Test Equipment Anonymous (TEA) group therapy thread

[Cerebus]

ned a new word today: "Kewl". I wanted to use it... 

Probably not a great idea, it makes one sound like one of Kevin and Perry:

[Neomys Sapiens]

Got a quick question....

I have a 10MHz OXCO that after a bandpass filter etc, is putting out 595mV P-P into 50ohms, how to best and simply get this to 0dB (0.775V) for a bit of a general reference? I'm thinking a buffer amp, but is there a best practice for this?
I just want a simple way to do it, for a little USB powered 'pocket 10MHz reference' I'm making for laughs.

When I had to provide a driver for such a signal once, I used the LH0033. This is unfortunately a buffer which provides only power gain. It is obsolete as well.

[mnementh]

eBay auction: #233034286419 eBay auction: #373803025167

are you effing me?   not kewl...

I just learned a new word today: "Kewl". I wanted to use it... 

Ummmm.... a quick search will show that I've used this term in here like a dozen times over the last few years... 

mnem

[Neomys Sapiens]

You still have not said what you want the AC supply for. It can't be for the meet slicer can it? That just needs an auto transformer. It will run 20% faster but that's not a problem.
The cheap option if you really want 50Hz is an on-line UPS (batteries not required). Most have a setting, switch or link for 50Hz output. Worse case change the crystal. Stillneed an autotransfomer of course.

oh no no no meat slicer behind an AC6800...

It is just for my lab, I am in USA and sometime I believe I can now get broken stuff for cheap and repair it.
I posted here because I did not expect the prices to be so effing high.
Pure TEA, no precise project yet. I am missing a decent ac power source brick, like a child miss ice cream sometime.

Sorry I am so TEA sick.

I wonder what your problem is. You are sitting in the largest market for used TE that exists. Most of us non-US members would be happy to have access to those possibilities without the often prohibitively high transportation charges and import duties.
You can either hunt for a California Instruments or Pacific Power device, you can go for lesser manufacturers such as Chroma, you can get a UPS to do such or you can modify an suitable audio amplifier or even a drive inverter (with filtering) for that purpose - and whatever the specific price is, it will be more affordable that for us in Europe to get clean and stable 60Hz AC power.

[mnementh]

ned a new word today: "Kewl". I wanted to use it... 

Probably not a great idea, it makes one sound like one of Kevin and Perry:   

This moke...?



Gewd laird... remind me to never bitch aboot my son ever again... 

mnem
"He wants to be good... he's just not that good at it." ~me

[ch_scr]

With regard to LED bulbs - cooling is king, and as a rule of thumb in that regard, heavier bulbs are better.

Yes but the G9 is a very small form factor, so cooling is difficult.

A "corn cob" LED-bulb is an excellent example for a design where it is very hard to get the cooling right - best to avoid them in general.
Still, only the most cunning designs (of what I have seen) have the LEDs itself fail - usually the power supply fails before.

At the time I bought the G9 retrofit, there were no other than corn type bulbs for G9 available. Still a lot of the latest Osram and Philips LED G9 do have several SMD-LEDs mounted on a Al-PCB, no COB.
Failing LEDs: I have several lamps that exhibit failing LEDs with a black spot. I suppose this is due to spikes in the mains? Often those LEDs are conducting a very faint current, so the others are flickering very dim.

Depending on the driver design (it can be as simple as a rectifier and a small 400V cap) spikes may go through.
But it is really hard to tell the reason, from a burnt LED alone. LED aging is mostly dependent on current and temperature.
One could ask: "Do they fail after a certain run time?" If yes, driver current (or LED temperature) is just too high.
"Do they fail new/old mixed but were on together at time of failure?" Maybe a spike occured then.
But current spike damage can accumulate and lead to later premature fail, masking the issue. 

[mansaxel]

Got a quick question....

I have a 10MHz OXCO that after a bandpass filter etc, is putting out 595mV P-P into 50ohms, how to best and simply get this to 0dB (0.775V) for a bit of a general reference? I'm thinking a buffer amp, but is there a best practice for this?
I just want a simple way to do it, for a little USB powered 'pocket 10MHz reference' I'm making for laughs.

Something says "Video amplifier IC" pretty loud at the back of my head.

