the URL (or just print the page to
PDF from your browser).
--
Richard Knoppow
dickburk@...
WB6KBL

Re: How to Use this Forum ..... ????

David DiGiacomo
 

On Sun, Mar 4, 2018 at 7:04 PM, tinkera123 <@tinkera123> wrote:
I cannot find anywhere, including in "Help", as to how to do the following. Can some either explain how it works .... or point to somewhere I can read it myself ....?????
1. How do I Private Message another Member of this Group ??
2. How do I 'archive' Topics that I feel I will need to refer to in the future ?? I am aware of the "Search" function.
Both of these are extremely easy on groups.io:

1. Starting from the message page or topic page, click on Reply, then Private.

2. Go to the topic page, then save the URL (or just print the page to
PDF from your browser).