Test Equipment

I've accumulated a fair amount over the years, most of it not worth too much. Still, it's occasionally of use. Most of it works, or did when last put away.

Inventory

Bench

Portable

Heathkit IM-28 VTVM

This was the first of many Heathkits my dad and I constructed when I was back in secondary school. It never worked quite right on high ranges, and some years ago I opened it up and checked over all the instructions, and found where some of the precision resistors on the range switch deck were mis-installed. I corrected this and it then worked correctly on all ranges. While I was there I replaced the 1.5 V dry cell (for the ohmmeter) with a 3-terminal regulator powered off the tube filament circuit, so that there would never again be a calibration drift or battery leakage problem. This meter is my main bench workhorse, and always has been. It has never had a problem, other than what I described above.

Heathkit IT-121 Transistor Tester

This is one of many Heathkits my dad and I constructed when I was back in secondary school. It's simple, but it works.

Heathkit IT-28 Capacitance Tester

This is one of many Heathkits my dad and I constructed when I was back in secondary school. I actually use this a fair bit, though not usually for measuring capacitance. It does work well for checking leakage and breakdown voltage, which is mostly what I use it for. (I use the GenRad or Fluke for capacitance measurements.) I love the 'magic-eye' tube.

Heathkit IP-17 High-voltage power supply

This is a Heathkit my dad constructed for use in his science classes. I ended up with it when he retired. All-tube construction, no solid-state devices in it at all. Intended for supplying power to tube-circuit breadboards. So far I've used it once, while repairing the Stroboconn.

Heathkit IO-102 Oscilloscope

This is the last of many Heathkits my dad and I constructed when I was back in secondary school. It never triggered right, and some years ago I opened it up and checked over all the instructions, and found where some of the transistors on the sweep board had been misinstalled. (Dad wasn't the most meticulous instruction-follower, it seems.) Once that had been dealt with it worked properly.

This is an uncalibrated 5 MHz 'scope, nothing too special. It has had some kind of intermittent connection in it for some years now, where the trace gets choppy and shrinks off to the right. Something bad in the horizontal circuit I'd guess, but without a second 'scope to chase it with it never got fixed. I just bang on the side of the case with a screwdriver handle until it settles down. Maybe someday? I now have other oscilloscopes, so this wouldn't be a particularly difficult proposition, but it's pretty low on the priority list.

Heathkit IM-5228 VTVM

I ran across these at the thrift store, and bought them as spares. (Two separate acquisitions, though fairly close together in time.) These are pre-assembled versions of the kit meter. One of them has FET replacements for the tubes. I haven't yet had to use them for anything, so they just sit. Only one of them has the input leads. It's a 1/4" mono phone plug, but with an extra-wide insulating band, so might be hard to replace properly. (It might be a stereo plug, but with the extra ring replaced with insulation.)

Precision E-310 sine-square wave generator

One of the pieces of test equipment my dad had for his science classes. I got it when he retired. I don't use it much, but it does fill in as an ersatz speedometer feed when testing Mercedes cruise controls. Tube, not solid-state.

EICO 232 VTVM

I ran across this at the thrift store, and bought it as a spare. Couldn't pass up a VTVM, though I certainly have no use for a fourth! At least it was cheap.

Leader LF-826 Frequency Counter

I'd designed and built my own frequency counter in high school, as they were expensive back then, but it never worked all that well and only had a TTL input. (I'd never built an input amplifier circuit for it.) I got sick of that POS and finally bought this. What can I say, it just works.

Leader 718-3D Power Supply

I'd designed and built my own power supplies in high school, as they were expensive back then, but they never worked all that well. After burning up the transformer in the last POS I'd made I finally bought this. What can I say, it just works.

Samlex PSA-305 Power Supply

When I bought the Leader I also bought this slightly heavier-duty one for a second supply. It's a POS, though, as it doesn't have foldback current limiting but rather a crowbar cutoff. Even a momentary overload will shut it down until you power-cycle it. Crappy, but I suppose better than nothing.

