Vectronics SWR-584B User Manual

Page 23

SWR-584B Instruction Manual

HF/VHF SWR Analyzer

Example: The highest resistance is 600 ohms, the lowest is 400 ohms. 400 x 600 = 240,000. The square

root of 240,000 is 490. The impedance is 490 ohms.

Using a potentiometer or resistor decade box:

1.) Connect the

SWR-584B

to one end of the system (in this case you can use a broadband matching

transformer).

2.) Adjust the frequency and note only the SWR change.

3.) Adjust the termination resistance until the SWR remains as constant as possible with very large frequency

changes around the operating frequency range.

4.) The resistance of the termination resistor is the surge impedance of the system.

7.4 Adjusting

Tuners

The SWR-584B can be used to adjust tuners. Connect the SWR-584B "ANTENNA" connector to the tuner's 50
ohm input and the desired antenna to the normal tuner output. This connection can be made with a manual RF
switch to facilitate rapid changeover, provided that switch has better than 50 dB port isolation.

WARNING: ALWAYS CONNECT THE COMMON (ROTARY CONTACT) OF THE SWITCH TO

THE TUNER. THE SWITCH MUST CONNECT EITHER THE SWR-584B OR
THE STATION EQUIPMENT TO THE TUNER. TRANSMITTING EQUIPMENT
MUST NEVER BE CONNECTED TO THE SWR-584B.

1.) Connect the

SWR-584B

to the tuner input.

2.) Turn on the

SWR-584B

and adjust it to the desired frequency.

3.) Adjust the tuner until the SWR becomes unity (1:1).

4.) Turn off the

SWR-584B

and re-connect the transmitter.

7.5

Adjusting Amplifier Matching Networks

The SWR-584B can be used to test and adjust RF amplifiers or other matching networks without applying
operating voltages.

The tubes and other components should be left in position and connected so that stray capacitance is unchanged.

To measure input circuits, a non-inductive resistor equaling the approximate driving impedance of each
individual tube is installed between the cathode of each tube and chassis.

To measure tank circuits, a resistor equaling the calculated tube operating impedance is connected from the
anode to the chassis with short leads.