NZART Amateur Examination                     page 8          NZARTX07 Security code 268509
- "Break-in keying" means:
- unauthorised entry has resulted in station equipment
disappearing
- temporary emergency operating
- key-down changes the station to transmit, key-up to
receive
- the other station's keying is erratic
- The purpose of a VOX unit in a transceiver is to:
- change from receiving to transmitting using the sound of
the operator's voice
- check the transmitting frequency using the voice
operated crystal
- enable a volume operated extension speaker for remote
listening
- enable the variable oscillator crystal
- The signal "QRN" means:
- I am busy
- I am troubled by static
- are you troubled by static?
- I am being interfered with
- The designed output impedance of the antenna socket
of most modern
transmitters is nominally:
- 25 ohm
- 50 ohm
- 75 ohm
- 100 ohm
- This commonly available antenna feedline can be buried
directly in the
ground for some distance without adverse effects:
- 75 ohm twinlead
- 300 ohm twinlead
- 600 ohm open-wire
- coaxial cable
-
The antenna in this diagram has two equal lengths of wire
shown as 'X' forming
a dipole between insulators. The optimum operating
frequency will be when the:
- length X+X equals the signal wavelength
- dimensions are changed with one leg doubled in length
- length X+X is a little shorter than one-half of the signal
wavelength
- antenna has one end grounded
- The purpose of a balun in a transmitting antenna system
is to:
- balance harmonic radiation
- reduce unbalanced standing waves
- protect the antenna system from lightning strikes
- match unbalanced and balanced transmission lines
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