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On 11/30/2021 10:03 AM, quadzillatech@... wrote:

any idea where to start checking then?,is there any common components can cause this?

-------- Original message --------From: Tom Lee <tomlee@...> Date: 12/2/21 6:02 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] TG501 2ns & 1ns operation Re: non-conductive toolsI often make my own from cast-off bits of FR4. A little filing action, and you've got your tool. Works great.--Tom-- Prof. Thomas H. LeeAllen Ctr., Rm. 205350 Jane Stanford WayStanford UniversityStanford, CA 94305-4070 12/2/2021 17:47, Dave Peterson via groups.io wrote:>?? The schematic depiction of switches in Tek schematics isn't always clear to me.>> Yes, I was clear on the 5, 2, and 1 ns circuits - really the 5ns and 1/2ns circuits, and that K450 switches between them. Thus my confusion regarding K450 DE-activating in 1ns mode. I further missed that in NOT 5ns mode the base of Q460 is pulled up by the disconnection of the 5ns pushbutton (S450A) and R451. And checking the 2ns and 5ns output I now understand why the 5ns mode jumps up in DC offset compared to the 2ns output. Incremental understanding.>> So the 2ns Filter output is disconnected from MARKER OUT, Q460 is off, anode of CR468 is pulled down by R465, and MARKER OUT is floating. That explains is susceptibility to noise. Recall I'm the guy who has Sutro Tower looming over my house blasting me with 100MHz broadcast frequencies. Still, the proximity of the 500MHz/2ns signal out of the 2ns Filter is plenty to appear on the MARKER OUT.>> I had (in the pictures) the 2ns level C515 set for a large output. Adjusting it to a minimum 2ns level results in a significantly smaller "noise" level on MARKER OUT in 1ns mode. No surprise. There also seems to be a balance between maximum 2ns level and maximum 1ns level. As this is all a tuned resonant type circuit, I'm not surprised. I'm working on rebuilding my small signal analysis chops. And again, I'll say I'm closer to full understanding. But it's always a closer approximation - never quite fully there.>> As an aside, since you brought it up: I've been looking for a suitable non-capacitive trimming screwdriver. I just tried making one out of hard plastic, but these aged devices tend to be kind of sticky. It can't stand up to the torque needed to turn some of the caps. So I have to resort to a metal trimmer to get the caps turned. I can do incremental adjustments and get the effects I need.>> I've been wary of buying plastic non-capacitive trimmers online. I suspect they'll be no better than I've been able to make myself. You mentioned ceramic. Do you have a particular brand or source for such? An Amazon link perhaps?>> Thanks.Dave>>>????? On Thursday, December 2, 2021, 04:18:29 PM PST, Raymond Domp Frank <hewpatek@...> wrote:>?? >?? On Fri, Dec? 3, 2021 at 12:41 AM, Dave Peterson wrote:>>> Nope, not intended nor expected. But I don't expect to see the MARKER OUT>> output to be putting out anything while in 1ns mode. The 1ns output on the 1ns>> ONLY BNC is otherwise fine - as good as my equipment can make out.>> The MARKER OUT should be pulled up by Q460, and I'm seeing a crappy 40mV ~2ns>> (500MHz) sine wave. I've taken a look at Q460. It's not socketed, so I'm not>> going to pull it at this point to check on a curve tracer. Not yet anyway. I>> would like to know what is expected. Am I right that it should be near +5v>> (minus a diode drop?)?>>> I'm not sure if you realize that 2ns and 1ns aren't generated by the 5ns+ circuits; they are separated by K450-S1, which selects either all 5ns+ signals or both the 1ns and 2ns signals. The fact that you can see 1,2 ns and 5ns+ signals indicates that K450-S1 does its selection job. For 1ns and 2ns, everything "above" K450-S1, i.e. from P468, doesn't count.>> The 2ns signal is the bandwidth-filtered result of a dirty signal going into the 2ns filter (CL510, C/L511, C/L512, CL513).> CR515 "sharpens" that signal, creating harmonics, which are then bandwidth-filtered out by C/L517, C/L518, C/L519 and C/L5120. the result is a "soft" signal with a frequency of 1GHz, presented at the "1ns only" BNC socket.>> The irregular 2ns signal in your picture looks like the result of mixing, caused by leakage: Bad screening by the aluminium cage covering the 1ns and 2ns etc. circuits may cause this. It should be a pretty tight and complete fit. Just the screws holding it in place and making contact isn't enough.> If you can make a setup where you can put pressure on the cage with power on, I wouldn't be surprised if the signal shape of 1ns and 2ns signals visibly varies, depending on pressure exerted on the cage cover.> If that is so, you may want to remove the cage lid and bend its sides together, even to a slightly smaller than 90 degree angle. Use some tool to fit the lid on and put in the screws.> Next, perform the adjustment for the 2ns and 1ns signals (C/L510 ...C/L520), unless everything looks perfect already. Preferably use a ceramic screwdriver, definitely not one with a metal tip. Simple peaking of the signal and watching for a regular signal on your scope will do the job; first 2ns, then 1ns, and repeat until no more changes. This usually is enough to achieve excellent results. The BW of your 'scope is only important in so far as it is able to show and trigger on the signal. Correct amplitude is not important.>> Raymond>>>>>>??? >>> >>

