Test Equipment Anonymous (TEA) group therapy thread

[0culus]

Well that's one lazy bastard we have here !

Here you go, still hot from the oven...

Thanks...someone (not me) soldered the white wire and the bare wire to the same lug of the fuse holder. Pretty sure that bypasses the fuse entirely, probably the same person who dropped it on the fuse holder and broke it off completely.  Well, no matter. Gonna rip it out and put a good one in...and wire it correctly.

[0culus]

Check this bodge job out.

[bd139]

LMAO that’s horrible. That’s got to be at least 50A that fuse 

Fun job of the evening. Not. Trying to build 300Hz RBW filter for my SA. This unfortunately requires me to build a half decent crystal filter which means matching a shit ton of crystals by hand then characterising them further later. Frequency binning in progress 

[Specmaster]

Suicide wiring 

Should be fine, they made sure it was on the neutral. 

Just don't blow the fuse...

? Fuse blew yesterday :

https://www.eevblog.com/forum/repair/tektronix-type-575-curve-tracer-repair-and-restoration/msg3682549/#msg3682549

I am still alive...  I still don't get what's wrong... it's wired according to the original schematic, it's just a bloody fuse in series with the AC and transformer primary, just like in any modern appliance I have ever seen.

You will have to be much more specific please, because I am really at a loss as to what bothers you here ?! 
I hate to be the one missing the elephant in the room, but...

I think bd is referring to the bare conductor from the fuse holder, surely it is easy enough to use a small length of normal insulated wire to make that connection. Are you sure that the fuse is in the neutral, that bare wire goes to the brown cable which is normally the hot wire.

[Saskia]

blank unisolated AC in contacts. Make you bzzzzzzt when you touch them even accidentally.

Ah that's all ? Well  all glowing Tek scopes are like that... there is 3000 or 500V DC all around the scope for you to die from, so the mere 240V AC from the power socket is understandably hardly a concern in comparison !? 

I thought BD spotted a particular wiring problem / bodge on my particular unit. Didn't think he was making a general purpose comment on all Tek scopes. My bad.

can't speak for any other of those wiring issues, I don't have any of those scopes.

[Vince]

Thanks...someone (not me) soldered the white wire and the bare wire to the same lug of the fuse holder. Pretty sure that bypasses the fuse entirely, probably the same person who dropped it on the fuse holder and broke it off completely.  Well, no matter. Gonna rip it out and put a good one in...and wire it correctly.

Ah well he bypassed the fuse to get the 575 going after he broke the fuse holder... luckily you will fix that.

Still, your 575 looks NIB compared to my crusty one. So, I will happily swap 575 with you. You will get an UNdamaged fuse holder, and me a pristine 575, I think it's fair no ? !

[Specmaster]

LMAO that’s horrible. That’s got to be at least 50A that fuse 

Fun job of the evening. Not. Trying to build 300Hz RBW filter for my SA. This unfortunately requires me to build a half decent crystal filter which means matching a shit ton of crystals by hand then characterising them further later. Frequency binning in progress 

Aren't those crystals already marked with their frequencies then? All of mine are, although I have checked them, but they were all correctly marked already?

[Vince]

I think bd is referring to the bare conductor from the fuse holder, surely it is easy enough to use a small length of normal insulated wire to make that connection.

Ah ok !    Well yeah I guess they could have... but again there much more lethal voltages exposed throughout the scope, so I guess the idea was that if a service tech is stupid enough to touch that wire, he would not survive working on any tube based piece of equipment to begin with. Darwin and all that, I guess ...but yeah, I agree, regardless, using an insulation wire would reduce exposure to AC so why did they not do it .... I don't know ....

Are you sure that the fuse is in the neutral, that bare wire goes to the brown cable which is normally the hot wire.

Wire colours mean nothing in France, plugs are not polarized. Brown or blue doesn't matter, you can't rely on colours...

[bd139]

LMAO that’s horrible. That’s got to be at least 50A that fuse 

Fun job of the evening. Not. Trying to build 300Hz RBW filter for my SA. This unfortunately requires me to build a half decent crystal filter which means matching a shit ton of crystals by hand then characterising them further later. Frequency binning in progress 

Aren't those crystals already marked with their frequencies then? All of mine are, although I have checked them, but they were all correctly marked already?

Yep. 4.9152 MHz with 30pF loading.

That’s fine for oscillators but not for filters! The motional parameters of the crystals are all slightly different so they can vary in the same fixture by up to 100Hz or so. To get a fairly ripple free narrow filter I need really tight matching between them. Ideally I need to find 8 within 5Hz or so with close Lm and Cm.

This is unfortunately why I’ve got a bag of 200 to go through to select some by hand.

This is also why crystals are a few pence each but crystal filters are £100+ 

[mansaxel]

LMAO that’s horrible. That’s got to be at least 50A that fuse 

Fun job of the evening. Not. Trying to build 300Hz RBW filter for my SA. This unfortunately requires me to build a half decent crystal filter which means matching a shit ton of crystals by hand then characterising them further later. Frequency binning in progress 

Aren't those crystals already marked with their frequencies then? All of mine are, although I have checked them, but they were all correctly marked already?

