Heathkit Refurbishment Gallery
A number of refurbishment projects have been completed by WhitakerAudio on Heathkit test equipment over the years. The process followed for each instrument is largely the same, as documented in the IM 5248 blog. At the most basic level, restorations involve: 1) cleaning the instrument, 2) repair of the electronics, 3), cabinet refinishing, 4) remaking the front panel, and 5) alignment and checkout. The focus of this blog is largely cosmetic; that is, the external appearance of the instruments. In all cases, the front panels have been made new through use of polycarbonate overlays produced by Metalphoto of Cincinnati (MPC). The cabinet finishes were done by a local powdercoat vendor.
The polycarbonate overlay is an excellent way to immensely improve the look of the instrument. The overlay is far superior in resistance to wear and fading than the original silkscreened panels. As detailed in the IM 5248 blog, the overlay is just that—a piece that overlays the aluminum front panel. For most restoration projects, the polycarbonate overlay represents the major expense. MPC is one vendor in this space. I have found their work to be superb. Like most custom items, the manufacturing setup is not insignificant and therefore vendors typically have minimum job price points. These vary by vendor, but in the case of MPC, the cost for producing two overlays was about the same as for producing 10 when the minimum job price was taken into consideration.
The entries detailed below are Heathkit test instrument restoration projects using the techniques detailed in the IM 5248 project blog. The end goal of this work was to refurbish nearly all test equipment on the bench to the style developed for the IM 5248. This work was time-consuming, and expensive. However, the end results were quite satisfying.
IG 37 – FM Stereo Generator
The IG 37 FM stereo generator is a product from the “brown era” of Heathkit test equipment. A later version, the IG 5237, is essentially identical, except for the color scheme, which features a white front panel and blue case.
Two screw-on “Amphenol”connectors are used on the front panel of the IG 37. During the upgrade, these were changed to the more common BNC type, which is also used on the IG 5237.
The refurbished IG 37 front panel is show above, and the overall instrument is shown below.
The original front panel is shown below on the left, and the new polycarbonate overlay is shown on the right.
IG 1275 – Lin/Log Sweep Generator
The IG 1275 is a perfect candidate for replacement of the front panel with a polycarbonate overlay. This instrument, like the IO 4510 oscilloscope, used a plastic insert over a metal base panel. With the passage of time, the insert tends to yellow (sometimes significantly).
The original panel insert did not have an adhesive backing (or perhaps it just disintegrated over the years). This caused the old insert to fit poorly in some cases. The new overlay solved this problem.
The refurbished IG 1275 front panel is shown above. The overall instrument is shown below.
The original IG 1275 front panel is shown below on the left, and the new polycarbonate overlay is shown on the right. The new one is an enormous improvement.
IG 5218 – Audio Signal Generator
The Heathkit IG 5218 is a classic audio generator. It was the latest (and last) version of the IG 18. The techniques used in previous update projects were repeated here.
User preference comes into play when the “look” of an instrument is under consideration. My preference is a clean white front panel with the contrasting blue cabinet.
The refurbished IG 5218 front panel is shown above. The overall instrument is shown below.
The original IG 5218 front panel is shown below on the left, and the new polycarbonate overlay is shown on the right.
IM 25 –Volt-Ohm Multimeter
The IM 25 is an instrument from the “brown” era of Heathkit test equipment. In order to match the look of the other refurbished instruments, white was selected for the overlay base color. The unit features a large meter and intuitive layout.
The refurbished IM 25 front panel is shown above. The overall instrument is shown below.
The original IM 25 front panel is shown below on the left, and the new polycarbonate overlay is shown on the right. The transformation was dramatic.
This instrument is a pleasure to use. The large, easy to read meter is a welcome break from LCD displays, which typically do a poor job of representing varying voltages.
IM 4110 – Frequency Counter
The obvious approach for the IM 4110 is to duplicate the look of the existing front panel to the extent practical. This was the starting point for development of the overlay. The original panel, with its translucent upper half, is quite difficult to duplicate with the available tools and processes. The compromise made for this overlay involves providing a window for the LED display, rather than having the entire upper portion of the panel open. As in the original, the basic panel color is white, with black lettering and spot color (red and blue) for the legends as required.
The refurbished IM 4110 front panel is shown above. The overall instrument is shown below.
The original IM 4110 front panel is shown below on the left, and the new polycarbonate overlay is shown on the right. The difference is quite remarkable.
