Date   
Re: Intermittent no trace / sweep.

vaclav_sal
 

Sorry, perhaps me posting my first one wrong way.
Why is there even a need for attachment?
I did not indicate that in both of my posts.
I think I am capable carrying on a discussion without pictures - if that was reason you mentioned attachment.

Re: Tek 7623A - Readout omits 2nd zeroes while cold

Roger Evans
 

Fabio,

I have looked at the pins you mention on U2232, particularly at pin 12, C1 which is involved in adding zeros. The behaviour of all the pins is consistent with a logic low of around 0.5V and a high level around 3V. The high level has a lot of switching noise looking like analogue ramps with an amplitude of close to 1V and the low level is clean but of very short duration so that you may not see it depending on your sweep speed and trigger settings. The narrow spikes carry the readout information and move and disappear when you change eg from 500mV to 1V per division, the 'noise' on the high logic level is largely unchanged.

Have you tried removing U2232 (and maybe U2244 and U2185 the row and column decoders) and cleaning pins? You may have the notorious TC IC sockets which are very prone to corrosion problems.

Regards,

Roger

Re: Nuvistors

James R. Bartlett
 

Hi Albert,
There are a good few on eBay.co.uk.
Most are in Germany which should be handy for you..
Plenty in the States as well.
Regards
jim
Ei2BB

On 26 April 2018 at 09:18, Albert Otten <aodiversen@...> wrote:


Does anyone have any data on Nuvistors (miniature metal-envelope
tubes), or have any to sell? I could use an 8056, and have some
7586s...
A useful site is Frank's Electron tube Pages, http://www.tubedata.org and
its mirrors.
The 8056 pdf for instance via http://frank.pocnet.net/sheets8.html :
http://frank.pocnet.net/sheets/049/8/8056.pdf .

Albert



Re: Nuvistors

Andre de guerin
 

Used to have some many years ago. Will check just in case any are still in the drawer but pretty sure I sold mine to someone on eBay.
www.cwgsy.net/private/mandoline "Error 008472. Horrible bug encountered. $Deity knows what happened."

On Thursday, 26 April 2018, 09:18:14 BST, Albert Otten <aodiversen@...> wrote:

>
    Does anyone have any data on Nuvistors (miniature metal-envelope
tubes), or have any to sell?  I could use an 8056, and have some
7586s...
A useful site is Frank's Electron tube Pages, http://www.tubedata.org and its mirrors.
The 8056 pdf for instance via http://frank.pocnet.net/sheets8.html :
http://frank.pocnet.net/sheets/049/8/8056.pdf .

Albert

Re: Nuvistors

Albert Otten
 


Does anyone have any data on Nuvistors (miniature metal-envelope
tubes), or have any to sell? I could use an 8056, and have some
7586s...
A useful site is Frank's Electron tube Pages, http://www.tubedata.org and its mirrors.
The 8056 pdf for instance via http://frank.pocnet.net/sheets8.html :
http://frank.pocnet.net/sheets/049/8/8056.pdf .

Albert

Re: Notes on bringing up an old Tek 570

Reed Dickinson
 

Hi John:

I have refurbished two 570 scopes and your suggestions are exactly the procedure I followed, but did not document. I replaced all the can electrolytic caps with modern high voltage tubular electrolytic models and mounted them under the chassis. I left the original canned caps in place but removed the hot leads.

I am sending a list of the parts I ordered to do the job.

Value (uF) Volts Quantity Substitute Jameco P/N Price each
1) .047 400 9 .05@1KV 332507 .59
2) .01 300 6 .01@1KV 97375 .19
3) .015 400 1 .02@1KV 332487 .55
4) .0047 400 2 .01@1KV 97375 .19
5) .001 500 5 .001@1KV 332436 .12
6) 15/20 450 12 22@450 331433 1.95
7) 80 500 3 120@400 2158426 1.95
8) .0068 3KV 3 .01@6KV eBay
9) .01 2KV 3 .01@6KV eBay
10) .005 4KV 1 .01@6KV eBay
11) .015 3KV 1 .01@6KV (use 2) eBay

Good luck, they are fantastic pieces of equipment and well worthy of an investment in time and money.

