Test Equipment Anonymous (TEA) group therapy thread

[BravoV]

Am I nuts now ? I mean the time type one.

Acquired a GPSDO board, this is easiest part, and now the hardest part, rising the GPS antenna high up above the roof.

[bd139]

Nice 

My QRP Labs one which arrived a few days back works nicely on the window sill

[Specmaster]

And my Citizen Atomic watches work very nicely on my wrist 

[tautech]

From the same source as the Advance, a couple of Philips CRO's, the 3070 bd139 gave me some advice about a couple of weeks back. All have Crete badges on them.



Winter's nearly here and hopefully there'll be some time to get them sorted.

Oh and there's a pair of these, again same source:
https://www.eevblog.com/forum/testgear/aaron-bs-310s-cro-mini-teardowm/

[bd139]

3217 is a nice scope too. Was my daily driver for a few years. Check the crouching RIFA hidden smoke screen in the back panel under the fibreglass separator on the voltage switch.

[Specmaster]

I used to have a 3217 as well, very nice scopes and the thing I used to like was the look of the push buttons and the clever use of the green band to signify if a button was in or out.

[tautech]

3217 is a nice scope too. Was my daily driver for a few years. Check the crouching RIFA hidden smoke screen in the back panel under the fibreglass separator on the voltage switch.

You betcha !
Any of this older stuff gets that obligatory check first !

Only saving grace is I do this sort of stuff in our detached garage so no competition for the SO's cooking odors. 

[bd139]

My 3217 went up in the living room. That was the first Philips thing that blew up on me 

I used to have a 3217 as well, very nice scopes and the thing I used to like was the look of the push buttons and the clever use of the green band to signify if a button was in or out.

Yes indeed very nice. Arguably on par with the best equivalent Tektronix scopes. Honestly I'd rather have a 100MHz Philips from that series than a Tek 465 but one hasn't come up yet. Also slightly intending on getting a decent HP 54600 series unit at some point, preferably one that works this time (although I made a killing on parts off that dead one)

[BravoV]

Nice 

My QRP Labs one which arrived a few days back works nicely on the window sill

Great, how many stable satellites it locked on at that nice position ?

[Specmaster]

That's a good point I know my sat nav gets about 5 at a time. What is the most accurate for time keeping, GPS or the Atomic clock?

[bd139]

Nice 

My QRP Labs one which arrived a few days back works nicely on the window sill

Great, how many stable satellites it locked on at that nice position ?

It's reporting 6 at the moment.

BTW the QRP Labs software is effing amazing. It's connected to their VFO kit. See https://www.qrp-labs.com/images/vfo/vs_op_1.04_A4.pdf page 11 for the data you can format the display with.

I haven't done much but assembled it yet but it'll lock the internal generator to the GPS 1pps and give you an accurage synthesized reference signal output. I'm going to add the OXCO kit as well. $56 spent so far on a signal source is not bad though.

That's a good point I know my sat nav gets about 5 at a time. What is the most accurate for time keeping, GPS or the Atomic clock?

AFAIK GPS but we're talking tiny differences. MSF also goes down regularly as there is no redundancy.

[BravoV]

It's reporting 6 at the moment.

I envy you, I got only 1 or 2 at the window, as the view blocked by leafs and the roof above. 
You must have a really nice view and wide open sky there from the window.

I haven't done much but assembled it yet but it'll lock the internal generator to the GPS 1pps and give you an accurage synthesized reference signal output. I'm going to add the OXCO kit as well. $56 spent so far on a signal source is not bad though.

Mine is used board from forum member here for <50 bucks excl s/h.

C'mon, you should add OCXO, a TE lair won't feel alive without a precision 10MHz.   

[Cerebus]

AFAIK GPS but we're talking tiny differences. MSF also goes down regularly as there is no redundancy.

All things being equal, with properly designed receivers that use all the tricks, the terrestrial LF timing receivers ought to be more accurate simply because they don't have to cope with the ionospheric variability that GPS does. That's qualified by saying you have to be close enough to the transmitter that you're not getting into weird propagation modes, but for LF that's quite some distance.

[bd139]

It's reporting 6 at the moment.

I envy you, I got only 1 or 2 at the window, as the view blocked by leafs and the roof above. 
You must have a really nice view and wide open sky there from the window.

I haven't done much but assembled it yet but it'll lock the internal generator to the GPS 1pps and give you an accurage synthesized reference signal output. I'm going to add the OXCO kit as well. $56 spent so far on a signal source is not bad though.

Mine is used board from forum member here for <50 bucks excl s/h.

C'mon, you should add OCXO, a TE lair won't feel alive without a precision 10MHz.   

Will order the OCXO kit later. A bank breaking $16

https://www.qrp-labs.com/ocxokit.html

AFAIK GPS but we're talking tiny differences. MSF also goes down regularly as there is no redundancy.

All things being equal, with properly designed receivers that use all the tricks, the terrestrial LF timing receivers ought to be more accurate simply because they don't have to cope with the ionospheric variability that GPS does. That's qualified by saying you have to be close enough to the transmitter that you're not getting into weird propagation modes, but for LF that's quite some distance.

