Kenwood TS-820S User Manual
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This manual has been written basically for use of model T5-8205. The
difference between models T5-8205 and T5-820 is that model T5-8205 has
digital display built-in as against model T5-820 has no digital display built-in.
Accordingly. if you have purchased model T5-820. you may skip over the
passages concerning digital display.
CONTENTS
TS-820S SPECIFICATIONS SECTION 1 FEATURES ,..
SECTION 2 INSTAllATION , 2.1 Unpacking
2.2 Operation location
2.3 Power Connections
2.4 Antenna
2.5 Microphone
2.6 Key
2.7 External Speaker and Headphone
2.8 RTTY (FSK)
2.9 Ground
SECTION 3 OPERATING CONTROLS 3.1 Front Panel Controls
3.2 Rear Panel Controls
SECTION 4 OPERATING INSTRUCTIONS
4.1 Preliminary Procedure
4.2 Receiver Tuning
4.3 Reading the Operating Frequency
4.4 Calibrating the Frequencies
4.5 RF GAIN
4.6 RF ATT
4.7 RIT
4.8 IF Shift
4.9 Noise Blanker
4.10 AGC (Automatic Gain Control)
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3
4
4.11 Transmitter Tuning
4.12 SSB Operation
4.13 CW Operation
6
4.14 Operation with a Linear Amplifier
4.15 Fixed Frequency Operation
4.16 Internal Cross Channel Operation
4.17 Mobile Operation
4.1 B DX Operation (Use of Processor)
4.1 9 RTTY Operation
4.20 SSTV (Slow Scan TV) Operation
4.21 Operation with a Phone Patch
4.22 Use of Monitor Switch
TS-820 BLOCK DIAGRAM 24
9
SECTION 5 CIRCUIT DESCRIPTION .., 26
5.1 Block Diagram
5.2 Board and Unit
6.3 Final Stage Power Amplifier
SECTION 6 MAINTENANCE AND ALIGNMENT 33
6.1 General Information
6.2 Accessories
6.3 Adjustment of Receiver Section
6.4 Adjustment of Transmitter Section
SECTION 7 TROUBLESHOOTING ,
TOP and BOTTOM VIEW OF THE TS-820
SCHEMATIC DIAGRAM
42
43
-IMPORTANT
40
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TS-820S SPECIFICATION
r-
FREQUENCY RANGE
MOD E ~ POWER REQUIREMENTS
PLATE POWER INPUT
AUDIO INPUT IMPEDANCE ...
AUDIO OUTPUT IMPEDANCE
AUDIO OUTPUT RF OUTPUT IMPEDANCE., FREQUENCY STABILITY,
160 meter band -1.80 to 2.00 MHz
80 meter band -3.50 to 4.00 MHz
40 meter band -7.00 to 7.30 MHz
20 meter band -14.00 to 14.35 MHz
15 meter band -21.00 to 21.45 MHz
10 meter band -28.00 to 28.50 MHz (A)
10 meter band -28.50 to 29.00 MHz (B)
10 meter band -29.00 to 29.50 MHz (C)
10 meter band -29.50 to 29.70 MHz (D)
WWV -15.0 MHz (receive only)
use. LSB. or CW, FSK
1120/220 VAC. 50/60 Hz operation
200 watts PEP for sse operation
160 watts DC for CW operation
~at!! for FSK operation
13BV DC operation
120 watts PEP for sse operation
90 watts DC for CW operation
60 watts for FSK operatio~-
50 k ohms (high impedance)
4 to 16 ohms (speaker or headphones)
More than 1.5 watts (with less than 10% distortion) into an 8 ohm load.
