Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 16858705 times)

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Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96625 on: August 05, 2021, 06:25:07 pm »
At a recent hamfest I picked up an hp651b oscillator cheaply; 10Ha-10MHz, 90dB attenuator, 300µV-3Vrms.



Looking at the outside, I was concerned that the storage had, um, been less than ideal.



The output on the lowest frequency scale shimmered in a rather sensuous way which I've been unable to capture in a photo or movie. The frequency and range switches were very noisy.



I quickly found the 600ohm BNC socket wouldn't accept a plug. That failure mode is a new one to me!



So, time to open it up - and the inside was very clean, including the traditional big tuning capacitor. I guessed the shimmering output was due to capacitor failure, but they all measured OK and the PSU rails were OK.




For amusement, what do you think the spec is of that original 80mm long electrolytic just above the orange cap inserted by a previous owner? I've unhelpfully obscured the µF/V specs with the green/red scribble, since I've never seen one like it before. EDIT: see https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3621795/#msg3621795

Eventually I figured out what the cause of the shimmering is. Bloody 50Hz being coupled into sensitive front end, especially a JFET gate and those excessively long grey and green wires from the tuning capacitor.

Anyway, apart from the frequencies being a little off (5% rather than the 2% spec), it seems to work OK. Getting the frequencies right requires SOT fiddling with resistors on the big range switch. Can't be bothered, especially since the frequencies shift when you put the covers on - not one of HP's finest efforts!
« Last Edit: August 06, 2021, 09:24:25 am by tggzzz »
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96626 on: August 05, 2021, 06:30:52 pm »
Thanks for the tear down on that. Very nice job. As for the capacitor, I bet it was “whatever the ham had in their junk box”
 

Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96627 on: August 05, 2021, 06:33:00 pm »
Thanks for the tear down on that. Very nice job. As for the capacitor, I bet it was “whatever the ham had in their junk box”

I'm sure that was the case, but it is a good substitute. I was thinking about the original silver cap above that. (Post modified to make that slightly clearer)
« Last Edit: August 05, 2021, 06:35:08 pm by tggzzz »
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".
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Offline mansaxel

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96628 on: August 05, 2021, 06:33:43 pm »
You really should have splurged on the right stuff, instead of stealing the lacing from Cerebus' combat boots...  >:D

My wife, the enabler, did buy me a lacing kit from Tecra Tools some years ago, and that one sure does have some twine. Its not flat and smart as the avionics/milspec twine, but instead extra heavy duty, thought out for lacing AWG2 zipcord to racking. I've got a roll of Alpha Wire flat waxed and a roll of Alpha dry as well, so most likely am set for life.

Lacing so rules over cable ties. Can't get over the Tek/-hp- habit of using clear nylon elastic tubing for lacing, though. Pretty common in some UK sourced gear too.

Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96629 on: August 05, 2021, 06:48:28 pm »
Better than dental floss, I imagine... which I saw old man Basche use a few times in 16mm film projectors and those prehistoric Wollensak Reel/Reels. >:D

mnem
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« Last Edit: August 05, 2021, 07:00:43 pm by mnementh »
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Offline GreyWoolfe

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96630 on: August 05, 2021, 06:52:57 pm »
Saskia, so sorry to hear of the travails of you and hubby.  My prayers are with both of you.  I have had more than my fair share of challenges the last couple of years but nothing compared to you both.

Here is a Covid PSA for US members.  If you are considering getting the shot and are married with appropriate life insurance policies, please don't get the shot until you talk to said insurance agencies.  At the private practice that Mrs. GreyWoolfe works, they have had 2 patients that have died of Covid after getting the Covid shot and the insurance companies in both cases refuse to pay out as it is not FDA approved and is listed as experimental.  That is one of the major reasons we both refuse to get the shot.  If Covid claims either one of us, we know the insurance company will pay out.

Please keep the anti vaccine  :bullshit: off here at least.
1/ If they had the vaccine it's highly unlikely they would die. Two in one practice highly unlikely unless it is a very big private practice.
2/ lots of reptutable sources say it's not true. e.g. https://www.reuters.com/article/factcheck-life-insurance-vaccine-idUSL2N2NJ2FP
3/ Checked my insurance Co and they say not affected even if you took part in a pre-approval trial.
4/ Insurance companies have been saved millions by the vaccine. In future not having the vaccine may increase premiums. One company in SA is doing this already https://www.wsj.com/articles/covid-19-vaccine-refusal-could-drive-up-your-life-insurance-premium-in-south-africa-11627658482
5/ How do you know insurance was not paid? In UK/EU that would be personal information and it would be illegal to reveal to others.
6/ last and not least IF YOU HAVE THE VACCINE YOU ARE HIGHLY UNLIKELY TO NEED TO CLAIM because of a covid death. Even if you did get Covid 19 the effects are likely to be much less and your medical bills co-pay etc much lower as a result. Would Mrs Greywollf really say " I'm so glad he didn't get the shot so there was no risk of life insurance not paying out. Shame he died and the medical bills were so high though" :palm:
I know you said to check, but people don't read that detail.

