Swann 400 Installation guide

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OPERATION AND MAINTENANCE
S\^'AN MODEL 40()
Osrrr
ELECTRONICS
Oceanside,
Ca
ilornia

OPERATIONandMAINTENANCE
MODEL 4OOSERIES
S]NGLE SIDEBAND TRANSCEIVER
INTRODUCTION
The Swan Model 400 Single Sideband
Transceiver, together with its acces-
sorre6 and optional equiprnent, is
designed to be used in either CW or
SSB mode6 on all portionB of the 80-,
40-, 20-, l5-, and I0-meter amateur
radio bands. Operation on AM (Single
Sidebaltd rrith Carrie!) is possible by
zero-beating the !eceived signal.
The Swan 400 generates the single side-
band signal by mean6 of a crystal lattice
filter, and the tran6ceive op€ration auto-
matically tunes the transmitter to the
receivedfrequency. Provi6ions a!e
included in the transceiver Jor ope!a-
tion on either upper or lower sideband,
and provisiong for cohplete band
coveraSe are included within the basic
Ba6ic circuitry of the single conversion
de6ign has been proven in thouaands of
hours ot opeiation of the very popular
Swan 240 and 350 series of transceivers.
Mechanical, electrical, and thermal
stability are exceptionally high, and all
oscillators are voltage legulated and
ternperature cornpensated. PuBh-to-
talk opeiation is po6sible in aU installa-
tiolrs, and operation with a tv,/o-contact
microphone is possible by use of the
FuDction Switch or the VOX accessory.
The basic tlansceive! iB deBigncd
for
use with either the Model 410 Frequency
Control Unit, which provides full covei-
age of all portions o{ the amateur bandd,
or with the Model 4068 Frequency Colttlol
Unit which providea coveiage of all phone
portiona of the 80 throrrgh l5 rneter bandE
and a 500 kc portion of the l0-meter
band, With a suitable power 6upply,
operation may be fixed, portabl€ or hobile.
Power input on all banda exceeds 400
Watts, PEP, on single sideband, and
320 Watts DC input on CW. The baaic
t
ranaceiver includeB autoDatic gain
control, (AGC) automatic lirniting control,
(ALC), aelectable sideband, grid-block
keying, calibrator, and speaker
Part I of this Manual covers the basic
transceiver. Parts II and lfl cover the
Models 4068 and 410 Frequency Conttol
Unita, !e6pectively. Part IV covers the
recohEended power Bupplies, Model
ff7-XB or ll?-XC lor ac operation
and
Model l4-ll7 for l2 volt dc operation.
Models a!e also available for 230volt
AC oDeration. O.cmr
ELECTRONICS CORP.

I MODEL 4OO
TRANSCEIVER
SPECIFICATIONS
FREOUENCYRANGES
Foll frequencycoverageof 80, 40, 20,
I5, and l0 meter amateur radio bands
in 8 ranges oJ 500 kc each, as Iollows:
3,5-4.0,7.0
-7.
5, t3.85-14.35,21.0-
2r,5, 28.0-28.5, 28.5
-29.
0, 29.0
-
29.5,29.2-?9.1rnc.
Model 4068 Frequercy Contlol Unit
Full phoneband coverage of 80, 40,
20, and l5 meters, plus a 500
kc
segmentof l0 lneters, as follows:
3
.
8
-4.
0, 7
.
r
-7
.
3
, 14.r5
-r4.35,
21.25
-21.45,
28.5
-29,
0 rnc.
POWER INPUT
bands.
cw
-320 Watts DC input on all bands,
AM (Sinsle Sideband With Carrier)
IZ5 Watts DC input on all bands.
DISTORTION
Distortion products downat least30 db.
UNWANTED SIDEBAND SUPPRESSION
Unwanted sidebaDddownat least40 db.
CARRIER SUPPRESSION
Carr:ier suppression at Ieast 50 db,
RECEIVER SENSITIVITY
Less than 0.5 Inicrovolt at 50 ohms
irnpedanc e for 6ignal-plus-noise to
noise ratio of I0 db.
AUDIO OUTPUT AND RESPONSE
Audio output through built-in speaker
approx. 3 watts to 3,2 ohrn load.
Response essentially flat 300 to 3000
cps on both teceive and transmit.
