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Welcome to VE7CA's Design Tools

1. Radio-Electronics Design Calculator

Trp Q 

Ser Shu

Diameter 

mm

Length 

mm

Turns 

 

 

Att

dB

BW 

kHz

L1 

dB

L2 

dB

G1 

dB

NF1 

dB

NF2 

dB

 



2. Level Nomogram (V at 50 ohm)   View Level Nomogram

  1. 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.
  2. 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.
  3. Letters in red represent S units, where each S unit is assumed to be 6 db per unit and S9 = -73 dBm.
  4. 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.