This project started when I recieved the HA-10 amplifier in the spring of 2005. My uncle W1DOG (Who now resides in Georgia) gave me the amplifier, it was in horrible shape. Looking back, I had one of those "It seemed like a good idea at the time" moments when I actually plugged the amplifier and turned it on. I also receeved the original HA-10 manual. Around the Spring of 2006 I decided to start restoring the amplifier.
As seen in the picture on the left, the amplifier chassis was very corroded and covered in dirt and mildew. The transformers also had quite a bit of rust on them. The picture on the top right shows the front panel in its original condition. Besides wiping down the front with soap and water, I decided to not do too much to it in fear of ruining the paint. I also don't believe the front panel is in very bad condition.
On the left is a closer view of the RF choke transformer, high voltage capacitor, and rectifier diodes. Notice the when I received the amplifier, the rectifier tubes had been replaced with a solid state rectifier modification. The amount of rust and deterioration is also clearly visible in this picture.
Working from the manual, I started on the last page of the construction section and dismantled the amplifier in exact reverse order. I tried my best not to damage any parts, although some hard to remove components such as diodes on the stand-offs did break. During this dismantling, I discovered that the band switch wafer was cracked. This was a serious problem because they are hard to find these days.
In the next photo, the High Voltage power transformer for +3000V power supply and the rectifier diode modification are visible. The amount of rust on the power transformer is apparent on the left of the transformer.
After stripping the amplifier down to the bare steel chassis, I painstakingly restored the metal as best as possible. I removed the rust and dirt with fine sandpaper and then a fine steel wool. After the metal was as clean and smooth as possible, I polished it with WD-40. This is a trick used by people who restore old amplifiers and radios. It shines the metal as well as leaving a protective coating on the metal. WD-40 repels water and is a very thin lubricant. This protects the metal from moisture which would cause rust.
Working from the manual, I started building the amplifier. This is truly and awesome experience because there is a good chance that no one has built this radio in at least 30 years! I am getting the chance to build a Heathkit amplifier using the original HA-10 manual that I was given with the amplifier. As I am going through the build process, I am replacing old components such as electrolytic capacitors. This is because electrolytic capacitors tend to dry out with age and fail, better to be safe than sorry!
There is a huge amount of history in this amplifier. I hope to write an article for QST magazine one day about the restoration, especially since 80% of the restoration was done when I was 16 years old! It was quite the endeavor to undertake. After polishing the metal chassis, I found scratching on the inside of the metal case which houses the components (not pictured). I will update the website with more information about the writing at some later date. What I did find has led me to believe that this HA-10 was used at the ARRL headquarters in Newington, CT to transmit the ARRL Code Bulletins! If this turns out to be true, I have a piece of history!