METERING
PA Cathode current, 0-800 rrla on
tran6mit S-Meter, 0-?0 db over 59
FRONT PANEL CONTROLS
Function Switch, Sideband Selector,
Phone-CW, AF Gain, Bandswitch'
Mic. Gain, Carrier Balance, PA Plate
Tune, PA Grid Tune, PA Load Coarse,
PA Load Fine, VOX-PTT
REAR PANEL CONTROLS
AND CONNECTORS
Bias Potentiometer, Grid -Block CW
key jack, Jones plug powe! connecto!,
VOX Connector, F requency Control
Unit Connecto!, Antenna, S-Meter Zero,
SPDT Relay Terrninal.
FREOUENCY CONTROL UNIT CONTROLS
Bardswitch, Main Tuning, RF Gain
2
VACUUM TUBE COMPLEMENT
Vl - 6EW6 VFO Amplifier
YZ - IZBE6 Transrnitter Mixer
vJ - ou.t\.o.urrver
V4 - 6HF5 Power Amplilier
v) - bill ) rowe r Arnprlri er
V6 - IZBZ6 Receiver RF Amplifier
Y? - IZBE6 Receiver Mixer
V8 - 6EW6 First IF Amplifier
V9 - l28.q.6Second
IF AmPlifier
Vl0 - IzAX7 Product Detector/Receiver
Audio
6BN8 AGC Amplifie r/ Detector
6GK6 Audio Output
l2I}A6 I00 KC Cryslal Calibrator
7360
Balanc€dModulator
12I}A6Carlier Oscillator
IZAXT Mic. Amplifier / Transrnit
Vl?- OAZ Voltage
Regulator
DIODE AND TRANSISTOR COMPLEMENT
QI,i 2N70
6Oscillator
QZ* 2N706
Emitter Follower
D40l TS
-2 ALC Diode
D4oz TS
-2 ALC Diode
D60l TS
-2 S-Meter Delay
Dl?01 IN29?4AZener VoltageRegulator
i. Transistor cornplement identical for
eithei Model 4I0 or Model 4068
Frequency Control Unit.
TRANSMITTER OUTPUT IMPEDANCE
Wide
-
range Pi-network output matche8
antennas
e6sentiallyresistive at 20 to
300 ohms impedance with provision8 for
both coarse and fine adju6t,
POWER REOUIREMENTS
vtr-
ylz-
vl3-
vl4 -
vl5-
vl6-
Filarnents
ReIay
Bias
Medium Voltage
High Voltage
DIMENSIONS
12.
6 volts, 5.5 amp
12volt6 dc, 250ma
-
Il 0 volts dc, 100rna
2?5volts dc, 150
ma
800 volts dc, 500 rna
Model 400 Transceiver
5-l/2 ir'. high, l3 in. wide, IL in. deep
Model 410 Frequencv Control Unit
5-l lZ A, t^rgn, 6-l/2 in. wide, I I in.
deep Control Unit
3 in, high, 1-3/4ir,. wide, 5 in. deep.
WEIGHT
Mode] 400Transceiver:
Model 410 Frequency Control Unit
Model 4068 Frequency Control Unit
t7lb, '-
91b.
3 lb.
Sinele Sideband Su Car!ie!
400Watts PEP,

PART I MODEL 4OO
TRANSCEIVER
CIRCUlT THEORY
GENERAL DISCUSSION
The Sr
ran 400 Transceiver plovides siagle
sideband,
Buppressed
ca!rier tran€ceive
operation; and generates the Bingle side-
band eignal by mean6 of a crystal lattice
filte!. To permlt a logical diEcussion of
thi6 lnode of operation, certain definitions
ate nece€5aly, In a normal AM signal
(double dideband
with carrier), a radio
frequency i6 modulated with an audio Jre-
quency signal. This is considered by
many to be merely a ca8e of varying the
amplitude of the carlie! at an audi.o
rate.
In fact, howeve!, there are actual.ly side-
band frequencies generated which ale the
!eBults of mlxing the RI. and A!' 6ignal3.
These sideband3 are the suh ot, and the
difference between the two hetelodyned
6ignals. For detection by means of
conventional diode detectols, the two
sidebands are mixed with the carlier to
detect aDdto demodulate the audio
intelligence. This inef{icient hean€ of
transrnis sion p€rrnits only approximately
25 per cent of the full tlanahitted power
to b€ used to tras6lnit intelligence.
There are other attendant drawbacks,
also. The bandwidth of the transmitted
6igna1is on the order of 6 kc, while the
actual dehodulated audio is 1e66than
3 kc. The lesult i. very limited use of
the band, and over half of the allotted
frequency range iB unuaablebecauge oI
heterodyne6, ioterference, and congestion.
