Affordable QRP kits at exceptional value
Hendricks Deluxe Tenna Dipper Kit
Designed by Steve Weber, KD1JV
The Deluxe Tenna Dipper provides a simple means of determining the 50 ohm resonant frequency of an HF antenna or ATU (Antenna Tuning Unit). The small size and battery operation makes the unit ideal for use in the field. It's perfect for antenna experimenters that don't want to tie a bunch of money up in the higher priced analyzers. It's even priced lower than most swr bridges, and this tells you "where" you are resonant, not just that it's matched, or not matched, like a simple swr bridge.
A voltage controlled R/C oscillator generates a 5 volt square wave signal. This signal drives a resistive Wheatstone bridge. One leg of the bridge is the "unknown" resistance, the antenna. A wide band step up transformer is connected across the bridge to detect the signal produced when the bridge is unbalanced. This signal is farther amplified by a Darlington pair transistor amplifier. A high brightness LED is used to visually indicate the current in the collector of the amplifier. When the antenna impedance at the unknown leg of the bridge is equal to 50 ohms, the bridge is in balance and the LED will go out. Hence the name for this device, the Tenna Dipper, as we dip the brightness of the LED to find the 50 ohm match.
Deluxe Tenna Dipper Assembly Manual (4/24 update)
Deluxe Tenna Dipper Decal Install)