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70 MHz Antenna Tuning Unit for the 4 Meter
197
A tunner witha balun T200-6 should give a better Q but the T200-2 was in stock and gave me sufficient tuning range, the capacitors are radio types and can be used up to 150 Watts
I built the Z-Match in about 3-4 days using available parts. decided I wanted to use my Z-Match for 7-21 Mhz operation so I adjusted the coil L1 to give me that range
After matching my antenna to a 1.0:1 SWR I measured the capacitor settings: 77pF on the TX side and 36pF on the antenna side
The inductor, the tricky thing in matching units with variable inductance. For the body I found an old pill container with a diameter of 4cm. The coil is then wound on this with 60 windings of 1mm enameled copper wire
For most applications, a capacity of 350 pF for C1 and 2x230 pF for C2 is sufficient, if you want to cover the bands 10-80 m, an extension for 160 m will be presented later
Antenna splitter per VHF-UHF per quattro ricevitori Chi dispone di una sola antenna e vuole collegarvi più di un ricevitore necessità di uno splitter
Amateur radio kits by Kanga US
50MHz to 28MHz RX Converter The concept of the rx converter is quite simple and nothing really new. the local oscillator is a standard colpitts crystal oscillator producing the 22mhz lo signal
23cm Yagi Antenna building Finished antenna at 1275 MHz SWR under 1:1.5 at resonant frequency
50 MHz preamp Gain 26dB with the BFG135 Preamps for 144 and 430 MHz, for 50 MHz, the BFG135a is a cheap transistor and in my view rather strong. It is not easily damaged by static discharge or RF power. FG connection
30 Volt Computer Power Supply Stack A bonus was that i discovered that these did not need a standby load connected to the supply to keep them running just apply mains power and close the Start lead to ground