Test Equipment Anonymous (TEA) group therapy thread

[Brumby]

I used to dismantle disposable cameras for the flash board ...

I did that too.  I have a couple of hundred of them up in the garage.

Any suggestions for them?

[tautech]

I used to dismantle disposable cameras for the flash board ...

I did that too.  I have a couple of hundred of them up in the garage.

Any suggestions for them?

Charging caps to be left for the unexpecting kids or grandkids ! 

[bd139]

Switchers when done properly are bloody marvelous, I had a Uni student do one for me out of 4000 IC's to get a proper VCO controlled one for a piss ant 6V 100mA PV.
It could charge a 2200uf cap to 150V in seconds in bright sunlight or a few minutes under a twin fluorescent light at night.

Dumb sucker didn't know much about HV clearances though as he did the PCB with a solid pour and 20 mil clearances ! 
Charge...charge.... CRACK....rinse and repeat ! 

Doh! I can almost picture that doing the HV disco in the dark 

I used to dismantle disposable cameras for the flash board ...

I did that too.  I have a couple of hundred of them up in the garage.

Any suggestions for them?

Charging caps to be left for the unexpecting kids or grandkids ! 

That's one use for sure.

1. driving various vacuum tube display technology
2. testing capacitor leakage.
3. electrocuting rodents.
4. electrocuting wasps (RODALCO2007 style)

[Brumby]

My kids are too old and my grandkids are too young.  Besides, I'm not into direct physical application.

What I'm not against is setting up a few of them to fire when someone opens a door... 

1. driving various vacuum tube display technology
2. testing capacitor leakage.
3. electrocuting rodents.
4. electrocuting wasps (RODALCO2007 style)

Better!

[bd139]

What I'm not against is setting up a few of them to fire when someone opens a door... 

Tax audit day? 

[med6753]

Here's an interesting tidbit. Around 1985/86 both the Tek 485 and 2465 were available in the Tek catalog. After 1986 the 485 was discontinued. The 485 was strictly analog with no cursors/readouts and an advertised B/W of 350MHz but only at 50ohm/5mv. At Hi-Z it was 250MHz. The 2465 has cursors/readouts, microprocessor control, and an advertised B/W of 300MHz up to +35 degrees C.

Cost of 2465 with no options: $5350 USD

Cost of 485 with no options: $9100 USD 

I have a hard time believing that the extra 50MHz response is worth nearly $4K USD more. Smaller CRT, but admittedly a sharper trace than the 2465. I'm not saying that the 485 isn't a good scope. It is. But     

[tautech]

Switchers when done properly are bloody marvelous, I had a Uni student do one for me out of 4000 IC's to get a proper VCO controlled one for a piss ant 6V 100mA PV.
It could charge a 2200uf cap to 150V in seconds in bright sunlight or a few minutes under a twin fluorescent light at night.

Dumb sucker didn't know much about HV clearances though as he did the PCB with a solid pour and 20 mil clearances ! 
Charge...charge.... CRACK....rinse and repeat ! 

Doh! I can almost picture that doing the HV disco in the dark 

Didn't need to be dark !
2200uF @ 150V lets off enough of a crack to really get your attention even in bright sunlight !

[med6753]

Switchers when done properly are bloody marvelous, I had a Uni student do one for me out of 4000 IC's to get a proper VCO controlled one for a piss ant 6V 100mA PV.
It could charge a 2200uf cap to 150V in seconds in bright sunlight or a few minutes under a twin fluorescent light at night.

Dumb sucker didn't know much about HV clearances though as he did the PCB with a solid pour and 20 mil clearances ! 
Charge...charge.... CRACK....rinse and repeat ! 

Doh! I can almost picture that doing the HV disco in the dark 

Didn't need to be dark !
2200uF @ 150V lets off enough of a crack to really get your attention even in bright sunlight !

I found out that a 3300uf/35V cap will let out one hell of a crack when discharged with a screwdriver. 

[tautech]

Switchers when done properly are bloody marvelous, I had a Uni student do one for me out of 4000 IC's to get a proper VCO controlled one for a piss ant 6V 100mA PV.
It could charge a 2200uf cap to 150V in seconds in bright sunlight or a few minutes under a twin fluorescent light at night.

Dumb sucker didn't know much about HV clearances though as he did the PCB with a solid pour and 20 mil clearances ! 
Charge...charge.... CRACK....rinse and repeat ! 

Doh! I can almost picture that doing the HV disco in the dark 

Didn't need to be dark !
2200uF @ 150V lets off enough of a crack to really get your attention even in bright sunlight !

I found out that a 3300uf/35V cap will let out one hell of a crack when discharged with a screwdriver. 

Nutthing like the values I've mentioned, they take little hunks out of a driver ! 

