| Products > Test Equipment |
| The worst products from HP and Tektronix. |
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| alm:
--- Quote from: coppercone2 on May 07, 2023, 09:33:28 pm ---the precision power supply from HP (6000 series) has the absolute worst switch ever. I mean the one you dial up with the buttons that everyone was raving about. Great supply, but that switch bank is just awful awful awful. --- End quote --- Why do you think it's awful? Ergonomics? Reliability? I have no problems adjusting the 6114A. I use it side by side with a similar Lambda LR-613DM precision power supply which has a rotary knob per decade, and I find both equally convenient to use. I do hate the controls of the IET VI-700 voltage / current source. Those thumbwheels are painful to the fingers and I do not enjoy repeatedly adjusting it. I guess the instrument was not made to be adjusted frequently. --- Quote from: Neomys Sapiens on May 08, 2023, 12:54:13 am ---And the 250MHz pulse generators from the TM500 series - I have yet to encounter a working one. --- End quote --- How large and (un)biased is your sample group? I also have a PG502 that has been working fine since I got it, so I'm questioning if this is a design flaw. |
| TERRA Operative:
--- Quote from: Neomys Sapiens on May 08, 2023, 05:26:13 am --- --- Quote from: TERRA Operative on May 08, 2023, 01:26:25 am --- --- Quote from: Neomys Sapiens on May 08, 2023, 12:54:13 am ---I would also nominate the TDS3xx/4xx series. They were obviously a sort of learning phase in regard to user interfaces for Tek which was nevertheless foisted on the customers. And the 250MHz pulse generators from the TM500 series - I have yet to encounter a working one. --- End quote --- Yeah, I took a look at the TDS3xx /4xx series, but why bother when you can select from the TDS5xx/6xx/7xx series... (besides physical size). Much nicer displays too. --- End quote --- Why bother with those when you can get a TDS3xxx/5xxx/7xxx? --- End quote --- Working on it.... I have my eye on a TDS7xxx series as soon as I sell off some gear to raise funds. :-BROKE --- Quote from: Neomys Sapiens on May 08, 2023, 05:26:13 am --- --- Quote from: TERRA Operative on May 08, 2023, 01:26:25 am ---Do you mean the PG502 or PG505 pulse generator? I have a PG502 that works and is adjusted nicely. --- End quote --- There was absolutely no need to rub that in further! :box: --- End quote --- As per above, wanna buy my PG502? :-DD (for real though, it's on the 'to be sold' pile) --- Quote from: Neomys Sapiens on May 08, 2023, 05:26:13 am --- --- Quote from: TERRA Operative on May 08, 2023, 01:26:25 am --- --- Quote from: Neomys Sapiens on May 08, 2023, 12:54:13 am ---And then there is the HP5334A universal counter (a capable and nice devive by itself), which, contrary to any other HP device I've seen, does not simply take the HP10881 OCXO, but needs a special adaptor board, which is pure unobtainium. --- End quote --- Would a replica via a Chinese PCB manufacturer be feasible? --- End quote --- Oh noe! The Chinese will hide secret jitter-enhancing elements in the PCB and further compromise my timebase! :scared: --- End quote --- :-DD |
| coppercone2:
--- Quote from: alm on May 08, 2023, 07:13:59 am --- --- Quote from: coppercone2 on May 07, 2023, 09:33:28 pm ---the precision power supply from HP (6000 series) has the absolute worst switch ever. I mean the one you dial up with the buttons that everyone was raving about. Great supply, but that switch bank is just awful awful awful. --- End quote --- Why do you think it's awful? Ergonomics? Reliability? I have no problems adjusting the 6114A. I use it side by side with a similar Lambda LR-613DM precision power supply which has a rotary knob per decade, and I find both equally convenient to use. I do hate the controls of the IET VI-700 voltage / current source. Those thumbwheels are painful to the fingers and I do not enjoy repeatedly adjusting it. I guess the instrument was not made to be adjusted frequently. --- Quote from: Neomys Sapiens on May 08, 2023, 12:54:13 am ---And the 250MHz pulse generators from the TM500 series - I have yet to encounter a working one. --- End quote --- How large and (un)biased is your sample group? I also have a PG502 that has been working fine since I got it, so I'm questioning if this is a design flaw. --- End quote --- its a piece of shit non serviceable complex mechanism that needs service. Not even snap hinges, but molten pins. And its all soldered down at right angles to a PCB edge pads in a 'creative' assembly method. And its all plastic in there too. Every time someone solders right angle PCB to each other a la stone hedge, electronics god cries I think that power supply switch spurred dac design because some engineer figured he can make a precision switch matrix without moving parts, and the first good DAC was made in a alcohol fueled haze of insanity entered post failed 6114A service attempt. The engi just knew deep down that management would never allow for the correct amount of mechanical hardware to make that mechanism not suck, so it was improvised, and a semiconductor fab was hijacked and made the first processor controlled precision power supply control chip. Without the 6114A, it would look like the first Alien movie by the year 2170, because they figured out switches. |
| W6EL:
Some people won't agree with this, but if you've gone over one, then you know. HP 8640B. The supposedly ultra-stable low-phase noise design suffers plenty from short-sided design choices when it's working. Let's start with the supposed phase noise claim. That phase noise is only available if: 1. You're locked to a 5 MHz ultra-stable source (and remember, using basic logic circuits to "divide down" a 10 MHz source induces what? Phase noise.) 2. You're ok with 100 Hz tuning steps. Yeah. Because you do not get the low-phase noise unless you can engage the PLL Locker. And the locker won't engage unless all the digits are shown on the 5 digit display. Oh, sure, you can lock and then de-tune the PLL circuit with a knob, which induces, you guessed it, more phase noise, as you're suddenly at the mercy of a variable resistor. But ok, fast forward and look at this beast honestly. Mechanics: It has a ridiculous linked-(un)limited-slip differential scheme going on, using plastic gears, between the FM deviation and the frequency range knob. Yes, multiple layers of complex gears. It's like taking apart a mechanical alarm clock. The gears crack over time and then begin to slip or just fall into pieces. Then there's the slider switches on the front panel. These break off because the enormous lever arm action coupled with the stiff click-click of the slider causes the brittle plastic to snap off. You can fix this by making your own metal replacements! Yea! And then you can glue them with epoxy to whatever is left inside the HP 8640B. Fun times! Don't forget the camshaft that the range knob operates. Oh, yes, not only does the range knob operate a nasty arrangement of plastic gears in the front, but it also operates an enormous enigma of camshaft switches deeper inside which switch around how the UHF cavity oscillator is divided down. But there's more to hate here. The PLL boards mate to the main board using these horrible and unreliable finger connectors. If yours hasn't failed yet, then it will! And then there's the usual. RIFA capacitors at the rear, sealed pots that need to be cleaned inside somehow, the occasional failed capacitor. We all expect that stuff. Oh and don't forget the broken gold fingers on the wafer-like switches. Yes, instead of normal wafer switches, HP etched switch paths on gold PWBs, sort of like how a modern handheld DMM handles the big switch. Except, to attach the wipers of the switch, they hot-melted the little gold fingers into (you guessed it) another plastic piece, which of course slowly falls apart. Don't forget to literally shake the gold pieces out when you first open one of these up -- they are basically impossible to replace without cannibalizing another instrument. Ultimately, a small amount of relays or even solid-state switching, plus some standard switches, would have saved this instrument from such an early demise. Don't believe me? Instruments made before and after it used other not-completely-fantastic-plastic methods to control the circuits. After many hours of gluing, grinding, probing, replacing, and swearing, you end up with a signal generator with low frequency resolution and phase noise specifications that it will never meet unless you have a cesium clock at 5 MHz to feed it with. To be fair I considered such (just for fun). |
| porter:
--- Quote ---HP 8640B --- End quote --- The controls are a interesting variety of technologies (analog meter, push button switches, crank, leds, sliders). It looks cool anyway. |
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