GenRad 1657 RLC Digibridge

This was a piece of test equipment surplussed by a company I worked for, I got it for free when they closed down the lab. It works very well indeed. Fast and accurate, and precise. Its capacitance range, however, isn't as wide as the Heathkit on the large end.

Hickok Variac

One of the pieces of test equipment my dad had for his science classes. I got it when he retired. I use it a fair amount, and one of the things that makes it unusual is that it's isolated (using a separate isolation transformer). I put it into a wooden case back in high school, as it was case-less, and somewhere along the way I broke the face off its side-reading voltmeter.

Lab-Volt Model 189A Variac

A thrift-shop special. A rather small one, but has variable 0–12 VAC and 0–12 VDC outputs in addition to the usual 0–120 VAC. From the selenium rectifier days. I haven't really used it for anything, it really is quite small, 1 A on the main output.

Staco Variac

A thrift-shop special. This one had a dent in the face that kept the knob from turning freely. I pounded that out and then it worked perfectly. It lives on the headboard of the bed, and dims the reading light. (It has also been taken to church a time or two, to dim the bank of stand lights for the bell choir, as it was easier to liberate from its nest than the Hickok, and the Lab-Volt wasn't big enough.)

Tektronix 2336 Oscilloscope

This was a piece of test equipment surplussed by a company I worked for, I got it for free when they closed down the lab. It worked nicely, until it blew its high-voltage multiplier. I rented a service manual and photocopied it properly, no small feat, then diagnosed it and found a NOS multiplier that was horribly expensive. Still worth it, given that the scope itself had been free, but no longer a screaming deal.

Its P6015A high-voltage probe is actually worth a bit of money. Certainly more than the scope, now.

Tektronix 561A Oscilloscope

A friend at work was moving and was going to throw this away if I didn't want it. In fact I did not want it either, but I hated to see such a finely-constructed piece of equipment hit the dump. It really is a work of art inside, and is a mix of tube and solid-state technology. It almost works, but recently the horizontal trace shrank to zero width. It's very drifty, that's for sure. I used it twice, at least, out in the garage before it stopped being usable.

Tektronix 475 Oscilloscope

After the betrayal of the 2336 I determined that I wanted a better bench scope, but my first choice, a nice 2465, has a bad reputation regarding reliability. They have NLA IC's in them that are failing now with age, after which you have a nice paperweight. The older generation, like the 465/475, is much higher regarded in a reliability sense, and has very few custom parts in it so you can keep them working if you want to. I never liked them all that much, we'd had one at work that was always the last choice of anyone looking for a 'scope, but I always figured I'd get one sooner or later. This was the first one I ran across. $40, at Goodwill. It had an intermittent 5 V power supply problem, which I fixed.

Tektronix TM-503

This three-bay test chassis was at a yard sale! I bought it because it was Tek, and cheap. It has a PG-501 pulse generator and a DC-504 counter module in it. No plans for it at this time.

HP 1630D Logic Analyzer

This was a piece of test equipment surplussed by a company I worked for, I got it for free when they closed down the lab. It's a nice piece of equipment, but not too usable in a home situation. It had a thermal HPIB printer for dumping waveforms, but the paper was expensive and didn't age well. I found an HPIB thinkjet printer at a thrift shop that tried to work, but the printhead cable was decaying. After scraping up some other thinkjets I found that all their printhead cables were decaying, and that repair parts were NLA. Disgusted, with inkjets in general and these in particular, I then got an HPIB-parallel converter and a small Epson Actionlaser 1100 HPPCL-compatible laser printer, and found that this combination could also print the waveforms. It can also sit for years and yet power on and work properly, which is just what I want. The analyzer saves its configuration (and captured waveforms) on a flimsy-seeming external HPIL tape drive, originally created for the HP-41 calculator family. It, fortunately, is not a particularly necessary piece of equipment, though it has not yet failed.