[tggzzz]

Here's an interesting tidbit. Around 1985/86 both the Tek 485 and 2465 were available in the Tek catalog. After 1986 the 485 was discontinued. The 485 was strictly analog with no cursors/readouts and an advertised B/W of 350MHz but only at 50ohm/5mv. At Hi-Z it was 250MHz. The 2465 has cursors/readouts, microprocessor control, and an advertised B/W of 300MHz up to +35 degrees C.

Cost of 2465 with no options: $5350 USD

Cost of 485 with no options: $9100 USD 

I have a hard time believing that the extra 50MHz response is worth nearly $4K USD more. Smaller CRT, but admittedly a sharper trace than the 2465. I'm not saying that the 485 isn't a good scope. It is. But   

The 24x5 scopes don't have high impedance inputs (despite appearances to the contrary) and don't have 50ohm inputs. The 485 has the latter, and it is rather useful at those frequencies

[bd139]

Here's an interesting tidbit. Around 1985/86 both the Tek 485 and 2465 were available in the Tek catalog. After 1986 the 485 was discontinued. The 485 was strictly analog with no cursors/readouts and an advertised B/W of 350MHz but only at 50ohm/5mv. At Hi-Z it was 250MHz. The 2465 has cursors/readouts, microprocessor control, and an advertised B/W of 300MHz up to +35 degrees C.

Cost of 2465 with no options: $5350 USD

Cost of 485 with no options: $9100 USD 

I have a hard time believing that the extra 50MHz response is worth nearly $4K USD more. Smaller CRT, but admittedly a sharper trace than the 2465. I'm not saying that the 485 isn't a good scope. It is. But     

That was a manufacturing generation overlap for you. The manufacturing cost of the 485 was definitely huge. It didn't have the high level of integration of the 2465, most of the parts were probably hand inserted, a lot of the parts were really expensive and the thing certainly took a while on the bench to fix all the one off per unit problems and calibrate it (look at all the compensation trimmers in it!) as well as the assembly of which none could really be automated.

Edit: also worth comparing to the TDS200 series as well which is a generation on from that again. This is basically the entire scope:

[McBryce]

Here's an interesting tidbit. Around 1985/86 both the Tek 485 and 2465 were available in the Tek catalog. After 1986 the 485 was discontinued. The 485 was strictly analog with no cursors/readouts and an advertised B/W of 350MHz but only at 50ohm/5mv. At Hi-Z it was 250MHz. The 2465 has cursors/readouts, microprocessor control, and an advertised B/W of 300MHz up to +35 degrees C.

Cost of 2465 with no options: $5350 USD

Cost of 485 with no options: $9100 USD 

I have a hard time believing that the extra 50MHz response is worth nearly $4K USD more. Smaller CRT, but admittedly a sharper trace than the 2465. I'm not saying that the 485 isn't a good scope. It is. But   

The 24x5 scopes don't have high impedance inputs (despite appearances to the contrary) and don't have 50ohm inputs. The 485 has the latter, and it is rather useful at those frequencies

How do you mean? My 2465 has 1Mohm and 50ohm inputs.

McBryce.

[tggzzz]

Here's an interesting tidbit. Around 1985/86 both the Tek 485 and 2465 were available in the Tek catalog. After 1986 the 485 was discontinued. The 485 was strictly analog with no cursors/readouts and an advertised B/W of 350MHz but only at 50ohm/5mv. At Hi-Z it was 250MHz. The 2465 has cursors/readouts, microprocessor control, and an advertised B/W of 300MHz up to +35 degrees C.

Cost of 2465 with no options: $5350 USD

Cost of 485 with no options: $9100 USD 

I have a hard time believing that the extra 50MHz response is worth nearly $4K USD more. Smaller CRT, but admittedly a sharper trace than the 2465. I'm not saying that the 485 isn't a good scope. It is. But   

The 24x5 scopes don't have high impedance inputs (despite appearances to the contrary) and don't have 50ohm inputs. The 485 has the latter, and it is rather useful at those frequencies

How do you mean? My 2465 has 1Mohm and 50ohm inputs.

Go and look at your front panel, and note down all the figures.

Have a look at the schematic, and see that the 50ohm input is "achieved" by adding an extra 50ohm resistor across the input.

[bd139]

Oh fun. So you end up with 50 ohms in parallel with ~50 ohms reactive impedance (15pF) at 200MHz? Hmm. That's going to have some interesting VSWR and compensation problems to overcome.

[tggzzz]

Here's an interesting tidbit. Around 1985/86 both the Tek 485 and 2465 were available in the Tek catalog. After 1986 the 485 was discontinued. The 485 was strictly analog with no cursors/readouts and an advertised B/W of 350MHz but only at 50ohm/5mv. At Hi-Z it was 250MHz. The 2465 has cursors/readouts, microprocessor control, and an advertised B/W of 300MHz up to +35 degrees C.