[Robert763]

How about something like an LT1814?
It can do bandpass filter duties and directly drive a coax cable apparently. Might help to simplify things.
https://www.analog.com/media/en/technical-documentation/data-sheets/18134fa.pdf

I'd guess 100MHz GBW isn't enough to make an active 10MHz R/C/OpAmp bandbass. I'd rather go for L/C filters. There's some quite easy to use filter design S/W around to easily calculate a higher order L/C filter. Same kind of S/W exists for active filters, too. I'll have to fire up the other computer where I have it installed.

Edit:
https://www.rfcafe.com/miscellany/factoids/Mother-All-Free-Filter-Software-Iowa-Hills.htm

The site linked (iowahills.com) appears to have disappeared

By some lucky coincidence, I've got a local copy here:
https://cb.wunderkis.de/wk-pub/www.iowahills.com/

Note: As too often, this S/W is for windows, but works nicely with wine on my linux desktop PC.

Err, as you want mostly low pass filtering to convert square to sine you don't need or want a fast amplifier. The low bandwidth actually helps as built in low pass filtering. As long as you have the required gain at 10MHz that's enough. A 25MHz GBW amp is probably enough for you application.  If you took a 1MHz GBW opamp and fed 5 V into it at a gain of 2 you would get near enough a 0dBm sinewave  out.
 

[mansaxel]

Wanted to finally receive SAQ on christmas,

One presumes that's some Ho-ho-horrific Ha-ha-hamateur radio callsign that only goes on the air for Christmas? 

Actually not, it is an actual, real, working, once-commercial WT station. The only electromechanical Alexanderson transmitter that is operative (or even exists!); it's sited in Grimeton on the Swedish west coast, was built in the 1920s to assure WT connection to USA et al.

Rumour has it that it was spared because it was a convenient VLF TX backup for comms to submarines in Skagerak and Kattegat. Since it is unique it's been made an Unesco World Heritage Site, the most electrical World Heritage there is.

It is something of a chore to get working; it's a 200KW three-phase motor driving a 17,2KHz AC generator.  The TX relay probably weighs 40 kilos. And it hammers away at best "former naval operator" WPM on the days they decide to try to get it alive, and actually succeed. The time we were there they'd fried a capacitor in the antenna tuner; a Ø 200mm ceramic disc that was cracked in two. Spares were available, and on second attempt they went on air.

Ear defenders are not optional in the transmitter room.

https://alexander.n.se/

[mansaxel]

@mansaxel: what is a Underhålls- & Trivselkväll?

It's an evening when the caretaker team meet to oil the generator, stop leaks in the cooling system, in general fix things and have a really nice time doing it.

Hams in Sweden are for the most part pretty civilised people. There are a bunch of weirdos among us too, but my impression is not as many as has been described in here for UK and US "scenes".

[mansaxel]

Like most cats, he does thoroughly enjoy his naps, and considers sleeping a high art form...




-Pat

Wife sez aaaaaw! As do I. Pet him from us.

[Cubdriver]

Like most cats, he does thoroughly enjoy his naps, and considers sleeping a high art form...




-Pat

Wife sez aaaaaw! As do I. Pet him from us.

Done!  He purrs his thanks to you.

-Pat

[med6753]

[Cerebus]

Was it just he, or did the firum go T.I.T.S.U.P.* for a few minutes there?

*Total Inability To Support Usual Performance

[nixiefreqq]

all the posts about hp5245's last week motivated me.

spent some time over the weekend and tested a pile of display boards.  found that many of the boards in the junk box were ok.

also found many with faults.  so far have repaired 6 of them. 

one had worn out neons in the display matrix.  would have expected them to die one at a time, but they were all dim and flakey even though the current limiting resistors and voltages tested good.

one had a wonky photocell matrix (the one printed on ceramic substrate in the readout block assembly).

and four had the same symptom of counting ok but not outputing a good carry pulse to the next decimal counter assembly.  all were repaired by replacing a silver mica in the output flip flop.  weird because the damn caps all tested good.......and silver micas are supposed to last forever. (it took me a long time to find this fix in the first one.....and it worked like a charm in all the rest).

the real puzzle is that some of the display boards in the junk box are unknown to me, and apparently not used in the 5245 family. 

anyone know what a 5232L-4B or 5245-6001 is used in?  (guess they will make good organ donors for the boards i have documentation for)



 

[med6753]

all the posts about hp5245's last week motivated me.

