[Elecraft] KPA500 RF Power Monitor Local display · WiFi Network · Remote Internet Access

[Keith Ennis]

KPA500 RF Power Monitor 3-in-1 Display: Local display · WiFi Network · Remote Internet Access

Overview

The KPA500 RF Power Monitor delivers real-time monitoring of six critical parameters for Elecraft KPA500 owners — all updating 10 times per second on a high-contrast 256×64 graphics display. No menu cycling, no squinting at the built-in LCD. A built-in WiFi web interface enables wireless monitoring and control from any smartphone, tablet, or computer, with unlimited simultaneous connections. Size: 4″ × 2″ × 4″.

Six Simultaneous Measurements

Power Output (0–700W) — 500ms intelligent peak hold; progress bar shows power relative to maximum
PA Voltage (0–99V) — Real-time voltage sag detection under load
PA Current (0–20A) — Correlates with output; early warning of abnormal operation
SWR (1.0–99.9) — Instant feedback during antenna tuning
PA Temperature (0–150°C) — Thermal monitoring to prevent overheating
Band (160M–6M) + Operate/Standby — Current band and amplifier state at a glance

Display Options


The display is organized in a 3×2 grid (top row: Power, Voltage, Current; bottom row: SWR, Temperature, Band). The web interface mirrors this layout with a retro green-on-black terminal aesthetic, responsive to any screen size, updated in real time via WebSocket — no app required.

WiFi Setup & Access

First power-on creates a "KPA500-Setup" network. Connect, select your WiFi, enter the password, and save — one-time, five-minute setup. Access via kpa500.local or direct IP from any device (iOS, Android, Windows, Mac, Linux). Local network only, secure by default. Web controls include Power ON/OFF and Operate/Standby toggle, plus over-the-air firmware updates.

Hardware / Software

Microcontroller: XIAO — 160 MHz RISC-V, 4MB Flash, WiFi 802.11b/g/n
Display: SSD1322 256×64, software SPI — Serial: MAX3232, 38,400 baud
Power: 9–14.8V DC, 100mA typical — Update rate: 10 Hz

Direct Serial Integration

Communicates with the KPA500 via RS-232 at 38,400 baud through a MAX3232 level shifter. No amplifier modification required. Bidirectional communication supports four simultaneous queries per cycle plus remote command transmission.

What's Included

Assembled and tested unit, DC power cable, RS-232 serial cable, printed quick start guide.

Installation

Connect the serial cable to the KPA500 RS-232 port, connect power, and mount the display. Monitoring begins immediately. WiFi configuration is one-time only. Add kpa500.local to your mobile home screen for app-like one-tap access.


WiFi requires network connectivity and a modern browser. The display operates independently of WiFi at all times. Internet remote access requires Tailscale (free) on remote devices.


Keith, KV5J

http://www.kv5j.com 

DDUinfo at yahoo.com