There are two updated versions of the IM 4110—the IM 4120 and the IM 4130. The updated instruments extend the operating frequency range from the basic 110 MHz. The newer instruments have an input selection switch and additional BNC input jacks. The procedure for making a new overlay is essentially identical to the IM 4110, except for the additional hardware.
A visitor to this site let me know about an upgrade to the IM 4110 series instruments. Replacement 7-segment LED displays are available that are plug-in compatible with the ones used in the Heathkit frequency counter (and possibly in other Heathkit instruments). These devices are available from Lite-On Inc., product number LSHD-5503. They can be ordered from DigiKey (and probably elsewhere); the DigiKey number is 160-1576-5-ND.
The difference between the old devices and new ones is dramatic, as demonstrated in the before and after photos below:
It can be seen that one segment of the old display was inoperative. Other segments worked intermittently.
The new devices are much brighter and, of course, all segments work.
Installation of the new devices is straightforward. Note, however, that the first device in the display should be installed upside down, relative to the rest of the devices. The dot on the first device indicates an overrun, while the dot in the remaining devices represents a decimal point.
Thanks to Chuck for his help on this!
IM 4180 – FM Deviation Meter
The IM 4180 measures the peak deviation (frequency modulation) of transmitters and signal generators whose carrier frequencies are between 25 MHz and 1000 MHz. The replacement overlay simplifies the front panel layout by eliminating the blue accent that was used on the original instrument.
The refurbished IM 4180 front panel is show above, and the overall instrument is shown below.
The original IM 4180 front panel is shown below on the left and the replacement polycarbonate overlay is shown on the right.
As with the other front panel replacements, the new overlay is a substantial improvement over the old panel. While it is possible to duplicate the dual color front panel in the overlay, the simplicity of the all-white look is preferred.
IM 5225 – Volt-Ohm Multimeter
The IM 5225 is an FET-based multimeter. It was the successor to the IM 25 series and was arguably the best VOM that Heathkit produced. While the IM 25 was loaded with features and had top-notch styling, it (and other multimeters of the day) required one or more batteries to operate. The IM 5225 eliminated that requirement.
The refurbished IM 5225 front panel is shown above. The overall instrument is shown below.
The original IM 5225 front panel is shown below on the left, and the new polycarbonate overlay is shown on the right.
With a number of different Heathkit instruments converted to the white base polycarbonate overlay, I have come to strongly prefer the consistent look of the white panel.
IM 5238 – AC Voltmeter
The IM 5238 is a popular, high performance ac voltmeter. The replacement overlay simplifies the front panel layout by eliminating the blue accent that was used on the original instrument.
The refurbished IM 5238 front panel is show above, and the overall instrument is shown below.
The original IM 5238 front panel is shown below on the left and the replacement polycarbonate overlay is shown on the right.
Owing to the construction of the overlay, aggressive cleaning is possible (if needed at some point in the future) without risk of damaging the printed legends.
IM 5258 – Harmonic Distortion Analyzer
The IM 5258 is a high-performance harmonic distortion analyzer. It features an auto-null feature that is very helpful in making accurate measurements.
The refurbished IM 5258 front panel is show above, and the overall instrument is shown below.
The original IM 5258 front panel is shown below on the left, and the polycarbonate overlay on the right.
As with the other projects documented here, the original front panel was scanned and reproduced in Adobe Illustrator. The finished overlay was produced by Metalphoto of Cincinnati.
IO 4510 – Dual Trace Oscilloscope
The transformation of the IO 4510 is quite remarkable. As with the other restorations, a polycarbonate overlay was used for the front panel and the case was given a powdercoat finish.
The refurbished IO 4510 front panel is show above, and the overall instrument is shown below.
The original IO 4510 front panel is shown below on the left, and the polycarbonate overlay on the right. The front panel for this instrument is somewhat complex, but manageable.
The original front panel color and legends were contained on a plastic insert. As such, use of the polycarbonate overlay made for a clean, uncomplicated installation.
IP 27 – Low Voltage DC Power Supply
The IP 27 power supply is a popular instrument from the early 1970s. The basic color scheme is a beige panel and brown cabinet with black trim. Following the approach taken in the other instrument refurbishment projects, a white panel was produced with black and red lettering. The cabinet was refinished in blue to match the other instruments in this line.
The refurbished IP 27 front panel is show above, and the overall instrument is shown below.
The original front panel of the IP 27 is shown below on the left, and the polycarbonate overlay on the right.
The new front panel and cabinet color completely remakes the look of the unit so it matches the “blue line” of instruments.
IP 2710 – Low Voltage DC Power Supply
The IP 2710 power supply is rated for 0 to 30 V dc output at up to 3 A. The front panel of this instrument is simple and straightforward. Two versions are available—one with an analog meter and another with a digital readout.
