Heathkit EK-2B

Manufacturer: Heathkit, USA
Model: EK-2B
Approximate Date Of Manufacture: ca 1965
Type: 6-tube Superheterodyne AM BC/SW band radio
Tube lineup: 5Y3GT, 6AQ5, 6AT6, 6BA6, 6BE6, 6C4
Status: working, restored
Where purchased: eBay, September 2005

Description

This radio was designed as an educational kit/course to teach electronics concepts while building up the radio. It has 6 tubes and receives the AM broadcast band plus 3 to 10 MHz shortwave. It has a BFO (for receiving CW and SSB transmissions), a speaker switch, and headphone jack. On the back are terminal lugs for antenna and ground (there is no built-in antenna). The design of the radio is something like a smaller version of my HR-10B receiver.

The case has some damage but it was repairable - it is made of thin wood with a paper covering. The 5Y3GT rectifier tube was intermittent (it had a visibly broken wire to the filament). When the tube filament is jiggled so it is connected, the radio works. The reception on the AM broadcast band is okay, but nothing is heard on shortwave (it may need a real antenna).

Two of the knobs are actually Marr connectors. A radio with the correct knobs can be seen here. It was dusty inside but in pretty good shape overall. The person who assembled it labelled many parts with stickers or marker directly the chassis. I need to get a copy of the manual or at least the schematic.

14 Sep 2005

Received the radio and made an initial inspection, as described above. I cleaned the chassis and case and removed the stickers that had been stuck on, including one that said "tuning capacitator" (sic). Glued the case where it had started to separate. I accidently dropped the 5Y4GT tube and it is no longer intermittent :-(

4 Oct 2005

The two knobs that were Marr connectors were removed. I put on two new knobs and used the one original knob for the tuning dial.

I traced some of the circuitry. It is quite tedious because it has a reasonably complex bandswitch. My search for a schematic or manual has only found one source: the original Heathkit company will sell me a copy of the manual for US$45. It is not quite as bad as it sounds as it includes the full manuals for a two part electronics course. I may go that route. I see another EK-2B selling on ebay today. I will try contacting the buyer and see if he wants a manual, maybe I can split the cost with him.

I'm hoping I can pick up the 5Y3GT tube at tomorrow night's OVRC meeting.

6 Oct 2005

I wasn't able to pick up the tube so I'll probably buy one off ebay.

After contacting the buyer of an EK-2B on ebay it turns out he has a manual on CD-ROM. He is going to send it to me.

7 Oct 2005

Took some pictures of the radio. Borrowed the 5Y3GT tube from my signal generator and put it in the radio. Works quite well on AM and shortwave, but I think it will be better after an alignment. It has no internal antenna so I used a short wire in the basement.

17 Oct 2005

I received the 5Y3GT tube which I purchased on ebay on 11-Oct-2005. Installed it in the radio and it works fine.

3 Dec 2005

The person with the CD-ROM manual never responded to my e-mails. However, I found a complete set of the EK course manuals (4) on ebay and purchased it. EK-1 covers Basic Electricity. EK-2A is Basic Radio Part 1, EK-2B is Basic Radio Part 2, and EK-3 is Basic Transistors. The EK-2B manual has the full assembly and alignment instructions and schematic for the finished radio.

I aligned the radio on broadcast and shortwave bands as per the instructions in the manual. As I expected, the alignment was way off. After alignment the performance was very good (at least as well as I can tell in my workshop -- there is a lot of interference on shortwave from the 100mbps computer LAN cables in the ceiling).

6 Dec 2005

I scanned the schematic and uploaded it to the BAMA web site. It is available here.

10 Dec 2005

I've also scanned the full EK-2A and EK-2B manuals. They are available on request for anyone who wants a copy (in PDF format).

19 Dec 2005

All four EK manuals have been scanned and are available at the BAMA web site. (Note: this site is often busy. If you can't access it try again later or use a mirror site).