Test Equipment Anonymous (TEA) group therapy thread

[med6753]

No shit Dick Tracy. The Obvious is obvious. Try to make a joke and someone has to ruin it. Fucking killjoy. 

We know how much you like to be miserable, if we go around letting you have fun you'll really be unhappy rather than creatively miserable. Now, aren't there some kids you have to chase off your lawn? Go on, you know you want to...

 

Who's miserable? Not this boy. I'm a happy and content grouchy old bastard. Being anti-social keeps the idiots away and that makes me overjoyed.

The kids can play on the lawn as much as they want. It's not my lawn. It's the landlord's. And he has to mow it and care for it, not me. But right now that would be a little difficult since it's covered in snow and ice.

Not many Americans see the beauty of renting, lol! 

I did the white picket fence and the manicured lawn and all the work and maintenance and up keep. Screw that noise.

[mnementh]

mnem

listed under free stuff?  Hmmm.....

The first thing to check is the head gaskets (two in a boxer engine) and coolant pathways.
They engineered the engine to a spec. and then had to go to lightweight 0w20 oil in order not to clog the oil channels in the block. Always, always, always be sure to warm up the engine before driving.  Then again, it is in Texas, so it probably has been warmed up all its life there     Nice cars for driveability and fun factor.  Not necessarily the easiest to wrench.  Then again, certain folks look for things to tinker on...

No, it's aboot 40 minutes away in Naugatuck. Problem is it smells like a scam, or worse, a lure to steal whatever vehicle you show up in. 4 years old, 120K... even with a blown motor that car will bring several thou at auction unless it's been totaled. If it has been totaled, still a thou or two for the motor/trans. All that plus total lack of details or pix makes my hackles rise.

mnem
 

[xrunner]

Two Weinschel 3.0 dB attenuators for $9.99. Simple but good quality is always a good thing.

[cyclin_al]

It is a logical deduction from physics: static friction is generally higher than dynamic friction - you don't want the wheels to spin and end up in the dynamic area.

It may well be a logical deduction on the surface, and at first glance it looks reasonable, unassailable even. However, it's obvious to me that a rally driver can get a car around a loose surfaced rally track, using all those very messy looking rally driving techniques that so very clearly involve dynamic friction, much faster than someone could get around the same track using tarmac driving techniques, and tarmac driving techniques adhere (no pun intended) to your tenet of avoiding dynamic* friction at all costs.

So basically there is more to it than a simple first order analysis will discover. What that is exactly, I don't know, but the methods adopted by rally drivers would strongly suggest that the art of maintaining control (with the greatest overall speed) on loose surfaces come down to more than simply maximising 'grip'.


Full disclosure: I have some little tarmac racing experience, a long time ago and was an RAC/ACU racing license holder (That is not as impressive as it sounds, it basically means you are permitted to race. They give it to you so that they can take it away again if you're a bad boy.). On the other hand I haven't a clue how rally drivers do what they do, despite having been navigator for a mate on some rallying** (it basically involves knowing where you are and reading pace notes off to the driver, you don't need to have a clue what's going on beyond that). All my driving and racing experience has been of the type that drums into you keeping the forces on your tyres within the envelope of their [rolling] static friction. I suspect that even if someone now showed me how to drive like a rally driver I wouldn't be able to make myself do it, backing off the second I hit the edge of that envelope.

*I'm sticking with SilverSolder's terminology even though it isn't quite kosher, and because without looking it up I can't remember the kosher terms. Tyres are rolling, so 'static friction' isn't quite the right phrase, neither is 'dynamic friction', but I think we all know what he means. I do remember that tyre dynamics is not a simple subject, and that tyres only 'roll' in a straight line and that dynamic forces involve 'deformation', 'slip' (which doesn't mean slipping) and lots of other terms that I have forgotten.

Edit:
**Just to drive home how unimpressive holding an RAC/ACU licence was, I seem to remember that I got roped in precisely because I did have a licence and navigators were required to have one for the class(es) he competed in. My license was obtained to lose 2 stroke motorbike races on tarmac, but it wasn't a licence for that in particular, it was just a license to participate in racing. So if anyone ever tries to impress you with having held an "RAC/ACU racing license", you have grounds to be very sceptical that it implies any particular proficiency.

