- 2024
- Dec
- 13
The Heathkit IO-21 Oscilloscope - Part 1: Observations
I’ve been wanting a small, AC powered oscilloscope for the bench, something that can do tube stuff without caring if you accidentally hit B+ for a second. Heathkit made several different styles that fit the bill, and I managed to run across this decent looking IO-21 3” scope for a reasonable amount.
It’s difficult to find one of these both in OK condition, and for a decent price. Like most items, people see “TOOOOB,” get some chatbot to write them garbage about how it’s a widely used accurate piece of equipment good for your toolbox, and slap a high price on it. It’s not, it’s something useful for a few of us, and the rest go and get one of those $60 Zotec Scopemeters for our toolbag.
Regardless, this is in ok shape. Most of the parts are there save for a terminal cap, which is no problem. I have many of those of the correct type from dead Heathkit devices of electronics past. It’s dirty, but that’s to be expected.
Note that many will label these as 10-21, but all scopes from Heathkit of this era were “IO” series.
The side
is a bit scruffy, and the back exhibits some broken plastic on the direct vertical inputs.
Those are just jacks, so they can be replaced if need be.
Time to take the back off…first impressions were this was built from a kit, and decently built.
But here’s a thing. The fuseholder was empty. That’s not a good sign, but here’s another fuseholder inside.
It’s not even really soldered, the one wire is just wrapped around the lower terminal of the mounted jack. Wut?
There’s a fuse in it, so I remove the extra fuseholder and put the fuse in the actual holder. Some have suggested that maybe someone was trying to parallel a fuse (maybe…) or didn’t have the correct physical size. Both are 3AG, so that’s not the case. I don’t know what was going on here, but hey - bonus fuseholder.
You’ll also note the large amount of insect debris here. That got a visit from Mister Shop Vac before proceeding.
The tube set is a mix of RCA made RCA branded, GE Made Sylvania Branded, and some washed tubes. This probably would have come with Mullard made Heath branded tubes, so this guy has seen a lot of use.
The ones in the back are 12AU7, but have nothing on them. No name, numbers, anything…chances are these came from a bulk reseller that would take used tubes, wash them of any marks, (maybe) test them and then (maybe) rebrand them as their own. That they work is amazing in itself.
Of note here is some capacitors used as filters for the CRT high voltage. 2x 1600V @ 0.01μF are prime candidates for being a Popping Patty, so they’ll need to go even if nothing else is wrong.
The bottom similarly reveals some capacitors that probably are going to need consideration, but overall it’s nicely built with just one add-in part that I assume was put there by someone other than the original builder.
Does it work? Some basic checks were made and I plugged it in. This device is a 6V parallel string for the tubes, and the 12AU7 are all folded over so they run on 6V. These tubes have their heaters split in the middle so you can operate on 12 or 6V, depending on your application. On almost all of them, only one side lit so a bit of wiggling later (dirty sockets) here comes a trace. It’s about as bright as it was when new, which is to say a bright room washes it out. But it’s there, and that’s the important thing - a dead CRT means a dead unit.
Stay tuned for the next part of this series, some cleanup and basic identification for parts that absolutely need to go.
Next part of this series: Coming soon.
- 2024
- Dec
- 11
An Olson TE-189 C-R Analyzer - Rebuild, part 2 - I only wanted to replace some capacitors.
After digging in to this unit, I determined that it was a basket case. While the unit itself wasn’t baked, the builder most certainly was. Probably less than 1 out of 5 wires in this thing (that weren’t bare interconnects on switches) was soldered securely. The rest? Bad or no solders, wires pulling out of their terminal, no wetting, too much solder, blobs everywhere. Burnt wires, solder drips…you name it. This thing was a how to on how to not solder. I realized that if I wanted to see this thing work reliably, it was going to be a partial rewire.
Here are some before and after shots of the cleanup crew’s work:
First is part of the drive for the eye tube. This consists of a capacitor coming in from the terminals on the front, a 1500pF capacitor, and a 10MΩ resistor on a terminal strip…with lots and lots of grounds attempting to terminate here as well.
