Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

Looking for suggestions... I know none of us here usually need motivation to acquire more TEA, but I've been assessing my lab over the last few days and have decided that the obvious missing device on my bench is a VTVM. What VTVM would you guys recommend? Keeping in mind - It shouldn't be the size of a truck. It shouldn't be some rarity that goes for silly money. It should be relatively easy to find in Europe. It should be a device where the schematics and parts are readily available.

McBryce.

Why a VTVM and not a FET-VM?   Why not a VTVM AND a FET-VM?

* whacks mansaxel on the snout with his own rolled-up newspaper because you said it*

There, FTFY.

mnem
The Recursion is strong with this one...

[0culus]

Hmm, a bit too much of a toy for my liking, also my eyes aren't up to squinting at a 2.8" 320x240 screen... Hook it to a 5" or greater screen and I might take a closer look, but I'd rather drop the cash on a HP/Tek etc, I just need to wade through the specs of all the different models...

HP 856x portables* are worth looking at if you don't need any real time capabilities for your application. The 8563E is a pretty sweet 26.5 GHz box, but there were several lower end options.
*they look like a portable CRO....but are much, much heavier...but at least they have a nice big handle. 

Agreed. The Tek49x aren't bad either.

I have an 8562B and 492AP, and both stretch my arms and compress my spine and knees. Acceptable for £350 and £250 respectively

A preselector is advantageous, unless you know how to avoid images

In both, replacing PSU electrolytics is an exercise in spelunking. The HP has an amazing hinge mechanism used to get at anything. The Tek doesn't require that for most things, but getting the "end cap" off the 492 shows you just how "clever" the designers were with squeezing connectors in there

As far as Tek goes, definitely don't want anything older than the 492 for sure. Don't be fooled by the 40 GHz spec...the 491 is a poor design and has serious performance issues that they fixed with the 492. The 492 itself is still somewhat suboptimal compared to the 494 in terms of center frequency accuracy (but it fixes the problems that beset the 491).

The 40GHz spec is with the external waveguide mixer, the front end of the 491 is bypassed. The 491 technically goes up to 12.4GHz. With a 494 and external mixer you could go up to 325GHz 

But yeah the 491 is really different and older than the rest of the 490 series.

Of course, that should be self evident to anyone who goes and reads the specifications. My comment was more geared towards "don't see 40 GHz for cheap and buy!" (unless of course you are trying to collect an example of anything and everything Tek ever made).

 My 8566B will do that too, except a 325 GHz mixer costs more than my house did. So unless someone gives me one, very unlikely I'll ever have one.  I'd rather get one of the HP made preselected mixers for the bands above the 8566B's own frontend. More likely to be useful to me, and they are preselected.

[Neomys Sapiens]

Good question... haha.

Couple gig bandwidth I guess. I can fix if needed but I don't want the rabbithole to be too deep. 2nd hand is fine for the superior (usually) price to features ratio. If I were to buy new, I'd probably look pretty hard at a Siglent.
I mainly need it for adjusting and repairing function generators and stuff. I don't do a bunch of RF stuff at the moment, but I do want room to grow.

Get an FSH4, at least it will not clutter your place too much.

[mnementh]

As far as Tek goes, definitely don't want anything older than the 492 for sure. Don't be fooled by the 40 GHz spec...the 491 is a poor design and has serious performance issues that they fixed with the 492. The 492 itself is still somewhat suboptimal compared to the 494 in terms of center frequency accuracy (but it fixes the problems that beset the 491).

The 40GHz spec is with the external waveguide mixer, the front end of the 491 is bypassed. The 491 technically goes up to 12.4GHz. With a 494 and external mixer you could go up to 325GHz 

But yeah the 491 is really different and older than the rest of the 490 series.

Of course, that should be self evident to anyone who goes and reads the specifications. My comment was more geared towards "don't see 40 GHz for cheap and buy!" (unless of course you are trying to collect an example of anything and everything Tek ever made).

 My 8566B will do that too, except a 325 GHz mixer costs more than my house did. So unless someone gives me one, very unlikely I'll ever have one.  I'd rather get one of the HP made preselected mixers for the bands above the 8566B's own frontend. More likely to be useful to me, and they are preselected.