1-Cause of death in both cases was covid.  Yes it is a very large practice-4 doctors and including the snowbirds that come down for the winter from the GWN, approx 5000 patients
2-Explain to the spouses that it isn't true, I'm sure you can make a case during their time of grieving.
3-It matters little what insurance companies across the pond are like. Here they are far more interested in getting your monthly premiums and fighting to not pay claims.  Been down that road myself.
4-Can't compare SA with US
5-The patients that Mrs. GreyWoolfe's doctor takes care of all love my wife. She is the initial POC on the phone, been there 19 years, knows most of the patients and their spouses on a first name basis and both told her.  Both her and I work under HIPAA oversight and she did not mention names.  She know far better than to do that.  No PII or PHI was spoken of.
6-Wouldn't be so sure of that.  All 4 doctors got the shot, her boss under pressure from the others and she and another have come down with covid, far more common than you think.  I don't really trust anything that the news services have to say here.  They have shown themselves to be bought and paid for.  There is no longer anything like accurate and truthful reporting and even when they are proven wrong, there is nothing more than a my bad and a mumbled apology buried on page 15.

I am not an anti-vaxer, far from it.  I was unable to get a pneumonia vaccine that my Dr, who by the way, is my wife's boss, wanted me to get as MY insurance wouldn't cover it and I couldn't pay the cost at the time.  I will be on Medicare in January so maybe I can get it then.  I could care less if you get the vaccine or not.  I didn't think I sounded like I was pushing the anti vax :bullshit:.  I am pro vaccine, just not this one.  I could care less what Reuters, et al are saying.  These 2 are real people that are having real battles with their insurance companies to pay the death benefits that are sorely needed.  I really doubt that this is the only practice it is happening in across the country.  Do I worry about dying from covid?  Not even.  I have had enough health issue the past few years, including just finishing up radiation treatment for an aggressive prostate cancer that I am still feeling the side effects 3 weeks later, not to mention the other nonsense I have to keep going through for the next 14-20 months.  When it's my time to go, it's my time.  I could just as easily die from being run over when I walk out to my mailbox across the street.  We have chosen not to get the vaccine as there are too many patients in the practice that have come down with covid that have had the shots for our comfort level.  From my real but very small view of things, there is a strong possibility of getting covid even with the shot as that seems to be where a real number of new cases are coming from.

---I know you said to check, but people don't read that detail.----Not read that detail?  In this crowd?  Where paying attention to the minutia is part and parcel to a successful or failed project?  Now, that's :bullshit: All I was trying to do is to pass on some real world information and that a short phone call will allow someone to get facts that can possibility influence choice.
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Offline mansaxel

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96631 on: August 05, 2021, 06:54:58 pm »
Better than dental floss, I imagine...

I might be movin' to Montana soon
Just to raise me up a crop of
Dental Floss
Raisin' it up
Waxing it down
In a little white box
I can sell uptown
By myself I wouldn't
Have no boss,
But I'd be raisin' my lonely
Dental Floss

Offline Cubdriver

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96632 on: August 05, 2021, 07:11:20 pm »
At a recent hamfest I picked up an hp651b oscillator cheaply; 10Ha-10MHz, 90dB attenuator, 300µV-3Vrms.



For amusement, what do you think the spec is of that original 80mm long electrolytic just above the orange cap inserted by a previous owner? I've unhelpfully obscured the µF/V specs with the green/red scribble, since I've never seen one like it before.

I suppose that back in the day, that might have been considered to be something of a supercap...

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96633 on: August 05, 2021, 07:44:46 pm »
For amusement, what do you think the spec is of that original 80mm long electrolytic just above the orange cap inserted by a previous owner? I've unhelpfully obscured the µF/V specs with the green/red scribble, since I've never seen one like it before.

42 Long.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 
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Offline factory

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96634 on: August 05, 2021, 08:32:18 pm »
At a recent hamfest I picked up an hp651b oscillator cheaply; 10Ha-10MHz, 90dB attenuator, 300µV-3Vrms.



For amusement, what do you think the spec is of that original 80mm long electrolytic just above the orange cap inserted by a previous owner? I've unhelpfully obscured the µF/V specs with the green/red scribble, since I've never seen one like it before.