50 ~ 75 ohms
AUDID FREQUENCY RESPONSE
CARRIER SUPPRESSION SIDEBAND SUPPRESSION IMAGE RATIO. HARMONIC RADIATION SPURIOUS RADIATION IF REJECTION , RECEIVER SENSITIVITY RECEIVER SELECTIVITY
TUBE AND SEMICONDUCTOR
COMPLEMENT
DIMENSIONS
WEIGHT
Within 100 Hz during any 30 minute period after warmup
Within :.t 1 kHz during the first hour after 1 minute of warmup
400 to 2600 Hz. within -6 db
Carrier better than 40 db down from the output signal
Unwanted sideband is be~ter than 50 db down from the output signal
Image frequency better than 60 db down from the output signal
Better than 40 db down from output signal
Bet~er than 60 db down from output signal (without harmonic radiation)
I F frequency is 80 db or more down from output signal
0.25 JlV S+N/N 10 db or more
SSB: 2.4 kHz bandwidth (- 6 db down)
4.4 kHz bandwidth (- 60 db down)
CW.: 0.5 kHz bandwidth (- 6 db down)
18kHz bandwidth (- 60 db down)
.(with optional CW filter installed)
1:o-tl205
Tubes
IC'S
FET'S
Transistors
DiOdes
38
31
95
195
3
30
74
167
3
5
13.2" wide x 5.9"high x 13.2" deep
37.4 Ibs.
3
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SECTION 1. FEATURES
1. Pll System, HF Band SSB!CW!RTTY
Transceiver
This transceiver employs newly developed PLl (Phase
Locked loop) circuit covering 1 8 to 29.7 MHz (WWV
15 MHz) for SSB, CW and ATTY operations
2. Minimum Spurious and Excellent Overload
and Crossmod. Characteristic
The adoption of FET balanced type mixer. MaS FET and
single conversion system minimizes spurious during
transmission and assures excellent overload and cross-
mod. characteristic during reception.
3. Built-in IF SHIFT Circuit
IF SHIFT circuit is built in the transceiver to shift IF pass
band without changing receive frequency The circuit is
also called the "pass band tuning circuir., It allows you
to eliminate radio interference or set the receive fre-
quency characteristic to the desired bandwidth simply
by manipulating one C<;Introl knob
4. Built-in RF Processor
The unique speech processor uses a quick time constant
at 455 kHz. Since this circuit is of RF type, it produces
little distortion and, unlike the clipper system, does not
deteriorate the tonal quality
5. RF NFB
RF NFB from the transmit final stage to the driver stage
improves the cross modulation distortion. The use of
the amplification type AlC further improves the quality
of transmit signals
6. Newly Designed Analog Dial
The combination of newly designed mono-scale and su-
b-dial provides easy reading of frequencies. The adop-
tion of a circuit that is completely free from changes in
carrier frequencies permits accurate indication of fre-
quencies on one dial pointer.
7. Digital Display Dial
The digital dial of TS-820S indicates transmit and
receive frequencies using carrier. VFO and local oscillator signals instead of converting VFO frequencies.
Thus. accurate frequencies can be read at all times at
any band and any operating mode.
Since the accuracy of frequencies is set up only by the
10 MHz standard oscillator. frequencies can be read accurately up to 100 Hz order by calibrating the oscillator
with WWV.
The green indication on the dial assures many hours of
fatigue less operation
8. D.H. (Displav Hold) SWITCH
BV pressing the DH switch. the frequency read on the
digital remains on. thus serving as a memory system
9. Rigid Structure and Easy Operation
The transceiver is built with a die casting front panel
and a rigid chassis, providing outstanding mechanical
stability for mobile operation All the operating parts
such as control knobs and dials are designed and arran-
ged according to human engineering technology to en-
sure maximum case of operation
10. Monitor Circuit
The monitor circuit allows you to hear your own voice
during transmission. which is normally impossible with
collventional transceivers This is very useful when
checking the modulation condition or adjusting tho AF
processor
11. Selector Switch for SSB/CW Receive
Frequency Response
During CW reception the audio frequency response IS
automatically narrowed to improve the clarity of sound.
12. Build-in Fixed Channel Circuits with AIT
(crystals are optionall
The fixed channel circuits with AIT permit the Uie with
the built-in VFO for more enjoyable operation
13. Transverter Connector
Transverter TV-502 (2m) can be connected for ready
operation. Changeover to HF or VH F is accomplished
automatically with the power switch of the transverter.