Jeebus... just listening to you guys talk, I wanna cover my junk with a lead apron...

mnem
...and why does everything suddenly taste purple...?

[Kosmic]

My 8566B will do that too, except a 325 GHz mixer costs more than my house did. So unless someone gives me one, very unlikely I'll ever have one.  I'd rather get one of the HP made preselected mixers for the bands above the 8566B's own frontend. More likely to be useful to me, and they are preselected.

If I remember correctly Robert got a 492 with the external mixer still in the screen protector. Of course you then need all the wavequide piping and connectors to use it 

[Neomys Sapiens]

Another one covered..
and I found out that I'm short at least one tip/ring to BNC adaptor.

[mansaxel]

Depends. If it is the 'Ecoflex' brand, I would not recommend it. It is mainly pandered to not-so-discerning hams and the occasional stupid and stingy company. In my opinion, it never pays to go for the lowest offer in a category.

I actually have a few lengths of Ecoflex 10, but those are fixed installs inside flexible conduit where exposed to the elements, for my dual-band and 70cm antennas. Seems to work.

[tautech]

Question time.

How to measure jitter on a scope (TDS784C) that doesn't seem to have an obvious delayed sweep function? Unless it's called something different and I'm too dumb to work it out......?

Use the H Pos control to shift the trigger point way off the display and measure jitter on a rising edge long after the trigger point.

Also, I keep needing a spectrum analyzer, what sort of thing you you guru's suggest I look for? Preferably not a multiple boat-anchor stack of HP iron.... HP or Tek? etc?

Be careful with the tiny VNA's based on Joe Smith's latest findings.....they use a square wave for the stimulus whereas the industry has always used a sinewave.

[mansaxel]

Why a VTVM and not a FET-VM?   Why not a VTVM AND a FET-VM?

* whacks mansaxel on the snout with his own rolled-up newspaper because you said it*

Awww!  Why me?

[tautech]

Good question... haha.

Couple gig bandwidth I guess. I can fix if needed but I don't want the rabbithole to be too deep. 2nd hand is fine for the superior (usually) price to features ratio. If I were to buy new, I'd probably look pretty hard at a Siglent.
I mainly need it for adjusting and repairing function generators and stuff. I don't do a bunch of RF stuff at the moment, but I do want room to grow.

SSA3021X Plus.
Later when you need more capability these can be coaxed into believing they're a SVA1032X.

[Kosmic]

Be careful with the tiny VNA's based on Joe Smith's latest findings.....they use a square wave for the stimulus whereas the industry has always used a sinewave.

Small clarification, Joe Smith was talking about the Nanovna and not TinySA.

As for the squarewave on the Nanovna, for most passive device under test, it's not going to matter though. They still give you extremely good value for your money.

[Neomys Sapiens]

Depends. If it is the 'Ecoflex' brand, I would not recommend it. It is mainly pandered to not-so-discerning hams and the occasional stupid and stingy company. In my opinion, it never pays to go for the lowest offer in a category.

I actually have a few lengths of Ecoflex 10, but those are fixed installs inside flexible conduit where exposed to the elements, for my dual-band and 70cm antennas. Seems to work.

We had several cases of cable failures with Ecoflex 10 and 15 where there were no visible traces of installation Gorilla involvement. So I'm suspicious of those, although 1GHz might be different.

[TERRA Operative]

Hmm, well I've been looking at Siglent. Maybe an SSA3021X+ that is convinced to identify as a SVA1032X might do the trick, once I sell of a bunch of gear to pay for it.

What do people think of the Siglent gear?

[tautech]

Hmm, well I've been looking at Siglent. Maybe an SSA3021X+ that is convinced to identify as a SVA1032X might do the trick, once I sell of a bunch of gear to pay for it.

A couple of TEA members have done the SSA-SVA conversion however my advice is not to be in a hurry to venture into the VNA rabbit hole and instead get to know the SSA part well first. SSA capability remains unchanged when it becomes a SVA.