I agree with everything you said about tarmac driving and about friction.
However, my opinion is that there are further nuances to rally driving.
I do not hold any tarmac racing qualifications, although I do hold a regional rally permit.  The permits here carry about the same weight that you describe; basically I should know what I am doing and am expected to act & drive responsibly.

The fact as I understand it is that tarmac driving techniques would in fact theory get you through the rally course faster than a rally car.  However, any error or unexpected surface or any other factor that is incorrectly judged for that matter results in loss of control and not finishing the course, which is not the desired result.

The general rally technique is to approach the limits, and then set the vehicle into a predicable oversteer and then release from the turn once pointed in the desired direction at a controllable speed.  This technique is not as fast as the tarmac technique.  However, when something does not go perfectly, the general mitigation is to hold the skid longer to reduce speed, or to adjust the rotation of the vehicle.  Once predictably recovered, then start building the speed back up again.  This technique is a bit slower than tarmac, but is much better at consistently handling the unexpected.

Of course, there are further nuances on timing when to enter the turn, when is optimal to complete the rotation, and planning for road curvatures of changing radius.

[cyclin_al]

[snip]

It is also a fact that switching ABS off on gravel can let you stop faster than leaving it engaged, because gravel builds up in front of the stationary wheels and gets a better grip than the "static friction" situation.  For most drivers, this is a completely theoretical scenario and they are better off leaving ABS on, and driving a little slower...   (do most cars even allow you to turn off ABS these days?)

None of this has anything to do with spinning wheels in the snow, though.   [snip]....

This gravel stopping scenario also applies to many different types of snow.  Not all types, and not on ice...

-- want to study types of snow; become a cross-country skier

[Brumby]

I've been to the snow ... once.

You can keep it.

[Specmaster]

I've been to the snow ... once.

You can keep it.

Freshly fallen snow is a thing of beauty until someone messes it up, and thats it, good for nothing else.

[cyclin_al]

mnem

listed under free stuff?  Hmmm.....

The first thing to check is the head gaskets (two in a boxer engine) and coolant pathways.
They engineered the engine to a spec. and then had to go to lightweight 0w20 oil in order not to clog the oil channels in the block. Always, always, always be sure to warm up the engine before driving.  Then again, it is in Texas, so it probably has been warmed up all its life there     Nice cars for driveability and fun factor.  Not necessarily the easiest to wrench.  Then again, certain folks look for things to tinker on...

No, it's aboot 40 minutes away in Naugatuck. Problem is it smells like a scam, or worse, a lure to steal whatever vehicle you show up in. 4 years old, 120K... even with a blown motor that car will bring several thou at auction unless it's been totaled. If it has been totaled, still a thou or two for the motor/trans. All that plus total lack of details or pix makes my hackles rise.

mnem
 

Ah, maybe it needed head gaskets before it was totalled 

-- there is no such thing as too good to be true .. it just aint true

[Cerebus]

I've been to the snow ... once.

You can keep it.

Freshly fallen snow is a thing of beauty until someone messes it up, and thats it, good for nothing else.

Very early one morning a few winters back I had the whole of West Ham Park to myself after a night of fresh snow. Just a few fox's foot prints, the odd patch shaped like a squirrel's backside,  a few crow's footprints and mine. Lovely.

[Zucca]

The power of chinesium strikes again!



Peekaboo

[Zucca]

Not only he fixed it, he went the extra mile to get the PF=1



I love him!

[tautech]

I've been to the snow ... once.

You can keep it.

Freshly fallen snow is a thing of beauty until someone messes it up, and thats it, good for nothing else.

Very early one morning a few winters back I had the whole of West Ham Park to myself after a night of fresh snow. Just a few fox's foot prints, the odd patch shaped like a squirrel's backside,  a few crow's footprints and mine. Lovely.

Just beware the yellow stuff !
First I was in was a few hours old when arriving at a hunting location decades ago in my teens. Sure it's pretty however the first right of passage is to make some of it yellow ! 

[Neomys Sapiens]

Are you sure about "TNC"-connector type ?

No.

What I am sure about is that the bit I looked at is stamed RAdiall with P/N 20260.

Looked that up on Google, as you do. First hit was an ebay ad whose title said it was TNC, so I stopped there ! 

https://www.ebay.fr/itm/322854805945

For me it looks like as miniQuick connectors. "miniQuick" or "MQ" are Radiall propriety connectors.