Reed Dickinson

On 4/25/2018 9:51 PM, John Atwood wrote:
A friend of mine just purchased an old Tek 570 Vacuum Tube Curve Tracer that hadn't been used in decades. He is a competent technical guy, but wasn't too familiar with old tube scopes. I made up a list of things to change and check, so I thought I would pass it on to the group.

Note starts here >>>

I've owned a Tek 570 for over thirty years and have tested thousands of tube on it. It is from around 1958 and has rounded corners and the black and white plastic meter. Here are my recommendations for initial bring-up and potential weak spots to address:

1. Before turning on, either: a) carefully reform the electrolytic capacitors or b) plan on replacing all electrolytic with new ones. This can be done by wiring them under the chassis and leaving the old cans in place. For reforming the capacitors, I recommend using a high-voltage adjustable power supply and slowly increasing the voltage across each capacitor until it draws 10 mA. Only after this decreases can the voltage be increased - eventually reaching the maximum rated voltage. A series resistor from the power supply can also be used to limit current.

2. Change all tubular paper capacitors. This is especially important if they are the black color-striped capacitors - these are notoriously bad. Regular mylar caps are a good replacement. Make sure to change the high-voltage capacitors in the CRT power supply, unless they are ceramic.

3. Check all the tubes on a tube tester and replace any weak tubes. Luckily all types are common. In later models the 6BQ7s were replaced with 6DJ8s. You could go back to using the 6BQ7, or you can use the Soviet 6N23P, equivalent to the 6DJ8/ECC88.

4. Spot check the resistance of the carbon-composition resistors. In some years they had a tendency to drift with age, always upwards in value. Replace any that are out of tolerance. About 1/5 of all my resistors had drifted out of spec.

5. Make sure to use silver-bearing solder on the ceramic terminal strips.

6. Lubricate the switches and pots with a drop of oil on the shaft and grease on the detents. I've found that military rifle grease works well here. A brief spray of DeOxit will clean the switches and pots. Use lightly. Also lubricate the fan.

7. I don't recommend changing the tube rectifiers to silicon - this will stress the rest of the system. Plus, the tube rectifiers used are common and cheap. If you want to replace the 5642 HV rectifiers with silicon, use only high-speed rectifiers.

8. The CRT is the same type as used in the Tek 575, so if there is a problem with the CRT, find a 575 parts unit. They are infinitely more available than the 570. The CRTs seem to be quite reliable, though.

9. In my 570, the readings were erratic at low current settings of the VERTICAL MA/DIV switch. It turns out that the current-sensing resistor string on this switch is grounded to the frame of the switch. If there is any corrosion where the switch is mounted to the front panel an erratic voltage drop is created. Running a wire from the switch frame to a ground point under the chassis solved this problem.

10. The step-generator circuits use some very high impedances. You may have to try several different 6AN8 tubes in the V8 and V38 sockets to get linear steps. It is helpful to use an oscilloscope on the step generator output to check for linearity.

Manuals and factory calibration procedure are available at: http://w140.com/tekwiki/wiki/570

end of note.
- John Atwood


Re: Notes on bringing up an old Tek 570

Craig Sawyers <c.sawyers@...>
 

Hello John

Both you and your friend are lucky guys to have got hold of a 570 each! They are rare as hen's teeth.

Only one comment. Silver-bearing solder could be confused with lead-free solder. Best to clarify with
tin/lead solder with 2-4% silver (I think the Tek original was 3%).

Craig

Notes on bringing up an old Tek 570

John Atwood
 

A friend of mine just purchased an old Tek 570 Vacuum Tube Curve Tracer that hadn't been used in decades. He is a competent technical guy, but wasn't too familiar with old tube scopes. I made up a list of things to change and check, so I thought I would pass it on to the group.