The refurbished IP 2710 front panel is show above, and the overall instrument is shown below.
The original front panel of the IP 2710 is shown below on the left, and the polycarbonate overlay on the right.
As with previous projects, the two-tone color scheme of the front panel was eliminated in favor of an all-white panel.
IP 2717 – High Voltage DC Power Supply
The IP 2717 is a popular variable high voltage power supply for experimenters and schools. Two variable outputs are provided (B+ and C–) in addition to filament voltages. A large number of these instruments are in circulation.
The refurbished IP 2717 front panel is show above, and the overall instrument is shown below.
The original front panel of the IP 2717 is shown below on the left, and the polycarbonate overlay on the right.
The remake of the IP 2717 was straightforward. No modifications of the unit were needed. The front panel remake was complicated in that there are a lot of items on the panel. When combined with a new finish for the case and new Davies knobs to match the other refurbishment projects, this turned out very well.
IP 5220 – Variable Isolation AC Power Supply
This project was a challenge. The first step was to remove all components from the front panel so it could be scanned to create the polycarbonate overlay artwork. Because of the construction of the unit, however, a conventional scanner was not used. The chassis and front panel are one piece of sheet metal. Problems relating to scanning included the size and weight of the piece.
Rather than use a scanner to capture the front panel, a photograph was taken and then imported into Adobe Illustrator where the artwork was created.
The refurbished IP 5220 front panel is show above, and the overall instrument is shown below.
The original front panel of the IP 5220 is shown below on the left, and the polycarbonate overlay on the right.
Note that in the refurbished IP 5220, a switch has been added on the front panel that allows the user to either have complete isolation from the ac input to the variable ac output, or to carry the neutral connection from input to output. This useful in a variety of situations.
Audio Test Load Set
This project involved updating the front panel of a special-purpose audio load test set. The instrument carries no Heathkit model number, and I can’t find it in old catalogs. It appears the unit was intended for service centers, rather than consumers.
In any event, the two channel load permits easy switching of the output of an amplifier under test between external speakers and an internal load. In addition, a switchable test port is provided.
The refurbished audio test load front panel is show above, and the overall instrument is shown below.
The original front panel of the audio test load is shown below on the left, and the polycarbonate overlay on the right.
Overlays Available
I have now collected all of the Heathkit test instruments that I plan on collecting. In the process of refurbishing the instruments, I have accumulated a number of extra polycarbonate overlays. In many cases, the cost to produce one is about the same as to produce 10. So, some extra copies are available. If you are interested in getting an overlay for one or more of the instruments shown in this blog just send me a message with the mailing information. (Please use the Contact Us page.) No charge. Happy to help another Heathkit enthusiast. In order to keep mailing costs low, continental U.S. only.
I currently have stock on the the following instruments:
- Audio Load Test Set
- IM 4110 Frequency Counter
- IM 4120 Frequency Counter
- IM 4180 FM Deviation Meter
- IM 5225 FET VOM
- IM 5238 AC Voltmeter
- IM 5248 IMD Analyzer
- IP 27 Power Supply
- IP 2710 Power Supply
- IP 5220 AC Power Supply
For the other instruments, you can download an Adobe Illustrator file of the overlay from the Available Downloads blog on this site and arrange with the vendor, Metalphoto of Cincinnati, to produce your own. (There are probably other vendors that can make such overlays, but I have had good results with Metalphoto.)
One note about the overlay for the IP 5220 AC Power Supply. If you look closely at the front panel file you will see that a new switch has been added to the left of the “ISOLATED VARIABLE OUTPUT” socket. This switch allows the user to either have the output fully isolated from the input, or to have the output neutral tied to line neutral. This is a simple change but requires drilling a new hole in the aluminum front panel. This change may be made, or not, at the user’s discretion.
After a year of work, all of the Heathkit instruments in my shop have been refurbished. The test equipment is housed in a group of open-frame racks. This is a space-efficient way to house the equipment, and makes it easy to access individual pieces.
It can be seen in the photo below that there are duplicates for some instruments, mainly power supplies. This has proven useful for various projects.
I had previously collected many more Heathkit instruments, but sold them off over time as it became clear what instruments I would use, and those that I would likely not use. The projects that I expected to do in the future drove those decisions. I have narrowed my focus to audio amplifiers and radio frequency systems (transmitters and receivers).
One copy of each Heathkit assembly/user manual has been collected for the workbench instruments. This is essential for ongoing maintenance.