spent some time over the weekend and tested a pile of display boards.  found that many of the boards in the junk box were ok.

also found many with faults.  so far have repaired 6 of them. 

one had worn out neons in the display matrix.  would have expected them to die one at a time, but they were all dim and flakey even though the current limiting resistors and voltages tested good.

one had a wonky photocell matrix (the one printed on ceramic substrate in the readout block assembly).

and four had the same symptom of counting ok but not outputing a good carry pulse to the next decimal counter assembly.  all were repaired by replacing a silver mica in the output flip flop.  weird because the damn caps all tested good.......and silver micas are supposed to last forever. (it took me a long time to find this fix in the first one.....and it worked like a charm in all the rest).

the real puzzle is that some of the display boards in the junk box are unknown to me, and apparently not used in the 5245 family. 

anyone know what a 5232L-4B or 5245-6001 is used in?  (guess they will make good organ donors for the boards i have documentation for)



 

Do you realize the potential gold mine you have there once the word gets out? 

Might be too late already. 

[nixiefreqq]

ya' mean like this?

[med6753]

ya' mean like this?

Yep, you'll become famous as the Great hp Rush of 2022. 

[m k]

Was it just he, or did the firum go T.I.T.S.U.P.* for a few minutes there?

*Total Inability To Support Usual Performance

Yes.

[mansaxel]

Was it just he, or did the firum go T.I.T.S.U.P.* for a few minutes there?

*Total Inability To Support Usual Performance

Yes.

And here I wanted to post about my latest acquisition; a [hp] 3552A Transmission Test Set (pic from ad):



Mine for SEK 196. About 20€ / 21US$. Local pick-up. Same seller has auctions out for a Tek 310A scope (inventory signed "IBM Deutschland"; if I win it, I'll feel like a german Med, grinching about in a Bavarian village and hating his neighbours, while painting everything König Ludwig-Blau) and a [hp] 200CDR Wide Range Oscillator. Pickup for what I win will be next week; already discussed with seller.

[Robert763]

The 3552A is a great little audiio test set. Signal generator and level meter in a box. I have a couple.
They are a bit of a "sleeper". One non-obvious application is measuring ripple and noise on low voltage power supplies. The level meter is sensitive but is DC blocked to >50V DC for use on telephone line circuits.

[med6753]

Was it just he, or did the firum go T.I.T.S.U.P.* for a few minutes there?

*Total Inability To Support Usual Performance

Yes.

And here I wanted to post about my latest acquisition; a [hp] 3552A Transmission Test Set (pic from ad):



Mine for SEK 196. About 20€ / 21US$. Local pick-up. Same seller has auctions out for a Tek 310A scope (inventory signed "IBM Deutschland"; if I win it, I'll feel like a german Med, grinching about in a Bavarian village and hating his neighbours, while painting everything König Ludwig-Blau) and a [hp] 200CDR Wide Range Oscillator. Pickup for what I win will be next week; already discussed with seller.

I'm glad I'm such as positive influence. 

[factory]

No bids on the HP 5326A.   Seller re-listed.   Most likely does not work.  Might be missing parts???    Only 50MHz. 

https://www.ebay.com/itm/324950098314


Is is worth  99EUR + 20.99EUR shipping + vat?  143.98EUR   ~  $165  or  £124.00


I'm slightly interested, mostly to save it from becoming a clock.

Assuming the tubes are still in it?

McBryce.

These come with the risk of dead tubes & dead custom counter/driver ICs, seven tubes are standard.
You should probably ask the seller for a picture of the back to see if any options are listed, or you could wait for a 5326B version for the DVM function, or the 5327B for both DVM & 550MHz prescaler.

The 5326A that was posted recently made 50$ + postage/import costs, as expected I got outbid, hope someone on here got it.

David

[factory]

For those in Europe (apart from UK, Switzerland, Norway) that have a 524x series counter, a voltmeter plug-in is available;
https://www.ebay.de/itm/384615128154



David

[Cubdriver]

For those in Europe (apart from UK, Switzerland, Norway) that have a 524x series counter, a voltmeter plug-in is available;
https://www.ebay.de/itm/384615128154



David

That's a relatively rare one - think that particular model was in my search for about a year.  Dunno if I'd pay that much for one, but the rarity could be considered a factor.



-Pat