Note starts here >>>

I've owned a Tek 570 for over thirty years and have tested thousands of tube on it. It is from around 1958 and has rounded corners and the black and white plastic meter. Here are my recommendations for initial bring-up and potential weak spots to address:

1. Before turning on, either: a) carefully reform the electrolytic capacitors or b) plan on replacing all electrolytic with new ones. This can be done by wiring them under the chassis and leaving the old cans in place. For reforming the capacitors, I recommend using a high-voltage adjustable power supply and slowly increasing the voltage across each capacitor until it draws 10 mA. Only after this decreases can the voltage be increased - eventually reaching the maximum rated voltage. A series resistor from the power supply can also be used to limit current.

2. Change all tubular paper capacitors. This is especially important if they are the black color-striped capacitors - these are notoriously bad. Regular mylar caps are a good replacement. Make sure to change the high-voltage capacitors in the CRT power supply, unless they are ceramic.

3. Check all the tubes on a tube tester and replace any weak tubes. Luckily all types are common. In later models the 6BQ7s were replaced with 6DJ8s. You could go back to using the 6BQ7, or you can use the Soviet 6N23P, equivalent to the 6DJ8/ECC88.

4. Spot check the resistance of the carbon-composition resistors. In some years they had a tendency to drift with age, always upwards in value. Replace any that are out of tolerance. About 1/5 of all my resistors had drifted out of spec.

5. Make sure to use silver-bearing solder on the ceramic terminal strips.

6. Lubricate the switches and pots with a drop of oil on the shaft and grease on the detents. I've found that military rifle grease works well here. A brief spray of DeOxit will clean the switches and pots. Use lightly. Also lubricate the fan.

7. I don't recommend changing the tube rectifiers to silicon - this will stress the rest of the system. Plus, the tube rectifiers used are common and cheap. If you want to replace the 5642 HV rectifiers with silicon, use only high-speed rectifiers.

8. The CRT is the same type as used in the Tek 575, so if there is a problem with the CRT, find a 575 parts unit. They are infinitely more available than the 570. The CRTs seem to be quite reliable, though.

9. In my 570, the readings were erratic at low current settings of the VERTICAL MA/DIV switch. It turns out that the current-sensing resistor string on this switch is grounded to the frame of the switch. If there is any corrosion where the switch is mounted to the front panel an erratic voltage drop is created. Running a wire from the switch frame to a ground point under the chassis solved this problem.

10. The step-generator circuits use some very high impedances. You may have to try several different 6AN8 tubes in the V8 and V38 sockets to get linear steps. It is helpful to use an oscilloscope on the step generator output to check for linearity.

Manuals and factory calibration procedure are available at: http://w140.com/tekwiki/wiki/570

end of note.
- John Atwood

Re: Tek 422 ac/dc power supply issues

 

"glad to hear the DC/DC converter is working that should be a relief.
so why is the Ac-Dc linear causing an issue??"

I found out it's not. It's the voltage.

"The Chopper xsistor is not too important which were my original thoughts prior to over thinking a replacement. It appears the venerable 2N3055 should be fine."

I tend to concur now that I know how slow they chop. I don't know about a 3-55 but hell, it might. What I don't see is an easy way to mount a TO-3 in there, maybe a TO-3P or whatever, some sort of flat pack type should be fine and they are available now with specs just as good if not better. A TO-220 would be great as long as one can be had with good enough specs, perhaps a 2SD401 ? We used them for just about anything. Not real fast but we apparently don't need real fast.

Either way, switching time is not causing the excess current drain, and neither would high saturation voltage. Now listen to my latest conclusion on mine, the waveforms :

At ~16 volts in;

50 uS https://groups.io/g/TekScopes/photo/44484/2?p=Name,,,20,1,0,0

~17 mS https://groups.io/g/TekScopes/photo/44484/3?p=Name,,,20,1,0,0

Now at ~30 volts in;

50 uS https://groups.io/g/TekScopes/photo/44484/4?p=Name,,,20,1,0,0

~17 mS https://groups.io/g/TekScopes/photo/44484/5?p=Name,,,20,1,0,0

At 16 volts in it runs cool. At 30 volts in the heat builds up fast. In both cases the AC transformer was completely disconnected and out of circuit.

