Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 1620405 times)

mansaxel, mnementh, exor and 5 Guests are viewing this topic.

Offline Kosmic

  • Frequent Contributor
  • **
  • Posts: 637
  • Country: ca
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29375 on: April 15, 2019, 05:21:31 pm »
RTL-SDR V3 is pretty good. A bit more expensive than the generic one but with the metal enclosure heat dissipation is a lot better (A problem to be able to lock the pll at different frequencies).

The creator of SDR# was eventually hired by AirSpy and is now developing software over there. SDR# is still available for free and you can use it with generic R820T based hardware (ex RTL-SDR V3).

For a overview of the different SDR platforms, check this link https://www.rtl-sdr.com/roundup-software-defined-radios/

FYI, you can find really cheap R820T + RTL2832 tuner for 6$ on ebay. https://www.ebay.com/sch/i.html?_from=R40&_nkw=RTL2832&_sacat=0&_sop=15
 

Online mnementh

  • Super Contributor
  • ***
  • Posts: 4380
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29376 on: April 15, 2019, 05:38:56 pm »
Er... Digital signals exist in the digital domain, by definition. There is nothing analogue about 0, 1, 0xdeadbeef etc.

Adding the time domain changes absolutely nothing of that
.
Quote

Okaaaayyy... I'm a little busy packing a 454 for shipping to its new home, but of course I've built a Mod-5 using flip-flops. Normally need at least two transistors to make a discrete flip-flop, and then something for the reset, but I remember reading a Hackaday about a DTL circuit that uses a single transistor as a flip-flop, but as tested it was limited to under 1 MHz operation. Not sure if that's what you had in mind, or something more along the lines of "analog computer" design wherein "operations" are performed as a function of RC/LC,etc time constants and LF heterodyning.
The circuit bd139 showed indicated one way. I think (without verifying it) that the Tek 184 uses a different way. No flip flops involved, only "glugs" - to use the lovely and descriptive) term frequently found in high precision voltmeters.
I remembered seeing bd's circuit from a while back, but couldn't be arsed to dig it up.  :-[

In my defense, I'm a little preoccupied saying goodbye to an old friend that's been with me for decades, but I haven't treated very well of late.  :-\

The only difference between a PWM voltage and a serial comms signal is convention (what is the acceptable amplitude/duration) and the fact of sampling over a given time window. Both have to exist as analog signals first.

This concept is obviated by the fact that multi I/O pins on modern processors often treat both interchangeably; creating an alternate serial data channel by modulating a PWM out at given frequency and amplitude to send serial data, or sampling an ADC IN similarly to receive serial data.

Come on man; we're arguing over semantics & terminology here.


mnem
*rummage... rummage... rummage...*

 

Online tggzzz

  • Super Contributor
  • ***
  • Posts: 9456
  • Country: gb
    • Having fun doing more, with less
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29377 on: April 15, 2019, 06:31:26 pm »
Er... Digital signals exist in the digital domain, by definition. There is nothing analogue about 0, 1, 0xdeadbeef etc.

Adding the time domain changes absolutely nothing of that
.
Quote

Okaaaayyy... I'm a little busy packing a 454 for shipping to its new home, but of course I've built a Mod-5 using flip-flops. Normally need at least two transistors to make a discrete flip-flop, and then something for the reset, but I remember reading a Hackaday about a DTL circuit that uses a single transistor as a flip-flop, but as tested it was limited to under 1 MHz operation. Not sure if that's what you had in mind, or something more along the lines of "analog computer" design wherein "operations" are performed as a function of RC/LC,etc time constants and LF heterodyning.
The circuit bd139 showed indicated one way. I think (without verifying it) that the Tek 184 uses a different way. No flip flops involved, only "glugs" - to use the lovely and descriptive) term frequently found in high precision voltmeters.
I remembered seeing bd's circuit from a while back, but couldn't be arsed to dig it up.  :-[

In my defense, I'm a little preoccupied saying goodbye to an old friend that's been with me for decades, but I haven't treated very well of late.  :-\

The only difference between a PWM voltage and a serial comms signal is convention (what is the acceptable amplitude/duration) and the fact of sampling over a given time window. Both have to exist as analog signals first.