I suppose that back in the day, that might have been considered to be something of a supercap...

-Pat

The smaller hp oscillators have a similar long capacitor, a non-polarised type. I won't give the value/voltage as I'm looking at a picture from one of mine ATM (I don't have any of the 65x series).

Found this picture from a hp 653A (H-01) in my archived pics, quite a bit more inside and some extra shielding around the tuning capacitor.



David
 
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Offline Robert763

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96635 on: August 05, 2021, 08:39:36 pm »
Greywoolfe said
"6-Wouldn't be so sure of that.  All 4 doctors got the shot, her boss under pressure from the others and she and another have come down with covid, far more common than you think."

I never said you would would not get Covid 19. I said it was highly unlikely you would have to make a life insurance claim for covid 19 for someone who had the vaccine.
 

Offline factory

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96636 on: August 05, 2021, 08:45:04 pm »

Did you take the heatshrink off Q3/Q5? according to the drawing they should be in a sleeve an in contact with that white ceramic washer (which is BeO so don't break it). If they are not in good therml contact you may have issues.

I pulled all the cards and took photos  so I could do a visual inspection.     Looks to me like Q3/Q5 were glued together!    I've never seen silicon grease harden like this but I don't often see 40 year old heat sink compound.

be very very very careful with that BeO washer.

it is not something you want to scratch, grind, file or break.   when BeO dust is inhaled it actually can kill you.


https://www.hse.gov.uk/pubns/indg311.pdf


edit  some of the german made hp pulse generators have BeO insulators in them too.  (the ones with slide switches).  use caution with them also.

The vertical plug-ins for the hp 180x series oscilloscopes also have BeO insulators, for the four vertical deflection output transistors, can't see any warning in the 1968 manual though.  :-\




Could those insulators for the vertical transistors in Med's troublesome 547 also be the same stuff, or not?  :-//

David
 
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Offline dl6lr

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96637 on: August 05, 2021, 08:45:14 pm »
Now in that horrible state where everything works properly again  >:(

Poor guy...  :-DD

Still struggeling with a piece of crappy SMPS for 24V truck power input and a lot of different output voltages. 1970s technology, military grade, conformal coating, no schematics available. Two modules, power module and control. Have tracked it down to the control circuits with the help of a working unit.
Next to do is to desolder a lot of components to check them. All the CNY18 and the LM224 are suspicious.

 
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Offline factory

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96638 on: August 05, 2021, 08:49:41 pm »
Those orange capacitors are Tants in disguise  >:D, had remand short circuit related failures in a PSU from a rail related bit of kit at work.

David
« Last Edit: August 05, 2021, 08:52:27 pm by factory »
 

Offline Saskia

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96639 on: August 05, 2021, 08:51:29 pm »

Ummm... *gulp* Any word yet on how bad the damage was...? I find myself also wondering why the stress EKG was canceled... but probably don't want to know the answer.  :o

mnem
*crosses claws, toes, wings and tail hoping for a hopeful prognosis*

Thanks for asking, the stress ECG was cancelled because the cardiologist wanted to be on the safe side and do a hematology screening first plus a normal ECG. They told him at the CPU that he absolutely needed to get the esophagus hernia and the stomach bleeding fixed to avoid running dry on that red lubricant ...

my bossboss will talk to my boss^3 tomorrow regarding permanent teleworking for me so that we can relocate to an area which is healthier for us, which would allow us to be near my daughter, and would put us just 10 km away from the next large hospital.

Wish me luck. If this got approved I could do permanent work from home and get a break.
 
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Offline factory

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96640 on: August 05, 2021, 08:58:52 pm »
Quick E3630A teardown. Went looking to see which variety of RIFA it has in it.

Overhead view



Looking towards front panel board. All analogue apart from the TC14433 ADCs.




What's with the random splodges of glue down the sides of several of the bigger capacitors? Someone get board on the assembly line?  :-DD

Did it come with a manual? I apparently have a spare original if needed.  ;)

David
 
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Offline factory

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96641 on: August 05, 2021, 09:29:35 pm »

Andrew - what kind of edge connectors does the Dana meter use?  If they're the 'conventional' type with the fingers on the card edge, you might look for HP extender cards - as such things go, they're relatively common on the Bay of Evil.  It's taken a while, but I've managed to find most sizes:

Search on things like "HP extender", "HP extender board", "HP Extender card" and the like.

(If, on the other hand they use the Fluke-style soldered in forks, well, you're forked.  Extenders for those in my experience are rarer than hen's teeth.)

-Pat

Dana use something I've never seen before.    The main board has pins like the ones commonly used for test points.   At either end are larger posts that locate the card.