On 12/2/2021 17:47, Dave Peterson via groups.io wrote:

The schematic depiction of switches in Tek schematics isn't always clear to me.

Yes, I was clear on the 5, 2, and 1 ns circuits - really the 5ns and 1/2ns circuits, and that K450 switches between them. Thus my confusion regarding K450 DE-activating in 1ns mode. I further missed that in NOT 5ns mode the base of Q460 is pulled up by the disconnection of the 5ns pushbutton (S450A) and R451. And checking the 2ns and 5ns output I now understand why the 5ns mode jumps up in DC offset compared to the 2ns output. Incremental understanding.

So the 2ns Filter output is disconnected from MARKER OUT, Q460 is off, anode of CR468 is pulled down by R465, and MARKER OUT is floating. That explains is susceptibility to noise. Recall I'm the guy who has Sutro Tower looming over my house blasting me with 100MHz broadcast frequencies. Still, the proximity of the 500MHz/2ns signal out of the 2ns Filter is plenty to appear on the MARKER OUT.

I had (in the pictures) the 2ns level C515 set for a large output. Adjusting it to a minimum 2ns level results in a significantly smaller "noise" level on MARKER OUT in 1ns mode. No surprise. There also seems to be a balance between maximum 2ns level and maximum 1ns level. As this is all a tuned resonant type circuit, I'm not surprised. I'm working on rebuilding my small signal analysis chops. And again, I'll say I'm closer to full understanding. But it's always a closer approximation - never quite fully there.

As an aside, since you brought it up: I've been looking for a suitable non-capacitive trimming screwdriver. I just tried making one out of hard plastic, but these aged devices tend to be kind of sticky. It can't stand up to the torque needed to turn some of the caps. So I have to resort to a metal trimmer to get the caps turned. I can do incremental adjustments and get the effects I need.

I've been wary of buying plastic non-capacitive trimmers online. I suspect they'll be no better than I've been able to make myself. You mentioned ceramic. Do you have a particular brand or source for such? An Amazon link perhaps?

Thanks.Dave


On Thursday, December 2, 2021, 04:18:29 PM PST, Raymond Domp Frank <hewpatek@...> wrote:
On Fri, Dec? 3, 2021 at 12:41 AM, Dave Peterson wrote:

Nope, not intended nor expected. But I don't expect to see the MARKER OUT
output to be putting out anything while in 1ns mode. The 1ns output on the 1ns
ONLY BNC is otherwise fine - as good as my equipment can make out.
The MARKER OUT should be pulled up by Q460, and I'm seeing a crappy 40mV ~2ns
(500MHz) sine wave. I've taken a look at Q460. It's not socketed, so I'm not
going to pull it at this point to check on a curve tracer. Not yet anyway. I
would like to know what is expected. Am I right that it should be near +5v
(minus a diode drop?)?