I have a factory SVA1032X after a couple of model upgrades and wouldn't now be without something with its capability. But like any of this stuff some RF knowledge needs be gained to use it safely plus acquisition of various fitments/cables to meet your needs.

[Robert763]

My 8566B will do that too, except a 325 GHz mixer costs more than my house did. So unless someone gives me one, very unlikely I'll ever have one.  I'd rather get one of the HP made preselected mixers for the bands above the 8566B's own frontend. More likely to be useful to me, and they are preselected.

If I remember correctly Robert got a 492 with the external mixer still in the screen protector. Of course you then need all the wavequide piping and connectors to use it 

It was a 492BP complete with the diplexer and 26.5 GHz mixer. The waveguide mixer happily detects "off air" signals from a harmonic generator (diode from a old LNB on a SMA with hairpin of wire driven at 3GHz) without any horn or "plumbing".
The TEK 492BP is a bit of a "sleeper". Very different from a "vanilla" 492 which does not even have direct frequency entry. The 492BP is basically a 494AP without the 10Hz RBW and it's associated touchy tmeperature controlled crystal filter.
Best RF perfomance for the money has to be a HP 8568A/B but it's a two box boat anchor.
I nearly bought a R&S FSH3 last month (SWMBO said it was bit much with January annual bills coming in). I've had a FSH3 before and it's a nice little analyser.
A lot depends on the local TE market Some of the Anritsu units may be more available to you. Don't forget that some radio test sets like the MT88xx and R&S CMU200,  CRTU have spectrum analysers built in but make sure the minmum frequency is low enough for you (or use an external mixer to down-convert.

[mnementh]

Why a VTVM and not a FET-VM?   Why not a VTVM AND a FET-VM?

* whacks mansaxel on the snout with his own rolled-up newspaper because you said it*

Awww!  Why me?

   *edited to reduce incendiary content*

Maybe this will serve as a reminder...?   

mnem
...also because AVGResponding hid his inflatable mallet. the bastard!

[Neomys Sapiens]

Why a VTVM and not a FET-VM?   Why not a VTVM AND a FET-VM?

* whacks mansaxel on the snout with his own rolled-up newspaper because you said it*

Awww!  Why me?

Real answer: do you think he could hit a Watershrew with that?

[Neomys Sapiens]

My 8566B will do that too, except a 325 GHz mixer costs more than my house did. So unless someone gives me one, very unlikely I'll ever have one.  I'd rather get one of the HP made preselected mixers for the bands above the 8566B's own frontend. More likely to be useful to me, and they are preselected.

If I remember correctly Robert got a 492 with the external mixer still in the screen protector. Of course you then need all the wavequide piping and connectors to use it 

It was a 492BP complete with the diplexer and 26.5 GHz mixer. The waveguide mixer happily detects "off air" signals from a harmonic generator (diode from a old LNB on a SMA with hairpin of wire driven at 3GHz) without any horn or "plumbing".
The TEK 492BP is a bit of a "sleeper". Very different from a "vanilla" 492 which does not even have direct frequency entry. The 492BP is basically a 494AP without the 10Hz RBW and it's associated touchy tmeperature controlled crystal filter.
Best RF perfomance for the money has to be a HP 8568A/B but it's a two box boat anchor.
I nearly bought a R&S FSH3 last month (SWMBO said it was bit much with January annual bills coming in). I've had a FSH3 before and it's a nice little analyser.
A lot depends on the local TE market Some of the Anritsu units may be more available to you. Don't forget that some radio test sets like the MT88xx and R&S CMU200,  CRTU have spectrum analysers built in but make sure the minmum frequency is low enough for you (or use an external mixer to down-convert.

What I like about the HP 856x in my company lab is the 'enhanced resolution x/t option', which enables you to make tuned pulse power measurements on selectable positions on a pulse train.

[mansaxel]

Maybe this will serve as a reminder...?   