Applied Microsystems EM-180 Z-80 In-Circuit Emulator

This was a piece of test equipment surplussed by a company I worked for, I got it for free when they closed down the lab. It's a nice little piece of equipment, but not too usable in a home situation. I spent a lot of hours with these, once upon a time, as it was the means to debug computer systems of its day, but now it's really just a memento. This is a very nice little emulator, from the days when you actually could make such things aftermarket. It also came with a service manual containing full schematics. You don't see much of that anymore.

Applied Microsystems ES-1800 68010 In-Circuit Emulator

This was a piece of test equipment surplussed by a company I worked for, I got it for free when they closed down the lab. It's a nice piece of equipment, but not too usable in a home situation. I spent a lot of hours with these, once upon a time, but now it's really just a memento. This is a nice emulator, from the days when you actually could make such things aftermarket. This particular one was converted by us (back in the day) from 68000 to 68010, and works pretty well.

Applied Microsystems ES-1800 68020 In-Circuit Emulator

This was a piece of test equipment surplussed by a company I worked for, I got it for free when they closed down the lab. It's a nice piece of equipment, but not too usable in a home situation. I spent a lot of hours with these, once upon a time, but now it's really just a memento. This is a reasonable emulator, from the days when you actually could make such things aftermarket. This particular one was not too easy to use, as the introduction of in-CPU cache memory was the death-knell of aftermarket emulation products.

Tektronix 577 Transistor Curve Tracer

This was a piece of test equipment surplussed by a company I worked for, a buddy got it for free when they closed down the lab. Recently he decided he was never going to use it, and passed it on to me. It has the D1 storage option, and a 177 test fixture. It came with the plastic protective box, a 013-0098-02 transistor adapter, a 013-0111-00 diode adapter, and a shop-made TO-3 transistor adapter. The tracer powers on OK, but it looks quite complicated to set up and I don't yet have a manual.

HP 4277A LCZ Analyzer

This was a piece of test equipment surplussed by a company I worked for, a buddy got it for free when they closed down the lab. Recently he decided he was never going to use it, and passed it on to me. It doesn't have any factory options, and came with a 16047A text fixture. It looks considerably more sophisticated than the GenRad Digibridge. I tried it out and it does seem to work, once I sprayed Caig Deoxit into the test fixture.

Leica Stereozoom 5

This was for sale at auction, I bought it for $175. With (broken) ring light and a manual. (The broken bulb is labeled 74-B WW.) These, apparently, are actually a Bausch & Lomb design that was taken over by Leitz. I'd wanted a nice dissection microscope for years, especially as my eyesight degrades with age, and finally ran across this one. Not as nice as I'd hoped, perhaps, but it might serve. The eyepieces are a bit out of adjustment, but there are online instructions for curing that.

Links: White Paper
Manuals

The broken fluorescent bulb is rare and expensive now, and so is not attractive to replace. I nabbed a discarded Sciencescope illuminator from work, halogen/fiber-optic type; it also needs a bulb (EJV, 150W 21V which is not expensive), but something else was wrong (hence the discard). There are other options, too: http://store.amscope.com/frl8-a.html

Tektronix R7623A Storage Oscilloscope

A friend owned this, but he was moving and lightening the load, and gave it to me. It came in the trunk of a car I bought. Supposedly working, no burns on the storage tube. Three bays, with AM-6565/U Amplifier, 7A1B Dual-Trace Amplifier, and 7B53A Dual Time base. Rack-mount, and supposedly once was used in the original skunkworks' FLIR lab. With three Philips probes.

Tektronix 7633 Storage Oscilloscope

A friend owned this, but he was moving and lightening the load, and gave it to me. It came in the trunk of a car I bought. Supposedly working, no burns on the storage tube. Three bays, with 7D13A Digital Multimeter, 7A26 Dual-Trace Amplifier, and 7B53A Dual Time base.

