Test Equipment Anonymous (TEA) group therapy thread

[bd139]

Damn it's midnight already. Was playing with toys and lost track of the time.

@Specmaster: FT-818 is going in my bag and I'm going on foot places with it. Multijet in Fiat means more parts to go wrong

@mnementh: it's really FT-817ND SP1 which is cool. It's the only thing in its price bracket and feature range still and it gains another watt, TXCO and bigger battery which is cool. It's a swiss army knife of a radio.

Considering antenna is knackered I got RTTY weather reports, CW on 80/40/30/20m, SSB on 40/20m on a bit of wire strung up around the living room and a local VHF contact who was pleased it wasn't via a Baofeng on 2m with rubber ducky that came with it.

And it doubles as a super handy bit of test gear for RF stuff.

It is tiny. My hands are quite large but it really is amazingly small.



@xrunner got my eye on one of those BG7TBL units as well. I can't get my GPSDO to stay phase locked. It locks for a bit and then drifts straight past it suddenly. Not sure what the deal is or if I can be bothered to work it out.

[mnementh]

@mnementh: it's really FT-817ND SP1 which is cool. It's the only thing in its price bracket and feature range still and it gains another watt, TXCO and bigger battery which is cool. It's a swiss army knife of a radio.

Yeah, that's kindof where I was going with my comment about it being a BOM refresh; the 817's been around for like... EVER. And for good reason. It appears from the discussion that the 818 is more a matter of bringing it up to date with contemporary components than intending to introduce anything groundbreaking.

There's nothing wrong with that; if it ain't broke don't fix it. How long did they flog the FT-101 in various iterations? Like 15 years, right?


mnem
"...burn the land and boil the sea;
you can't take the sky from me..."

[bitseeker]

A few months ago my GPSDO bit the dust. It had a Symmetricon unit inside I think they pull them from commercial equipment. It worked for about three years.

That's a bummer. Yeah, they come from cell towers and whatnot. I'm sure they had a hard life before they retired into GPSDO boxes.

Last week I decided to get a BG7TBL unit Model 2017-10-09. It's been well reviewed elsewhere on this forum, it's very nicely constructed. It works really well and is ready to go a lot faster than the other unit. Has both 10 MHz sine and 1 PPS. It also outputs NMEA serial data which can be used with a program called VisualGpsView and displays some nice information updated about once a second.

Oh, cool. Is that one of the corrected versions? I remember early ones had some jitter issues or something to that effect. (Memory isn't what it used to be...)

[VK5RC]

I felt the need to measure some nV! Keithley 181 (supposedly working) arrived today, have to alter the line voltage input 1st.
PS interested in 818, much different than the 817?
regards Rob

[Berni]

I have thought about getting a GPSDO for my lab but i have no idea how am i going to get the antenna outside apart from juryrigging it out the window.

[Vgkid]

Those Muirhead rotary switches are yummy , I wouldn't mind having some. Too much money for me though(not overly common over here) .

[bitseeker]

I felt the need to measure some nV! Keithley 181 (supposedly working) arrived today, have to alter the line voltage input 1st.

You have a probe for that? I contemplated getting a 181, but that connector put me off. I'm having a hard enough time with the old two-lug triax on the 220 and 614.

[Ero-Shan]

I have thought about getting a GPSDO for my lab but i have no idea how am i going to get the antenna outside apart from juryrigging it out the window.

I've acquired a GPSDO several weeks ago, and got an antenna and 15 meters of cable last week. What I haven't got is a path for the cable from my lab to the outside. Not much different to your situation, except that I've already thrown out some money.

[bd139]

My current GPS receiver antenna gets taped to the living room window. Where there is a will there is a way

That will get a 3d fix in under a minute and tracks 9 satellites.

[Berni]

You have a probe for that? I contemplated getting a 181, but that connector put me off. I'm having a hard enough time with the old two-lug triax on the 220 and 614.

Oh yes i had quite the time hunting down my precious 2 lug triax connector for my Keithley electrometer. I happened to find the same brand and type of connector that's used on the cable that Keithley makes. So i just unscrewed the body apart and just swapped over the outer shell of the connector with the one that had the 2 lug nut. So now i have a spare complete 3 lug triax connector from the spare parts.

