Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

Still wouldn’t touch them.

TE connectivity make decent ones as well.

Good question: you’ve got a £2000 instrument and you run it on £5 cables.  ... I’ve worked places where the probes and cables cost more than the instruments.

Yes, this is one time when the cables might well be very important, unlike audio cables and the great cons being conducted with them.

[beanflying]

BNC cables and adapters are on my shopping list as the scope is now 100MHz not Hantek 20MHz crap.

Up to now Cheap and Cheerful has been 'ok' but the hash from the cables both into and out of what I am looking at is becoming a PITA.

[Mr. Scram]

They’re all shit. I tend to buy Amphenol ones from respectable outfits. They really not much more expensive and the connectors don’t snag like some of the cheap ones. Braid coverage is important as well to stop spinal leakage. Chinese no brand ones seem to have as little as possible.

Last time I checked I ended up with something like $30 a cable, which is a bit too much. However, now I'm finding ones that are about $10 a pop and that seems reasonable enough.

Somehow they generally seem to be with a set attenuation, though. That's useful, but can be a pain when you need to string more together too.

[bd139]

Just seen autocorrect fail above. Spinal should be shield. Bloody phone.

Just to note, all cables have loss. RG58 isn’t the best stuff out there for loss. It’s the most reasonable compromise

[Specmaster]

The higher the frequency as well, the higher the loss, faster scopes etc demand better cables otherwise your just wasting your money.

[beanflying]

 Back when we were younger and even before I was born this thing of beauty was state of the art wiring for filters.

100k to 200k max is a guess 

Must find a place for it!

[tggzzz]

Last time I checked I ended up with something like $30 a cable, which is a bit too much. However, now I'm finding ones that are about $10 a pop and that seems reasonable enough.
Somehow they generally seem to be with a set attenuation, though.

The "somehow" is basic physics.

The manufacturers provide statements of attenuation vs frequency, usually in the form of tables. For standard types of cables (i.e. most of them) many people publish comparison tables. Attenuation at intermediate frequencies can be calculated using standard formulae.

Examples:
http://www.bcar.us/cablespec.htm
http://lss.fnal.gov/archive/other/lbl-cc-2-1b.pdf

[beanflying]

Unfortunately evilbay or aliexpress using 'lowest price first' are not manufacturers of truth or believable quoted specifications.

A recent video from fearless leader about 4mm banana jacks was interesting but his horrid batch didn't match my identical looking product at all. You want good it is off to the usual expensive suspects to buy genuine (not claimed to be) products. Or you do your own testing and decide to use or not.

Must invest is some of these speaking of ambit claims and Audiophile BS 'noise stoppers'

[Specmaster]

Are they noise stoppers because you can use them as ear plugs 

[bd139]

I think you’re supposed to hammer them into your temporal lobe 

[beanflying]

I am thinking suppository inserted by fellow audiophiles 

[Specmaster]

They will certainly keep the dust out 

[mnementh]

Gah been off TEA for a few days. Ear infection knocked me out. Missed all my watched items 

On a positive note got a massive dipole antenna, 30A switching supply,  a drum of RG8 and a not too miserable little 100W rig  turning up today and tomorrow. Can’t move so I’m going to become an EMC issue for the neighbours instead 

Feeling better now then, with all of those toys that you managed to snare despite missing some watched items 

Whats happening with this TEA group, we keep sliding down the position on the board lately. We always used to in the top 3 or 4, and very often top, tonight we are 32nd from the top, are we not finding anything on the ole Bay to post about or is money tight for everyone after Christmas.  Speaking of money, all of the money that you kissed goodbye to when your house chain collapsed, that would have brought a serious amount of TEA related goodies, that would have seriously given me the right hump.

Yes indeed feeling better. Been holding onto some cash for this enterprise for a bit. Wooh picture of arrival number one.



Currently working out which Anderson Powerpoles to buy. This bugger sucks 22A (!) at 13.8V so I don't want to smoke the connectors. Also the cable it comes with is as as stiff as and twice as thick as coat hangers.

There is literally bugger all happening on ebay. Diddly squat. It's terribly boring.

Very pissed about the cash gone out of the window but at the end of the day you can't dwell on things like that. Look forward and buy more things to play with instead.

