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Silver rectangular amplifier unit with front controls and ventilation slots

RM Italy

RM Italy KL 503 linear amplifier 250 W AM FM SSB CW 12-14 A

SKU CH-SFK1-WMED5

Delivers up to 250 W AM/FM and 450 W PEP SSB across 20-30 MHz with 26 dB preamp gain

  • 250 W max output on AM, FM, SSB and CW modes
  • 450 W PEP max on SSB for strong single-sideband signals
  • 26 dB preamp gain boosts weak incoming signals
  • Electronic switching with polarity inversion protection
  • Compact 170×295×62 mm chassis fits tight installations

Linear amplifier for mobile HF bands

The RM Italy KL 503 is a linear amplifier built for 20-30 MHz mobile installations. It accepts 1-6 W drive on AM, FM and CW, and 2-12 W on SSB, delivering up to 250 W carrier or 450 W PEP. A 26 dB preamp stage and six-level output control suit operators who want strong signal presence from a vehicle.

Practical limits of 12-14 A supply

The unit draws 12-14 A and is protected by three 10 A fuses, so the vehicle charging system and wiring must sustain that load continuously. Electronic switching with inversion polarity protection guards the amplifier, yet voltage drop on long or undersized cables will reduce available output and can trip the fuses during extended transmissions.

250 W carrier / 450 W PEP output decision

The single figure that decides fit is the 250 W maximum carrier power (450 W PEP on SSB). Stations needing only modest mobile gain will find ample headroom, while operators targeting higher legal limits or base-station duty cycles must look beyond this model.

How it compares

Measured against everything we stock in Car Audio Amplifiers, at today’s prices. Recalculated every night.

Price $177.99
Cheaper than about 61% of the 158 comparable items (median $225.49).

Specifications

Product
Brand nameRM Italy
Model nameRmkl503

Questions about this item

Should I choose the 250 W AM/FM/CW model or the 450 W PEP SSB version?

The KL 503 is a single unit that delivers up to 250 W on AM, FM and CW, and up to 450 W PEP on SSB; you do not select between separate versions.

What does the 250 W output figure mean when the amplifier is installed in my vehicle?

It is the maximum continuous carrier power available on AM, FM and CW modes when the amplifier is driven by 1–6 W and supplied with 12–14 A from the vehicle electrical system.

Which transmission standard does the amplifier use and what practical limit does it impose?

The amplifier operates on the 20–30 MHz HF band and covers AM, FM, SSB and CW modes; its practical limit is the 3×10 A fuse rating that protects the 12–14 A supply circuit.

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