14. ,Built-in AC Power Supply. and DC Operation with
Optional DC-DC Converter
DC- DC Converter DS-1 A (option) can be attached to
the transceiver for mobile operation.
16. Wide Variety of Auxiliary Circuits
and Devices
The transceiver is completed with a noise blanker
circuit, VOX circuit, side tone circuit, marker cIrcuit,
built-in speaker. 3-position AGC switch, heater swItch.
IF OUT terminal and linear terminal
The following devices are available as optional extra:
Remote VFO (VFO-820), CW Filter (YG-88CI, Digital
Display (DG-1 AI. Transverter (TV-502S). Microphone
(MC-50), Low Pass Filter (Lf-30A)
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2.1 UNPACKING
Remove the TS-820S from its shipping box and packing
material and examine it for visible damage. If the equipment
has been damaged in shipment. save the boxes and packing
material and notify the transportation company immediately. It is a good idea to save the boxes and packing material
in any case because they are very useful for shipping or moving the equipment.
The following accessories should be included with the transceiver:
1 Operating Manual
1 Microphone Plug
1 Jumpered 9-pin Plug (installed)
5 RCA Phono Plugs
1 Alignment Tool
2 Plastic Extension Feet
with Screws
1 AC Power Cord
1 Speaker Plug
1 8P US Plug
4 Fuse (6A x 2, 4A x 2) .
2.2 OPERATION LOCATION
As with any solid state electronic equipment the TS-820S
should be kept from extremes of heat and humidity.
Choose an operating location that is dry and cool. and avoid
operating the transceiver in direct sunlight. Also. allow at
least 3 inches clearance between the back of the equipment
and any object. This space allows an adequate air flow from
the ventilating fan to keep the transceiver coo).
2.3 POWER CONNECTIONS
Make sure the POWER switch on the front panel of the
TS-820S is turned oft. the stand-by switch is put in the REC
position. and that the voltage switch on the back of the
TS-820S is switched to the correct line voltage (120 or 220.)
Connect the POWER cord to an appropriate external power
source.
2.4 ANTENNA
Connect a 50 ~ 75 ohms antenna feedline to the coaxial
connector on the rear panel.
Fixed Station -Any of the common antenna systems designed for use on the high frequency amateur bands may be
used with the TS-820S. provided the input impedance of the
transmission line is not outside the capability of the pi-output matching network. The transmission line should be of
the coaxial cable type. An antenna system which shows a
standing wave ratio of less than 2 : 1 when using 50 or 75
ohm coaxial transmission line. or a systerp that results in a
transmission line input impedance that is essentially resisti-
ve. and between 15 and 200 ohms will take power from the
transceiver with little difficulty. If openwire or balanced type
transmission line is used with the antenna. a suitable antenna tuner is recommended between the transceiver and
the feed line. Methods of construction and operating such
tuners are described in detail in the ARRL Antenna Handbook. and similar publications. For operation on 75 and 40
meter bands. a simple dipole antenna. cut to resonance in
the most used portion of the bands. will perform satisfacto-
rily. For operation of the transceiver on the 10. 15. and 20
meter bands. the efficiency of the station will be greatly increased if a good directional rotary antenna is used Remember that even the most powerful transceiver is useless
without a proper antenna.
Mobile Station -Mobile antenna installations are critical.
since any mobile antenna for use on the high frequency
bands represents a number of compromises. Many amateurs lose the efficiency of their antenna through improper
tuning. Remember the following points when using the
tS-820S with a mobile antenna.
The "Q" of the antenna loading coil should be as high as
possible. There are several commercial models available
which use high "Q" coils.
The loading coil must be capable of handling 1tle power of
the transceiver without overheating. In the CW mode the
power output of the transceiver will exceed 80 watts.
The SWR bridge is a useful instrument. but unfortunately it
is quite often misunderstood. and overrated in importance.