Marconi Instruments 2019 80kHz–1040MHz Signal Generator

This was a piece of test equipment surplussed by a company I worked for, I got it for free when they closed down the lab. What is interesting is that it had an old asset tag on it from another company I used to work for that closed its lab! It blows fuses at power-on, it may have electrolytic capacitors in it that need re-forming. [No, the torroidal power transformer is smoked. No coming back from that.]

Leader 718-5D Power Supply

I've been using the 718-3D for years, and it has worked perfectly, always did what I want. (Unlike the Samlex.) It then occurred to me that I could just buy another one, used this time, for a second trouble-free supply. So, I did. The 5A one was what was available at the moment on eBay.

Fluke 83 DMM

I'd wanted a good DMM for some time, so I bought this one new, full retail. It has been an excellent meter in the ensuing years. I did blow the current fuse once, and that's a bit hard to come by and expensive, so it pays to be careful.

I like it better than the 87's because:

  1. Longer battery life
  2. Larger digits
  3. Analog total bargraph, rather than analog last-digit sweep

The display started to flake out after some years and I found that disassembling and cleaning the LCD-to-PCB standoff with alcohol restored it to perfect working order.

Simpson 260 6P VOM

My dad had one of these, they are rugged and handy. I found this one at a thrift shop. Something is fried inside, not all the ranges work right. Mostly I've used this for DC current measurement. I found a schematic for it that could help, if I should ever make the time to try to fix it.

Fluke 87 DMM

I ran into two of these at pawnshops, at reasonable prices, and bought them. About $100 each, as I recall. (Two separate acquisitions, though fairly close together in time.) It's always nice to have a second quality meter around, and why not a third? I like these better than the 83 because:
  1. True RMS
  2. Faster
  3. More precise
  4. Backlight

Mostly I use the 83, though.

Fluke i410 400A AC/DC current probe

A very handy adjunct to the Flukes, especially for automotive work like starter current draw, etc.

Fluke 80T-IR temperature probe

A very handy adjunct to the Flukes, especially for automotive work like head temperatures, AC temperatures, etc. It had an internal wire whisker short on the cable that caused me grief for a time, but I finally found and fixed that.

OTC 200/2000A current probe

A heavier-duty version of the Fluke i410. I couldn't pass it up, though have yet to find a situation where the Fluke didn't do the job. I think I bought it with one of the Fluke 87's at a pawnshop that was closing. $50?

PDI 60A current probe

A gift from my brother, this is very handy for smaller circuits than the Fluke i410. Certainly it's much smaller!

Tektronix 834 serial protocol analyzer

This was a piece of test equipment surplussed by a company I worked for, I got it for free when they closed down the lab. It worked nicely, so far as I could tell, but its single-line display was limiting and it only worked on Async lines up to 9600 baud. I'm sure it was very expensive in 1980 when it was made, but it's pretty limited. After 34 years of sitting around, though, I think its EPROM firmware has faded, and it now only throws an internal self-test checksum failure. Modest attempts to resurrect it failed. It's probably done for. Too bad, it was kind of a cute tool, and is very well constructed.

See: http://w140.com/tekscope-scans/Indiv-Issue-Scans/12-4-Dec-1980.pdf

Maytag wattmeter

I love the name on this! Your basic moving-vane wattmeter, I believe.

Kill-O-Watt watthour meter

These are very handy tools for figuring out power consumption of intermittent-operation devices like refrigerators, or modern computers. It also gives you any other power line statistics you might want. (Hz, V, A, Watts, kiloWatt-hours, VA, and power factor.) I bought one new retail, and ran into the other at a thrift shop, unused and in the blister pack, for a vastly reduced price. Score! I keep the second one on the Kohler genset.

Kurz Model 443 air velocity meter

A thrift-shop find, about $13. A portable analog-meter-based tool intended for HVAC ducting measurements, but usable in other situations. It works by measuring the wind chill on a heated probe. Range from about 2 feet/minute to 12,000 feet/minute (136 MPH), in three ranges. Seems to be working, the built-in NiCd battery even took a charge. Dates from 1986. Complete with case, charger, and manual (including theory of operation and schematic).