All of the grounds were removed and single-pointed back to the other side of the chassis. The old parts were replaced with new, high quality parts - the input capacitor went from one of those leaky metal can Japanese parts to a new film cap, the 1500pF ceramic disk (with half it’s coating missing) is now a 600V polystyrene, and the resistor is just a good metal film part. The terminal is now clean with a single wire leading to it. Unfortunately, since the screw for this also holds the 4μF capacitor, I couldn’t solder it down, but it’s tight and clean.
Next is the socket for the eye tube. Almost every wire is burnt in some place, be it here or below the chassis. The black wire is j-hooked together, and the yellow wire has far more exposed copper than is safe. Even the 1MΩ resistor is poorly placed, having too much lead on one side and a “Oops, I cut it too short” lead on the other. Here it was just rewiring everything with fresh wire and properly twisting the filament leads. The resistor now lays in the socket with the proper spaghetti coating.
Last is the tube socket for the power supply. This has quite a bit of voltage on it, so it needed cleaned up. Twisted filaments, and fresh wire leading directly out of the socket fixed this one. I admit that the copper is a bit too much, but I’m happy with the results overall. The previous build had some solder balls here, and the fialments were all terminating to this point. I’ll brush this down to get the flux off before final inspection.
Prety much everything except for a couple pieces of coated wire and a couple of capacitors that are still good have been or are being replaced, including the big 500Ω balancing resistor that was flopping around the transformer. Even the AC has been moved off to it’s own isolated terminal strip for ease of disconnect in case of trouble.
I’m waiting on some Blue wire for the measurement section of the device (I’ve tried to keep the original color scheme as much as possible) so hopefully this will be done in a week or so. Stay tuned for the final part of the build, coming soon!
Next part of this series: https://wereboar.com … er-the-waiting-game/
Previous part of this series: https://wereboar.com … -intermission-parts/
- 2024
- Dec
- 11
The 1970s live in this Elenco M-1200 meter.
I didn’t need this device, but it came home with me as part of my “Can’t leave the hamfest without a voltmeter” program…It came from Fort Wayne and was a couple of bucks.
The real reason I picked this up is because of the design. This is so 1970s it hurts, although it probably was made in the 1980s. It’s a simple DMM and offers all of the things you’d need in a meter.
The device can run on batteries or external DC, as evidenced by the back. No mention of the required voltage, however, and the device is old enough that a headphone jack is used instead of coaxial for the power input. Since the device has 4x “C” cell as it’s internal supply, I’d assume the external power should also be 6V.
It’s woodgrain all around.
Inside, there’s not much. A power supply board with some circuitry for the meter, batteries, and the business end of the device (under the front panel.) Without the batteries, this thing would be quite light.
Here’s the main board. It’s most certainly an ICL7117 based device, as evidenced by the big DIP in the middle.
But does it work? I hooked it up to a nearby USB charger device, and it did read - although the decimal point was flaky. I had to wiggle the switch a little to get it to show up. (The 7117 is a simple 3 1/2 count ADC with 7 segment output. It’s up to the user to scale it and provide decimal points.) I didn’t check the unit for accuracy, just operation. I did notice a segment seems to come and go as well, so maybe some solder joints are cracked. Who knows.
What’s going to happen to this? If it’s accurate, it will probably go in my rack as a rail monitor. Otherwise, it’s just a cool piece of old tech.
- 2024
- Dec
- 11
Some miscellaneous NIXIE devices to a new home.
I have a giant pile of crap that needs to go - probably to Hamvention - but I’ve been giving it away as I find people who are interested. A co-worker had a fake NIXIE clock on his desk, so I asked if he wanted some real stuff. He said yes, and here it is:
The first is a Fairchild Volt/Ohm meter. It does DC and Ohms. That’s all. It’s intact but rough, and looks like it may have had a handle at one time. Yes, it’s THAT Fairchild.
The tubes in this guy are nice and bright, surprising for as poor of condition it’s in. It seems to work, but could use a calibration:
A disagreement of 0.04VDC. Not bad!