I believe the process called "matching" or "selection" is taking place.

[0culus]

Thanks...someone (not me) soldered the white wire and the bare wire to the same lug of the fuse holder. Pretty sure that bypasses the fuse entirely, probably the same person who dropped it on the fuse holder and broke it off completely.  Well, no matter. Gonna rip it out and put a good one in...and wire it correctly.

Ah well he bypassed the fuse to get the 575 going after he broke the fuse holder... luckily you will fix that.

Still, your 575 looks NIB compared to my crusty one. So, I will happily swap 575 with you. You will get an UNdamaged fuse holder, and me a pristine 575, I think it's fair no ? !

If you were close enough, I'd sell it to you after I finish fixing it. Unfortunately these aren't very shippable due to the fragility of the CRT mount setup....very much need to do local pickup.

[mansaxel]

Wire colours mean nothing in France, plugs are not polarized. Brown or blue doesn't matter, you can't rely on colours...

but but but the grounded french plug is polarized, no?

I don't care, to me live and neutral are equivalent in 1-phase circuits. The Schuko plug indeed is unpolarized. But the french plug can only go in one way.

[0culus]

OK, it is rewired correctly now. I also found that I don't have any extra 4A slow blow fuses on hand so I'll have to order some before proceeding with troubleshooting. I really need to make me a dim bulb set up.

[AVGresponding]

Here's one for you to have a tilt at Saskia:

https://www.ebay.co.uk/itm/174936181156

[Vince]

Wire colours mean nothing in France, plugs are not polarized. Brown or blue doesn't matter, you can't rely on colours...

but but but the grounded french plug is polarized, no?

No it isn't.

All you know is that neutral is connected to earth.. but you can't rely on colour wire to know which wire is actually neutral or live...
You can't know just by looking at the power outlet, where is the neutral and where is live. If one really cares about it, he can just test for it by himself...

[Vince]

Thanks...someone (not me) soldered the white wire and the bare wire to the same lug of the fuse holder. Pretty sure that bypasses the fuse entirely, probably the same person who dropped it on the fuse holder and broke it off completely.  Well, no matter. Gonna rip it out and put a good one in...and wire it correctly.

Ah well he bypassed the fuse to get the 575 going after he broke the fuse holder... luckily you will fix that.

Still, your 575 looks NIB compared to my crusty one. So, I will happily swap 575 with you. You will get an UNdamaged fuse holder, and me a pristine 575, I think it's fair no ? !

If you were close enough, I'd sell it to you after I finish fixing it. Unfortunately these aren't very shippable due to the fragility of the CRT mount setup....very much need to do local pickup.

No worries  -->  you can sell it me void of CRT (and void of all tubes as well it you want), just the empty shell. My CRT works fine as do all the tubes.
This way no risk during transport + you can sell it cheaper to me + you get to keep some spare parts for your remaining 575 ! 
Shipping cost wold probably be prohibitive though... I don't know.


Anyway, not in a position to buy anything expensive at the moment, and need to build the garage to get more space, so it won't be on the agenda for at least a couple years I would think !  So.... let's carry on with the restoration of my ruin, who knows maybe I will do a good job at it, it will sparkle and I won't even feel so jealous of yours anymore ?! 

[Saskia]

Here's one for you to have a tilt at Saskia:

https://www.ebay.co.uk/itm/174936181156

bid placed ...

[Wolfgang]

Check this bodge job out.

Thats a very convincing applicant for the Darwin award. Chapeau !! 

[Zucca]

The noise it produces is quite excessive so this one will go to a room where the noise will not bother me.

any rack server gizmo is sooo fuu noisy... not good for your delicate audioquality ears....
I have to calm down also my C2960X

[Zucca]

Check this bodge job out.

looks like a mosquito HV trap

[Kosmic]

¹ Sadly, the lawyers from Keysight pulled an ugly stunt and called off Ben Riddle, because of NDAs, intellectual properties and other stupid reasons.
Keysight is working really hard to permanently damage their reputation.     

Not sure what's going on with Keysight. Apparently, they stopped selling critical parts for the 3458a to individuals. This is particularly a problem with the ADC board that tend to die in 50% of the 3458a.

Was always thinking of eventually getting a 3458a but recently changed my mind since I might well end up with an unrepairable brick.

Probably has more to do with the fact that they are making new 3458As again. 

https://www.keysight.com/us/en/product/3458A/digital-multimeter-8-5-digit.html

They never really stopped producing the 3458a. Doesn't really explain why they don't want to sell parts anymore. Why do we have to pay for the service on top of the parts ? which is super expensive. The only real reason I see is that they are making a lot more money that way.

I tried to buy some parts for my 34401a some times ago with Keysight Canada and it was really not a good experience. I had to call someone (no online store) and they were charging me shipping (super expensive for a small plastic part) and a fee because I was not ordering enough. A simple 15$ part ended up being 80$.

