- 2026
- Jan
- 22
Checking out some recent acquisitions - #4 - Odd Heathkit Stuff
Here’s a device I picked up as part of a stack of stuff - A Heathkit IB-5281 RLC Bridge. This “more modern” equivalent of the old eye tube tester, and dates to the late 1970s. This is probably the last gasp of this type of device, as digital capacitance checkers started to become more readily available as the 80s moved on.
There was a whole set of devices in this range including:
AF Generator
RF Generator
RLC Bridge
Signal Tracer
Multimeter
They’re all in giant blue plastic boxes:
The device has a fairly short range of values it can test, and definitely seems to be geared towards the transistor era. One of the neat features is this device can also do matching by comparing the component in Zs with Zx, and dialing the main indicator away from 1.0 to give a determination on how close a match they are.
The top has a handle and a space that pulls up for cable storage:
And the back has the power input.
The device requires +/- 9VDC, and can run on either a pair of 9V batteries - which you have to disassemble the case to get at - or an external power supply. Originally, this would have had a molex connector similar to an old floppy drive power input, but the previous owner removed it and added a terminal strip.
Inside of the device is pretty sparse.
A single board with all the components, the mode switch, meter, and value pot. The batteries go in holders at the back, if you choose to use them.
Let’s hook a part up to this and see what it does. I chose a bumblebomb from the Simpson 715 that is currently on the bench. It’s marked 0.047μF but reads about 0.052μF on my digital meter.
Lead length is important here. I tried these cheap long leads, but ended up having to rig up a set of shorter ones to get an accurate reading.
To use this, you:
Connect the unknown.
Set the range switch appropriately.
Turn the value dial as far away from the believed value of the unknown.
Adjust the meter level until it’s “10.”
Turn the value dial to get as close to “0” on the meter as possible.
Adjust the meter level control back up towards “10.”
Re-adjust the value dial to null again.
Repeat the above two steps until you can’t go up and/or null anymore.
I ended up with this for the part under test:
So…it works as expected, even though I can see the level pot wearing out quick since you’re constantly adjusting it. I have to wonder why that control didn’t get a nice knob - that little plastic shaft is difficult to turn accutrately, especially considering that meter is quite unstable. Who knows.
I’ll probably keep this, just for the novelty, but who knows. You may see it and it’s brothers at a show near you.
Next part of this series: Coming soon.
Previous part of this series: https://wereboar.com … 3-radio-shack-lives/
- 2026
- Jan
- 21
A Simpson 715 AC VTVM Part 3: Continuing capacitor replacements.
In the last part, we started to replace some of the parts that are known problems in older devices. While most of these probably won’t do anything to fix the non-zero issue (and that is probably some other parts out of tolerance) - they will need to be replaced if this meter is going to go into service with any reasonable expectation of working.
This part sees some of the components in the meter circuit replaced, and takes care of most of the (current) work on the bottom of the device. There’s a capacitor-resistor pair that we’re going to replace, and this is a component directly in the meter circuit. There’s also another resistor on the topside that’s part of this circuit, but that isn’t going to get replaced until later.
Here’s the components we’re working with:
In particular, the capacitor and the 2W 680Ω power resistor are being replaced. The 30Ω resistor is for later. The capacitor and resistor mentioned are soldered across one another, so removing the capacitor means the resistor gets removed as well.
I didn’t need to use a 2W part here, but that’s what I had on hand. It’s pretty much the same size as the old 1/2W carbon comp, so why not.
Here’s what we’re going to replace:
This part attaches to a terminal strip that carries a wire up to the meter board, and snakes down to a tube socket on the other side. They unsoldered fairly easily, and I was able to bend leads and remove the parts intact for later testing.
The new parts don’t need to go in the same way, they are small enough that they can simply run directly to the connection points with a little bit of ‘lectric sketti.
That was much easier than I expected, and I took the time to remove the filter capacitors as well. That’s next.
The old part was pretty much +100% at 1.4Ω ESR, so it’s getting tired.
Next up is the filters, then the meter board goes back on with some parts attached to it. Stay tuned!
Next part of this series: Coming soon.