I'm not sure if you realize that 2ns and 1ns aren't generated by the 5ns+ circuits; they are separated by K450-S1, which selects either all 5ns+ signals or both the 1ns and 2ns signals. The fact that you can see 1,2 ns and 5ns+ signals indicates that K450-S1 does its selection job. For 1ns and 2ns, everything "above" K450-S1, i.e. from P468, doesn't count.

The 2ns signal is the bandwidth-filtered result of a dirty signal going into the 2ns filter (CL510, C/L511, C/L512, CL513).
CR515 "sharpens" that signal, creating harmonics, which are then bandwidth-filtered out by C/L517, C/L518, C/L519 and C/L5120. the result is a "soft" signal with a frequency of 1GHz, presented at the "1ns only" BNC socket.

The irregular 2ns signal in your picture looks like the result of mixing, caused by leakage: Bad screening by the aluminium cage covering the 1ns and 2ns etc. circuits may cause this. It should be a pretty tight and complete fit. Just the screws holding it in place and making contact isn't enough.
If you can make a setup where you can put pressure on the cage with power on, I wouldn't be surprised if the signal shape of 1ns and 2ns signals visibly varies, depending on pressure exerted on the cage cover.
If that is so, you may want to remove the cage lid and bend its sides together, even to a slightly smaller than 90 degree angle. Use some tool to fit the lid on and put in the screws.
Next, perform the adjustment for the 2ns and 1ns signals (C/L510 ...C/L520), unless everything looks perfect already. Preferably use a ceramic screwdriver, definitely not one with a metal tip. Simple peaking of the signal and watching for a regular signal on your scope will do the job; first 2ns, then 1ns, and repeat until no more changes. This usually is enough to achieve excellent results. The BW of your 'scope is only important in so far as it is able to show and trigger on the signal. Correct amplitude is not important.

Raymond

On Thursday, December 2, 2021, 04:18:29 PM PST, Raymond Domp Frank <hewpatek@...> wrote:

On Fri, Dec? 3, 2021 at 12:41 AM, Dave Peterson wrote:

Nope, not intended nor expected. But I don't expect to see the MARKER OUT
output to be putting out anything while in 1ns mode. The 1ns output on the 1ns
ONLY BNC is otherwise fine - as good as my equipment can make out.
The MARKER OUT should be pulled up by Q460, and I'm seeing a crappy 40mV ~2ns
(500MHz) sine wave. I've taken a look at Q460. It's not socketed, so I'm not
going to pull it at this point to check on a curve tracer. Not yet anyway. I
would like to know what is expected. Am I right that it should be near +5v
(minus a diode drop?)?

I'm not sure if you realize that 2ns and 1ns aren't generated by the 5ns+ circuits; they are separated by K450-S1, which selects either all 5ns+ signals or both the 1ns and 2ns signals. The fact that you can see 1,2 ns and 5ns+ signals indicates that K450-S1 does its selection job. For 1ns and 2ns, everything "above" K450-S1, i.e. from P468, doesn't count.

The 2ns signal is the bandwidth-filtered result of a dirty signal going into the 2ns filter (CL510, C/L511, C/L512, CL513).
CR515 "sharpens" that signal, creating harmonics, which are then bandwidth-filtered out by C/L517, C/L518, C/L519 and C/L5120. the result is a "soft" signal with a frequency of 1GHz, presented at the "1ns only" BNC socket.

