Note
The KS-1 was designed as the power supply for the KL-1 linear amplifier, but was put in the catalog about six months before the KL-1 was released, so it was clearly also designed for use with home brew amplifiers.
In spite of it’s obvious bulk and mass, the KS-1 provides only the 1500/3000 volt B+ for the KL-1. Filament and bias voltages, and all voltage regulation, are accomplished onboard the KL-1.
Topside components on the KS-1 include the 866A tubes, plate and filament transformers, an oil-filled 8- to 30-Henry swinging choke, an oil-filled 8 uF 4000 volt capacitor and a cage containing four 60kΩ, 100-watt bleeder resistors. These are wired in series-parallel for a total resistance of 60kΩ at 400 watts. Caution: These resistors dissipate about 150 watts and will get very hot in normal operation. Note: Oil-filled capacitors are extremely durable and should not required reforming.
The circuit uses two 866A mercury vapor rectifiers in a full-wave, single phase configuration with swinging choke input filtering. A 60-second time delay relay prevents the rectifier tubes from seeing any high voltage until the tubes have fully warmed up.
The KS-1 represents an astonishing amount of hardware for what it is, and once the KL-1 was released, almost everyone recognized that individually, and as a pair, they were way too much of everything. Efforts began immediately to design an amplifier with an integrated power supply, and the result was the much more compact and affordable HA-10.
The rear panel contains sockets for two old-style medium-base household fuses. The rational for using this style of fuse was that they were readily available, as virtually everyone had them laying around near the fusebox in the basement.
The power supply is designed to be remotely controlled from the KL-1 amplifier via a six-wire interconnecting cable.
The DC output can be selected for 1500 or 3000 volts, but the 1500 volt choice is possible only if the plate transformer has been wired for 240 volt operation, but actually operated from 120 volts.
Caution: The plate transformer and filter choke are oil filled.
Warning: Refer to fusing requirements in the specification. Never install a fuse in the unused fuse socket.
Warning: Always provide a connection between the KS-1 chassis and ground. The AC line filters are of sufficiently low impedance to place the chassis well above ground potential when the line cord is plugged in, unless the chassis is grounded separately.
Warning: Lethal voltages are present while operating.
References:
Review. QST. Jul 1960, p. 42.
Maximum DC output power: 1500 watts
Nominal DC voltage output: 1500 or 3000 volts
Maximum DC current output: averageL 500 mA, peak: 1000 mA
Regulation:
180 to 600 mA (typical linear amplifier): 8%
0 to 300 mA (typical class C amplifier): 10%
0 to 500 mA: 15%
Ripple: less that 1%
Recommended ambient temperature: 50 to 100 F
Fuse requirements (refer to Figure 2):
240 VAC / 3000 VDC operation: 15 amp fuse in both sockets
120 VAC / 1500 VDC operation: 15 amp fuse in socket A only
120 VAC / 3000 VDC operation: 25 amp fuse in socket A only
Power requirements: 120/240 VAC, 50/60 Hz, 10/20 amps
Size: 17.75 wide x 12 high x 13 deep: Weight: 95 lbs
Tubes: (2) 866A, (1) Amperite 115NO60, octal base time delay
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