Previous part of this series: https://wereboar.com … x-the-no-zero-issue/
- 2026
- Jan
- 19
The Dayton Hamvention is coming up soon.
While still about 4 months away, there’s no better time to get your ticket as you can get the early boar price of $26, mailed to you at no extra charge. This is good for all three days - May 15th, 16th and 17th.
Ticket prices increase March 1st, so there’s no time like the present to get one if you plan on attending. Get your ticket here: https://hamvention.org/purchase-tickets/
See you there!
- 2026
- Jan
- 17
A Leader LBO-310A Oscilloscope - Part 1: Observations
A friend picked this cute little scope up for me cheap because I’ve been looking for a small, actual CRT scope.
The Leader LBO-310A is a simple 4MHz scope that dates to about 1976. It doesn’t offer much except scope. Let’s take a look.
The device itself is pretty clean, both inside and out. The outer shell still has the plastic covering on the metal, so essentially underneath of this cover it’s brand new. Inside, there’s a little bit of the white corrosion that you get with this vintage of Japanese equipment, but nothing major. This scope was used, but not abused.
Even the cord is still good on this thing. This is one of the few devices that’s come across my bench that doesn’t need a new power cord.
Inside is pretty sparse. This guy is transistorized, so no vacuum fire bottles except for the CRT:
There’s a lot of places for extra components, so this probably was used in other things, or had options that this unit doesn’t have. There is another board behind this one, that’s a power supply board - it’s not really visible unless removed from the unit - there will most likely be some better shots of that later.
So - does it work? It does, that was demonstrated in the ad, but let’s try it out and see if it actually responds. First thing I notice is the pots are gooey and touchy, so it gets some Deoxit…in particular the vertical position pot is very touchy. More on this later.
I’m using a signal generator I picked up at Fort Wayne, a Heathkit IG-72 that I recently did a checkout post on. It needs a little adjustment but will work for this purpose. And yes, the device responds nicely.
The CRT is nice and bright, and the trace sharp. It does need a little rotation, so I’ll pull the manual and see which one of the internal adjustments does that for us.
The vertical position pot does have an issue - right about where it would be set for the trace to be in the middle of the screen, it’s dead. That’s not surprising, that’s probably where it sat most of it’s life, and I believe this unit came from a shop. That’s not a big deal, it looks about like one of those cheap Alpha pots that ratshack used to sell. I’m sure I can pic something up that will work here without issue, and I’ve ordered a couple of devices that should go in here without issue.
Stay tuned for the replacement!
In the meantime, here’s an operator’s manual, service manual, and a catalog page. The operator manual is in barely readable shape, but it’s there. https://wereboar.com … 0A%20Manuals.pdf.zip
Next part of this series: Coming as soon as I get parts.
- 2026
- Jan
- 16
The Sabtronics 2010A DVM Part 2: Parts and documentation.
The Sabtronics 2010A DVM presented earlier is fully operational, sans a bad display element. Those displays, The Fairchild FND357, are generally only available as old stock - but they are available. I found a seller with some reasonable prices online and made a purchase:
I bought a handful just in case. These will be stored with the unit while I finish up some other things.
In the meantime, I dug the original shipping box and literature out of storage. While it looks like some of the literature is just looseleaf copied from a different model, I do have the original manual for the 2010A. I’ve scanned some of the documentation, and will scan the actual manual when I have the chance. Here’s the docs - they look like information for an earlier device: https://wereboar.com … 0Information.pdf.zip. These are also included in the January 2026 archive zip, if you’ve downloaded that.
There was some other literature in the box, including invoices. Here’s all of those shots:
These must have been popular - this guy’s order was delayed somehwhat. But, for $90 ($430 on 12/2025) these were cheaper than many alternatives, and fully within hobby pricing.
I will get to the display replacement as soon as possible, stay tuned!
Next part of this series: Coming soon.
Previous part of this series: https://wereboar.com … ut-and-observations/
- 2026
- Jan
- 16
The Wereboar Documents Archive zip for January, 2026.
It’s been a while since I’ve zipped up all the files in the document library, so it’s high time I do it again.