Oh, I know and remember the weapon of choice, full and well. I was just asking why I was being hunted with it, when I was the one -- perhaps in a roundabout manner -- that first suggested FET or other solid state VOMen?  I'd understand that the second to come up with the suggestion could be hunted with the THWACKer for not reading up well, but the first to do so? (Had I been hit for forgetting the R&S vtvm, as I did, I'd taken it  as well deserved.)

Anyway, I was the one who brought the Dragon-Slaying News-Bearer into play, so I suppose I'd better stoichally endure :-D

No harm done.

[0culus]

As far as Tek goes, definitely don't want anything older than the 492 for sure. Don't be fooled by the 40 GHz spec...the 491 is a poor design and has serious performance issues that they fixed with the 492. The 492 itself is still somewhat suboptimal compared to the 494 in terms of center frequency accuracy (but it fixes the problems that beset the 491).

The 40GHz spec is with the external waveguide mixer, the front end of the 491 is bypassed. The 491 technically goes up to 12.4GHz. With a 494 and external mixer you could go up to 325GHz 

But yeah the 491 is really different and older than the rest of the 490 series.

Of course, that should be self evident to anyone who goes and reads the specifications. My comment was more geared towards "don't see 40 GHz for cheap and buy!" (unless of course you are trying to collect an example of anything and everything Tek ever made).

 My 8566B will do that too, except a 325 GHz mixer costs more than my house did. So unless someone gives me one, very unlikely I'll ever have one.  I'd rather get one of the HP made preselected mixers for the bands above the 8566B's own frontend. More likely to be useful to me, and they are preselected.

Jeebus... just listening to you guys talk, I wanna cover my junk with a lead apron...

mnem
...and why does everything suddenly taste purple...?

Just wait till you talk to the gamma spectroscopy hobbyists. 

[BU508A]

Looking for suggestions... I know none of us here usually need motivation to acquire more TEA, but I've been assessing my lab over the last few days and have decided that the obvious missing device on my bench is a VTVM. What VTVM would you guys recommend? Keeping in mind - It shouldn't be the size of a truck. It shouldn't be some rarity that goes for silly money. It should be relatively easy to find in Europe. It should be a device where the schematics and parts are readily available.

McBryce.

Why a VTVM and not a FET-VM?

Because only the VT can glow during normal operation. 

[Robert763]

As far as Tek goes, definitely don't want anything older than the 492 for sure. Don't be fooled by the 40 GHz spec...the 491 is a poor design and has serious performance issues that they fixed with the 492. The 492 itself is still somewhat suboptimal compared to the 494 in terms of center frequency accuracy (but it fixes the problems that beset the 491).

The 40GHz spec is with the external waveguide mixer, the front end of the 491 is bypassed. The 491 technically goes up to 12.4GHz. With a 494 and external mixer you could go up to 325GHz 

But yeah the 491 is really different and older than the rest of the 490 series.

Of course, that should be self evident to anyone who goes and reads the specifications. My comment was more geared towards "don't see 40 GHz for cheap and buy!" (unless of course you are trying to collect an example of anything and everything Tek ever made).

 My 8566B will do that too, except a 325 GHz mixer costs more than my house did. So unless someone gives me one, very unlikely I'll ever have one.  I'd rather get one of the HP made preselected mixers for the bands above the 8566B's own frontend. More likely to be useful to me, and they are preselected.

Jeebus... just listening to you guys talk, I wanna cover my junk with a lead apron...

mnem
...and why does everything suddenly taste purple...?

Just wait till you talk to the gamma spectroscopy hobbyists. 

You called?
My big detector is a 2 litre NaI(Tl) crystal. It's part of a Mirion SPIR Ident system. To bring TE into it the Maximus Energy software uses a Pico Technology USB 'scope for aquisition. The 16 bit ones have better resolution. I have a portable system based on that.
http://maximus.energy/index.php/category/gamma-detection/

[mnementh]

Maybe this will serve as a reminder...?   

Oh, I know and remember the weapon of choice, full and well. I was just asking why I was being hunted with it, when I was the one -- perhaps in a roundabout manner -- that first suggested FET or other solid state VOMen?  I'd understand that the second to come up with the suggestion could be hunted with the THWACKer for not reading up well, but the first to do so? (Had I been hit for forgetting the R&S vtvm, as I did, I'd taken it  as well deserved.)