In the single sideband, suppressed carlier
rrode of transhioeion, only ono sideband
of the Rr. and AF heterodyned signal is
tranBmitted, the other sideband and the
carrier being Buppressedto a level which
effectively permits using only the audio
intelligence bandwidth. This results in
increasing the transrnission efficiency
many times ove!, and pellnits an effec
-
tive doubling of the use of the allocated
frequenciea.
It rnust be remerrlbered that in the single
aideband, suppresned calrier mode of
transhission, both the unn,antedside-
band and the calrier ale oaly Buppressed,
not entile1y eliminated. Thu6, with a
transmitted sigDal frorn a transmittei
with 40 db sideband 6uppression, the
other, or unwanted sideband is pleBent,
and it i6 transrnitted, but its leve1 is
40 db below the'wanted sideband. When
3

I MODEL,lOO
TRANSCEIVER
A. Circuit Theory (cont)
BLOCK DIACRAM, RECFJIVE
B],OCK DIACRAM, TRANSMIT
FIGURE
3 CRYSTALFTLTER,
TYPTCAL
CHARACTERISTIC

I MODEL 4OO
TRANSCEIVER
A. Circuit Theoiy (Cont)
this signal is leceived at a level of 20 db
over 59. the unwanted sideband will be
pre6ent at a leve1 oI approximately 55.
The sahe is true of carrie! guPPression.
With carrier suppression
of 50db, and
a signal
level of 50
db over 59, carlier
will be present at a level of approxirnately
53 to 54.
In the Model 400 Transceiver, the single
sideband,
suppressed
carrie! signal is
generated by the crystal lattice filter
method. Refer to the schematic diagram'
and
to FiSule6 I and 2, Block Diagrams
SIGNAL CENERATION
In the TRANSMIT position (i. e., when the
pu6h-to-talk switch on the lnicroPhone i3
pressed ot when the Function Switch is
moved to TRANSMIT), the transmitter
portion of the transceivel is activated,
and generates a sinSle sideband,
suppressed
ca!!ier signal
in the follow_
ing manner: Carrier is Senerated
by Vl5,
Carrier Oscillator, which is a Pierce
oscillator, with the crystal oPerating in
parallel resonance. This stage operates
in both th€ ttansoit and leceive rnodes.
When transmitting, the RF outPut oJthe
oscillator is injected into the control grid
of the Balanced Modulator, VI4. This
balanced modulato! is a beam deflection
type, and opeiates 5imila! to a cathode
ray tube in that the elect!on bearn frorn
the cathode i6 deflected to one outPut
plate or the other by the charge aPPear_
ing on the deflection Plates. The RF
energy fed to the cootrol Srid of the
balanced modulator appeals on both
plates oI the output, in the absence of
signals to the deflection plates. The two
output plates feed the carrier to Trans_
forrner Zl40I in push PuU, and the two
RF signals cancel each other out in the
output ot the transforn:rer. The defl€c -
tion plate reference voltages are adjusted
bv means of the ca!rier balance control
60 that with no audio, the RF being Ied
to the output plates will cancel out' and
the output lror'j. Zl40l will be zero,
Audio from Microphone Amplifier Vl6
is superilnposed on one deflection Plate,
thereby unbalancinS lhe modulator, and
the two sideba$ds resulting froh the 3uln
and diff€rence frequencies of the audio
and carrier appear as a double sideband,
suppressed carrier si8na1
in the outPut
o{ Translormer Zl40l. The catrier
suppression is aPproximately 50 db.
The double sideband, suPPressed
carrier
siSnal is then couPled to the crystal filter'
which euppreeees one sideband, and
permit6 the other sideband to be fed to
the First IF Amplifier, V8. The carrie!
frequency crystal alrdthe filte! crystalg
are selected so that in the LSB poBition
on 4Oand 8Ohete!s, the sideband siSnal
is Senelated
with a calrier frequency
of
5l?2. 8 kc, and this siSnal \till fall within
the bandpass of the filt€r 6uch that the
lower 6idebandwill be attenuated by at
least 40 db. See Figure 3. On the USB
positronof 40 and 80 meiers, the carrier
clystal is 5I?6.8 kc, which positiond
the
double 6ideband signal on the other side
of the response culve oJthe filter,
attenuating the upper sideband by at
Ieast40 db. In lhe single conversion
mixing proces6, these sidebands become
inverted.