Basically. the SWR bridge will indicate how closely the antenna load impedance matches the transmission line With
long transmission lines. such as will be used in many fixed
station installations. it is desirable to keep the impedance
match fairly close in order to limit power loss. This is parti-
cularly true at the higher frequencies. The longer the line.
and the higher the frequency. the more important SWR becomes. However. in mobile installations the transmission
line seldom exceeds 20 feet in length. and an SWR of even
4 to 1 adds very little power loss. The only time SWR will
indicate a low figure is when the antenna presents a load
close the 50 ohms. but many mobile antennas will have a
base impedance as low as 15 or 20 ohms at their resonant
frequency. In such a case, SWR will indicate 3 or 4 to 1,
and yet the system will be radiating efficiently.
The really important factor in your mobile antenna is that is
should be carefully tuned to resonance at the desired fre-
quency. The fallacy in using an SWR bridge lies in the fact
that it is sometimes possible to reduce the SWR reading by
detuning the antenna. Field strength may actually be reduced in an effort to bring SWR down. Since field strength is
the primary goal. we recommend a field strength meter for
antenna tuning.
5
For antenna adjustments. the transceiver may be loaded
lightly. using the TUN position instead of operating at full
power output. This will limit tube dissipation during adjust-
ments. and will also help to reduce interference on the fre-
quency In any case. do not leave the transmitter on for very
long at one time Turn it on just long enough to tune and
load. and get a field strength reading. Start out with the antenna whip at about the center of its adjustment range. Set
the VFO to the desired operating frequency and then adjust
the PLATE control for a dip. and then the LOAD control
Then observe the field strength' redding The field strength
meter may be set on top of the dash. on the hood. or at an
elevated location some distance from the car.
Change the whip length a half inch. or so at a ti.me. retune
the finals each time. and again check the field strength at the
antenna. Continue this procedure until the point of maxi-
mum field strength is found. This adjustment will be most
critical on 75 meters. somewhat less critical on 40. until on
10 meters the adjustment will be quite broad. After tuning
the antenna to resonance. the finals can be loaded to full power.
2.5 MICROPHONE
Attach the microphone connector to a suitable microphone
as shown in Figure 2 Be sure that the PTT switch of the mi-
crophone is separate from the microphone circuit. as shown
in Figure 3.
It should be noted that a microphone with a 3 P plug having
a common earth terminal cannot be used.
The microphone input is designed for high impedance (50k
ohms) microphones only. The choice of microphone is important for good speech quality. and should be given serious
consideration. The crystal lattice filter in the transceiver provides all the restriction necessary on audio response. and
further restriction in the microphone is not required. It is
more important to have a microphone with a smooth. flat re-
sponse throughout the speech range.
The microphone manufacture's instructions should be followed in connecting the microphone cable to the plug With
many microphones, the push-to-talk button must be pressed
to make the microphone operative For PTT operation, this
feature may be disabled, if desired, by opening the microphone case and permanently connecting the contacts which
control the microphone.
The standard microphone sensitivity is within the range of
-50 dB to -60 dB. If a microphone having a higher sensi-
tivity is used. the AlC circuit will not function properly In
this case. insert an attenuator as shown in the illustration at
right or connect a resistor (10k ~ 33k ohms) in parallel
with the capacitor 100 pF (C94) in the IF unit
(X48-1150-00) of the transceiver.
MIC
TS-820S
MIC Connector
2.6 KEY
If CW operation is desired. connect a key to the KEY jack
2.7 EXTERNAL SPEAKER AND
HEADPHONES
Receive audio output from the TS-820S is 1.5 watt at 4 to 16
ohms. The TS-820S has a built-in speaker. However If an
external speaker is desired for fixed station or mobile operation. simply connect it to the SPEAKER jack on the real pa-
nel. The speaker may be any good 8 ohm permanent ma-
gnet type in the 4 inch or large size The internal speaker IS
disconnected when an external speaker is used.