The irregular 2ns signal in your picture looks like the result of mixing, caused by leakage: Bad screening by the aluminium cage covering the 1ns and 2ns etc. circuits may cause this. It should be a pretty tight and complete fit. Just the screws holding it in place and making contact isn't enough.
If you can make a setup where you can put pressure on the cage with power on, I wouldn't be surprised if the signal shape of 1ns and 2ns signals visibly varies, depending on pressure exerted on the cage cover.
If that is so, you may want to remove the cage lid and bend its sides together, even to a slightly smaller than 90 degree angle. Use some tool to fit the lid on and put in the screws.
Next, perform the adjustment for the 2ns and 1ns signals (C/L510 ...C/L520), unless everything looks perfect already. Preferably use a ceramic screwdriver, definitely not one with a metal tip. Simple peaking of the signal and watching for a regular signal on your scope will do the job; first 2ns, then 1ns, and repeat until no more changes. This usually is enough to achieve excellent results. The BW of your 'scope is only important in so far as it is able to show and trigger on the signal. Correct amplitude is not important.

Raymond

On 12/2/2021 6:41 PM, Dave Peterson via groups.io wrote:

Nope, not intended nor expected. But I don't expect to see the MARKER OUT output to be putting out anything while in 1ns mode. The 1ns output on the 1ns ONLY BNC is otherwise fine - as good as my equipment can make out.
The MARKER OUT should be pulled up by Q460, and I'm seeing a crappy 40mV ~2ns (500MHz) sine wave. I've taken a look at Q460. It's not socketed, so I'm not going to pull it at this point to check on a curve tracer. Not yet anyway. I would like to know what is expected. Am I right that it should be near +5v (minus a diode drop?)?

On Thursday, December 2, 2021, 03:31:39 PM PST, Harvey White <madyn@...> wrote:
IIRC, the marker is labeled 2ns to (whatever), which makes me suspect
that there was never intended to be a marker out at 1 ns.? Haven't
looked at the output, though.

Harvey


On 12/2/2021 5:51 PM, Dave Peterson via groups.io wrote:

I guess my next question would be: is that horrible 40mV p2p signal coming out of the MARKER OUT "normal" in 1ns mode? Yuck.

I can see how mitigating coupling through the contacts of K450 could be challenging. But does this indicate any issues with Q460, CR468, or any other associated components and wiring? It seems that Q460 should be pulling MARKER OUT up.

On Thursday, December 2, 2021, 03:31:39 PM PST, Harvey White <madyn@...> wrote:

IIRC, the marker is labeled 2ns to (whatever), which makes me suspect
that there was never intended to be a marker out at 1 ns.? Haven't
looked at the output, though.

Harvey


On 12/2/2021 5:51 PM, Dave Peterson via groups.io wrote:

I guess my next question would be: is that horrible 40mV p2p signal coming out of the MARKER OUT "normal" in 1ns mode? Yuck.

I can see how mitigating coupling through the contacts of K450 could be challenging. But does this indicate any issues with Q460, CR468, or any other associated components and wiring? It seems that Q460 should be pulling MARKER OUT up.

On 12/2/2021 5:51 PM, Dave Peterson via groups.io wrote:

I guess my next question would be: is that horrible 40mV p2p signal coming out of the MARKER OUT "normal" in 1ns mode? Yuck.

I can see how mitigating coupling through the contacts of K450 could be challenging. But does this indicate any issues with Q460, CR468, or any other associated components and wiring? It seems that Q460 should be pulling MARKER OUT up.

On 02/12/21 09:28, David C. Partridge wrote:

I have to ask how you handle the transition from coax to the Xmas lights? And how you interpret the results.

A picture of two may be worth a 1000 words.
D.

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Glydeck via groups.io
Sent: 02 December 2021 05:23
To: [email protected]
Subject: Re: [TekScopes] 1502 TDR RECORD functions

Good question. I don’t think it matters. An interruption in the transmission line does not care if it’s a LED or a bulb. I’m so trying this on some recalcitrant light strings.

Glydeck KD6NEW

On Dec 1, 2021, at 6:32 PM, Paul Amaranth <paul@...> wrote:

?Was that incandescant or LED lights?