In that example, the 8-bit digital signal is transmitted by the modulation scheme you mention. The serial comms voltages are a first-order hold of the sampled digital signal.

There are, of course, many other ways of transmitting digital signals. A 64 bit digital signal could be transmitted on 64 separate frequencies e.g. COFDM, or as multiple amplitudes and phases e.g. 64QAM with added noise:


Quote
This concept is obviated by the fact that multi I/O pins on modern processors often treat both interchangeably; creating an alternate serial data channel by modulating a PWM out at given frequency and amplitude to send serial data, or sampling an ADC IN similarly to receive serial data.

That is indeed one implementation technology that is around at the moment.

There have been many over the years, e.g. one from near where I grew up:



Quote
Come on man; we're arguing over semantics & terminology here.

It is a deeper distinction than that, and philosophically quite interesting.

But it isn't (pure) TEA, and while it may deserve a separate thread, it isn't too relevant to a TEA thread. (Not that direct relevance has been too important in the past!).
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Online GreyWoolfe

  • Super Contributor
  • ***
  • Posts: 3180
  • Country: us
  • NW0LF
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29378 on: April 15, 2019, 06:43:54 pm »
This probably should have gone into the 'what did you buy today' thread but I know how much everyone absolutely HATES nixie tubes.  I was at my ham club's annual tailgate party and the president of the club offered this to me for $2.00.  He said it wouldn't power up and he didn't check the fuse.  When I brought it home, I did a quick check of the fuse and it was good.  I was outttatime as there was much to do, so I played with it a bit today and found the oddball fuse holder knackered.  I wasn't able to restore continuity, so I spliced in a an inline fuse holder I had and it worked.  I will let it warm up and I will warm up my DMMCheck + and get some readings off of it.  It does have the AC and Ohms converters and the read input.  The case looks like it has been rode hard and put away wet.  There are what appears to be rust lines on it, like a wet piece of equipment has been put on it and left to rust.  Also, there was only 1 foot, 1 partial, 1 very small piece of foot holding the screw in place and 1 missing.  I added feet to it so it at least sits up off of the bench.  It was last calibrated 2/13/92 with the AC calibrated from 50 Hz to 50 KHz.  After I check measurements, I will add more pictures and maybe even a peek under the skirt.  Then there will be the job of trying to find a place for it.  I don't really have a need for a pizza box but it does have nixies.

EDIT:  After running a couple of minutes, it appears the 3rd tube from the right wants to display all the numbers.  Any suggestions what to look for and does anyone have the service manual for it?

EDIT 2:  Tube is fine.  I wiggled it around as I couldn't quite get a grip to pull it and reseat it.  Issue went away.  I am thinking of spending $10 and getting the manuals and schematics from Artek Manuals.

« Last Edit: April 16, 2019, 01:46:24 am by GreyWoolfe »
That which doesn't kill you still requires a co-pay.
 
The following users thanked this post: med6753

Offline med6753

  • Super Contributor
  • ***
  • Posts: 3479
  • Country: us
  • Tek nut
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29379 on: April 15, 2019, 07:24:21 pm »
Decided to go to my local post office and find out when the hell the 4x attenuator will be delivered. The answer involves .gov so serve up the  :bullshit: :bullshit: on a plate.  :palm:

Anyway, the package is indeed in JFK customs. As it was explained to me first class mail goes through customs real quick. Qservice sent the attenuator registered mail. That causes the package to fall into a customs black hole only to emerge whenever customs gets good and ready. And until they do USPS can do NADA. So both me and USPS are at their mercy until they get off their ass and release the package.  :rant: :rant:
An old gray beard with an attitude.
 

Online bitseeker

  • Super Contributor
  • ***
  • Posts: 7709
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29380 on: April 15, 2019, 07:25:04 pm »
Things that make you go, hmmm...

(Unsure of the scale, but an appropriately sized version of that might work as a cover for a 454 screen.)
You don't say...  >:D
Yeah, well, I just had to, since you left it in that post so teasingly without even so much as an "ahem." :-DD

ahem.  >:D

 :scared: :popcorn:
I TEA.
 

