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Posted on Saturday, September 08, 2001 - 7:37 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Documentation on the KL-40 Linear Amplifier

Wow! What a great little amplifier Just a little bit bigger than a pack of cigarettes, but really packs a punch. The audio quality is excellent, and it is compact enough to mount anywhere. Very simple to install and operate, and there are heat sinks on the sides and top of this unit. Feed it with 1 1/2 watts and have a blast!. Just 1 1/2 watts of input will give you a dead key of 14 watts and good forward swing, and SWR is excellent. I tested this equipment with a Galaxy 99V and I got a dead key of 14 and forward swing to 35 watts. It will do more, as the table below shows, but you don't want to overdrive this amp.

The KL-40 will comfortably swing to 35-40 watts with full modulation on AM and FM, and SSB mode.

What's the point of buying an amp that does less than 50 watts? Let's say you can't afford to buy an export radio but want the power of an export radio. You can buy a good SSB radio for around $150, use this amp with it, and you're still under $200. Far less than the cost of one of those, "big radios".

The KL-40, even for what is considered by some as an "economy amplifier", boasts incredible audio quality. Modulation was crisp, clear and offered a noticeable increase in audio when the unit was in use. At no time was I advised by other operators that this unit made my transmissions sound broken up or muffled.

This is truly an efficient amplifier, and what better proof than the SWR meter while this unit was in operation. Standing wave was just as good while using the amplifier as it was while in "barefoot" mode. As a matter of fact I could see no measurable difference. This is truly a quality piece of equipment for the price.

While this is a great piece of equipment for the money it has its drawbacks. There is no mounting bracket for this unit, nor is there any way to attach one to it, but there is no heat sink on the bottom, you could use velcro or double-sided tape to mount it to the top of your radio. The documentation that comes with the amp shows the schematic diagram, installation instructions (which are vague), and tells the user that operating the equipment may be illegal. This equipment is of Italian origin, as the instructions are written in that language first.

This particular amp doesn't seem to have the need to be "modified" to work when you get it, although some users reported that you may need to connect the center conductor to the SO-239 connector inside the amp.

All in all you can't beat this deal. For less than $40 you can't go wrong. I would recommend this amp to anyone!

Price: $30 - 40.

Manufacturer: RM Construzioni Elettroniche

4 1/4" Wide
2 3/4" Deep (Excluding SO-239 connectors and ON/OFF switch)
1 3/8" High

Weight: Less than 5 ounces.}

Mounting Bracket: No

Power Connector: Two (2) 18 AWG wires (one red, one black) each 16 inches in length.

Power Requirements: 13.8 VDC (negative ground)

Power Consumption: Less than 5 Amps (at maximum output)

Input wattage limits: 1-5 Watts (AM/FM) 2-10 Watts (SSB)

Output Wattage: 35-40 Watts (full modulation) AM,FM, and SSB.

RF Connection: Two (2) teflon SO-239 connectors.

ON / OFF Switch: Yes, push in for ON, out for OFF.

Fused Power Connector: No

Fused Internally: Yes (5 Amp / 250 Volt glass type fuse)

Internal Parts: This is a single transistor amplifier, with no tunable components, less the three coils mounted in the circuit. The board uses no surface mount parts. All components are of the radial and axial type.

Transistor: This unit runs a single MOS RM3 transistor. I disassembled the amplifier and could fine no number on this particular component whatsoever. However Copper Electronics has factory replacement parts including this transistor readily available, on the cheap.

Input and Output wattage for the KL-40 Linear Amplifier.

AM Watts IN (dead key)AM Watts OUT (dead key)
1 1/2
2 1/2
3 1/2
4 1/2