Tektronix P6042 Current Probe

A friend owned this, but he was moving and lightening the load, and gave it to me. It came in the trunk of a car I bought. Rated DC–50MHz, 1mA–1A/division into a 50 ohm oscilloscope set at 50mV/division, it plugs into the wall and feeds a voltmeter or oscilloscope. Supposedly it has a drift problem, but so long as you zero it right before taking a reading it works fine.

Log (belated)

Friday, June 1, 2012

I bought a $40 Tektronix 475 oscilloscope at Goodwill, it came with two aftermarket probes. It was acting weird at the store, but OK at home. Later it was acting weird again. Both channels were acting the same, likely it's something common like the power supply. (Older Tek scopes that are broken often have power supply problems.) I downloaded a service manual for it from BAMA.

Saturday, June 2, 2012

I opened up the Tek 475, and determined that the 5 V supply is not working right, the Fluke 83 said it was 4.2 V, with nearly 1 V of AC. I was able to use the old Tek 561 for a few minutes, before it crapped out (lost horizontal sweep), and the waveform was not smooth DC but rather what you might see with a bad filter capacitor, diode, or an extreme load. I checked the diode bridge in-circuit with the Fluke's diode setting, it seemed to be OK. I think I'm going to have to remove the interface board in order to get at the big filter capacitors, which is a real pain. Later I found there was no voltage on the 5 V bus, perhaps things are getting worse? I see that this (older) 475 does have the retrofit larger diode bridge assemblies from the newer versions of the design, which is good. I found a much cleaner (and larger) scan of the manual on the Tektronix site itself, though I had to sign up to get it.

Sunday, June 3, 2012

More fooling with the 475. I got out the Tek 2336, which has a persistent focus problem. (Criminy, I have four oscilloscopes now, and not one of them is good!) I was able to see the wonky waveform on the 5 V line, even through the fuzzy focus. Unfortunately, while probing around the 5 V circuitry, on my way towards bolstering the main filter cap as a diagnostic step, a slip of the probe managed to short a nearby 136 V (!) line to the + terminal of the 5 V rectifier bridge, SNAP!, and it no workie no more. Q1454 (2N2222A, metal) has a C-B short, and I believe Q1456 (MPSU45 darlington) is also blown. In disgust I dragged out the bench power supply and back-fed 5 V into the touch point, and the scope worked again, properly even! (It draws about 400 mA, which seems reasonable given the 20 V input to the regulator and the size of the heat sink on Q1456, and pretty much negates the 'overloaded' potential cause. I believe this also eliminates shorted crowbar diodes or downstream filter capacitors from consideration.) I walked the voltage around the scope's regulation point and I could see the output of U1454B (MC1458) swing from rail to rail, so I think it is OK. I dug a plastic 2N2222 out of the parts pile and installed it. While the metal parts have only one pinout, I was distressed to find mixed information on 2222's out there, they're either CBE or EBC, and it does matter a bit! The best information that I could find for my particular part was EBC, pins facing me flat side up. So I turned the part over and bent the leads into the metal part's CBE configuration before installing it into the board's socket.