[bd139]

TDS210 tear down and BNC repair: https://www.eevblog.com/forum/testgear/tektronix-tds210-teardown-and-bnc-replacement/

All went well 

[med6753]

TDS210 tear down and BNC repair: https://www.eevblog.com/forum/testgear/tektronix-tds210-teardown-and-bnc-replacement/

All went well 

Excellent! 

[VK5RC]

@bitseeker re the 181
There are a couple of Amphenol connectors I believe fit, I can confirm the first one does (I have it) and it fits nicely.
 
One is readily available, Mouser PN 654-97-3106A-16-11P Amphenol PN 97-3106A-16-11P about USD$20

The other takes a while - I think it is supposedly better from the temp-coeff point of view but is more expensive!
About USD$40 each !   Mouser PN. 654-97-3107A-16-11P. Amphenol PN 97-3107A-16-11P

Expensive as they are they are cheaper than Triax  connectors. **********!!!!!!!

I plugged it in and it proceeded to blow up 2 of its 4 its Tantalums - I was describing this to my wife and she very astutely nicknamed them "Tantrum" capacitors. Replaced them and it works OK I get roughly correct reading on both its ranges and they appear stable - I can't test it further at this stage.
 I have to make a set up to generate a voltage I can then measure down below 1mV and also a "Short" and some test leads, I found some nice pure copper alligator clips and one of Pomona mini-hooks are copper as well. 
Inside it looks like good / real Keithley gear
Regards Rob

[bd139]

Stop making me want Keithley gear 

[Specmaster]

The only Keithley item I had, paid £33 for it spent some time cleaning, calibrating and gave it a new lick of paint and then sold it for £125 so not a bad little earner 

[Johnny10]

I know I can look this up but doesn't the HP3457 measure to the same level as the Keithley 181?

[xrunner]

That's a bummer. Yeah, they come from cell towers and whatnot. I'm sure they had a hard life before they retired into GPSDO boxes.

This is the one I had before -

http://andybrown.me.uk/2016/11/12/gpsdo-ebay/

These may have been in service for many years before getting pulled. Perhaps the OCXO failed, not sure. I could still get messages from the unit, but it stopped supplying 10 MHz. 

Oh, cool. Is that one of the corrected versions? I remember early ones had some jitter issues or something to that effect. (Memory isn't what it used to be...)

I don't know about that, but I have no indication of any issues so far. There is a BG7TBL GPSDO page here on the forum as you know,

https://www.eevblog.com/forum/testgear/bg7tbl-gpsdo-master-reference/

but it doesn't show my model (2017-10-09). Perhaps I need a photo-shoot for it? By the way, BG7TBL is an amateur radio call sign from China, so the guy is a ham.

I have thought about getting a GPSDO for my lab but i have no idea how am i going to get the antenna outside apart from juryrigging it out the window.

My antenna is inside, on top of a high shelf, and the system works great. But, perhaps you are in a two-story building?

[VK5RC]

@Johnny10
I just had a quick look,
HP 3457 goes to 30mV range, 6 1/2 digits, error 0.004% reading +/- 365 counts, = max error approx 3.77uV
Keithley 181 2mV range 5 1/2 digits, error error 0.006% reading +/- 5 counts, = max error approx 0.17uV
FYI 3458 100mV range 8 1/2 digits, error 5ppm of reading, 3ppm of range, error max about 0.8uV
 

[med6753]

More work on the 465. It's proving to be a real bastard.

I lost the trace on channel 2 again. Tracked it down. Q92 was open. Double confirmed it. Swapped it into channel 1 and it killed it and checked it on my tester. As luck would have it I had an exact replacement. It is the same part number of the transistor I ordered weeks ago when I thought there were issues with the channel 2 trigger circuit.

The replacement X10 attenuator didn't really help all that much. There are still issues with the switch deck and I'm going to have to pull it apart again and really check it more carefully. I have to pull the board again anyway to replace the BNC's. If I can't figure out what's wrong I may have to look at getting a parts 465 and replace the entire board.

Tomorrow I'll pull the board out and report what I find.

[bd139]

I find in these circumstances that applying a D.C. voltage to the channel BNC and signal tracing works best. Get another scope on the input stage of each amp and wiggle the input voltage to see if the output moves. Each amp step is a simple differential input and output long tail pair amp with oodles of frequency compensation so it’s easier tracing it through igoring all the compensation caps and stuff that way.