Online bitseeker

  • Super Contributor
  • ***
  • Posts: 7709
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29381 on: April 15, 2019, 07:26:48 pm »
I got an RTL-SDR Blog V3 kit a few months ago. I don't know if it's better or worse than the NESDR or others. Apparently there are knockoffs of the RTL-SDR Blog V3, so I bought mine from the RTL-SDR Blog's eBay store.

For software, I use it with SDR#. It seems the original SDR# URL now redirects to airspy.com. I'm not sure what that means. You can still get SDR# on their download page, but it seems to be bundled with other stuff, now.

I got the dongle primarily to be able to check if a transmitter (e.g., RF remote) is functioning. But, using it to listen to FM and shortwave works as expected, too.

RTL-SDR V3 is pretty good. A bit more expensive than the generic one but with the metal enclosure heat dissipation is a lot better (A problem to be able to lock the pll at different frequencies).

The creator of SDR# was eventually hired by AirSpy and is now developing software over there. SDR# is still available for free and you can use it with generic R820T based hardware (ex RTL-SDR V3).

For a overview of the different SDR platforms, check this link https://www.rtl-sdr.com/roundup-software-defined-radios/

Thanks for the info, Kosmic. I suspected some kind of acquisition or something.
I TEA.
 

Online bitseeker

  • Super Contributor
  • ***
  • Posts: 7709
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29382 on: April 15, 2019, 07:28:08 pm »
How does the RTL-SDR do at lower frequencies? The NooElec NESDR is specced at 65MHz bottom end and they sell an up converter for covering HF and the lower end.

Most of them don't go below 24Mhz. This is due to the R820T chip. Was initially designed to receive digital TV and was suposed to only work between 42Mhz and 1000Mhz. Can actually do 24 - 1700Mhz

https://rtl-sdr.com/wp-content/uploads/2013/04/R820T_datasheet-Non_R-20111130_unlocked.pdf

The RTL-SDR V3 can do 500 kHz - 24 MHz via direct sampling. I haven't tried it, yet. From what I read, before this version, there was a hardware hack to enable it. No need to anymore.
I TEA.
 
The following users thanked this post: beanflying

Online mnementh

  • Super Contributor
  • ***
  • Posts: 4380
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29383 on: April 15, 2019, 07:28:38 pm »
Er... Digital signals exist in the digital domain, by definition. There is nothing analogue about 0, 1, 0xdeadbeef etc.

Adding the time domain changes absolutely nothing of that
.
Quote

Okaaaayyy... I'm a little busy packing a 454 for shipping to its new home, but of course I've built a Mod-5 using flip-flops. Normally need at least two transistors to make a discrete flip-flop, and then something for the reset, but I remember reading a Hackaday about a DTL circuit that uses a single transistor as a flip-flop, but as tested it was limited to under 1 MHz operation. Not sure if that's what you had in mind, or something more along the lines of "analog computer" design wherein "operations" are performed as a function of RC/LC,etc time constants and LF heterodyning.
The circuit bd139 showed indicated one way. I think (without verifying it) that the Tek 184 uses a different way. No flip flops involved, only "glugs" - to use the lovely and descriptive) term frequently found in high precision voltmeters.
I remembered seeing bd's circuit from a while back, but couldn't be arsed to dig it up.  :-[

In my defense, I'm a little preoccupied saying goodbye to an old friend that's been with me for decades, but I haven't treated very well of late.  :-\

The only difference between a PWM voltage and a serial comms signal is convention (what is the acceptable amplitude/duration) and the fact of sampling over a given time window. Both have to exist as analog signals first.
In that example, the 8-bit digital signal is transmitted by the modulation scheme you mention. The serial comms voltages are a first-order hold of the sampled digital signal.

There are, of course, many other ways of transmitting digital signals. A 64 bit digital signal could be transmitted on 64 separate frequencies e.g. COFDM, or as multiple amplitudes and phases e.g. 64QAM with added noise:


Quote
This concept is obviated by the fact that multi I/O pins on modern processors often treat both interchangeably; creating an alternate serial data channel by modulating a PWM out at given frequency and amplitude to send serial data, or sampling an ADC IN similarly to receive serial data.