The 16 volt readings were using a full wave rectified source running into 10,000 uF external filter, in a Kelvin type connection. About 1 volt P-P ripple.

The 30 volt readings were using a full wave rectified source running into 1,500 uF plus the 2-1,300 uF in the Tek PS itself. About 3 volts ripple.

No heat buildup at 16, fry eggs at 30.

Looking a the waveforms, at 30 volts there is so much disturbance at the collector of Q 1174 the scope won't sync. At 12 volts it syncs fine. The "slo" waveforms were with the sweep down to match the ripple. At 12 volts you can see an aberration at 120 Hz, at 30 it seems to be random and looks like arcing actually. (I am familiar with that look from the TV days)

If I were you I would look for similar aberrations in the waveforms in that unit. It is a simple matter of slowing the sweep. You can take it to some factor of 16.67 mS if 60 Hz where you are, or 20 mS if 50 Hz. This allows you to isolate the ripple and the error correction involved. Just rock it in free running. If you see what I saw at 3- volts in, your problem is similar at least.

However I can't call it an arcing T 1201 yet. The drive has top be ruled out and I am not sure how to do that. The base waveform is no doubt susceptible to the Miller effect and that will even affect the waveform at the primary of T 1171. (in an HOT or LOPT circuit the effect is very profound) I think that means the ripple is responsible for the aberration in the chopper waveform at 16 volts input, especially since it reduces when the 10,000 uF is bridged in parallel with the input.

T 1201 is still a prime suspect, the voltages going to the drive circuit are regulated, (have to make sure of that of course) while the voltage into the primary of T 1201 is allowed to vary with the input. Unfortunately I think I am going to find T 1201 bad, and I think the chances of getting one are about the same as me winning the gold medal in Women's gymnastics.

It might be a DC only scope now...

Re: 465B won't trigger

blackholenulled
 

I popped out the transistor pair in the downstream A trigger view circuit and the voltages didn't change, so that leaves out that circuit as causing problems.

So I did like Fabio said and pulled out the preamp transistor pair, and biased the input to the chip with two parallel 100 ohm resistors to ground. Now we're getting somewhere. The input was close to zero (don't remember now exactly) and 1 and 16 were -.755 volts. So it seems the chip works.

Ohmed the transistors but that didn't tell me anything specifically about their condition. So since the B trigger side has an identical pair of preamp transistors, I swapped those into the A trigger side. Voltages were -30 mV on the input to the chip, and -.755 at 1 and 16. Tested the trigger and now I can get a trigger! I also have the A trigger view.

The chip isn't coming out unless it were to turn out to be bad. It's very soldered complete with solder fillets.

So somehow the original preamp transistors are bad, or at least one is. I just need to source them, which so far the internet is telling me they are obsolete (of course). Any ideas anyone?

Manufacturer part number: SF50031, which comes back to 2N5245 N channel JFET, which is obsolete. It's late and I haven't tried to cross reference that yet.

As a side effect the trace seemed to have some ac coupled into it. It hasn't done that before but I'm wondering if it's because the case is off?

Thanks Fabio and everyone else!