I noticed with scopes that the broken bits are usually right near the front end or right near the plate drivers.

In theory you should be able to isolate the knackered bit before disassembly in system. Once you’ve removed it the circuit is different :

[med6753]

I find in these circumstances that applying a D.C. voltage to the channel BNC and signal tracing works best. Get another scope on the input stage of each amp and wiggle the input voltage to see if the output moves. Each amp step is a simple differential input and output long tail pair amp with oodles of frequency compensation so it’s easier tracing it through igoring all the compensation caps and stuff that way.

I noticed with scopes that the broken bits are usually right near the front end or right near the plate drivers.

In theory you should be able to isolate the knackered bit before disassembly in system. Once you’ve removed it the circuit is different :

Your suggestion is a good one. I was using a simple sine wave to trace out where channel 2 was not passing signal and causing trace loss. I can press against the board and the signal changes height...sometimes significantly. That tells me there are still issues with the switch deck itself. I suspect it's worn possibly beyond repair but we'll see.

[med6753]

Sometimes you hear some strange stuff on the police/fire scanner that you wish you hadn't. Some individual on a job site just tried to commit suicide by taking nail gun and blasting two nails into his skull. He then decides to call 911 and report he just tried to kill himself. Believe it or not he is still conscious and alert and talking to dispatch on phone. They just located him. 

Edit....they are requesting a medivac chopper.

[Specmaster]

I find in these circumstances that applying a D.C. voltage to the channel BNC and signal tracing works best. Get another scope on the input stage of each amp and wiggle the input voltage to see if the output moves. Each amp step is a simple differential input and output long tail pair amp with oodles of frequency compensation so it’s easier tracing it through igoring all the compensation caps and stuff that way.

I noticed with scopes that the broken bits are usually right near the front end or right near the plate drivers.

In theory you should be able to isolate the knackered bit before disassembly in system. Once you’ve removed it the circuit is different :

Your suggestion is a good one. I was using a simple sine wave to trace out where channel 2 was not passing signal and causing trace loss. I can press against the board and the signal changes height...sometimes significantly. That tells me there are still issues with the switch deck itself. I suspect it's worn possibly beyond repair but we'll see.

Have you swapped out the obvious failure point, R51 I had a similar thing on a HP1740A and on close up examination the resistor had a fine hairline fracture, replaced it and hey bingo I had a rock solid signal after that.

[Cerebus]

Sometimes you hear some strange stuff on the police/fire scanner that you wish you hadn't. Some individual on a job site just tried to commit suicide by taking nail gun and blasting two nails into his skull. He then decides to call 911 and report he just tried to kill himself. Believe it or not he is still conscious and alert and talking to dispatch on phone. They just located him. 

Edit....they are requesting a medivac chopper.

Phineas Gage was tamping an explosive charge with an iron rod when the charge detonated and drove the 35mm diameter tamping rod vertically through his head. Within a few minutes of this he was on his feet, walking and talking. Here's an illustration of the path the rod took:


You can survive massive brain trauma if the trauma is in just the right place. Gage is notable, not just for surviving the injury but as one of the earliest clues to the functions of parts of the frontal lobe of the brain, evidenced by significant personality changes he underwent as a result of the accident.

[BillB]

Sometimes you hear some strange stuff on the police/fire scanner that you wish you hadn't. Some individual on a job site just tried to commit suicide by taking nail gun and blasting two nails into his skull. He then decides to call 911 and report he just tried to kill himself. Believe it or not he is still conscious and alert and talking to dispatch on phone. They just located him. 

Edit....they are requesting a medivac chopper.

Phineas Gage was tamping an explosive charge with an iron rod when the charge detonated and drove the 35mm diameter tamping rod vertically through his head. Within a few minutes of this he was on his feet, walking and talking. Here's an illustration of the path the rod took:

You can survive massive brain trauma if the trauma is in just the right place. Gage is notable, not just for surviving the injury but as one of the earliest clues to the functions of parts of the frontal lobe of the brain, evidenced by significant personality changes he underwent as a result of the accident.

Jeez, this thread took an awful turn.