That is indeed one implementation technology that is around at the moment.

There have been many over the years, e.g. one from near where I grew up:



Quote
Come on man; we're arguing over semantics & terminology here.
It is a deeper distinction than that, and philosophically quite interesting.

But it isn't (pure) TEA, and while it may deserve a separate thread, it isn't too relevant to a TEA thread. (Not that direct relevance has been too important in the past!).



 :P

Things that make you go, hmmm...

(Unsure of the scale, but an appropriately sized version of that might work as a cover for a 454 screen.)
You don't say...  >:D
Yeah, well, I just had to, since you left it in that post so teasingly without even so much as an "ahem." :-DD

ahem.  >:D

:scared: :popcorn:

You'll be glad I did.  ;D

mnem
IT FITS!!!
 

Online bitseeker

  • Super Contributor
  • ***
  • Posts: 7709
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29384 on: April 15, 2019, 07:49:34 pm »
I TEA.
 

Offline wch

  • Frequent Contributor
  • **
  • Posts: 422
  • Country: us
  • always certain, often wrong.
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29385 on: April 15, 2019, 07:55:35 pm »
I admit it, I have a case of 427A envy, so I was on ebay, you know, just looking around.  From Israel comes this beauty, which was apparently stored in a bucket of water:



The seller is asking a mere fifty dollars for it and will spring for shipping.  Oddly enough, he included no photos of the instrument's interior. :-DD

Then on CL and found this:



Which was apparently found outside in a pile of trash. Based on the number of broken knobs, it must have been dropped face down at one point. The seller actually powered it up on a variac and said it didn't catch on fire. He is currently entertaining offers.

I admit that I am tempted by the 468. I think I have a problem.  ::)
proceed until apprehended
 

Online bitseeker

  • Super Contributor
  • ***
  • Posts: 7709
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29386 on: April 15, 2019, 08:11:29 pm »
I wonder if that 427A is from the infamous seller in that geo-location. Then again, it's in too good of a condition. ;D
I TEA.
 

Offline factory

  • Regular Contributor
  • *
  • Posts: 194
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29387 on: April 15, 2019, 08:37:22 pm »
I wonder if the 427A description was lost in translation.
Quote
This item is in very good condition
Just noticed the side frame is split.
Why is the condition listed as "New other" ?  :palm:

David
« Last Edit: April 15, 2019, 08:39:59 pm by factory »
 

Offline Tomorokoshi

  • Frequent Contributor
  • **
  • Posts: 742
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29388 on: April 15, 2019, 08:53:30 pm »
I wonder if the 427A description was lost in translation.
Quote
This item is in very good condition
Just noticed the side frame is split.
Why is the condition listed as "New other" ?  :palm:

David

Looks like it was used to measure the salinity of the Dead Sea. That is, by dropping it in and seeing how the calibration changed after drying out.

I found that many listings fall back on various... interpretations... of English to, let's say, more flexibly describe the product. It leaves the buyer open to various levels of wishful-thinking.
 

Online bd139

  • Super Contributor
  • ***
  • Posts: 10639
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29389 on: April 15, 2019, 08:55:35 pm »
Well known house clearance dude down the road from me is selling a Tek 310A on ebay. He's said he will strip the valves out and send just those on the auction. I am going to attempt to save it before some valve ferengi gets it and it ends up in a skip  >:(

Edit: I skipped the 453. Didn't have time to go and get it in the next week.
« Last Edit: April 15, 2019, 09:00:11 pm by bd139 »
 

Online bitseeker

  • Super Contributor
  • ***
  • Posts: 7709
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29390 on: April 15, 2019, 08:58:18 pm »
I wonder if the 427A description was lost in translation.
Quote
This item is in very good condition
Just noticed the side frame is split.
Why is the condition listed as "New other" ?  :palm:

Probably careless copy+paste operations. It seems the vast majority of test equipment is posted as "New (other)" despite being described as untested. :palm:
I TEA.
 