Also there is some weird relativistic stuff going on with GPS due to time dilation and spacetime curvature. Think assuming one observer and nothing nasty, 38uS a day needs compensation. 1 pps ticks account for that I think i.e. the satellites are ticking slightly slower than ground time.

Screws one's head up thinking about it.

Edit: also yes, poor weather affects GPS (UHF) propagation. LF I never did any analysis for but there must be a massive skip zone.

[Specmaster]

Just done a current test on the 3478A and while I don't have an actual current reference standard, I have set up a test using a bench PSU and 3.3K resistor, set the current on a meter and then checked it on a number of other meters, which all agree within a couple of micro amps and then checked it with the 3478A which is reading the same.

So I did a sort of transfer calibration and what are the chances 6 meters all drifting in the same direction and by the same amount? If Dave can dismiss the chances of 2 drifting in the same direction and time then so can I by an order of magnitude more.

Verdict a cracking deal at just £65 for 5.5 digit, calibrated meter.

[Brumby]

We need a green emoticon ...


Nah...  I'll just live vicariously.

[bd139]

Just done a current test on the 3478A and while I don't have an actual current reference standard, I have set up a test using a bench PSU and 3.3K resistor, set the current on a meter and then checked it on a number of other meters, which all agree with a couple of micro amps and then checked it with the 3478A which is reading the same.

So I did a sort of transfer calibration and what are the chances 6 meters all drifting in the same direction and by the same amount? If Dave can dismiss the chances of 2 drifting in the same direction and time then so can I by an order of magnitude more.

Verdict a cracking deal at just £65 for 5.5 digit, calibrated meter.

Definitely. Another TF930.

I've actually sat down and did some thinking and if another one turns up I might grab it and use it as a reference to cal this one

Done some thinking and scribbling about calibration backup and restore as well. Reckon I can do it for the price of a shit arduino clone and a centronics connector (under a tenner). Would reduce the risk considerably.

[Specmaster]

Just done a current test on the 3478A and while I don't have an actual current reference standard, I have set up a test using a bench PSU and 3.3K resistor, set the current on a meter and then checked it on a number of other meters, which all agree with a couple of micro amps and then checked it with the 3478A which is reading the same.

So I did a sort of transfer calibration and what are the chances 6 meters all drifting in the same direction and by the same amount? If Dave can dismiss the chances of 2 drifting in the same direction and time then so can I by an order of magnitude more.

Verdict a cracking deal at just £65 for 5.5 digit, calibrated meter.

Definitely. Another TF930.

I've actually sat down and did some thinking and if another one turns up I might grab it and use it as a reference to cal this one

Done some thinking and scribbling about calibration backup and restore as well. Reckon I can do it for the price of a shit arduino clone and a centronics connector (under a tenner). Would reduce the risk considerably.

Go for it, it could well be something that other forum members would be willing to purchase from you?

[bd139]

Not in the mindset of selling it but will document it for public use

[Cerebus]

Just done a current test on the 3478A and while I don't have an actual current reference standard, I have set up a test using a bench PSU and 3.3K resistor, set the current on a meter and then checked it on a number of other meters, which all agree within a couple of micro amps and then checked it with the 3478A which is reading the same.

So I did a sort of transfer calibration and what are the chances 6 meters all drifting in the same direction and by the same amount? If Dave can dismiss the chances of 2 drifting in the same direction and time then so can I by an order of magnitude more.

Verdict a cracking deal at just £65 for 5.5 digit, calibrated meter.

Count yourself lucky that I picked up a Keithley 197 a year back for just over £50. Lucky, because I saw that second 3478A and did give it a minute's thought, and would have definitely snaffled it if I hadn't already got the Keithley. I'm holding out for at least 6¹/₂ digits on the next bench DVM acquisition.

[bd139]

I'm sticking at 5.5 for now. 6.5 costs a lot more to cal when I fuck it up 

[Specmaster]

Well I'd be interested in one, just checked on the old Bay, nothing but plenty in the states for way more money then we paid, as you say, its another TF930, a cracking piece of kit.

There is however a decent HP 3466A on the bay https://www.ebay.co.uk/itm/hewlett-packard-3466A-digital-multimeter/302717095143?hash=item467b584ce7:g:XYAAAOSw6aJa4JuP which a really good meter, I love mine and have fitted the battery option as well so it can used as a portable. I also have the battery charging/switching board for the Solatron 7045 which needs a bit of work on it to bring back into use as someone has disconnected the diodes. Might have a go at that later if I feel in the mood as thats also a reasonable 4.5 digit meter although I prefer the 3466A, no pesky bloody relays for start.

[bd139]

I saw that one. I would probably buy that if it was the bench form factor unit. The plastic cased HP ones I have found problematic in the past. I had a top range HP 5315A counter with OCXO, battery and C optiona couple of years ago but the thing just slipped around on the bench like mad so I got rid of it.

[Specmaster]

I'm sticking at 5.5 for now. 6.5 costs a lot more to cal when I fuck it up 

Added to that, the fact even now with ours when on low ranges, that last digit changing is a distraction, do you really want to have 2 digits changing doubly distract you? 

[bd139]

Yeah definitely. Got to be honest I have chucked it in 3 digit mode a couple of times to get rid of that distraction