On a positive note I don't think the place I was going to buy was very "antenna friendly". This might go in my favour in the long run 

You really should look into moving away from Sermos/APP connectors; they're unnecessarily bulky, expensive and simply don't have the low contact resistance required for seriously high current loads. Look into the XT60 (30A continuous/60A surge rated) or XT90 (90A continuous/120A surge rated) series commonly used for RC electronics; not only are they cheap as beans, (well, the XT60s are; ECC and XT90s are still generally cheaper than Sermos/APP connectors) you can plug them directly into 3S/4S LiPo packs running 12.8/11.4V nominal  at or 16.8/15.2V nominal.



If you need really small, there are XT30s rated 15A continuous/30A surge. 





ARRIS/AMASS makes an "Anti-Arcing" version of the XT90 that has a "precharging" resistor built-in; it makes contact just as you plug the connector together to charge up capacitors in equipment through a resistor before the plug completely seats for full power; this prevents arcing common with high-current connections that damages connectors and equipment.

Really... I used to swear by Sermos/APP connectors for DC power; now I swear at them. They're a PITA to disassemble, they fall apart all the time (even with CA on the joints) and they crack out at the drop of a hat. The only thing they have going for them is the fact that the contacts are interchangeable; stackable is a matter of argument, as the more you stack them the more they fall apart.

Also look into the power wiring used for RC applications; we have 12ga fine strand with silicone sheathing that is just butter-soft & flexible, and pretty cheap, even from Amazon.


mnem
*Juicy*

[bd139]

Those are rather cool. Thanks for the tip. Will look into that. To be honest today I just double wrapped the thing round the binding posts and screwed it down hard. Works, doesn’t get hot.

 When I was doing RC stuff (cars) we had little red block connectors with two blades. One was at 90 degree angle to the other. Can’t remember what the hell they were.

Got my switcher. It's quite happily blowing 15A into dummy load and doesn’t even bother to start up the fan. Quite impressed. Also only drops 70mV on a load transient. No overshoot!

[mnementh]

Those are rather cool. Thanks for the tip. Will look into that. To be honest today I just double wrapped the thing round the binding posts and screwed it down hard. Works, doesn’t get hot.

 When I was doing RC stuff (cars) we had little red block connectors with two blades. One was at 90 degree angle to the other. Can’t remember what the hell they were.

Got my switcher. It's quite happily blowing 15A into dummy load and doesn’t even bother to start up the fan. Quite impressed. Also only drops 70mV on a load transient. No overshoot!

ACCCKKK! Deans' Connectors! *Crosses fingers to ward off the harbingers of evil*

No, seriously... unshrouded connectors are a severe safety hazard, even in (especially in?) model RC. I lost my best-tuned car, and a race I was leading by half a lap, due to a Deans' connector working half-unplugged and arcing across a shock tower, blowing the top of the shock apart from the tower. The resultant crash looked like something from "Dukes of Hazzard"; cartwheeling end-over-end a dozen times before coming to a stop well inside the pit area.

Never. EVER. Again.

   

I was going to suggest a modded HP DPS-1100W for your power; 900W @12.4V (that's on 120V; 1200W @220V) in a package the size of a carton of cigarettes for about $20 delivered.You can get 13.5V with a simple internal mod; if 12V is okay you just need one 470-1000ohm resistor to turn it on.



There are also a number of vendors offering a plug-in board made for xxxCoin Mining at around $16 that hotwires the PSU, provides a 3-digit voltmeter and breaks the power out into 8-12 6-pin MOLEX connectors as commonly used on high-current Video cards; it depends on what you feel is more convenient. It is my understanding that this form of xxxCoin Mining (using multiple GPUs in tandem) is grossly inferior to Mining using custom ASICs, which are proliferating rapidly over the last few months. If this is the case, awesome cheap widgets like these may not be long for this world, so maybe a good idea to get a couple even if you're just thinking about it.

[EDIT]

Found it on AliEx for $14.30 for the next 14 hours

Found it here on AliEx for $11.43 with ePacket Shipping

Found a much more basic version here on AliEx for $5.88 with ePacket Shipping

Here's the whole search from AliEx, including various versions with & without cables

[/EDIT]


mnem
*Back to the bench*

[Cerebus]

Yes but Cambridge Instruments is a good quality maker, a top tier one if ever there was. Surprising really that the casing isn't made from walnut like a Rolls Royce dashboard is.

Why use cheap ol' native Walnut when you can use expensive imported tropical hardwoods like Mahogany, which is what that looks like to me. it's either Mahogany or Sapele (sometimes called African Mahogany).

