Rf Att; Rit; If Shift; Noise Blanker - Kenwood TS-820 Operating Manual

4 .6 RF ATT
If the transceiver is operated in a short-distance (wi thin
several hundred meters) and strong signals o f nearby fre·
quencies are received. t he wanted signals are blocked. Also.
if the wanted signals are very strong. the S meter is scaled
out. In this instance. set the ATT switch to ON. The input
signals to the RF amplifier are attenuated by abou t 20 dB.
providing distortionless
rec~ption .
4 .7 RIT
By using the RIT knob. the receive frequency of VFO can be
shifted by about ± 3 kHz and th e frequency of fixed channel
by about
±
1 50 Hz without changing th e transmit fre-
quency. If the frequency of the opposite station is deviated.
your receive frequency can be set to the station by turning
the RIT switch to ON and using the RIT knob. The st ate of .
RIT can be checked bh the indicator in the window of the
d1al.
4 .8 IF SHIFT
By using the IF SHI FT knob during reception. the pass band
frequency of the crystal filter can be shifted by about
±
1. 7kHz because of adoption of PLL (Phase Locked Loop)
circu it in the local oscillator circuit. This is one of the major
features of TS -·820 and can be used in the following cases:
1. Adjustment o f Tonal Quality and Interference Rejection
during SS8 Reception.
When the transceiver is used in USB mode, turn the IF
SH IFT knob in the
"+"
direct ion and the lower frequen-
cies are cut out. Turning the knob in the " - " direct ion
cuts out the higher frequencies (these procedures are
reve rsed for LSB mode) . Adjust the knob so that the to·
nal quality suits you r listening preference. The IF SHIFT
knob is also effective in eliminating interference w hen
the receive signals are superposed on nearby signals.
2. Adjustment of Tonal Quali ty during CW Operation
For detailed descriptions. refer to Section 4.1 3 "CW
operation".
3 . FSK (RTTY) Operation at 850Hz Shift
For detailed descriptions. refer to Section 4. 19 "RTTY
operation".
4 .9 · NOISE BLANKER
The TS-820 has a sophistica t ed built-in noise blanker
designed to reduce ingition type impulse noise. The noise
blanker
IS
particularly im portant for mobile opera tion. When
necessary, acti vate the noise blanker circuit by flipping the
NB switch up.
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4.10 AGC (A UTOM A TIC GAIN CONTROL)
Set the AGC switch to the position appropriate for the
rece1 ved signal. Generally for SSB reception set . the AGC
switch to SLOW. for CW reception set the AGC switch to
FAST. and for reception of a very weak signal the switch
may be set to OFF.
4.11 TRANSMITTER TUNING
Connect the TS --820 to a 50 ohm dummy load or a 50 ohm
antenna with an SWR of less than 2 : 1 be fore making any
tmnsmitter adjust ments. The life o f the fina l tubes is directly
related to the SWR of the antenna and to the length of t u-
ning periods.
Refer to Table 2 for the initial switch settings of the TS -820
for transm itting. Tune t he main tuning knob to th e desired
operating frequency.
PLATE IDLING CURRENT (See Fig. 7)
Tum the 1 nain tuning knob to the desired operating fre- ·
quen cy wtthin the amateur band selected. Flip the stand-by
switch t o SEND and check that the plate current (IP) is 60
ma. I f the plate current is not correct. adjust the rear panel
BIAS con rrol for a correct 60 ma of idling current and return
the stand-by switch to REC.
C A UTION : If tile plate current is very much higller than 60
ma do not leave the stand-by switch on for more than a few
seconds. Excessive plate current shortens the life of the fi-
nal tubes.
DRI VE TUNING (See Fig. 81
Shift the METER switch to A LC and the MODE switch to
TUN and peak the A LC reading (maximum meter deflection)
with the DRIVE control. The stand -b y switch is in the SEND
position for adjustment.
NOTE :
If
there is no A LC reading indicated, increase the
CAR control until there is an A LC reading.
PLATE TUNING {See Fig. 8)
Turn the METER switch back to I P, leave the MODE switch
at TUN and flip th e stand-by switch to SEN D. Quickl y adjust
the PLATE control to dip the plate current (a minimum meter
reading). Return the stand-by switch to REC.
NOTE : The TU NE position perm its tuning of the final tank
circu it at reduced power without danger to the tubes. With
the MODE switch in the TUN position, the screen voltage o f
the finals is reduced to approximately 50% and the keying
circui t is shor ted.