HA-14 "Kompact Kilowatt"
The Heathkit HA-14 "Kompact Kilowatt" linear amplifier was sold in 1965 - 1968, with optional HP-14 12vdc mobile and HP-24 120/240vac fixed power supplies. Designed for both mobile and base operation, the HA-14 has an IAS (Intermittent Amateur Service) rating of 1 KW PEP. Due to tube cooling and power supply design considerations it is for SSB operation only, and while in a nominally horizontal position. The HA-14 system was not designed for AM or CW or other high duty cycle modes.
The amplifier uses two 572B power tubes in parallel in a traditional grounded grid configuration. The matching power supplies are solid state. The size and shape of the amplifier matches the Heathkit "Hot Water" series monobanders for easy stacking.
The HA-14 has developed a reputation as a powerful and reliable mobile SSB Kilowatt amplifier when operated as intended. This includes tuning the antenna properly, first. Since it has fixed a 50 ohm output with fixed loading it is meant to feed an antenna which is correctly tuned to the 50-75 ohm impedance range. A built-in SWR bridge and meter make for easy monitoring.
Since this amplifier works very well in fixed station service, perhaps more of them are used fixed than mobile. I ran one every day for years in fixed service feeding a cubical quad antenna, driven by a variety of Heathkit HW series and similar transceivers. It is amazing how well this little box works!
In fixed service, where ragchewing or contesting may be more intense, it is important to supplement the tube cooling, especially if the amplifier is in an enclosed space. Adequate cooling is easily achieved by laying a large 'muffin fan' on top of the case above the tubes. To minimize air leaks between the fan housing and the amplifier case build a simple 'gasket' between them using weather stripping. To keep the fan noise low add a resistor in the fan lead to slow it down.
It doesn't take a lot of extra airflow to keep the HA-14 noticeably cooler. Some users mount a small fan or two on the backside. Since the 572B's are 'instant on' tubes, further cooling is achieved by switching it off except as needed.
Kilowatt Kompact's have been a bit difficult to find for many years, especially with the HP-14 mobile power supply. But in the current economic environment they do appear from time to time on eBay.
This HA-14 interior looks nice and clean. There is no obvious salt air corrosion. The soldering appears marginally acceptable but should be checked carefully. No components appear stressed due to short leads, and there are no obvious modifications.
Observe the scorch marks on the top right of the case, directly above the amplifier tubes. This HA-14 has been "run hot and put away wet". Chances are these finals were overworked and undercooled and may be soft. Proper cooling would probably have avoided this damage.
More information:
Click Here for HA-14 Linear Amplifier
Click Here for HP-14 DC Power Supply
Click Here for HP-24 AC Power Supply
Click Here for Manuals with Schematics
Click Here for the Cables/Connectors
Modifying The Heath HA-14 For 6 Meters - by W7MY
Please send your comments, photos, schematics, hints, articles, stories and links to:
Dave W6OVP@arrl.net Vancouver, WA