If you’d like a copy of everything I’ve collected for projects here, you can grab a copy of it from dropbox: https://www.dropbox. … ro3&st=djfaezpv&dl=0. The file is about 410MB, and is all of the files in a big .zip for easy extraction.
image courtesy of freepik
- 2026
- Jan
- 15
Remember these?
Used to be every technician had a set of them in their toolbox. They were a required purchase when I was a student in vocational electronics. My set generally vanished years ago, and Radio Shack quit selling them long before they became a piece of history.
Turns out you can still get that exact same set. It’s not in the ratshackpack, but you take what you can get.
So I guess I’ll be over here playing with my diddlestick.
- 2026
- Jan
- 15
Some changes here at projects - We’re (mostly) finished.
I’m (more or less) done re-doing images here. I did find a couple that I messed up and missed, and a few that were deleted before I realized what I did (use that trash can!) but everything should be back in place. Thankfully, the Internet Archive had that all stored…feel free to submit pages there if you want!
What did I do?
1: Cropped a lot of images to show the relevant parts only. You don’t need to see a photo with 1/3 of it being the dirty mat on my desk.
2: Resized a lot of images so they are faster loading - a 2000×2000 image of a single resistor isn’t useful, and just wastes your time.
3: Moved a lot of things around on the back-end. I had images everywhere, but created folders for various projects and moved general images into appropriate folders.
4: Renamed most of the images so you know what they are if you download and store, and then come across the image some time later. The only things that didn’t get completely renamed were event photos since there’s a lot of those. They’re in their own folders, and that may be a project of it’s own.
Anything else?
There are a few document links still pointing towards my old OX drive. Those documents are still there for now, but you can find everything at the Wereboar Documents Library here: https://wereboar.com … r=wereboar-documents
I’m going to set a search on those old links and replace them as I find them, or simply point to the docs library in general.
edit: As best I can tell, all links to OX drive have been removed. I’ll leave the files there for a while, but probably will remove them no later than July of this year in case someone wants to grab them from an old link.
That all?
Yep, everything should be back in place, the pages should look better, and you should get image downloads a lot quicker. There may be some short delays as new thumbnails are generated for you, but I tried to take care of all those beforehand during preview setup.
As always, if you find anything broken, please hit the mastodon link at the bottom of each page and let me know. Thank you for visiting, and I hope you’ve found something of interest here.
- 2026
- Jan
- 15
A Simpson 715 AC VTVM Part 2: Attempting to fix the no zero issue.
In the last part, we determined that this device was nothing more than a rebadged Heathkit AV-3, so documentation beyond the simple schematic was definitely available - including the tube voltages chart. That goes a long way towards an attempt to make this device work.
The Simpson 715 is a dedicated AC voltmeter in a small package. It’s not necessarily of the greatest use these days, but the package is kind of cool, so I decided to give it a go. It works, but won’t zero fully.
There are a number of capacitors in this meter, and some in the meter driver circuit itself. But for the most part, there are a number that must be replaced for continued operation, so I’m going to go ahead and get those replaced before continuing - and perhaps that will fix the zero issue.
For this part of the issue, the following capacitors (identified by a yellow box) will be replaced:
For the most part, these will be like for like parts, same value and voltage, except for the filter capacitor. This one is 150VDC, but it’s going to have to be higher voltage if I want to use this thing. Why? This little guy.
This selenium rectifier will need to be replaced as well. The problem here is that for a brief moment, the voltage on the filters is the rectified line voltage minus the voltage drop of the device. This is because until the tubes are asking for current, there’s no drop on the power supply divider resistor, and the full voltage appears on the capacitors. This isn’t a problem for a selenium device, which has a voltage drop in the 10s of volts. But, for a modern 1n4007, you’re going to have the full rectified voltage on the parts. It’s imperative to take the voltage of the filters up to a value that can withstand that.
Older parts may have also seen this higher voltage, but those old filter capacitors could withstand surges due to having thicker dielectric material and other construction quirks that we don’t use anymore. For this device, I’ve chosen 250VDC parts instead of 150VDC. I’m not going to replace the selenium rectifier until the device works, but that will be a future part of this series. For now, let’s just replace capacitors.
In order to do so, the unit has to come apart. The chassis is connected to the meter face at 6 points:
2 on the input terminals, these get unsoldered and removed for a cleaning bath.