Ah yeah searching for pics of MQ stuff indeed yields results that match what I have here, thanks !
So MiniQuick it is then, and it's proprietary Radiall stuff at that, OK thanks for the info   

Will scroll back and edit / correct my post then...

For a quick and easy help (with the exception of some more exotic ones) download the 'connector finder' from Pasternack.

[SilverSolder]

It is a logical deduction from physics: static friction is generally higher than dynamic friction - you don't want the wheels to spin and end up in the dynamic area.

It may well be a logical deduction on the surface, and at first glance it looks reasonable, unassailable even. However, it's obvious to me that a rally driver can get a car around a loose surfaced rally track, using all those very messy looking rally driving techniques that so very clearly involve dynamic friction, much faster than someone could get around the same track using tarmac driving techniques, and tarmac driving techniques adhere (no pun intended) to your tenet of avoiding dynamic* friction at all costs.

So basically there is more to it than a simple first order analysis will discover. What that is exactly, I don't know, but the methods adopted by rally drivers would strongly suggest that the art of maintaining control (with the greatest overall speed) on loose surfaces come down to more than simply maximising 'grip'.


Full disclosure: I have some little tarmac racing experience, a long time ago and was an RAC/ACU racing license holder (That is not as impressive as it sounds, it basically means you are permitted to race. They give it to you so that they can take it away again if you're a bad boy.). On the other hand I haven't a clue how rally drivers do what they do, despite having been navigator for a mate on some rallying** (it basically involves knowing where you are and reading pace notes off to the driver, you don't need to have a clue what's going on beyond that). All my driving and racing experience has been of the type that drums into you keeping the forces on your tyres within the envelope of their [rolling] static friction. I suspect that even if someone now showed me how to drive like a rally driver I wouldn't be able to make myself do it, backing off the second I hit the edge of that envelope.

*I'm sticking with SilverSolder's terminology even though it isn't quite kosher, and because without looking it up I can't remember the kosher terms. Tyres are rolling, so 'static friction' isn't quite the right phrase, neither is 'dynamic friction', but I think we all know what he means. I do remember that tyre dynamics is not a simple subject, and that tyres only 'roll' in a straight line and that dynamic forces involve 'deformation', 'slip' (which doesn't mean slipping) and lots of other terms that I have forgotten.

Edit:
**Just to drive home how unimpressive holding an RAC/ACU licence was, I seem to remember that I got roped in precisely because I did have a licence and navigators were required to have one for the class(es) he competed in. My license was obtained to lose 2 stroke motorbike races on tarmac, but it wasn't a licence for that in particular, it was just a license to participate in racing. So if anyone ever tries to impress you with having held an "RAC/ACU racing license", you have grounds to be very sceptical that it implies any particular proficiency.

I agree with everything you said about tarmac driving and about friction.
However, my opinion is that there are further nuances to rally driving.
I do not hold any tarmac racing qualifications, although I do hold a regional rally permit.  The permits here carry about the same weight that you describe; basically I should know what I am doing and am expected to act & drive responsibly.

The fact as I understand it is that tarmac driving techniques would in fact theory get you through the rally course faster than a rally car.  However, any error or unexpected surface or any other factor that is incorrectly judged for that matter results in loss of control and not finishing the course, which is not the desired result.

The general rally technique is to approach the limits, and then set the vehicle into a predicable oversteer and then release from the turn once pointed in the desired direction at a controllable speed.  This technique is not as fast as the tarmac technique.  However, when something does not go perfectly, the general mitigation is to hold the skid longer to reduce speed, or to adjust the rotation of the vehicle.  Once predictably recovered, then start building the speed back up again.  This technique is a bit slower than tarmac, but is much better at consistently handling the unexpected.

Of course, there are further nuances on timing when to enter the turn, when is optimal to complete the rotation, and planning for road curvatures of changing radius.

Driving at the limits is an art form!  - beautiful when well executed.

[DH7DN]

What do the Tek-experts here think about this Rohde & Schwarz 7623A scope?
Is it overpriced? Seller is asking EUR 550.- for it plus shipping.



And what is this on the backside?