Headphones should also be 8 ohms impedance. Whel"l.the
headphones are connected to the front panel PHONES Jack
the speaker is disabled.
2.8 RTTY (FSK)
For ATTY operation. connect a teletypewriter to the ATTY
KEY jack on the rear of the transceiver Since this Jack IS
connected to the switching circuit for shifting frequencies. a
relay should be inserted in the closed loop of the teletypew-
riter for keying operation.
2.9 GROUND
So preventing to receive an electric shock. TVI and BCI.
select a good. effective ground for installation and then connect an earthing wire to the backside of GND terminal Use
a heavy earth line as big as possible. It is because short line
wiring is regarded as most effective for operation.
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Fig. 2 Microphone Connection Wiring
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8
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~,."-"". -,"
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3.1 FRONT PANEL CONTROLS
CD METER
The meter monitors six different functions. depending on
the position of the METER switch. In receive the meter is
automatically an 5-meter The 5-meter shows received signal strength on a scale of 0 to 40 db over 59 In transmit
the meter function depends on the position of the METER
switch. as described below
~ METER SWITCH
VFO INDICATOR
@
The VFO indicator is a light emitting diode which illuminates
whenever the TS-820S's internal VFO is controlling the trans-
ceiver's operation. The indicator is not lighted during fixed
channel, or remote VFO. operation
RIT INDICATOR
@
This light emitting diode is illuminated when the RIT circuit
is turned on. showing that the transmit and receive frequencies may be different
The position of the METER switch determines the function
of the meter The switch selects one of the following func-
tions (see Section 4 for nominal meter readings):
ALC
IP
RF:
caMP:
HV
(Automatic Level Control) -In thIs position the
meter monitors the ALC voltage of the internal
ALC circuit (or the AlC voltage feedback from a
linear amplifier operated in conjunctIon with the
TS-820S). For SSB operation the ALC reading for
voice peaks shquld be within the indicated ALC
range of the meter. The ALC voltage adjustment
is made with the MIC control for SSB and with
the CAR control for CWo
(Plate Current) -In this position the meter monitors the plate current of the final tubes. The meter scale is calibrated from 0 to 350 ma.
(Output Power) -In this position the meter mo-
nitors the relative output power of the transcei-
ver. There is no meter scale for this Rosition.
Normally the reading should be adjusted with the
RF VOLT control for a 2/3 scale meter reading.
This indicates the state of compression when the
speech processor is operated.
(High Voltage) -In this position the meter monitors the high voltage from the power supply. The
meter scale is calibrated from 0 to 10. indicating
0 to 1000 volts.
SUB-DIAL
<1)
The sub-dial is turned with the main tuning knob to select
the operating frequency of the transceiver It is calibrated at
50 kHz intervals from 0 ~ 500 kHz.
@ DIAL SCALE
The unique mono-scale permits direct reading of frequencies
over the range of 0 to 500 kHz graduated at 1 kHz irller-
vats. Operating frequency can be obtained by adding the
frequency read on the dial to the frequency (MHz) indIcated
on the BAND switch.
(ii DIAL CALIBRATE KNOB
This knob is used to calibrate the reading on the dial scale.
It should not be used for turlll\g purposes
@ MAIN TUNIG KNOB
This knob turns the VFO and dial scale to select the fre-
quency to be added to the bslld frequency to establish the
transceiver's operating frequency
@ STAND-BY SWITCH
This two position lever switch selects one of the following
functions
REC:
The transceiver is receiving unless the microphone PTT switch is switched to transmit, or the
VOX circuit is activated.
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@ ATT INDICATDR
This indicator uses a light emitting diode. It is illuminated
when the RF A TT switch is turned to ON
FIX (FIXED CHANNEL OPERATION)
@
INDICATOR
The FIX indicator is a lightemltting diode which illuminates
whenever the TS-820S's internal fixed frequency oscillator is
controlling the transceiver's operation
10
SEND
The TS-820S is locked into the transmit mode in
this switch position.