2 on the meter itself, these unbolt and the board slides back.
1 on the switch, this is a nut that comes off.
1 on the pilot lamp, another nut that comes off.
Knobs, pilot jewels, and terminals all go in the ultrasonic bath for a much needed cleaning, and the face is left in an easy to clean state as well.
The meter itself is interesting. This being a Simpson device, they made their own meter movement and specified it be calibrated in a certain way:
We’re left with a chassis.
This is mostly just an exercise in delicacy, removing parts from old terminals. I get to use my new solder pick set here!
The big 0.033 on the switch goes first. This type of part tends to crack and leak. For some reason, I didn’t take a picture of it before coming off…
I may take that back off and put some ’sketti on it.
Next is that bumblebomb you can see behind the switch. These also crack and leak, although this one doesn’t seem to be one of the oil-filled capacitors. (By leak, I mean they absorb moisture and change value.) It’s not across the line, so no safety cap needed here.
I try to reuse the old tubing where possible, but some new was required.
Next is an electrolytic. A new part, much smaller than the old, goes in.
It never ceases to amaze me about the difference in sizes. Sure, the old ones had some advantages, but still…
The next one has to wait a while, but here is the part that will go in. Similar size comparison:
This part has a 680Ω resistor across it, and I’m going to replace both parts at the same time as the resistor is soldered directly across the capacitor’s leads. There’s also a 30Ω resistor after this pair that will get replaced, as all of these are directly on the meter legs.
I’m currently waiting on some parts to arrive and will install those when available. Stay tuned for part 3!
Next part of this series: https://wereboar.com … acitor-replacements/
Previous part of this series: https://wereboar.com … simpson-715-ac-vtvm/
- 2026
- Jan
- 15
The Sabtronics 2010A DVM Part 1: Checkout and observations.
I purchased this meter at Dayton 2024 on Sunday. It was still in the box, had all documentation with it, and was in excellent condition save that the seller said it had one segment in the display out. I couldn’t pass it up for $20, considering it’s both that awesome 1970s blue and has some historical interest.
Sabtronics was a company that appeared in the 1970s. Based in Texas, they were pretty much the first company that offered a hobbyist priced digital voltmeter you could either buy as a kit or assembled. It offered 3 1/2 digits of precision, was fully calibratable by the end user, and even offered an optional True RMS module. Sabtronics offered other devices - frequency counters, signal generators, etc. - essentially your entire test lineup, all made in the USA for reasonable prices. The stuff even ran on batteries, if you so desired.
Unfortunately, the coming of the Japanese meters and equipment did them in, as they were unable to compete with prices offered for imported junk. Isn’t that a familiar story?
(I’ll post pictures of the box and the documents ASAP, I need to dig them out of their hiding spot!)
Here’s the front of the meter, and you can definitely see there’s a segment out.
This segment did work for a while, so I assume there’s something inside the LED package that’s broken.
The top is that lovely blue.
Inside is clean. There’s a spot for some extra parts. The displays are on their own board on a long ribbon, which should make replacement easy.
In the back is a battery holder. It’s broken, of course - that cheap plastic wasn’t very good no matter where it was built. It gets old and brittle. Was this why the device was retired?
These do have the option to run on 10VDC (!) which is a very odd voltage. I have a power adapter from another Sabtronics unit, which is what I’m running it on.
The back is normally covered by a cover that has a slide latch. I noticed that it didn’t set in the hole well, I assume due to age and plastic changing over the years. Attempting to put it back in made it crack, which is probably why every other Sabtronics device I’ve seen is missing the cover. I probably will reattach this piece with some extra plastic and glue, remove the battery holder, and permanently attach the cover. I don’t need to run this on batteries.
Ignore the extra parts, those are from the Simpson 715 that’s on the bench beside this guy.
So, does this thing work? Sure does, although I’m not sure if it’s correct.
One (or both) of those meters is wrong. I’m not sure who, but I’ll take the Sabtronics in to work and check it with our voltage calibrator. As for the display, I have some of the proper Fairchild displays on order from a NOS seller. Those should be here soon, stay tuned!
Next part of this series: https://wereboar.com … s-and-documentation/