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Welcome to VE7CA's Design Tools 1. Radio-Electronics Design Calculator Trp Q  Ser Shu Diameter  mm Length  mm Turns      PI/T Att dB BW  kHz L1  dB L2  dB G1  dB NF1  dB NF2  dB   2. Level Nomogram (V at 50 ohm)   View Level Nomogram Vrms is the voltage that you measure with a RF probe attached to an analog volt meter. For example, 0.4 Vrms = +7 dBm across a 50 ohm load. Vpp is the peak to peak voltage that is displayed on a scope. If you want a power of +7 dBm from a 50 ohm source into a 50 ohm load, place a 50 ohm resistor across the source and using a high impedance scope probe you need to measure 1.3 Vpp to obtain +7 dBm. Letters in red represent S units, where each S unit is assumed to be 6 db per unit and S9 = -73 dBm. W = Watts. Looking at the chart we see that 1 Watt represents 30dBm across a 50 ohm load. 3. LPDA, Log-Periodic Dipole Array Design Gain dBi Tau Sigma Bend deg F Min. Mhz F Max. Mhz Feed Zo ohms Ele. Dia. mm Line Dia. mm Analysis No Algebra 4. Antennas and Propagation Calculator Input Input Output Frequency MHz Wavelength m Distance km Wavelength m Free space Loss dB Isotropic Gain dBi Wavelength m Capture Area m2 Capture Area m2 Wavelength m Isotropic Gain dBi dBi Temperature K Bandwidth kHz Noise Power dBm Frequency MHz Iono. MF Abs. dB/100km Separation mm Wire Dia. mm Balanced Line Zo ohms Shield Inner Dia mm Ctr. Cond. Dia. mm Coaxial Line Zo ohms Relative Permativity Expression =     5. Broad Band Amp. Bias + Feedback Vcc V RL Ohm N Ie mA Fmin MHz Rcc Ohms Rb1 Ohms Rb2 Ohms Re Ohms Cc1 uF Cb1 uF Pq W Pmax dBm Enter Info in #Col1, press 'Calc', Col#2 shows component values (Cc1/Cb1 min. values) and Col#3 shows the DC quiescent collector dissipation and the nominal output power capability. The gain will depend on Transistor Beta, Ft, etc. and the emitter feedback. If Re||Ref (ie. Ref) is zero, there is no feedback and max. gain but the gain drops off above say Fc=10 MHz. To increase Fc (and reduce gain), increase Ref (XCef less than 0.1*Ref!). If the gain is too low when desired Fc is achieved, a transistor with higher Ft is needed, 1000MHz is good for Fc=50MHz/G=15dB. Rin may be over 50 ohms. If 50 ohms is desired, shunt with appropriate AC res. or transform the input up. High DC Beta (90 or over) is assumed. Transformer: N=Sqrt(Zo/Zc). 6. Incremental Tuning (XIT/RIT) Control Bias Vs V V1 V V2 V Voff V VSat V R2 Ohms R1 Ohms R3 Ohms R4 Ohms Here you can determine the bias resistors for generating variable-capacitance diode bias for an Incremental Tuning circuit. Only the resistors 1,3,4 shown are designed here given R2. Other interface components depend on the application. The following should be noted: 1. The switches must be open-collector type, selecting only one bias at a time. 2. Vo should be connected to the oscillator tuning diode through a choke. 3. +ON is 0 to Vs and has a very short transition time. It is high to turn on incremental tuning and must not change state while there is tranmitter output power. Incremental tuning range is from V1 to V2, the minimum and maximum tuning voltage at Vo. Voff is the voltage at Vo when incremental tuning is off. VSat is the saturation voltage of the transistor switches.