OnZ0, 15, and l0 meters, where oPera-
tion i6 generally on upPer sideband, the
siBnaI
i6 generatedwith the same carrier
crystal used in generating the lower side-
band on 40 and 80 meters. The five
crystal filter used in the tranaceive!
results in an improved reaPonae
characteristic on the low frequency end
of the bandpass, and advantage is taken
of this eflect to provide better sideband
suppression on the lnost used 6ideband
for each frequency band,

I IV{'IEL 4OOTRANSCEIVER
A. C
i.cuit Theory (Cont)
The single sideband, suppressed carrier At the sarne tirne, one d€flection plate of
signal Jrom the First IF Amplilier is fed the balanced rnodulator is grounded, un-
to the Transmitter Mixer, V2, u'here balancing the modulator and allowing full
signals Irom the VFO Amplifier are carrier input for tuning puiposes, A
mixed, and the resultant signal at the similar procedure is followed in the CW
final transmitted frequency is alnplified position of the Phone -CW switch, to allow
through the Transrnitter Mixer, the full carrier output duiing CW operation.
Driver, V3, and the Power Amplifiers, During CW operation the cathode of V168
V4 and V5. The signal from the VFO i6 opened from grotrnd, cuttrng ofI the
Amplifier iE initiated in the particular tube. This allows CW operation with no
Frequency Control Unit being used. The danger of pickup of audio through an open
signal frorn the Frequency Control Unit microphone, Attempts to operate on CW
is routed to the VfO Amplilier, and on by keying the lnicrophone jack, and insert-
40 and 80 rneteis, is subtractively ing carrier, are not recommended.
mixed with the single sideband signal
from the IF AmpliIier. On 20, 15, and RECEM
l0 meters, the frequencies are additively
mixed, resulting in output on the opposite In RECEIVE position, or at any time when
sideband, the transrnitter is not in TRANSMIT or
STANDBY, all circuits used in transmitting
When in TRANSMIT, thc gain oI the First are disabled throrgh the relay controlled
II Amplifier is controlled through the circuits, thc relays being energized Ior
Automatic Limiting Control network transmitting, and de-energrzcd for receiv-
D40l-402, etc., to control the gain of ing. Rclay K2, when de-energized, allows
the stage in response to the average in- signals frorn the transrnitting tank circuit
put power to the power amplifiers. This and antenna to be ted to the Receiver RF
ALC system will cornpensat€ {or any Amplifier, V6, where thcy are amplilied,
extremely strong input signaLs, but does and then {ed to the control giid oI the
not completely eliminate the necessity of Receiver Mixer, V?. The local oscillator
proper adjustrnent ol the Mic. Gain signal from the VFO Amplifier is now
Control. Although this feature wil] used to heterodyne the received frequency
prevent the transmitter Jroln flat-topping to the IF frequency, either upper or lower
and spurious ernissions, considerable sideband. A11IF arnplification is
distortion may occur if the Mic. Gain accomplished at this Jrequency, nominally
control is not properly adjusted. Refei 5l?4.5 kc, and in the Product Detector
to Operating Instructions. Vl0A, the IF lrequency is heterodyned
with carrier frequency generated by
TUNE AND CW OPERATION Carrier Oscillator, VI5, to res$lt in
detection of the sarne sideband used to
Normally, the Jrequency oJ the carrier generate the transmitted signal. It i6
oscillator is approximately 300 cps out- thus not possible {or the transceiver to
side the passband of the crystal lattice receive a 6ignal on any frequency other
filter. In TUNE position, to enable the than that to which the trarlsrnitter is tuned,
transmitter to be tun€d to the maximum nor to detect the wrong sideband. This
power output condition, the frequency of simple single conversion de6ign results
the carrier oscillator is moved approxi- in an extrelnely stable signal, and an
mately 500 cps to place it well within image response down more than 80 db.
the passband ofthe cry6tal lattice filter, Since the VFO frequency from the

1 MODEL 4OO
TRANSCEIVER
A. Circuit Theory (Cont)
Frequency Control Unit is deterrnined by
circuit elements which are far removed
frorn any heat source, and the voltage
regulation is very precise to the transis-
tor oBcillator, frequency stability is
extiemely good.