The card has connectors that fit on to that.








Ahh, crap - that's as bad if not worse than the Fluke forks.  I suppose it was slightly cheaper manufacturing-wise as they didn't need to gold plate the fingers, and overall the contact pairs are perhas a hair cheaper than a nice edge connector.  Miserable to work on after the fact, though.  What spacing are they - 0.1 or 0.156?  Maybe cobble something together using a single-row breakaway pin header soldered to a receptacle that would mate with the motherboard pins?

-Pat

Those gold plated pins & sockets look a lot like those found in 1980's Tek oscilloscopes, in fact I was looking at some earlier in the Tek 214* at work.

You have missed the Telfon? insulated pin & blue socket, to the right of the row of pins/sockets, HP/Dymec seem to use the same in some voltmeters, the 2402A has quite a few and I've yet to identify something to use to make jumper wires top go with the standard extender board (of course the original custom extenders are complete unobtainium  :horse:).


*The dead Tek 214 at work has been resurrected, I've been playing with it in the morning break for a few weeks and have finally worked out the lower PCB had the connectors bent & misaligned and another cable had fallen out (going to top PCB), causing no horizontal or vertical deflection.
A couple of weeks ago I charged the batteries outside the unit (power cord is missing) and they did work, but found them dead again today (just as well as they were starting to leak), I cut the important wires off the battery packs and connected a temporary permanent lead for 12V input to get it working.

I'm impressed with it  8), OK it's only 500kHz, but it triggers perfectly from the current probe for the motor inverters we repair. The 20MHz Fluke 123 on the other hand is utterly useless for this task, maybe it would better used as a wheel chock in another department.  >:D
The only thing I can't try is the storage function, as the previous site took it apart and never put the actuator rods back.  |O
Can't upload any pictures either as we are forbidden from taking them at work, nor can I rescue it for my collection.  :--

David
 
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Offline bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96642 on: August 05, 2021, 09:36:57 pm »
What's with the random splodges of glue down the sides of several of the bigger capacitors? Someone get board on the assembly line?  :-DD

Did it come with a manual? I apparently have a spare original if needed.  ;)

David

I think it was a trend after 2010. My conspiracy theory is they are using it bring good luck after the capacitor plague :)



Anyway some black magic fuckery here with one annoyance. So was futzing with the desktop PC and managed to finally get a version of Linux working on it that both supports the built in Intel i219 card and the B560 chipset. Writing this post on it now...



However it uses Wayland and fractional scaling as I have a 27" 4k monitor. If you use it at integer scale factors (100% or 200%) it's too big or too small. If you use it fractional factors, some apps (see Kicad above) are blurry because the use the X backend rather than Wayland backend. GRRRRRRRRR. This works 99% ok on windows and 100% ok on macOS  >:( >:( >:(

I am considering turfing the 4k monitor and just getting a 27" 1440p one. Might be less of a pain in the butt  >:(
 
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Offline BU508A

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96643 on: August 05, 2021, 09:42:27 pm »
Quick update about the VFD for my 34401A which I've ordered in China.

It came with some serious bended contacts as you can see it in this picture:


I did some (careful!) bending of those contacts and putted it on a pegboard without copper overlay (in Germany we are calling them "Knäckebrot"  :) ). Worked out fine so far. Perhaps at the weekend I'll attack the 34401A with the display change.

Here are some pictures:

side view, long side:


side view, short side:


detailed view to the contacts:

« Last Edit: August 05, 2021, 09:44:41 pm by BU508A »
“Chaos is found in greatest abundance wherever order is being sought. It always defeats order, because it is better organized.”            - Terry Pratchett -
 
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Offline nixiefreqq

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96644 on: August 05, 2021, 09:44:41 pm »
At a recent hamfest I picked up an hp651b oscillator cheaply; 10Ha-10MHz, 90dB attenuator, 300µV-3Vrms.



For amusement, what do you think the spec is of that original 80mm long electrolytic just above the orange cap inserted by a previous owner? I've unhelpfully obscured the µF/V specs with the green/red scribble, since I've never seen one like it before.

I suppose that back in the day, that might have been considered to be something of a supercap...

-Pat

mine has a metal cover over that center section.  and the caps inside all suffer from that plasticizer loss that makes them appear to be covered in fungus.  so i looked up C7 in the manual.  weird indeed.
free range primate
 

Offline duckduck

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96645 on: August 05, 2021, 09:48:37 pm »
Components that I ordered from Digi-Key that were sent via USPS are noted by USPS as "Delivered to mailbox" and there is no sign of them for over a day now. Quack! I was really looking forward to being able to finish my 12AX7 test jig this weekend. I've already opened a case with USPS. This is awful because USPS marking this "delivered" is going to make it difficult for me to get very far with Digi-Key. In my favor, I have years of history of ordering from them and it seems unlikely that I would try to scam them out of USD20 worth of jellybean resistors and capacitors.

