Heathkit were an American manufacturer of good quality electronic kits for a wide range of items including test equipment, audio and radio equipment and (later) robots. In the UK, Daystrom (Gloucester) produced UK versions of many of the kits, using valves and components available here, transformers with 240V primaries etc. In the 1970s Daystrom moved into thickness gauges for the steel industry and in due course sold off the kit side to Cedar Electronics. The company are now called Thermo Radiometrie (Gloucester) Ltd and were my employer between 2000 and 2005. Heathkit are still in existence in the USA (now known as Heathkit Educational Systems) but are not now producing kits.
Some Heathkit products are displayed at the Heathkit Virtual Museum website. Circuit diagrams for many Heathkit products are available for free download at my archive of the Circuit Archive website. I understand that Heathkit can still supply full manuals for many of their kits for about $25 each.
From my experience, Heathkits are generally good quality, although build quality obviously depends on the ability of the original constructor. Items that have survived until now must have been built well enough to work though, otherwise they would probably have been thrown away years ago.
Wavebands - MW, LW
Transistors - OC44, OC45, OC45, OC81D, OC81, OC81
Date - Early 1960sStatus - In my collection
This set was bought for me as a Christmas present in 2003 on eBay. It pops when switched on, but does not receive anything.
Thanks to Chris and David for identifying the model for me. I have now obtained a manual from classicheathkit (see top of page).
Wavebands - MW, LW
Transistors - AF117, AF117, AF117, OC71, OC81D, OC81, OC81
Date - Mid 1960s ?Status - In my collection
I bought this interesting set for £10 at the Winter 2001 Wootton Bassett swapmeet.
The set is quite large for the contents, but of course this made it easier to assemble. There is a metal chassis covering the top and two sides, and the PCB is suspended across the middle with fixings at either end only. I would have thought the chassis would tend to reduce the signal strength picked up by the internal aerial.
The set works, but there are two distinct peaks on each station when tuning, so the IF alignment is obviously out. Some of the cores are damaged, which suggests someone has been here before with the wrong tool. The "Real Hide" case is split part-way along the folding edge at the top of the back, but I have had some success repairing this with UHU Fabric Glue. One of the brass caps from the control knobs was missing, but I found it in a plastic bag inside the set.
I have now obtained a manual from classicheathkit (see top of page).
AG-9U (Audio Signal Generator)
Range - 1Hz to 110KHz
Valves - EF94, EL821, EZ81
Date - 1958Status - In my collection
I bought this useful piece of test equipment from a Radiophile swapmeet in 1999 (I think). It probably cost no more than a fiver. After some time sitting on the shelf in a semi-working state I decided to repair it properly and have given the details in the Recent Repairs section.
RF-1U (RF Signal Generator)
Range - 100KHz to 100MHz (200MHz on harmonics)
Valves - 12AT7, ECF80, Metal rectifier
Date - Late 1950sStatus - In my collection
I have had this useful RF signal generator for a few years. Previously I used an Altai transistorised signal generator, but this Heathkit works a lot better so the Altai has been sold.
The output socket on the right would originally have been an aerial type, the same as the audio sockets on the left. A previous owner had removed this and fitted two BNC sockets. One was connected as the correct output (which is still there and still connected). The other was connected to a circuit cobbled together on a piece of veroboard (using a couple of op-amp ICs) connected to the RF signal before the attenuator. I have no idea what it was supposed to do, because it did nothing when I got the unit, so I removed it and the extra transformer that had been added to power it, and returned the circuit to its original state. The holes in the panel have been filled with Araldite (epoxy resin) and painted over using enamel paint. It still shows because the paint wasn't quite the right colour, but I will deal with that at some stage.
One knob was originally missing. Since I didn't have anything to match I moved the remaining knobs around and fitted a pointer knob to the range selection switch.
I have also recently inherited a manual for this unit. An identical unit was sold at the bring-and-buy stall at the December 2001 Wootton Bassett, complete with manual. The purchaser forgot the manual, and he could not be found on the day, so Mike Barker (the organiser) said I could have it. The manual contains detailed assembly and faultfinding information as well as details on how to use the unit for aligning radio equipment.
IM-36 (Transistor Tester)
Date - 1960s or 1970s ?Status - In my collection
I purchased this unit for about five pounds in the auction at the Summer 2003 Wootton Bassett swapmeet. It is complete and appears to be working, but I have not gone right through the test procedure in the manual yet. The circuit is purely passive (resistors, pots, switches and batteries) so only tests the DC conditions of the transistor.
It is powered by seven "D" cells. These would normally be quite expensive, but I purchased four packs of two Panasonic batteries, for £1 per pack, from a local "Everything £1" shop.
EU-30A (Decade Resistance Box)
Range - 1 ohm to 9.999999 meg-ohms
Date - 1970s ?Status - In my collection
I found this decade box in the skip at work. As found, one of the terminal posts was broken, most of the case screws were missing, and there were some felt-pen markings on the top suggesting that the "x 1M" section had been bypassed. It was also filthy.
Once disassembled I found that the section had indeed been bypassed (a piece of thin wire crudely soldered across it) but with the wire removed there was nothing wrong! So I have no idea why that was done. I replaced the terminal post with another of similar vintage, and gave everything a good clean with foam cleaner. I checked all the resistors with a meter. They were all fine (they were 0.1% so more accurate than my meter) apart from one on the "x 100K" section that was a couple of percent high. A suitable resistor in parallel (27M-ohms) bought it back into line.
The only other thing missing was the feet. These were the stick-on types and had not remained stuck, so I added a pack of suitable replacements to my next CPC order.
A decade resistance box allows the user to dial-up any value of resistance. The seven switches are for (from the right) ohms, tens of ohms, hundreds of ohms etc., up to M-ohms. Each switch has 10 positions marked 0 to 9. This decade box is fitted with mainly 0.1% resistors (the 1 ohm section has 1% resistors). This type of equipment is useful where one needs to select a value of resistor by trial-and-error. Rather than soldering in different resistors to check, this box can be connected to the circuit and the correct value established, then the nearest practical resistor can be fitted permanently. It is of more use to designers than repairers generally, but can be useful when redesigning a set to use a different valve for example.
This unit is branded "Heath" rather than "Heathkit" so it may have been sold as a ready-assembled product.