Automatic Cain Control, (AGC) is pro-
vided by the AGC Amplrfier/Detector,
VlI, which provides an AGC signal for
control of the gain of V6, Receiver RF
Amplifier, V7, Receiver Mixer, and V9,
TRANSM]T AND RECEIVE SWITCH]NC
AII transmit and receive ewitchrng i6
performed by relays Kl and K2. In
TRANSMIT position, only those tubes
that opelate in the transmit mode a!e
operative, aU others being biased to cut-
off through the relay contacts, In the
RECEM position, with the relay de-
energlzed, the tubes that are norhally
used only in tran3mittiDg are cut oft in
the sarne manner. Relay K2, which
when de-energized feeds signals frorn
the output pi-network to the receiver,
and is used also to control any external
switching. In the TRANSMIT po3ition,
the meter indicates the cornbined cathode
current oI the two Power Amplifiers.
In the RECEM po6ition, it indicates the
voltage acro6s R902 in the cathode of the
Second
IF Amplifier, V9, which is
iDversely proportional to the AGC volt-
age used to control the gain of the tube.
Thus the S-Meter reads le{t to right on
transmit, and right to left on receive.
POWER RATING
The Swan 400 is capable of 400 watts,
PEP input under steady two-tone te6t
.onditions, when operated with any of
the recommended power supplies. The
peak envelope power, when voice modu-
lated, i5 considerably more, tyPically
500 \ratts, or rnore,
Recommended power supPlies produce a
no-load plate voltage ol approximately
925 volts. Under TUNE conditions, or
CW operation, this voltage rnay drop to
as Iow as ?20 volts. Under steady state
two-tone modulation, the voltage will
drop to apploxirnately 750 volt3, If Power
Amplifier idling current is 50 rna, and
two tone plate current, ju8t before flat-
topping, is 3?5 ma, the peak two -tone
cullent will be 560 rna. The PEP input
wiu then be ?50 volts x 560 ma = 420 watts,
Under voice modulatio!, beca[rBe average
power i6 considerably Iess' the Pow€r
Amplifier plate and screen voltages will
be mainta)ned hiSher, even during voice
peaks, by the power supply filter capaci-
tors. Peak voice plate cu!rent will thele-
fole also be higher than with two-tone
test conditions. Under typical operatinS
conditions, peak plate current befole
flat-topping will be 625 lna at 800 volts,
to result in a peak envelope power inPut
of 500 watt8.
Reading6 ol cathode current would not
reflect this 500 watt power inPut' how-
ever, because oI the dampiDg in the
cathode current meter. The meter damp-
ing i6 such that the rneter i3 unable to
respond to variations oJ cathode current
in the audible range. Cathode current
readings under normal voice input, should
not exce€d approximately I50 to 175 rna.
POWER AMPLIF]ER PLATE DISSIPATION
There is olten a mi sund€r standing about
the plate dissipation of tubes operated as
AB ampliliers under voice modulation,
In the Swan 400, while in the transmit
position, and with no modulation' the plate
voltage will be 890 vo1te, the plate current
50 rna, and the power input will be 50 watts.

I MODEL 4OOTRANSCEIVER
A, Circuit Theory (Cont)
Authorities agree that the average voice
power is l0 to 20 dbbelow peak
vorce
power. Normally some peak
clipprngin
the Power Amplilier (
anbe tolerated,
and a peak-to-average ratio oJ only 6 db
rray sometimeg
occur. unde! sucha
condition, the average power input will
be 125\ratts, and plate current will be
about 156rna. With an average Po'\r/er
Amplilier efficiency of 55 per cent, plate
dissipation
wilt be 57watts, or 28,
5
watts per tube. The 6HF5 is rated at
28 watt6 continuous duty cycle in normal
TV service. Thus it can be seenthat
under normal operating conditions th€
PA tubes in the Swan 400 are not being
driven very hard. Only dLrring
the tune
up is there any need to exercise caution
by lirniting the length of time the unit is
held in the TUNE position to about 30
seconds
at a time,
B. INSTALLATION
CENERAL
The Swan 400 traogceiver has been
designed to provide the utmost in ease
of operation, stability, versatility, arld
enjoyment. Maximum enjoyment Irorn
your Swan will depend to a great extent
on the installation. For fixed station or
portable use, operation with the Model
I I?XB or I t?XC power supply provides
a ( ompa( t dr rdngement with maxrrnum
ease oI op<ration. AII swrt(hrn8 is
performed in the transceiver. For
mobile installations, the Model l4-I1?
supply provides switching ar rangements,
and speaker output rnay be fed through
the car broadcast receiver 6peaker,
POWER SUPPLY
The Swan Models II?XB or ll?XC power
Eupplies provide aU neces6ary voltages
required by the transceiver. The
supplies corne equipped with a pre-wired
plug and cable, all !eady for plu8ging
into the transceiver, The Model l4-II7
supply lor mobile operation includes all
necessary cables, conn€ctor plug, luses,
and installation hardwa!e. The Jones
plug lor connection to the transcervet ts
furnished with the unit.