The second piece is a Time Systems counter. This is most certainly a piece of space race equipment put together by a company that sprung up to support the frenzy of the time. It’s a counter/timer with three ranges of measurement.
The back has a bunch of card edges on it. Probably brings out all of the data from the timer, but in what format - who knows.
There’s very little information about this company, and too many businesses today named “Time Systems.” I have to assume they’re like all these little companies from the period - appeared and made some equipment, 10 years later when technology made things cheaper they just kind of faded away.
Let’s set the generator to 1kHz and see what this thing does:
Seems to be what I’d expect with this sig gen. The switches need a good cleaning, as they need to be wiggled to get the clock to run.
Testing against my “known” device:
These are off to their new home. Stay tuned for more Junk from the Hamvention Pile, I mean “Projects from the Bottom Drawer!”
- 2024
- Dec
- 10
An Olson TE-189 C-R Analyzer - Intermission: Parts
Almost all of the parts in the TE-189 C-R analyzer are available, save for the switches and the panel lamp. While the switches would essentially put the unit in the parts bin, other things like the panel lamp can be replaced with something else. It’s just a neon bulb in a package.
The one on my device was long since dead, so I tried to peel the case apart and replace the oddball neon bulb inside with something else. The case plastic was old and crumbly and that went about as well as you’d expect. It didn’t. On the off chance there was something similar out there, I did some searches and ran across the exact part on an auction site. And when I say “exact,” it’s OEM…
This is a pair of Herald Electronics miniature neon panel lamps. Herald Electronics of Chicago, originally called American Electronic Parts, was a sub-brand of Olson, and as such, one of their suppliers. Olson didn’t publish the fact that they owned this other brand, so Herald was apparently able to sell parts and supplies to other vendors for resale, without incurring the “We don’t want to buy from a competitor” thing you’d get by buying from your competition.
Herald, of course, sourced their product from various Japanese manufacturers, and vanished when Olson did. It was quite the surprise to find these parts, still new. I bought them right away. Here it is in the 1974 Olson Catalog:
There were 3 pieces for $2.19. Figure 14, part number PL-148J. Someone bought a set, used one, and put the rest in a drawer. Fortunate for me!
It came with the original pack-in paper pamphlet:
Interesting that the paper specifies a 100k resistor for longer life. The TE-189 has a 50k, so that probably didn’t help the lamp life. I replaced it with a 100k as specified.
The parts themselves are exactly what I needed, down to the little alignment tabs on the bottom. No surprise, they are the exact OEM part. I love the little dogbones they gave with the lamps.
And, of course, it fits in like it was made to be there. Here it is, waiting for wiring in to the panel.
I’m waiting for some wire and a new 500Ω power resistor. The mail is not cooperating right now, so stay tuned!
Next part of this series: https://wereboar.com … ace-some-capacitors/
Previous part of this series: https://wereboar.com … yzer-rebuild-part-1/
- 2024
- Dec
- 4
An Olson TE-189 C-R Analyzer - Rebuild, part 1.
SO…I thought that the TE-189 job would just be some tidy up and new capacitors. No, that’s not going to work. Turns out that the builder of this device (I hope this was a kit!) managed to get about 50% of the solder joints to hold. The rest were nothing more than burnt wire and insulation, badly wetted connections, and connections that were just kind of wrapped around one another and soldered with prayer.
I spent some time last night installing the new filter capacitor. Since a 5μF @ 700VDC is kind of hard to get at a reasonable price, I chose to use two 10μF @ 450VDC instead. These were connected in series to give the requisite capacity at 900VDC. I wrapped them in heatshrink and gave it a red band to identify the positive side of the device. That’s when I started to notice how badly the thing was wired.
You can see a brown wire attached to the same terminal as the positive side of the filter. This wire was just kind of stuck in the solder and came right off when I hit it with the iron. There was enough left that I could cut and strip and insert properly.
The grounds on this thing are a complete mess. A small terminal on the switch had multiple leads inserted in it - rather, attached to it. One was in it. One was wrapped on it. One just kind of hung there. A big blog of solder attempted to hold it all together. Grounds are flying everywhere in this thing instead of coming back to a single point. Plenty of other wires were the same with some just wrapped around other leads and soldered right into the insulation. Even the original filter was a wrap-job and wasn’t wetted properly.