He probably named it "Rohde & Schwarz" because of the "Rohde & Schwarz Vertriebs GmbH" sticker on the top of the chassis. I think R&S Vertriebs GmbH was a Tektronix oscilloscope distributor in West Germany during the 1960's and 1970's. It's a Tektronix 7623A unit. The connectors on the backside seem to be standard (at least I have them on my Tek 7613)

Estimated price according to 2021 Covid-19 vintage TE price inflation 
7A13 ~90 EUR  (relays may be defect and almost impossible to repair)
7A18 ~25 EUR  (75 MHz general-purpose amplifier)
7B53 ~30 EUR  (nice 100 MHz dual timebase)
Tek 7623A Mainframe: depending on its condition... the screen may have burn-ins due to misuse of beam intensity, ~40-70 EUR

Total price: ~185...210 EUR

It's a very heavy (~14 kg) and bulky unit so this may add some 20 EUR to the shipping.

So in conclusion: <180 EUR (good deal), =< 230 EUR (not good, not bad), > 250 EUR (unrealistic to be sold, yet hope dies last), 550 EUR (I smell Ferengi cerumen: Greed is eternal) 

[Zucca]

Boat Anchor ALARM!!

[mnementh]

mnem
my work here is done.    

[Zucca]

Funny I can hear the bang sound even if my PC has no speakers.

[Brumby]

mnem
my work here is done.    

At the risk of ruffling scales ... something feels rather apropos by having that posted by the Dwagon.

[Specmaster]

mnem
my work here is done.    

Must have been a rare flying boat 

[tggzzz]

I've been to the snow ... once.

You can keep it.

Freshly fallen snow is a thing of beauty until someone messes it up, and thats it, good for nothing else.

One of my most memorable ski runs was on a "green" run with new snow and two ski tracks about a foot deep. Since the green run was along a single-track road, it was predictably unsteep.

Stick both skis in the grooves and just go for it, like a train on a track. That is until going round a sharp bend to find someone sprawled across the entire track - at which point I did the classic cartoon "straight off into the woods". Great fun.

The only two types of snow I loathe are sheet ice and breakable crust.

[Cubdriver]

some TEA content 



David

A fine bit of hardware.  I took pics of the innards of mine months ago, but being my lazy self never got around to uploading them.  Typical me. 

-Pat

[TERRA Operative]

Mine is the same one with the options, but I'm getting strange output level unless I'm reading the adjustment section of the manual wrong... I don't have the manual on me now, but IIRC it was low output with the two 300ohm resistors connected, but within spec with them disconnected. The manual reads a bit weird though, it takes me reading each step a few times to work out exactly what they are trying to explain to do.
Everything else seems fine so far though.

I bought the parts to make the RC normalizer for the AM502 today, so I'll have another go at it soon.

Mine puts out level just right into a 600@ termination, measured across a number of meters.  I think we agree that that is what is desired.

Regarding TM500 contents,  I've come up with a Heath Robinson consisting of a FeelTech FY3200 function generator, an USB cable, a Perl Script, and for demonstration purposes, a Heavy Duty Avometer.    This allows me to set levels on the FY3200 and iterate around them, so that I can exercise the reed relays of the AA501A. I'll try to get it on video for a laugh.

Well I got mildly(!) irritated at trying to hook up the termination resistors while performing the adjustments, so I whipped up this test adapter design. (Not all 3D models are populated, imagine banana jacks out the back and toggle switches on the front).
If you are interested, I can send you a kit for the cost of parts and shipping once it's all in my hands.

[med6753]

Next project. Build of a custom storage cart for the several 500 series plug-in's.

Removed the plug-in storage rack assemblies from the scope carts to use in a cart that will be on casters and be stored under bench 2. At this point just have the front built up so I could test fit the storage racks. That's complete so will build up the back half of the cart then proceed with sanding, stain, and poly.

[25 CPS]

Even with good sync to all devices that require a reference input to be genlocked, video switchers are notorious for introducing timing problems into NTSC systems due to propagation delay.  If Vince moves here, he can have fun with nice, even frame rate numbers that are ruined by multiplying by 1000/1001

treize:~ mansaxel$ dc
2
k
1000
1001/
30*p
29.97

So that's where that perverse figure comes from! *barf*

That's where it came from.  Doing the same thing with 24 gives 23.976 for film rate being put through 3:2 pulldown.