Anyway, I was the one who brought the Dragon-Slaying News-Bearer into play, so I suppose I'd better stoichally endure :-D

No harm done.

Mostly because it seemed so ironic. But you can still blame AVGResponding for hiding his inflatable mallet, thereby making you the easy target.

Ummm... did you mean to stoically endure, or to stochastically endure? 

I mean... I'm pretty sure you are fully capable of doing it either way; just the latter... Well, I'd pay good money to watch that. 

mnem
"Oh, look... dinner and a show...!" 

[mnementh]

Looking for suggestions... I know none of us here usually need motivation to acquire more TEA, but I've been assessing my lab over the last few days and have decided that the obvious missing device on my bench is a VTVM...

Why a VTVM and not a FET-VM?

Because only the VT can glow during normal operation. 

Nuh-uhhhhh!!! I can glow during normal operation too... just takes a few toddies for my body at lunchtime. 

mnem
"Lunchtime... launchtime...? Depends on your personal ABV, dunn'it...?"

[Vince]

Mouarf.... trying to fix a VCR, first one in my life, never worked on these things before...
It was given to me and I thought hell, would be cool to (try to...) fix it as an exercise and to have at least one VCR around, you never know when you might need one... seeing as I tend to like old stuff, who knows, might come handy one day.

Anyway. First it did not power up at all. Was bloody RIFA. Removed it, works fine now. don't have VHS tapes but the old guy who donated the VCR also donated a tape of Star Wars the Phantom Menace.

Anyway it plays the tape... audio is just fine, I can hear the movie sound track just fine, but no video ! 

I tried using SCART and video composite on two different LCD monitors equipped with these I/O, and every time the same answer : " No sync ", and a black screen, so not happy.

Looked at the schematic, have partial ones, not the main board sadly... but have the one for the rear panel PCB that carries the I/O connectors, and plugs right angle to the mother board.
I see that the video composite signal comes from a chip on this board, and is served to both the RCA jack AND the SCART connector. Apparently SCART has both RGB and composite signals available. I don't know which one the monitors actually use when I ask them to display SCART. Anyway, at least if make some sense that both SCART and composite would not work...

Anyway, I scoped the composite signal on the RCA jack, and to me looks like a I do have my composite signal ?!  So why doesn't it work ?! 

I know squat about video let's be clear.... I simply looked at Google to find diagrams of what it should look like. I have my negative sync pulse, about 5us as it should. Total frame length is about 64µs as measured with the cursors, which is what it should be about. So as far as sync goes, the LCD monitors should be able to detect a signal eh ?! 

My two main worries that might explain the problem (?!), tell me what you think :

- Noise... as you can see from the video clip below and my screenshot, there is lots of noise... but that could just be my probing setup which is more than awful of course, not having a BNC to RCA adapter nor even a coax cable.. so just using my probe in x1 and a little contraption made from recycled RCA jacks. It's too ugly to be showed here, don't want to stoned.

- Looks like there is a HF signal superimposed on everything, whose vertical excursion spans the entire composite signal... looks like faint squiggly lines at the top and bottom of the waveform.  This does not show on wave form diagrams I see on the net.. however I understand there are two combined signals on these things, "luminance" and "chrominance", so maybe what looks like squiggly lines is just one of those two signals and everything is fine . I am so clueless it's painful.

- Voltage levels : 99% of the diagrams I found do NOT indicate voltage levels. Instead they use funny "IRE" units, whatever that means, to give the proportions of the various parts of the signal, but not actual voltages. Proportions look fine on my signal, I find. Video content is about 2+ as high as the sync pulse.
The rare diagrams I found that did indicate voltage levels, showed a 1Vpp excursion, but I get as you can see 2.5Vpp or so ! 

It's so horrible to hear the sound track of Star Wars but not being able to see the video even though I can see it on the scope !!! 

Anyone here with working knowledge of composite signals ? I am in Frog land so I guess we are talking SECAM, though from what I see, SECAM / PAL / NTSC have very similar looking wave forms...