Cost of 2465 with no options: $5350 USD

Cost of 485 with no options: $9100 USD 

I have a hard time believing that the extra 50MHz response is worth nearly $4K USD more. Smaller CRT, but admittedly a sharper trace than the 2465. I'm not saying that the 485 isn't a good scope. It is. But     

That was a manufacturing generation overlap for you. The manufacturing cost of the 485 was definitely huge. It didn't have the high level of integration of the 2465, most of the parts were probably hand inserted, a lot of the parts were really expensive and the thing certainly took a while on the bench to fix all the one off per unit problems and calibrate it (look at all the compensation trimmers in it!) as well as the assembly of which none could really be automated.

Just so.

If the 24x5 had 50ohm attenuators, they would have exceeded the 485's performance in all respects. But they don't!

[tggzzz]

Oh fun. ...  and compensation problems to overcome.

Or not overcome But it is no worse than "high" impedance scope probes.

The input structure is common to most low-end scopes, analogue and digitising. That's why the 485 continues to be interesting.

Here's the 2465 input attenuator section...



Here's the input and first part of the 485's two parallel attenuators, 50ohm above, 1Mohm//20pF below. Note the RF relay and the legend "1Mohm//20pF or 50ohm"

[bd139]

Yes indeed. From the overcome side I was thinking externally but that's verging on rocket science. Building wideband matching networks for that stuff; forget it.

Added 485 to shopping list

Edit: actually removing 485 from shopping list. I don't NEED one. I'd LIKE one but I'm supposed to be downsizing!

[tautech]

Yes indeed. From the overcome side I was thinking externally but that's verging on rocket science. Building wideband matching networks for that stuff; forget it.

Added 485 to shopping list

Edit: actually removing 485 from shopping list. I don't NEED one. I'd LIKE one but I'm supposed to be downsizing!

That's where I was with 2465B a year or two back but then studied the thread again and decided bugger that !
Soon after the SDS2352X-E was released so I got one of them instead. 

[bd139]

Yeah I did consider that myself. It's "fuck you Tektronix and Keysight" pricing that is 

[tggzzz]

Yes indeed. From the overcome side I was thinking externally but that's verging on rocket science. Building wideband matching networks for that stuff; forget it.

Added 485 to shopping list

Edit: actually removing 485 from shopping list. I don't NEED one. I'd LIKE one but I'm supposed to be downsizing!

Have a look at the schematics I added to my previous post, and then go and wash your mouth out with soap.

[tautech]

Yeah I did consider that myself. It's "fuck you Tektronix and Keysight" pricing that is 

Yeah well my signature says rabid aka mad and I got a SDS5054X too !
Do I need to crack it to 1 GHz, nah but I might !

[bd139]

Yes indeed. From the overcome side I was thinking externally but that's verging on rocket science. Building wideband matching networks for that stuff; forget it.

Added 485 to shopping list

Edit: actually removing 485 from shopping list. I don't NEED one. I'd LIKE one but I'm supposed to be downsizing!

Have a look at the schematics I added to my previous post, and then go and wash your mouth out with soap.

Thanks for the schematics. I was just in the 485 service manual then looking at exactly that.

I'm only trying to talk myself out of it in the short term  . I need to clean out the queue a bit first I think. Talking of which LittleDiode are fucking useless. Took 3 days for them to dispatch a single LM723 and then they sent it second class. So a week so far.  . I literally live about 15 minutes from them.

Edit: meant to say: going to hit another hamfest, the ARAC boot sale, on Sunday this week. I am only going with the mind of a Ferengi however. Profit over everything. Need to get some funds together for other purchases (TE of course!)

[med6753]

I knew tossing that stink bomb out there would wake up tggzzz....and it did. 

[tggzzz]

I knew tossing that stink bomb out there would wake up tggzzz....and it did. 

If this thread descends into adolescent trolling, it is in trouble. 

That's a sad observation to have to make in post 38000.

[nixiefreqq]

just gotta' get this off my chest.

took the pledge a long time ago to never ever become a tekaholic.

and then along comes med and points out that the guys in new jersey still have some 485's.

leave it to damn new yorker to tempt me with blue boxes from the garden state.

if i cave in to temptation "EXCELSIOR" will become my new favorite curse.



ps  always thought the official motto of the empire state was "wadda' you lookin' at".  turns out it is "excelsior". 

pps  just realized that "excelsior you fathead" was one of sheps lines.  if you are gonna steal....steal from the best.

If you're trying to make me feel guilty it ain't working.  You better get one before addicted2analogtek grabs them all. 

you almost got me!  my finger was hovering over the "buy it now button".

but then it struck me...........i simply do not have the skills to wrassle a 485 to the mat.