[Specmaster]

I think bd is referring to the bare conductor from the fuse holder, surely it is easy enough to use a small length of normal insulated wire to make that connection.

Ah ok !    Well yeah I guess they could have... but again there much more lethal voltages exposed throughout the scope, so I guess the idea was that if a service tech is stupid enough to touch that wire, he would not survive working on any tube based piece of equipment to begin with. Darwin and all that, I guess ...but yeah, I agree, regardless, using an insulation wire would reduce exposure to AC so why did they not do it .... I don't know ....

Yeah for sure there are far higher voltages in the scope, but they do not leave bare wires carrying them all over the place where it is perfectly feasible to touch them accidentally do they. That wire on the fuse holder is not just a terminal such as the one on the fuse holder, but a long exposed wire, some 20 to 30 mm into the chassis, right where fingers and hands, and not to mention tools might well be used. That fact alone makes that a deadly situation that should not have been there.

Having non polarised plugs in France just makes things even more dangerous, without other higher voltages present as well, 230 Volts is not a voltage to take lightly, especially with the sheer power of the 230 volt system is capable of delivering.

[mnementh]

LMAO that’s horrible. That’s got to be at least 50A that fuse 

Fun job of the evening. Not. Trying to build 300Hz RBW filter for my SA. This unfortunately requires me to build a half decent crystal filter which means matching a shit ton of crystals by hand then characterising them further later. Frequency binning in progress 

Aren't those crystals already marked with their frequencies then? All of mine are, although I have checked them, but they were all correctly marked already?

Yep. 4.9152 MHz with 30pF loading.

That’s fine for oscillators but not for filters! The motional parameters of the crystals are all slightly different so they can vary in the same fixture by up to 100Hz or so. To get a fairly ripple free narrow filter I need really tight matching between them. Ideally I need to find 8 within 5Hz or so with close Lm and Cm.

This is unfortunately why I’ve got a bag of 200 to go through to select some by hand.

This is also why crystals are a few pence each but crystal filters are £100+ 

Awww... who do you think you're kidding, bd? We can hear you grinning like a fool all the way over here.  You like this shit almost as much as winding toroids... 

mnem
 

[vk6zgo]

It's all good fun until he starts asking where he could find a cheap, big klystron. 

Nahhh...klystrons are fairly narrowband. If he asks where he can get a coupled cavity TWT and a BWO to drive it, then I'll worry. 

No, brute force electronic countermeasures is so passe. Stealth is the way. work out what muxes she uses most and how long a noise burst is needed to upset the decoder then just inject that. Much harder to detect.
Beware that she may go to cable though.

I remember scanning around with an RTL-SDR stick a few years ago and finding an stray narrow FM signal on a few hundred Mhz - not any ISM band I could recognize - that turned out to be audio from a TV. Not sure if they had an wireless headphone transmitter from some weird part of the world or it was blasting out of the TV. If the latter, it should be susceptible in the other direction as well...

Some years ago, I found such kind of signal in the 860MHz range - it was the elderly neighbours wireless TV headphone, indeed.

Many years ago, when I looked after country TV stations, we had a complaint from the WA Police, that every morning, when the ABC commenced transmission, their VHF comms got wiped out.
We came along, armed to the teeth with spectrum analysers & anything else deemed appropriate, gave the site a full going over, only to find nothing!

Rang the Boss, who passed it on to the Cops.

It later turned out that a local lady had an antenna amplifier, which was unstable, & prone to oscillation.
She was a great fan of the National broadcaster, & every morning, at startup time, would fire up the TV & the amplifier.
The latter was spewing crud right across the VHF high band , straight down the throat of the Police comms antenna.

The amp was a legacy device from when the nearest TV transmitter was several hundred km away, & was no longer necessary.
I don't know who talked her out of using it, whether the  "nice local policeman", the licencing authority, or someone from our own organisation, but she did, & all was well---------she could continue her viewing, the cops could continue their policing, & we could get back to some real problems!

[vk6zgo]

Fluke 8050A appeared on eBay. Unstable readings due to beer accident   

Well, we've all been there....

Ummm... in your case, I 'spect the unstable readings are due to meeting up with a mate and "accidentally" drinking 3 pitchers of beer. Yourself.

mnem
*remembers singing the wibbly-wobbly-walky-walk song more than a few times myself*

[Fx: googling] So, 1 pitcher = 3 1/3 imperial pints (aka proper pints)  = 1.89 L.

OK, guilty as charged; the evening's only just starting on 2 pitchers (6 2/3 pts), but in my day I probably wouldn't have stopped at 3.

Nah, the beer isn't to blame!
After all, you are only drinking it as chasers after the Scotch!

I've only been really, severely, drunk on a few occasions, & in the two worst, it was Scotch with beer chasers.

The first was in Wyndham, a "cowtown" in tropical Western Australia.
The second was in "John O' Groats" in midwinter.

In climate, you couldn't find two more dissimilar places, but both were pretty much "at the end of the road", & the people in each place were "fond of a drink"!