Hello Lorn,
I also own a 464 and mine also had a problem triggering... And while looking at your description I looks like deja vu to me.
On mine one of the FET transistors of the input circuitry were leaky...(it had about 200kOhms impedance between source and gate, while reverese biased. The good ones measure Infinite, or very high Megohms.
The leak developed a voltage drop on the 1M resistor at their gates and make the output voltage to have a huge offset of... wow! 70mV...(that's 1/10th of what you're getting).
70mV offset was enough to take the preamplifier IC so off that trigger would only work by adjusting the level potentiometer near its end of range and, still, after warming up, the offset would grow just a bit more and then even taking the Level potentiometer to the end was not enough to make it trigger.
On yours it seems the offset is some 0.7V, so no wonder why it doesn't trigger.
Your course of action is exact and removing the FET transistors will allow you to rule-out if the positive offset is coming from the IC, or if it's coming from the buffer stage into the IC.
It's likely, however, that if you just leave pins 2 and 3 opened, as they will get when FETs are removed, you will be fooled by false voltage readings at pins 2 and 3, due to the input pins need some biasing.
So, after you remove the FET ICs, connect a resistor of - say - 51R between pins 2.3 of the preamp IC to ground.
The impedance at the other side of this balanced input differential amplifier is roughly 50Ohm, so biasing pins 2,3 with 50Ohms will make the input perfectly balanced.
In this condition, pins 2 and 3 must read a low voltage, close to 0V. By no means it can be more than 50mV... as I told, my 464 had 70mV and that was enough to screw up the triggering.
Alternatively, you can check the FET input buffer's offset, by taking the IC out and measuring voltage directly at pins 2.3 of the IC socket...
Don't worry, taking the IC out is safe... nothing that's past of the IC will burn because the IC isn't present. (I had this same doubt back then).
Set the Trigger input to EXT, coupling to DC, and ground the Ext. input, so that you're sure that you're not feeding DC into the input buffer, and its output should be very close to 0V.
If the transistors are perfectly matched and thermally even, in theory, the DC offset of this input buffer is exactly ZERO.
Good luck,
Rgrds,
Fabio

Re: Nuvistors

vaclav_sal
 

I think this one is 6CW4 , if interested where do I mail it?

464 intermittent trace / sweep

vaclav_sal
 

I would like someone to help me to figure out why my trusty 464 won't keep the sweep going.
I do have shop manual.
The scope been sitting on my desk , unused for over two years.
As far as I can tell the CRT works OK.
The only visible / mechanical problem is that the delay sweep knob pulls out but has no indentation.
So the scope MAY be in "delay sweep" mode - but I cannot really tell.
I will provide more details when I get a reply.
Vaclav in Houston

Re: BNC Installation Tool

Vince Vielhaber
 

That's the same one from the ebay link - same vendor and manufacturer too.

Vince.

On 04/25/2018 07:59 PM, Glenn Little wrote:

First find from my friend Google.


https://www.amazon.com/BNC-Tool-Connector-Tightening-Wrench/dp/B00MEW0SCM

On 4/25/2018 3:18 PM, Larry McDavid wrote:
Someone here mentioned a BNC installation tool. I took that in context
to mean a tool that holds a chassis-mount female BNC jack while
tightening the backside nut but I don't find any such tool when
searching, only tools to disconnect mated BNC connectors.

Did I misunderstand what was suggested for straightening bent BNC
connectors or can someone point me to such a tool?

Re: BNC Installation Tool

Glenn Little
 

On 4/25/2018 3:18 PM, Larry McDavid wrote:
Someone here mentioned a BNC installation tool. I took that in context to mean a tool that holds a chassis-mount female BNC jack while tightening the backside nut but I don't find any such tool when searching, only tools to disconnect mated BNC connectors.

Did I misunderstand what was suggested for straightening bent BNC connectors or can someone point me to such a tool?
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

Re: BNC Installation Tool

Vince Vielhaber
 

And here's one covering the installation tool.

https://patents.google.com/patent/US4759122A

Vince.

On 04/25/2018 05:59 PM, Ed Breya via Groups.Io wrote:
I just stumbled across this about BNC repair:

https://patents.google.com/patent/US4416143

Ed

Re: Eli Heffron's electronic junkyard

Albert LaFrance
 

Just wanted to contribute to this compilation of long-gone electronics
surplus dealers.



From the late 1960s through the early '80s, I knew of three such stores in
the northern Virginia suburbs of Washington, DC. For a "paper" town, DC
generated quite a bit of electronic surplus, due to government R&D
facilities like NBS and NASA Goddard, military installations, and numerous
contractors and manufacturers serving the national-security market.