@ VOX SWITCH
This two-position lever switch selects one of the following
functions.
MAN
With the switch in this position. the transceiver is
switched into transmit or receive by the stand-by
switch or the PTT switch on the microphone.
TUN
Used for adjustment of transmit conditions. The
input power to the final stage is low as compared
with that for CW so that the final stage tubes can
be protected against damage due to overloading
during adjustment. Since the KEY circuit is inoperative in the TUN mode, the transceiver cannot
be used for transmission or reception.
vox
@
With the switch in this position. the VOX circuit is
turned on for voice operated transmit on. SSB semi-automatic break-in operation on CWo
NB SWITCH
off. The noise blanker is designed to reduce pulsating ignition type noises. When the lever switch is flipped up. the
circuit is turned on.
@ MONI (MONITOR) SWITCH
This switch is used to demodulate part of the output of the
transmit IF amplifier for monitoring transmit signals.
@ AGC SWITCH
The AGC switch controls the AGC (Automatic Gain Control)
circuit giving the operator three choices:
OFF: It may be desirable to turn the AGC off when re-
ceiving a very weak signal.
FAST:
The FAST AGC position is designed for use in CW
operation.
SLOW:
Use the SLOW AGC position for SSB operation
@ PHONES JACK
CW:
use
Used for CW operation
Used for USB operation It is internationally de.
termined that the 14. 21 and 28 MHz bands be.
long to USB.
LSBThe NB switch turns the built-in noise blanker circuit on and
Used for LSB operation. It is internationally determined that the 3.5 and 7 MHz bands belong to
LSB.
For RTTY operation with teletypewriter.
@) COMP lEVEL KNOB
Pull this knob during sse operation. The speech processor
is activated and the talk-power is increased. Adjust the
state of compression by turning the knob while observing
the COMP meter.
@ DELAY KNOB
The DELAY control adjusts the holding time of the VOX cir-
cuit for VOX or break-in CW operation. The control will have
to be adjusted to the preference of the individual operator.
@ ANTI VOX KNOB
This control adjusts the level of the anti VOX signal fed in to
the VOX circuit. Adjust the control to prevent feedback of
the speaker from tripping the VOX circuit.
The headphones jack allows use of a 4 to 16 ohm set of
headphones with a 1/4" phone plug attached. When the
phones are plugged into the transceiver. the speaker is disconnected.
@ MIC CONNECTOR
The microphone connector is four pronged. allowing use of
the PTT microphone. Figure 2 shows how to wire the plug
on the microphone cable.
@ MODE SWITCH
The MODE switch is used for selection of type of waves or
for TUNE operation.
@ VOX GAIN KNOB
This control adjusts the sensitivity of the VOX circuit by ad-
justing the gain of the VOX amplifier. for voice controlled
operation.
@ RF ATT SWITCH
With this switch set to ON. ATT (attenuator) of about 20 dB
is connected to the antenna circuit. protecting the RF amplifier and mixer circuit from strong input signals.
@ RIT SWITCH
This is the switch for the AfT (receiver incremental tuning)
circuit To turn on the circuit, press this switch; to turn off,
press it once again. The AIT indicator is illuminated when
11
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the RIT circuit is ON By turning the RIT knob. the receive
frequency of VFO can be changed by :t3 kHz and the fre-
quency of fixed channel by :t 150 Hz without changing the
transmit frequency.
@ BAND SWITCH
This 11-position switch selects all the necessary circuits to
tune the transceiver to the desired 500 kHz band.
fixed channel crystals are installed in the transcei.
verI.
@ H. SW (HEATER) SWITCH
This switch turns the heater circuits of the three transmitting
tubes on and off. The heaters would normally be turned to
OFF to reduce power consumption in mobile or portable re-
ceiving.
@ FUNCTION SWITCH, ,
This 7 -position rotary switch selects one of the following
transceive functions.
GAL
FIX:
CAL.