The MPS-U45 is a tougher animal, it's not too common anymore, although electrically equivalent parts are readily available. There's another one on the 475's PCB, Q1482, which is for driving the graticule lights. Well, I don't need those today! I swapped it into place, being careful to get the heat sink and insulators right, and it didn't help. I was still getting wonky voltages, and was (for awhile) getting 8 V on the 5 V line—I may have lost one or two of the incandescent indicator lamps, which operate off of the 5 V supply. I swapped the op-amp with the other one and there was no difference; I used the Fluke to test the diode and resistors in the regulator circuit. Crap. I finally said 'screw it' and went to the junkbox and liberated an old 7805 TO-220 voltage regulator and screwed it into place on the heat sink. I ran the input to the transistor's Collector hole, picking up the unregulated voltage, and the output to the other side of the Emitter resistor, and grounded the reference lead. (Which was also grounded through the heat sink, and I did not use the insulator package. I strung them on one of the hookup wires for safekeeping, just in case I ever want to try to fix this 'properly'. I soldered the diode bridge back in place and stitched a 1000µF capacitor onto it to help bolster the (likely tired) original filter capacitor. I then fired it up. The bus only has 4.9 V on it, but the scope seems to be working. I put back the graticule light driver, but it didn't work. Perhaps that transistor was also taken out while it sat in the Q1456 site? Oops.

I then cleaned up the giant mess I had made in the living room (since the workbenches are so crapped up I can't do work like this on them anymore; there's a clue, there), and I put the 475 on the bench in place of the 2336, which I rigged for portability and set aside. (I just need to remember to dig into it and fix the focus. I checked the schematic, and from the look of it it's either an open or disconnected resistor in the HV divider for the focus grid.)

Monday, June 18, 2012

While researching the MPS-U45 I had found that it had been used extensively in some pinball machines back in the day, and it turns out that I work with a couple of pinball collectors. I had checked with them, but they didn't have any spares. One of them threw an order of four in on his next care package from his favorite supplier, and I got them today. $2 each, which is not too bad for these, esepcially since I didn't have to pay shipping, which would have probably cost as much or more than the parts did. (There are cheaper alternatives, but they have different pinouts.)

Thursday, January 10, 2013

A buddy I used to work with was cleaning house, and decided he actually had no use for the Tektronix 577 Transistor Curve Tracer or HP 4277A LCZ Analyzer he'd nabbed at the lab clearance where I got the HP 1630D Logic Analyzer, the Applied Microsystems emulators, and the GenRad Digibridge. So they came to my house. No manuals or other accessories. These were expensive pieces of equipment originally, and it looks like I'd still need to shell out $2–3,000 if I were buying warranted units now. As if!

Saturday, January 19, 2013

At the Rheinland auction of the defunct Logan Industries cable-making site I bought a Leica Stereozoom 5 microscope, with illuminator. (Bulb is broken.) $175.

Turns out the bulb is a rarity, now, and is something like a $100 item. Not attractive to replace.

Tuesday, February 5, 2013

They were throwing away a broken Sciencescope microscope illuminator at work, a fiber-optic type that was originally a $1000+ unit. It wasn't the fuse or the bulb so they just threw it out and bought an LED illuminator instead. I grabbed it, it needs an EJV (150W, 21V) bulb. (They kept that for another use.) Assuming it can be fixed. Bad switch contacts, etc.?

Wednesday, May 15, 2013

I used the 577 Curve Tracer to try to determine the sex of a zener diode I was salvaging from a defunct DVD player I was discarding, it seemed like the thing to do. (I try to salvage the high-voltage electrolytic capacitor from any switching power supply I discard, for use in tube equipment, along with anything else interesting and easy to get that I see while doing so.) I didn't remember how to use the tracer, but I flailed around and got it to work. (Diodes are particularly easy, no base or base drive required, so I figured I had a chance working blind.) The tracer worked OK, but the vertical sensitivity knob was very noisy, so I removed the 177 test fixture (where that control lies), opened it up, and shot all the switch contacts with Caig DeOxit. I wiped a bit on the edge connector of the fixture too. After reassembling it then behaved itself, and I was eventually able to determine that the diode's breakover voltage was a surprisingly high 30V! Huh. I taped the diode to a piece of paper and wrote its voltage on it before putting it in the junk box. Lotsa time spent on this quickie salvage operation, but tool repair and education are always worth something. (I didn't care about the diode, but I thought it was a good excuse to get refamiliarized with a curve tracer, which I had not used since college—more than 30 years ago.)