Sasco Electronics was an old storefront on King Street in Alexandria, across
the Potomac from DC. Thanks to the construction of a Metro station, the
area is now very upscale, with lots of trendy restaurants, boutiques and
antique shops, but back then it was mostly utilitarian businesses like auto
parts and office supplies. Sasco's display windows and deep, narrow sales
floor were crammed with all kinds of equipment and parts, all at very low
prices. There was also a dungeon-like basement, with bare light bulbs on
the ceiling and rows of crude wooden shelves piled high with every
imaginable type of part, especially big transformers, inductors and
capacitors, most of it top-quality stuff salvaged from military and
commercial gear. The owner was usually seated behind the counter puffing on
a pipe, while a kid at a bench in the back disassembled some piece of
equipment for parts.



Ritco Electronics was a similar operation, housed (as best I can recall) in
one or more large sheds or garage-like buildings in Annandale. Perhaps due
to their larger space, they seemed to have more big/heavy, complete pieces
of equipment than Sasco did.



Electronic Equipment Bank in Vienna was the biggest of the three, and the
one I'm most familiar with since I worked there, for owner Dick Robinson,
occasionally and part-time for a couple of years. Dick was an EE who had
previously been in test equipment sales (for HP, I think). Unlike the other
stores, whose customers were pretty much all hams and other hobbyists, EEB
also did a substantial commercial business. This was in an era when a lot
of vacuum-tube "boatanchor" test gear like Tek 500-series scopes and those
big HP signal generators (606/608?) were still considered viable lab
instruments and could bring real money.



EEB was housed in a large space in a warehouse building with a loading dock,
with neighbors like an HVAC contractor and building supply distributors.
There was an office for Dick and a bookkeeper/admin lady, a showroom, a lab
with two benches, a library/lunchroom with at least six four-drawer file
cabinets stuffed with manuals, a calibration standards lab equipped with
various salvaged items, and a vast storage area on two levels, divided into
several rooms, with heavy steel shelving and equipment piled high
everywhere.



A lot of our stock came from the federal government (GSA) surplus auctions
at the Washington Navy Yard, held in the cavernous former Naval Gun Factory.
The equipment was usually sold in lots which seemed to be randomly assembled
by someone unfamiliar with the merchandise; rumor had it that the security
guard at the exit was there not to prevent theft, but to make sure that no
winning bidder got away without taking *everything* he'd ended up buying!



To get his often huge hauls back to the store, Dick would sometimes hire a
young man of the hippie persuasion, who drove a Step-Van (former Postal
Service truck. I believe) painted in a Star Trek motif, complete with the
Enterprise's "NCC-1701" number, and with a bed for his German Shepherd on
the passenger side.



At some point Dick had acquired two enormous balun transformers, probably
from some high-powered military HF station. They were two long brass
cylinders, maybe 10-12 inches in diameter and 8-10 feet long. They'd been
sitting in our warehouse forever, with no interested customers. But when
our trucker saw them, he immediately knew what to do with them - they became
the "engines" on the roof of his four-wheeled "starship"!



Anyway, one of EEB's specialties was 500-series Tek scopes. They were piled
everywhere in the showroom and warehouse, along with every kind of plug-in.
I worked on a lot of them, and was able to fix quite a few despite my
minimal knowledge of electronics, thanks to the excellent manuals and
assistance from some of Dick's friends who had worked in field service for
Tek or for the various instrument rental and calibration companies in the DC
area.



Albert



From: TekScopes@... <mailto:TekScopes@...>
[mailto:TekScopes@...]
Sent: Sunday, July 31, 2016 9:40 PM
To: TekScopes@... <mailto:TekScopes@...>
Subject: [TekScopes] Re: Eli Heffron's electronic junkyard





I believe that the place in Amesbury was Delta Electronics, I think I still
have one of their old catalogs. Used to run up there a lot in the late 70s.
He would let you wander the place and I do remember the pigeons on the 3rd
floor. Not much good stuff up there on the 3rd floor anyway. Meshna was also
a popular spot, got the 68705P3 for my first Morse Code keyboard from
Meshna. Came out of a gas pump control.