How did this thing even work? Or did it? The neon bulb was dead so it spent some time on during it’s life…
I decided to solder a terminal strip directly to the chassis. Clean and wet the chassis and terminal, and hit it with the 80W iron. I know I’m talking about solder quality, but my 80W device is just not enough for this task. I’ll pick up something bigger this year. It did a (poor looking) job, so all grounds will now come back to this point.
There are around 10-ish ground connections going to all different places in the unit. I’m going to run them back to this double lug so they’re all at the same point. That involves removing a lot of other stuff, including jumpers across the transformer terminals, and a lot of stuff on the other side of the chassis. I’m going to run all of these and then slowly work my way across replacing wires that are in need of replacement. It’s going to be slow going.
Here’s an example of what I’m seeing - this is the ground for the 450-0-450 portion of the power supply. It was just kind of shoved through a terminal on the transformer and hit with some solder that didn’t really wet the lead. The across the line cap was then wrapped around the lead and soldered without removing any insulation - the capacitor just kind of melted into the plastic and didn’t really wet. It all goes away.
There’s a big lump of grounds just to the right of this that I’ll correct, and then start replacing capacitors and fixing the tube socket and the HV power supply.
Next part of this series: https://wereboar.com … -intermission-parts/
Previous part of this series: https://wereboar.com … yzer-considerations/
- 2024
- Dec
- 3
An Olson TE-189 C-R Analyzer - Considerations
I’m getting ready to replace some of the parts in this device, and I decided to take a look at what I’m doing and consider things.
I recently cleaned up an older B&K Capacitor Checker, and (in theory) this device should be a good reference instrument for measuring parts in this device. I decided to check things and it made me wonder if I really should replace all of them. There are some that will most certainly get a new part in their place, but others…
The first is the 400pF mica capacitor. I originally thought this thing was a mod, as it has a capacitor and a trimmer. However, I’ve seen another unit under rebuild and it has the same thing. The trimmer itself is plastic, so there’s no way this thing is approaching 600V, but it adjusted down perfectly and I had a good 400pF on the meter.
The big 4μF was similarly in good condition with this meter.
This one has good ESR and has a big 1k resistor to absorb the brunt of any voltage, so I think this and the 400pF will just be left alone for now. I have replacements in case they do need to go, but they don’t right now.
What does need to go is all of these metal can parts, especially the across the line capacitors and the filter. For the 40nF capacitor, I chose some 1% film parts at 630V and paralleled two of them for 40nF:
For the filter, two 10μF in series at 450V to make a 5μF at 900V. This part will probably get some heat shrink to strengthen the assembly. I chose this route because it was much cheaper than trying to find a part rated the appropriate voltage.
There are some resistors as well that seem out of tolerance, but those will need to wait. It’s not like this thing is going to be as accurate as a modern digital meter, but my concern was to prevent electrical problems.
The entire parts set to be replaced (save the 4μF):
1x 5μF filter capacitor assembly, electrolytic.
1x 40nF test capacitor assembly, film.
1x 0.01μF input blocking capacitor, film.
1x 1500pF capacitor for the eye, polystyrene.
2x 0.047μF across the line capacitors, safety film.
1x A1C neon bulb for the front panel.
Also, I am going to replace a poorly placed 1MΩ resistor across the eye tube, and perhaps the 1K and 500Ω resistors used in the test circuit (with the 500Ω just kind of hanging there in the air.) The latter two are both high-wattage parts (of unknown power) so a 10W part should be more than plenty on these.
That’s it for now - the next step is to put the parts in. That shouldn’t take long, but I’m also going to clean up some of the wiring as it’s in terrible shape. Stay tuned!
Next part of this series: https://wereboar.com … yzer-rebuild-part-1/
Previous part of this series: https://wereboar.com … some-notes-on-parts/
- 2024
- Dec
- 2
My 2025 Hamfest and Show List
As 2024 winds down, I find myself looking forward to the shows in 2025. I’m planning on going to most of the same ones, with perhaps a few new ones if time allows. I have quite a list this year, but I expect some of them will have to slip simply due to time constraints. One in particular, the 2025 Tri-State Radio Fest, may conflict with the TUSCO ARC show, so it’s a decision on what to attent.