[Specmaster]

Yes but Cambridge Instruments is a good quality maker, a top tier one if ever there was. Surprising really that the casing isn't made from walnut like a Rolls Royce dashboard is.

Why use cheap ol' native Walnut when you can use expensive imported tropical hardwoods like Mahogany, which is what that looks like to me. it's either Mahogany or Sapele (sometimes called African Mahogany).

Thanks, but what ever it is, sure looks great

[bd139]

Those are rather cool. Thanks for the tip. Will look into that. To be honest today I just double wrapped the thing round the binding posts and screwed it down hard. Works, doesn’t get hot.

 When I was doing RC stuff (cars) we had little red block connectors with two blades. One was at 90 degree angle to the other. Can’t remember what the hell they were.

Got my switcher. It's quite happily blowing 15A into dummy load and doesn’t even bother to start up the fan. Quite impressed. Also only drops 70mV on a load transient. No overshoot!

ACCCKKK! Deans' Connectors! *Crosses fingers to ward off the harbingers of evil*

No, seriously... unshrouded connectors are a severe safety hazard, even in (especially in?) model RC. I lost my best-tuned car, and a race I was leading by half a lap, due to a Deans' connector working half-unplugged and arcing across a shock tower, blowing the top of the shock apart from the tower. The resultant crash looked like something from "Dukes of Hazzard"; cartwheeling end-over-end a dozen times before coming to a stop well inside the pit area.

Never. EVER. Again.

   

I was going to suggest a modded HP DPS-1100W for your power; 900W @12.4V (that's on 120V; 1200W @220V) in a package the size of a carton of cigarettes for about $20 delivered.You can get 13.5V with a simple internal mod; if 12V is okay you just need one 470-1000ohm resistor to turn it on.



There are also a number of vendors offering a plug-in board made for xxxCoin Mining at around $16 that hotwires the PSU, provides a 3-digit voltmeter and breaks the power out into 8-12 6-pin MOLEX connectors as commonly used on high-current Video cards; it depends on what you feel is more convenient. It is my understanding that this form of xxxCoin Mining (using multiple GPUs in tandem) is grossly inferior to Mining using custom ASICs, which are proliferating rapidly over the last few months. If this is the case, awesome cheap widgets like these may not be long for this world, so maybe a good idea to get a couple even if you're just thinking about it.

[EDIT]

Found it on AliEx for $14.30 for the next 14 hours

Found it here on AliEx for $11.43 with ePacket Shipping

Found a much more basic version here on AliEx for $5.88 with ePacket Shipping

Here's the whole search from AliEx, including various versions with & without cables

[/EDIT]


mnem
*Back to the bench*

Good solutions there. I’ve got access to a metric fuck ton of HP C7000 supplies out of our blade systems. They are 12V 200A jobs. Could bring one of them up

My car also exploded. The connector overheated, melted and shorted. This caused the shell to vacuum form itself to the firey mess. Fortunately the solder melted before it got really bad.

[mnementh]

Are you sure? I could have sworn the C7000 backplane was 48V, as its design was lifted from CISCO's ATM Backbone design pretty much lock, stock & barrel... err, designed for compatibility thereof...

NM... brain faRT. that was the battery-powered setup, which then had its own AC power system for charging.

mnem
*Cudgels his memory with a swift thwack*

[bd139]

Well I managed to make smoke come out of my dummy load 

100W peak. Hmm. 20 seconds TX = woosh.

Interestingly the resistors in it have a shit tempco. Down to 16 ohms from 50 when hot. Thermal runaway here we come.   

[Specmaster]

Maybe you'd be better off in the tin shed after all then, more fire resistant 

[bd139]

Also known as an oven if I happen to be in it 

[mnementh]

I'm just gonna leave this here, where any dummy load might trip over it... 


mnem
*From the "Crude, but effective..." Department*

[Specmaster]

Also known as an oven if I happen to be in it 

Also known as a cremator when flames shoot out of the dummy load 

[bd139]

  My other half didn’t even turn her head when I said “fuck me that’s hot”. Think she’s used to it now.

I'm just gonna leave this here, where any dummy load might trip over it... 


mnem

That’s, err, interesting. In a 1950s style, similar to smoking a pipe while cleaning a live radio chassis with a bottle of IPA open on the living room table.