Coming from the Hartford area, we would hit Active Electronics in
Framingham, then up 495 to Verrada in Lowell continuing on to Delta which
was near where 495 and 95 merged. From there, down 95 to the Lynn/Lynnfield
area for Poly Paks and Meshna and then on to Boston to Solid State Sales and
a few computer stores in that area. Made for a long day...

ed WA1TWX

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Re: BNC Installation Tool

Ed Breya
 

I just stumbled across this about BNC repair:

https://patents.google.com/patent/US4416143

Ed

Re: BNC Installation Tool

Pete Lancashire
 

Tek had a very strong "do it ourselves" attitude. Since they had to make
many jigs and tools they made many of the tools even one could buy them I
use to have a small collection of parts used to make tools, for example
unused "raw" Execlite handles and shaft material. When ready one would heat
the shaft push it into the handle and twist finally letting it cool.

Think about it, you have one of the best model shops around and the
machinist, when idle a perfect time filler.

-pete

On Wed, Apr 25, 2018, 2:34 PM Ed Breya via Groups.Io <edbreya=
yahoo.com@groups.io> wrote:

A quick search found this in a few seconds:


https://www.google.com/search?q=bnc+connector+wrench&client=firefox-b-1&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwj014jPrdbaAhWI_p8KHTdwD1wQsAQI8gE&biw=1610&bih=870#imgrc=RDB-6NXnhJ1qoM
:

Note there are a lot of tools, including a number of offset, slotted hex
drivers for the BNC back-nuts, etc - kind of equivalent to a crow-foot
socket, but nicer, low profile for getting in close-quarters behind the
panel. Didn't see any of these nut driver style ones for holding the front
though. I'm still convinced these were commercial products. Tek could have
made them in-house, but I doubt they needed to. Even way back, there must
have been plenty of demand for various BNC tools, and someone to fill it.
Every connector type has special tools to go with it.

Ed



Re: 465B won't trigger

Fabio Trevisan
 

Lorn...
Ah, in time... about your writing:

On Wed, Apr 25, 2018 at 12:28 pm, blackholenulled wrote:

I'm still suspicious about the readings on pins 1 and 16. It will be
interesting to see if they change when biasing 2 and 3 with the resistor.
Since between pins 2,3 and pin 1 there's only the base-emitter junction of the IC's input transistor... if the input is at 0,7V or so, it's expected that pin 1 will rise to about 0V, instead of staying at the nominal -0.8V or so... This even testimony in favor of the IC, that its input transistor isn't defective.
As for pin 16, since this is a differential input pair, the upper side being heavily (postively) biased, it's natural that it will bring the emitter of the complementary xsistor up... In fact, this is exactly what the differential input pair is meant to do.
One may be fooled by the fact (so often found on Oscilloscope's Vertical and Trigger amplifier circuits, ICs or discrete) that the transistors don't have their emitters tied together to a single "long tail" resistor and thus, not spotting right away a differential amp., but Y connected emitter resistors and Delta connected are mutually convertible and the set is indeed a differential input pair.
If one is heavily driven into conduction, the other will be driven into cutoff from its emitter.
R
FT

Re: BNC Installation Tool

Ed Breya
 

A quick search found this in a few seconds:

https://www.google.com/search?q=bnc+connector+wrench&client=firefox-b-1&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwj014jPrdbaAhWI_p8KHTdwD1wQsAQI8gE&biw=1610&bih=870#imgrc=RDB-6NXnhJ1qoM:

Note there are a lot of tools, including a number of offset, slotted hex drivers for the BNC back-nuts, etc - kind of equivalent to a crow-foot socket, but nicer, low profile for getting in close-quarters behind the panel. Didn't see any of these nut driver style ones for holding the front though. I'm still convinced these were commercial products. Tek could have made them in-house, but I doubt they needed to. Even way back, there must have been plenty of demand for various BNC tools, and someone to fill it. Every connector type has special tools to go with it.

Ed