As of the date of posting, not all shows have updated their dates for 2025. Check back soon, I will post actual dates as soon as I know about them. Links to pictures will be posted here as soon as I’m done with them, and I’ll do a year-end wrap up as well.
Johnstown Swappers Day and the Scott Antique Market aren’t really hamfests, but enough electrical and other goodies show up that it’s worth going if you’re in to general flea market type items. I’ve added The Cincinatti Hamfest to the list this year, and I may still try to get to the Van Wert show and Kalamazoo show, all depending on how things go. Dayton, of course, is a will-go no matter what, and we may have a table this year.
Sunday Creek Amateur Radio Federation Hamfest
Shade Community Center
2380 Old U.S. 33
Shade, OH 45776
January 19
8A-Noonish
Admission $6
http://www.arrl.org/hamfests/sunday-creek-amateur-radio-federation-hamfest-4
Event photos: https://wereboar.com … mfest-in-shade-ohio/
Cuyahoga Falls Amateur Radio Club Hamfest
Emidio & Sons Party Center
48 E. Bath Road
Cuyahoga Falls, OH 44221
April 5
8A - 1PM
Admission $8
https://sites.google.com/cfarc.org/cfarc/hamfest
Event photos: https://wereboar.com … nnual-cfarc-hamfest/
TUSCO ARC Hamfest
Commercial Building at the Tuscarawas County Fairgrounds
295 South Tuscarawas Ave
Dover, OH 44622
April 26
8A - 1PM
https://www.w8zx.net/hamfest
Event photos: https://wereboar.com … -2025-tusco-hamfest/
ACARA Athens Hamfest
Athens Community Center
701 E State Street
Athens, OH 45701
April 27
8A - 12P
https://www.ac-ara.org/
Event Photos: https://wereboar.com … -2025-acara-hamfest/
Dayton Hamvention
Greene County Fair and Expo Center - The Whole Thing
210 Fairground Road
Xenia, OH 45385
May 16 17 18
Hours vary by day, opens at 9AM
https://hamvention.org
No table, we sold it all!
Friday Photos: Coming soon!
Saturday Photos: Coming soon!
Sunday Photos: Coming soon!
Breezeshooters Hamfest
Butler, PA
Butler Farm Show (Kind of a fairgrounds thing)
625 Evans City Rd
Butler, PA 16001
June 8
8A - 2PM
https://breezeshooters.org/ns/
Event photos: Coming soon.
Columbus (OH) Hamfest
Aladdin Shrine Center
1801 Gateway Cir
Grove City, OH 43123
August 2 (Announced on ARRL pages)
8A - 1PMish
https://www.arrl.org/hamfests/columbus-hamfest-6
Event photos: Coming soon.
Johnstown Swapper’s Day
Johnstown Community Sportsmen’s Club
7357 Sportsman Club Rd NW
Johnstown, OH 43031
Labor Day Weekend (Fri Sat Sun)
7A - 6P
https://jcscohio.org/swappers-day/
Event photos: Coming soon.
Findlay Radio Club Hamfest
Hancock County Fairgrounds
1017 E. Sandusky St.
Findlay, Ohio 45839
September 7
8A - 1PM-ish
https://www.findlayradioclub.org/
Event photos: Coming soon.
The Cleveland Hamfest and Computer Show
Berea Fairgrounds, Eastland Entrance
160 Eastland Rd
Berea, OH 44107
September 28
8A - 12P
https://www.hac.org/
Event photos: Coming soon.