Online bitseeker

  • Super Contributor
  • ***
  • Posts: 7709
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29391 on: April 15, 2019, 09:00:06 pm »
Well known house clearance dude down the road from me is selling a Tek 310A on ebay. He's said he will strip the valves out and send just those on the auction. I am going to attempt to save it before some valve ferengi gets it and it ends up in a skip  >:(

Beware of the Valve Ferengi! :scared:
I TEA.
 

Online bd139

  • Super Contributor
  • ***
  • Posts: 10639
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29392 on: April 15, 2019, 09:05:23 pm »
Yeah this dude:

 
The following users thanked this post: Tomorokoshi, mnementh

Online bitseeker

  • Super Contributor
  • ***
  • Posts: 7709
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29393 on: April 15, 2019, 09:57:24 pm »
He forgot his tube earrings.
I TEA.
 
The following users thanked this post: bd139

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7226
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29394 on: April 15, 2019, 10:46:51 pm »
I admit it, I have a case of 427A envy, so I was on ebay, you know, just looking around.  From Israel comes this beauty, which was apparently stored in a bucket of water:



The seller is asking a mere fifty dollars for it and will spring for shipping.  Oddly enough, he included no photos of the instrument's interior. :-DD

Then on CL and found this:



Which was apparently found outside in a pile of trash. Based on the number of broken knobs, it must have been dropped face down at one point. The seller actually powered it up on a variac and said it didn't catch on fire. He is currently entertaining offers.

I admit that I am tempted by the 468. I think I have a problem.  ::)

You sure do, a problem with your feet, I'd run like hell from them both
Who let Murphy in?
 

Offline med6753

  • Super Contributor
  • ***
  • Posts: 3479
  • Country: us
  • Tek nut
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29395 on: April 15, 2019, 10:58:21 pm »
Yeah this dude:



Hurry up and get it before the bastard strips the tubes out.  :scared:
An old gray beard with an attitude.
 

Offline med6753

  • Super Contributor
  • ***
  • Posts: 3479
  • Country: us
  • Tek nut
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29396 on: April 15, 2019, 10:59:31 pm »
I admit it, I have a case of 427A envy, so I was on ebay, you know, just looking around.  From Israel comes this beauty, which was apparently stored in a bucket of water:



The seller is asking a mere fifty dollars for it and will spring for shipping.  Oddly enough, he included no photos of the instrument's interior. :-DD

Then on CL and found this:



Which was apparently found outside in a pile of trash. Based on the number of broken knobs, it must have been dropped face down at one point. The seller actually powered it up on a variac and said it didn't catch on fire. He is currently entertaining offers.

I admit that I am tempted by the 468. I think I have a problem.  ::)

You sure do, a problem with your feet, I'd run like hell from them both

If that were a 465B I'd buy it in a minute. Perfect parts mule.  ;D
An old gray beard with an attitude.
 

Online bitseeker

  • Super Contributor
  • ***
  • Posts: 7709
  • Country: us
  • Lots of engineer-tweakable parts inside!
I TEA.
 

Online bd139

  • Super Contributor
  • ***
  • Posts: 10639
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29398 on: April 15, 2019, 11:09:41 pm »
Yeah this dude:



Hurry up and get it before the bastard strips the tubes out.  :scared:

Auction. Have to wait it out.  :--
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7226
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #29399 on: April 15, 2019, 11:28:47 pm »
I admit it, I have a case of 427A envy, so I was on ebay, you know, just looking around.  From Israel comes this beauty, which was apparently stored in a bucket of water:



The seller is asking a mere fifty dollars for it and will spring for shipping.  Oddly enough, he included no photos of the instrument's interior. :-DD

Then on CL and found this:



Which was apparently found outside in a pile of trash. Based on the number of broken knobs, it must have been dropped face down at one point. The seller actually powered it up on a variac and said it didn't catch on fire. He is currently entertaining offers.

I admit that I am tempted by the 468. I think I have a problem.  ::)

You sure do, a problem with your feet, I'd run like hell from them both

If that were a 465B I'd buy it in a minute. Perfect parts mule.  ;D
Switches themselves might well be munted besides broken knobs
Who let Murphy in?
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf