- 2025
- Feb
- 4
A Simpson 715 AC VTVM
This device is an AC only VTVM with a dB scale. It’s often mentioned as a meter made for audio use. It’s a compact, good looking unit.
The front is mostly taken up by the meter face:
The back has nothing except the screw holes and a metal grommet hole for the cord.
When I received this meter, it had a rubberized 3-prong grounded plug on it. I’ve seen pictures of others with 2-prong, but the schematic seems to indicate the chassis was grounded. I’ve got a two-prong on it for testing, but will replace with the proper cord later.
The inside of the unit is pretty busy.
Tube compliment is:
12AT7
12AT7
6C4
Power is provided by a selenium rectifier for the transformer. It’s a pretty simple device, an input amplifier to provide the high impedance, a cascode amplifier to drive things, and the signal voltage is rectified right on the meter. Nothing too fancy here.
However, like many things from this time period, it doesn’t work right. That’s probably due to the capacitors leaking, or perhaps something else has gone wrong over the years. The Simpson manual provides a schematic, but no real troubleshooting information.
What would be helpful here is voltage information for the tubes and some “Does it do this?” information.
Enter the Heathkit AV-3.
There’s no picture, you can find plenty of them all over the internet. However, what’s odd about this unit is that some of them have “Simpson Elec Co” on the meter face. Why is that? Well, here’s the schematic for the AV-3:
You’ll notice, other than parts placement on the schematic, that it’s the same thing. Heathkit must have contracted Simpson to assemble these for people who wanted to purchase an assembled unit. Since this was also sold as a kit, that means one of Heathkit’s lovely manuals must exist for the unit. BAMA and other souces didn’t have it, so I sourced one from ManualMan, and there it is:
This thing may have a chance at living again. Stay tuned!
- 2025
- Jan
- 31
The Heathkit EK-1 multimeter.
Here’s a picture of the EK-1 next to it’s big brother, the AA-1:
Isn’t that adorable? It’s so small.
The EK-1 was a piece of equipment you build as a teaching aid for an electronics course of the same name. It’s interesting in that it’s a voltmeter/ammeter with no battery requirements - although the ohms function does require a single C-cell. The Ω/V rating is pretty low, since it’s really nothing more than a meter with some resistors in it - no active components here! The only AC function is a neon lamp to check 110VAC, so this is a glorified appliance test box.
Still, it’s cool in that it looks like a piece of Heathkit equipment, there’s no batteries needed for the most part, and it can sit there on the bench ready to go as a power supply test unit, or a tester for anything else where a bit of load won’t bother it.
It’s going to go on the bench as soon as I give it a contact cleaning and a new battery. (The AA-1 is also in queue.) You’ll probably see it in some shots in the future, stay tuned!
- 2025
- Jan
- 28
This is a test of the gallery plugin for Flatpress.
This is a test - does the gallery plugin here allow for multiple galleries on one page? If this page is broken, then no - it does not. If you see two galleries, then it worked. For 2025’s hamfest wrapup, I’m planning on putting all galleries on one page…thus the test.
SCARF 2025
. <--- this is here because the gallery plugin doesn't seem to terminate properly.
Fort Wayne 2024
.
Test succeeded.
This was a test, we now return to your regularly scheduled helping of old test equipment.
- 2025
- Jan
- 28
The Heatkit AF-1 Analog Frequency Meter, Intermission.
One of the things I’ve been considering with the Heathkit AF-1 I have on the bench right now is the potentiometers. The originals were 200Ω wirewound rheostats, but the original owner of the device replaced some with 5kΩ carbons. No idea why.
New parts will bring increase the precision of the device (as much as you can with an analog meter of this type!) so I’m torn. Leave the old parts in place and assume the original builder knew what he was doing, or get new 200Ω devices.
The blue pot in the foreground is a 10-turn, 2W, 200Ω device. These are relatively cheap (~$2) if you buy them direct, so I picked up a couple. One 200Ω, one 5kΩ. I’m planning on restoring the power supply on this device first, so I’ll put one in circuit and see how it does.
Of course, the only problem is they are the finest chinesium. Will they hold up? Stay tuned and we’ll find out!
Next part of this series: Coming soon.
Previous part of this series: https://wereboar.com … -meter-part-4-parts/
- 2025
- Jan
- 22
What do you mean I have a problem?
I don’t have a problem.
Well, maybe I do have a little bit of a problem. But they all work. They’re just waiting…for…something. Yes, that’s it.
- 2025
- Jan
- 20
I’ve done a little maintenance on things here at wereboar.
I had to do a little low-level maintenance on things, and that involves doing some regeneration on stuff deep inside the system.
Everything should be back to normal save I’ve removed the last posts sidebar item. The main page shows 10 posts, so I didn’t see a need to re-show those same 10 posts in a widget. That probably saves you 0.01s per reload…
Regardless, if you see something broken, please let me know on LinkedIn or Mastodon.
- 2025
- Jan
- 20
The SCARF 2025 hamfest in Shade, Ohio.
This is my second year going to this show. It’s a small show, and was a bit smaller than last year - probably due to the fact that it was snowing like crazy when we left, and that probably kept some people away. Regardless, it still had that nice cozy feeling to it, and there was plenty to see for a small show. I picked up a set of Heathkit test equipment, mostly for one of the pieces (but the whole set was cheap!) and my fellow show-goer picked up a nice Dell i7 4th micro machine for his home entertainment center.
Here’s what I saw that was interesting at the show:
.
Not a lot of pictures because of the size of the show. This year’s theme seems to be starting out with AM CB stuff again, much like last year - it’s literally everywhere, everything from big base stations to modern car portables. That’s probably going to be like PC compatible stuff and videotape was some years ago - things changed, and people are cleaning out until it’s gone.
There’s a couple of shows in February and March, but the next one I’ll probably hit is the Cuyahoga Falls show in April. That gives me some time to go through the things I have. It’s “fix and keep” or “get rid of” time, and having a couple of months with no new stuff coming in will help.
See you at the hamfest!
- 2025
- Jan
- 18
I guess the wire was supposed to be the fuse?
Here’s some wire from the appliance test box I posted about a few days ago. One piece is the line cord, the other some of the internal wiring.
I should mention that this box was rated for 15 amps AC.
The black one is the power cord. It’s nice, heavy, stranded red copper. The closth-covered one? Nah, bro. That’s 18GA and is rated for 14A. Other wire in the box was 18GA PVC coated, and certainly would have started smelling a little funny had you ran this device at max capacity - indeed, that metal toggle on the front had a terminal where the solder had melted away and it was just hanging on by a thread. Something in there had been hot for a long time.
I had made a joke about self-fused wire and a portable house fire in waiting on LinkedIn, but it didn’t go over well. People were getting very upset over it and I decided that was something not appropriate for the audience there. I guess my sense of humor is just strange.
Regardless, this thing wasn’t anywhere near rated for it’s nameplate capacity. I’m really surprised there wasn’t more heat damage evidence on the various connections. All of that old stuff has been removed and discarded, the only thing that will be in use is one of the ceramic sockets and a new meter that I’ll install before use.
The post about the device itself: https://wereboar.com … -waage-066-test-box/
- 2025
- Jan
- 17
What to do with this thing? The Waage 066 test box…
Some time ago I posted about this device that I picked up at the Butler Hamfest. It’s a dim-bulb tester designed for appliance service - Waage made (and still makes) resistive heating element devices, so something like this would be right in line with their products - assuming you didn’t burn the small gauge wire inside the thing up!
(Dim bulb testing means having a lightbulb in series with the device you’re working on - if the device is shorted, the lamp will absorb the voltage, preventing damage to your device, It’s a common tactic in working with old radio and television devices where you could destroy an unobtainable part if something is shorted.)
Since it’s not really of much use to anyone as-is, I think I’m going to try and repurpose this into some sort of display piece. I’ll try and find a voltmeter that will fit the hole, fix the pilot lamp, and place a low-wattage bulb in the one socket. Make it into an accent lamp of sorts.
I think that’s probably the best use for this, as I hate to see it scrapped. Stay tuned, hamfests are starting up for the year and I’ll be on the lookout for a meter.
- 2025
- Jan
- 16
The Heatkit AF-1 Analog Frequency Meter, Part 4 - Parts.
After going through and correcting the schematic, I now have a list of parts to order. The only one I don’t need is the 2.5K resistor that feeds the plate of the voltage regulator tube - I already have a small supply of 5W qualified parts, and will use one of those instead of buying more.
Other than that, this is my list:
All of these are exact values, except for the 0.05μF - 0.047μF is close enough here, and probably is closer to the original value part due to lower tolerances.
If you’d like to purchase these for yourself, the text of the part numbers:
104MWR630K
103MWR630K
102MPW630K
CDV19CF100JO3F
CD15FD101FO3F
473MWR630K
MFR50SFTE52-220R
MFR50SFTE52-2K2
MFR50SFTE52-220K
MFR50SFTE52-100K
MFS1/2DCT52R1004F
MFR1WSFTF52-2K7
PR02000203301FA100
MBE04140C4700FC100
For most of these items, I’m purchasing at the price break simply because these are common values and I can use them elsewhere. Resistors are probably overkill here at 1%, but they’re cheap - some of the half-watt units are under $2.00 for 100 pieces. A couple of the parts, like the 470Ω resistors, I’m buying multiples of the highest wattage used in the unit, again - for the price break. A 1W part in a 1/2W spot is meaningless with a point-to-point chassis as open as this one.
The only ones I’m keeping to quantities needed are the more expensive items - the 10pF and 100pF mica units are rather expensive, so I get what I need. Your purchases depend on your needs, however.
I’m going to go over the list one more time, then place an order.
Some may think that this isn’t really a good use of money or time due to the fact the device is quite obsolete, but that isn’t the value of the exercise. I like this unit, it’s a cool piece, and it’s going to go on my bench once completed.
Stay tuned for parts!
Next part of this series: https://wereboar.com … -meter-intermission/
Previous part of this series: https://wereboar.com … hematic-corrections/