Tuesday, January 21, 2014

Found the Kurz 443 air velocity meter at the thrift shop. $13, looks like a steal.

Wednesday, July 30, 2014

I tried to use the Tektronix 834 RS-232 protocol analyzer today to watch an RS-232 line on an old PC, but it failed its ROM (EPROM?) checksum. I tried reseating the socketed parts, with Deoxit spray, but no joy. It is probable that the 1980 vintage EPROM is fading. I guess it's dead, it seems unlikely that I could fix it, even were I all that interested! It worked the last time I tried it, but that was several years ago. I suppose it could be fixed by refreshing the EPROM, but I'd need a good image, which just isn't available. There's an outside chance one could be recovered from the failing device itself by playing with the supply voltage while reading, but that's a lot of work with very little possibility of success.

Saturday, February 28, 2015

The 560 SL I bought came with two Tektronix storage oscilloscopes in the trunk: a R7623A and a 7633. The PO was moving, and lightening the load. One of them used to live at the original FLIR lab in the skunkworks. Came with an operator's manual and three Philips probes. Also included was a Tektronix P6042 current probe.

Saturday, March 7, 2015

I tried to use the Tektronix 2336 oscilloscope again today, and again it was totally out of focus; the trace was a full major division wide. Some days it did not work, and some days it did, but not recently. Today, though, I finally opened it up and found that one of the three wires to the focus control had broken off, resulting in no voltage to the tube's focus grid, rather than the ≈1,500 V it should have on it. (Probably from stress when I had replaced the high voltage multiplier some years ago, since the multiplier is located on the board the focus control goes to.) In spite of the care I tried to take when disconnecting the 7kV anode wire I managed to get nailed anyway. Ouch! Fortunately (?) it all went through me and not any of the circuitry. Anyway, the operation was not a particularly difficult one, and it seems to work fine again. It's my smallest oscilloscope, and the newest—it would be nice to again be able to rely upon it.

Tuesday, March 1, 2016

While cleaning out the old building at work (for the move) they were discarding a Marconi Instruments 2019 Signal Generator, so I grabbed it. It hadn't been used in years, and had blown fuses. My guess is that it has electrolytic filter capacitors that need re-forming. What is interesting is that it had an old ISC asset tag on it. I remember seeing this unit at ISC, my first job!

Saturday, February 17, 2018

I had the bright idea to try to use the Marconi to inject a strong multi-kilohertz signal into some lead-acid batteries as a de-sulphating measure, and tried to get it going. I found one shorted power supply filter capacitor inside, which I replaced with a junkbox spare, and the unit started looking like it would work. Unfortunately I moved it off of the fused Variac (which I used while re-forming the filter capacitors) too soon, as I had bypassed the Marconi's own fuses since I didn't have any of what it wanted. Mistake. While playing with the front panel trying to figure it out the lights flickered, a horrid buzzing came out, the unit went dark and smoke started coming up from the torroidal power transformer. Game Over!

Tuesday, February 27, 2018

I had loaned out the Fluke 83, and was using the Fluke 87 as a spare. But, its leads were terrible. I ordered a set of actual Fluke TL71 silicone leads, $17, and they came today. They look good, and work. They have tip protectors, which sound good but are surprisingly annoying.

I also managed to blow the 87's 1A current fuse. These are expensive/difficult to find, because they're rated to interrupt 600V. (BBS-1 fuse.) I ordered three more for $11.

The cheap ($11.50) battery desulphator kit I bought came. An actual kit, I had to solder it together. It seems to function, but whether or not it can do anything with a battery remains to be seen.

Wednesday, March 14, 2018

The used Leader 718-5A power supply I ordered a few days ago came. (About $65, shipped.) Definitely shopworn, but it works. I straightened the bent fins and took the dent (mostly) out of the case, and used fader spray on the controls. Seems to work just fine. Will be a much better second supply than that wretched Samlex, though that one does go up to 30V as compared to this one's 18V. No fan, good current foldback ability.

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