Just wanted to follow up on this one. USPS route carrier knocked on my front door today. When I opened it, he handed me the previously-lost box from Digi-Key and said "I misread the address on the label. I just wanted to apologize to you. I'm sorry." Looks like the people that he mis-delivered it to had opened it and then, finding nothing worth keeping, had put it back in their mailbox with a note. I checked it against the packing list and every piece is there. The label that Digi-Key applied was not very clear. There are a couple of numbers that could be (and indeed were) mis-read. Glad that mystery is resolved.

Of course, in the meantime, I ordered the same components again from Digi-Key and had them delivered to my house via FedEx...  |O

EDIT:

Digi-Key did right by me and refunded the whole late shipment: parts, shipping, and tax. "[Digi-Key has] created the credit memo on invoice [redacted] due to the currier[sic] error. Due to Digi-Key processing the parts can be scrapped at your location. We will not need them returned." I have been alive long enough to know just how rare this type of happy ending is.
« Last Edit: August 06, 2021, 06:37:41 pm by duckduck »
 
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Offline Saskia

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96646 on: August 05, 2021, 09:54:40 pm »
On a more positive note I am at 49 lbs weight loss.
 
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Offline Cubdriver

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96647 on: August 05, 2021, 09:58:52 pm »
At a recent hamfest I picked up an hp651b oscillator cheaply; 10Ha-10MHz, 90dB attenuator, 300µV-3Vrms.



For amusement, what do you think the spec is of that original 80mm long electrolytic just above the orange cap inserted by a previous owner? I've unhelpfully obscured the µF/V specs with the green/red scribble, since I've never seen one like it before.

I suppose that back in the day, that might have been considered to be something of a supercap...

-Pat

mine has a metal cover over that center section.  and the caps inside all suffer from that plasticizer loss that makes them appear to be covered in fungus.  so i looked up C7 in the manual.  weird indeed.

Mine came from a silent key's estate, and had spent an unknown amount of time in a slightly damp shipping container in a storage yard.  It too has the shield under the bottom center board and some sleeved electrolytics that are rather ugly looking - feels like they have a lumpy wax coating.  That said, it fired up and puts out a signal.  It will need some work (at the very least the range switch is electrically very dirty; likely several of those caps will need to go in the bin, too), but it's nice to see that it's not DOA.













Interesting profile on the breadslicer's rotor plates, too - rounded edges at the low-C end, and more flattened or faceted at the high C end:


-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 
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Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96648 on: August 05, 2021, 10:09:48 pm »
At a recent hamfest I picked up an hp651b oscillator cheaply; 10Ha-10MHz, 90dB attenuator, 300µV-3Vrms.



For amusement, what do you think the spec is of that original 80mm long electrolytic just above the orange cap inserted by a previous owner? I've unhelpfully obscured the µF/V specs with the green/red scribble, since I've never seen one like it before.

I suppose that back in the day, that might have been considered to be something of a supercap...

-Pat

mine has a metal cover over that center section.  and the caps inside all suffer from that plasticizer loss that makes them appear to be covered in fungus.  so i looked up C7 in the manual.  weird indeed.

Mine has that cover too; I removed it to take the photo and access the capacitors to measure them.

Fortunately I my caps don't have the "fungus". The nearest I've seen is on the black plastic inter-board "comb" connectors in Tek scopes.
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".
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Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #96649 on: August 05, 2021, 10:19:03 pm »
Mine came from a silent key's estate, and had spent an unknown amount of time in a slightly damp shipping container in a storage yard.  It too has the shield under the bottom center board and some sleeved electrolytics that are rather ugly looking - feels like they have a lumpy wax coating.  That said, it fired up and puts out a signal.  It will need some work (at the very least the range switch is electrically very dirty; likely several of those caps will need to go in the bin, too), but it's nice to see that it's not DOA.

My range switch was very noisy too. Drops of DeOxit D100 and repeated turning have sorted that out.

Quote
Interesting profile on the breadslicer's rotor plates, too - rounded edges at the low-C end, and more flattened or faceted at the high C end:


Why haven't I thought of that name!

This is one of those times when a SA or scope FFT is useful. For reasons I don't understand, the harmonic content is lower when all the vanes are "meshed" (i.e. low end of a frequency range) and noticeably worse when "unfurled" (i.e. high end of a frequency range).
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
 


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