RMT
CAL25 kHz:
This position allows calibration of the 1"5-8205'5
internal VFO to one of the transceiver's fixed fre-
quency channels (if an optional fixed channel crystal is installed), With the switch in this position a
signal is generated at the selected fixed channel
frequency and the main tuning knob can be tuned
to zero beat the calibrating signal,
This position alloWs calibration of the VFO-820
(remote VFO) to the transceiver's operating fre-
quency. With the switch in this position. the
transceiver generates a calibrating signal and the
VFO-820 can be tuned to zero-beat the calibra-
ting signal.
With the switch in this position. the transceiver's
calibrator circuit generates a marker signal at
every 25 kHz for normal calibration of the internal
VFO.
VFO:
The switch is kept in this position for normal
transceive operation.
~~ POWER SWITCH
The POWER switch turns all the power on and off in
TS-8205.
@ RIT KNOB
This knob is used to change receive frequency when the AIT
circuit is in operation Set the center position (0) of the
AIT knob to the AIT -OFF.
@ IF SHIFT KNOB
By using this knob during reception. the center frequency of
the IF crystal filter can be shifted by :t 17 kHz. facilitating
the adjustment of the tonal quality of receive signal or elimi-
nating radio interference from nearby frequencies. For normal operation. this knob should be set to the center position
(click is heard).
(:j~ MIC GAIN KNOB
This knob is used for adjustment of the gain of MIC amplifier
during sse operation. Adjust so that the meter pointer does
not deflect beyond the ALC lone.
@ CAR (CARRIER) LEVEL KNOB
Used to adjust carrier level during CW operation. Adjust so
that the meter does not deflect beyond the ALC lond.
VFO.R
FIXR:
FIX:
12
With the switch in this position. the TS.820S's internal VFO controls the receive function and the
internal fixed channel oscillator controls the trans-
mit function (if fixed channel crystals are installed
in the oscillator).
With the switch in this position, the TS-820S's internal VFO controls the transmit function and the
built-in fixed channel oscillator controls the receive function (if fixed channel crystals are installed in the oscillator) The VFO.R and FIX.R allow
cross-channel operation without an external VFO.
With the switch in this position. the IS-820S's
fixed channel oscillator controls the transmit and
receive function of the transceiver (if accessory
@ AF GAIN KNOB
This knob adjusts the gain of the receiving audio amplifier
The audio volume of the received signal increases as the
control is turned clockwise.
@ RF GAIN KNOB
This control adjusts the gain of the receiver sections RF am-
plifier. Turn the knob fully clockwise for maximum gain and
for a correct S-meter reading Turn the control counter--
clockwise to reduce the gain.
@ FIX CH (FIXED CHANNEL) SELECT SWITCH
This four-position rotary switch selects between four diffe-
rent fixed frequency channels which can be installed Inside
-
the transceiver. Fixed frequency operation is convenient for
operation on often used frequencies. The fixed channel oscillator replaces the VFO when the FUNCTION switch is placed in the FIX position.
@
DRIVE KNOB
The D RIVE tuning control tunes the plate tank circuit of the
12 BY7 A driver as well as receiver's antenna and mixer
coils. In receive the DRIVE control is tuned for maximum
sensitivity (maximum S-meter deflection). In transmit the
DRIVE control is tuned'for a maximum ALC reading. When
the control is correctly tuned for transmission it will be cor-
rectly tuned for reception.
@
PLATE KNOB
The PLATE control adjusts the plate tuning of the two final
amplifier tubes.
@
LOAD KNOB
The LOAD control adjusts the loading of the pi-circuit bet-
ween the final section and the antenna. The control is adjust
as described in Section 4 for impedance matching.
@
DH (DISPLAY HOLD) SWITCH
With this switch set to ON, the frequency below 100 kHz on
the display dial remains on even when the main dial knob is
rotated This feature is useful to memorize the original frequency when checking other frequencies. The DH switch
being ON turns off the lights for "MHz" frequencies, elimina-
ting a worry about mis-reading frequencies.
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