The Scioto Valley Amateur Radio Club Hamfest
Pike County Fairgrounds
311 Mill Street
Piketon, OH 45661
Date TBA
8A - 12P
https://www.arrl.org/hamfests/scioto-valley-amateur-radio-club-hamfest-2
Event photos: Coming soon
MARC Hamfest
Military Air Preservation Society Hanger (MAPS)
2620 International Parkway
Green, OH 44232
Date TBA
8A - 1P
http://w8np.net
Event photos: Coming soon
Fort Wayne Hamfest
Allen Country War Memorial Coliseum
4000 Parnell Ave
Fort Wayne, IN 46805
November 15 16
Hours vary by day, opens at 9AM
https://www.acarts.com/hfmain.htm
Event photos: Coming soon
Scott Antique Market November
Ohio Expo Center (State Fairgrounds)
717 E 17th Ave
Columbus, OH 43211
Usually Thanksgiving weekend
Hours vary by day, check before you go.
https://www.scottantiquemarket.com/
Event photos: Coming soon
Scott Antique Market December
Ohio Expo Center (State Fairgrounds)
717 E 17th Ave
Columbus, OH 43211
Usually the weekend before Christmas.
Hours vary by day, check before you go.
https://www.scottantiquemarket.com/
Event photos: Coming soon
Always check dates and times before going, and I’ll see you there!
Late additions (all of these may not be a go, but look interesting):
Central Pennsylvania Hamfest
Clearfield County Fair Grounds, Agriculture Building and grounds
5615 Park St
Clearfield, PA 16830
September 14
8A - 1P
https://clearfieldcountyarc.net/hamfest/
Event photos: Coming soon
Early Television Museum Fall Swap Meet
The Early Television Museum
5396 Franklin St
Hilliard, OH 43026
Usually early October
10A - 2P
https://www.earlytelevision.org/swapmeet.html
Event photos: Coming soon
Buffalo Ham Swap Meet
Leavitt Funeral Home
801 Victor Street
Belpre, OH 45714
September 20
8A? - ??
Admission is generally free, but they sell cheap raffle tickets for a nice (need not be present) prize drawing.
https://buffalo10meter.net/
Event Photos: Coming soon
Cincinatti Hamfest
Clermont County Fairgrounds
1000 Locust Street
Owensville, OH 45160
August 9
8A - 2P
https://cincinnatihamfest.org/
Event photos: Coming soon.
If I go to any of these events, I’ll move them up into the main section, or move ones I don’t get to attend for whatever reason back down to this section.
The ARRL Ohio Section hamfest list can be found at this link. It generally updates as shows announce, so your favorite show may not be there yet.
- 2024
- Dec
- 1
Photos from the November 2024 Scott Antique Market.
This month’s show ended a few hour ago, and I made it out there on a very chilly, windy Saturday morning. For some reason, it opened later this year…some whispers about something that happened with the other show in Atlanta but I couldn’t pin it down. Doesn’t really matter, I guess, we entered about 8:45 and started wandering the not-quite-open aisles.
As usual, the place was packed with vendors and there was a lot to see. Not a whole lot I wanted to take home, but a radio that caught both my and my fellow show-goer’s eye decided to go home with me for a superb price. Check out that device, there will hopefully be a series of posts about making it sing again.
Here’s what we saw at the show:
.
Next show is the weekend before Christmas. See you there!
- 2024
- Dec
- 1
The B&W Model 200 Signal Generator Part 3 - setting it aside for now.
In the last part, I determined that the tubes (save perhaps the 6×5) were not at fault in causing this device to act up. After I wrote that post, I sat down with it just a bit more and did some poking.
First thing was to put a good 10k power resistor in place of the one that rose to 160k when warm. No change in operation. Second was to give it a good look-over one more time.
I noticed that there was some goo coming out of the electrolytic in the oscillator section. That’s not good.
Ok, so that capacitor is probably bad. I measured the DC voltage on it.
There’s a really slow variation in the DC that matches the oscillator’s on-off cycle. I did some quick bypass with new caps, paralleling the presumed bad devices:
No change.
This thing has more problems than I originally assumed, and the lack of any information on the unit is hampering my ability to work with it.
For the time being, this goes back on the “needs work” shelf, as I already have a working generator and need to get some other devices fixed. If I can get to it before Hamvention, then I’ll take another look. Stay tuned!
Next part of this series: Coming sometime maybe.
Previous part of this series: https://wereboar.com … or-part-2-diagnosis/