8
Power requirements for the Swan 400
are shown in the following table. Pin
connections to the Jones type power
connector are also listed as an aid in
connecting other brands or horne-brew
power eupplies.
+AC or DC
EXTERNAL SPEAKER CONNECTIONS
Audio output from the transceiver is pro-
vided at pin 12 of the Jones plug. The
other speaker lead goes to the common
chassis ground at pin 6. Output impedance
is between 3 and 4 ohms. For mobile
installations, the car broadcast speaker
rnay be used, in ]vhich case a DPDT
Pin Nornrnal Minirnum Maximurn
High
Voltage 8800vDc
5OO
MA 600VDC 1000vDc
lli. Powe r
Mediurn
Voltage t0 z?5vDc
I50MA 225VDC 325 VDC
Bias
Voltage 3-
110vDc
IOOMA -100
vDc -I30
VDC
Filament
Voltage 412.6 Y'N
5.5 alnp. II.5V t4.5v
Relay
Voltage 5r2 VDC
250MA IO
VDC 14.5 VDC

I MODEL 4OO
TRANSCEIVER
B. Installation (Cont)
seLector s\ritch should be installed to
select either the broadcast receiver or
tranaceiver output.
MICROPHONE
The rnicrophone input is designed lor
high impedance rnicrophones only. The
choice oI microphone is imporlant, for
good speech quality, and ehould be given
serious consideration. Th€ crystal
lattice filter in the transceive! provides
all the restriction necessary on audio
response, and fr.rrther restriction in the
microphone is not required. lt is more
irnportant to have a mic rophone with a
smooth, flat response throughout the
speech range. The microPhone PIug
should be a standard l/4 in. diamete!
three-contact type. The tiP connection
is for push-to-talk relay control, the
ring connector is for the microphone
terminal, and the sleeve is for the com-
rnon chassis ground. The manufactu!elis
instructions should be followed in connect-
ing the lnicrophone cable to the Plug.
With many microphone6, the push-to-talk
button rnust be pressed to make the
rnicrophone operative, even though the
panel function switch i5 in the transmit
position. This leatule rnay be disabled,
iJ desired, by opening the microphone
case and permanently connecting the
contacts which control the microPhone.
ANTENNA
Any of the common antenna systems de-
signed for uEe on the high frequency
amateur bands may be used with th€
Swan transceiver, provided the input
impedance of the transmission line is not
outside the capability ol the pi-output
matching network, An antenna which
reflects a standing wave !atio on 50 or
?5 ohm rransmiss;on line, below aPproxi -
matety 4: I at the proposed oPerating fre -
quency, or a system tha! results in a
transmission line iiput impedance that
is essentially resistive and between l5
and 500 ohlns will take power from the
transceiver with little ditficulty. If tuned
open-wire trallslnission line is used to
excite the antenna, a suitable antenna
tuner should be used between the trans -
ceiver and the antenna to Provide a
reasonable irnpedance match between the
unbalanced coaxial output and the balanced
open-wire line. Methods oI constructing
and operating such tuners ale described
in detail in the ARRL Antenna Handbook,
and sihilar publications. Fo! oPeration
on the 75- and 40-meter bands, a simPle
dipole antenna, cut to resonate in the
rnost used poltion oI the band' will Per-
forrn satisfactorily. For operation on
the 10, I5, and 20 meter bands, the
efficiency of the station will be Sreatly
increased if a good di!ectional rotary
antenna is uBed.
MOBILE ANTENNA
Mobrle antenna rnstallations are critical,
since any mobile antenna fo! use on the
high frequency bands repre6enta a num_
ber oI cornpromiBe6. Many alnateurs
Iose the ef{iciency oJ their antenna through
improper tuning. Points to remernber
about the rnobile antenna used with the
Swan 400 are:
I, The rO" o{ the antenna loading coil
BhoIrId be a6 high as possible. There
are several comme rcial models
available which use high "Q" coils,
including the Swan Model 45 and
Model 55 5 band "Swantennas.'
2. The loading coil must be caPable oJ
handling the power of the Model 400
without overheating. In TUNE
position, the power outPut of the
transceiver Inay exceed 250 watts.
wide spaced, heavy wire loading
coils are essential, 9