I have an entire bin full of LED strings that are dead and that might
be worth a try.

Paul

On Wed, Dec 01, 2021 at 01:51:54PM -0800, fiftythreebuick wrote:
Tom, the 1502 is one of the most useful instruments around!

I just finished finding the fault in a long string of Christmas lights with mine! :-) Definitely something essential to have around...

Tom

--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix/Linux - We don't do windows

On 12/2/2021 2:41 PM, Chris Wilkson via groups.io wrote:

On Thu, Dec 2, 2021 at 10:56 AM, Harvey White wrote:

Couple things on USB that might help.

You can easily buy a TTL to USB converter.? Takes TTL level (as from
uart/usart) signals, either 3.3 or 5.0 volts, and translates them to a
USB signal.? That USB signal, when plugged into a PC, enumerates as a
serial port.? You set the baudrate at the terminal to match the TTL
baudrate.

In a number of microprocessor boards (my experience is with the ST-MICRO
boards), the USB chip on the board used for programming also has a
virtual terminal function (at the same time as debugging).? The USB chip
is hardwired to a USART output on the processor.? If you don't use those
pins for something else, and don't disconnect them, you can initialize
that particular USART on the processor and use it to communicate through
the debugging cable.? Your debugging system runs an instance of a
terminal program.

In addition, if you enable the fprint functions in your system and
direct them to the USB usart channel, you can get ongoing outputs from
the processor to the computer for monitoring a process.? You could also
use the console in and out functions, but those may need to be
redirected in your program.

Really easier than you might think.

As to emulating a true HID device, I haven't tried that, haven't needed
to, but I suspect with the right drivers, emulating an HID device
(mouse, etc) might be easy enough.

Harvey


On 12/2/2021 12:07 PM, Chris Wilkson via groups.io wrote:

This is fantastic work, Holger!

I have a disembodied P7001 that I keep meaning to add to a 7704 so I can

play with it. Or, finally accept that I will never get to it and pass the
p7001 to a new owner.

Your project tilts my internal debate toward "keep it". :)

Quick question on Teensy: Can it be configured as a USB HID host?
I have many homebrew projects that would benefit from a USB keyboard-to-TTL

converter but I'm honestly intimidated by USB complexity so I haven't done
much research on USB hosts.

Hi Harvey,

My need is actually in the other direction. There is no PC involved anywhere.

There are a million ways to connect a random electronics project to a PC through USB, typically using an FTDI IC with a virtual com port in Windows. Which is the way you described. Or using a development board from an MCU manufacturer or something in the Arduino ecosystem. But cursory searches turn up little info on preexisting solutions for connecting commercial USB devices (keyboard, mouse, usb stick, whatever) to a random electronics project.

Here's an example of what I want to do. I have a working USB keyboard (standard COTS device) that I want to interface to a vintage CPU. Say a 6502 for example. Or even to a discrete TTL design. So I need a USB *host* that can talk to the keyboard and spit out raw data on the other side in serial or preferably parallel format. I went down the PS2 -> TTL route years and years ago. It was fairly trivial. But USB host implementation is a whole different animal.

Best,
Chris

On Thursday, December 2, 2021, 12:25:40 PM PST, Raymond Domp Frank <hewpatek@...> wrote:

On Thu, Dec? 2, 2021 at 08:52 PM, Dave Peterson wrote:

Why does switching 2ns/1ns push buttons change the 2ns output at all!? Given
the schematic for the 10ns Amplifier input U450C.

S350-1 and S350-2 are closed in the 1-2-5 ns position.
With collector of Q270 low (Out of Lock filter), S450B (2ns) connects Marker Out to C515 (2ns signal) via K450-S1 K450.
With 1 ns button depressed, K450-S1 opens that link, reducing and changing load on 2ns filter output and 2ns filter is coupled only to 1ns filter.

Raymond