DRAKE L7 Manual do Operador descarregar pdf (Página 21)

220

of grid current with the LOAD control

until

0.565

plate Amperes

reached. Leave the

exciter power at this level and redip the plate cur-

rent with the PLATE control and then bring the

grid current back to

220

with

the LOAD con-

trol. The

will

be very close to being tuned up

and only small adjustments of the driving power,

and PLATE and LOAD controls will be necessary

to obtain

0.565

plate Amperes with

220

grid

current at resonance.

The forward power meter is a more sensitive indi-

cation of plate tank resonance than plate current

dip, and the PLATE control should be adjusted for

maximum forward power while still maintaining

the relationship of

0.565

plate Amperes to

220 mA

grid current. In case

0.565

plate Amperes cannot

be reached because of low exciter power, tune the

amplifier for maximum forward

Watts at

maximum exciter power.

3-5.

OPERATION

NOTE

While transmitting with the L

over

extended periods of time, the final amplifier

plates may show a bright red color. This

normal and does not detract from the life of

the tubes. If the plates display a very bright

orange color

is advisable to check the

amplifier to determine that

not being

overdriven and that it

tuned up properly.

The power should not be turned off

immediately after long periods of

transmitting, but the amplifier should be left

on standby for several minutes with zero

plate Amperes to allow the final amplifier

tubes to cool down.

3-6.

CW AND RTTY OPERATION

For CW and RlTY operation the Mode switch

should be in CW position. With the exciter on and

the key depressed, adjust the drive level

until

the

product of plate voltage and plate

cqrrent

at or

under maximum legal input power.

3-7.

SSB OPERATION

For SSB operation the Mode switch should be in

SSB position

and the red light that indicates high

plate voltage ("SSB") should be on. The trans-

mitting AGC threshold must be set before using

the amplifier. With the Mode switch in CW posi-

tion the transmitting AGC threshold is adjusted

by applying a strong single audio tone into the

microphone input of the exciter either by

oscil-

lator or by whistling a single tone into the micro-

phone with the exciter adjusted for maximum out-

put. With this single tone applied, turn the AGC

control clockwise until the plate current

0.580

Amperes. If you desire to run less than

kilowatts

PEP,

turn

the AGC control clockwise until the

single tone plate current decreases to the power

level you desire. Return the Mode switch to SSB.

The AGC threshold needs to be set once on each

band When making large changes in frequency

within a band, the amplifier should be checked for

plate tank resonance while still maintaining the

relationship of

0.565

plate Amperes to

220mA

grid

current on CW. Under normal voice operating

conditions, the exciter should be adjusted to run

the L

Plate Meter between

0.300

0.400

Am-

peres. Plate current of

-.400

Amperes is the maxi-

mum legal input allowed and this level should be

reached only occasionally and never exceeded. If

the exciter has no provisions for transmitting

AGC, the output from the amplifier should be

monitored with an oscilloscope to check for peak

clipping.

3-8.

AM OPERATION

For

operation the Mode switch should be in

SSB position and the red light that indicates high

plate voltage

("SSB") should be on. The

works

quite

favorably on

with the compatible Drake

line of Transceivers and Transmitters since these

units

use controlled carrier modulation. Trans-

mitting AGC

not used on

with the Drake

units,

and the amplifier output should be moni-

tored

with

an oscilloscope to check for peak clip-

ping.

the L

to be used with a

100%

modulated

transmitter, the exciter should be adjusted to

run the amplifier at

500

Watts DC input with an

unmodulated carrier.

3-9.

SWR CALCULATION

The SWR of the load connected to the amplifier

can

be determined by using the forward and re-

flected power readings from the L

wattmeter and

the SWR calculator. Refer to figure

3-3.

The cal-

culator is used by laying a straight-edge across the

scales at the forward

anclmflected meter readings

and reading the VSWR straightedge. The

wattmeter indicates forward and reflected power

at all times, so that SWR can be calculated using

only the exciter. For measuring the exciter RF out-

put power a higher degree of accuracy can be

obtained by using the

300

Watt forward scale

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 36 37

Comentários a estes Manuais

Sem comentários

DRAKE L7 Manual do Operador Página 21

Comentários a estes Manuais