SILTRONIX 1011B Betriebsanleitung PDF herunterladen (Seite 11)

of the First IF Amplifier is controlled through the Auto-

matic uvel Control (ALC) network (using the AGC Ampli-

fier VIO) to control the gain of the stage in response to the

average input power to the Power Amplifier. This ALC

system \vill compensate for any extremely strong input sig-

nals, but does not completely eliminate the necessity of

proper adjustment of the Mic. Gain Control. This feature

will help prevent the transmitter from flat topping and spur-

ious emissions, but considerable distortion may occur if the

Mic. Gain Control is not properly adjusted. Refer to Oper-

ating Instructions.

f CAUTION 1

CARE MUST BE EXERCISED WHEN TUNING

FOR THE 100 KHz HARMONICS OF THE

CALIBRATOR. SEVERAL SIGNALS MAY

BE HEARD, ALTHOUGH THEY WILL BE

DEFINITELY WEAKER THAN THE COR.

RECT HARMONICS.

TRANSMIT AND RECEIVE SWITCHING

TUNE AND CW OPERATION

Transmit and receive switching is performed by relay KI.

In TRANSMIT, only those tubes that operate in the trans-

mit mode ar~ operative, all others being biased to cutoff

through the relay contacts. In RECENE, with the relays

de-energized, the tubes that are used only in transmit are

cut off-in the same manner. Relay Kl when de-energized,

feeds signals from the output Pj-netwcrk- +~ .the receive~.

Note that relay KI will not operate when the BAND

SWITCH control is in "CB" position.

Normally, the frequency of the carrier oscillator is approxi-

mately 300 Hertz outside the 6 db passband of the crystal

lattice filter. In TUNE position, the frequency of the car-

rier oscillator is moved approximately 800 Hertz to place it

well within the passband of the crystal lattice filter. A

similar procedure is followed for CW to allow full carrier

'ootput during -cw operation.

RECEIVE

POWER RATING

In RECENE position, or at allY time when the transmitter

is not in TRANSMIT, all circuits used in transmitting are

disabled through the relay controlled circuits, KI. The

relay is energized for transmitting and de-energized for re-

ceiving. One contact, when de-energized, allows signals

from the transmitting tank circuit and antenna to be fed to

the Receiver R.F. Amplifier, V5; where they are amplified

and then fed to the control grid of the Receiver Mixer, V6.

The local oscillator signal from the VFO Amplifier is now

used to heterodyne the received signal to the IF frequency.

All I.F. amplification is accomplished at this frequency,

nominally 5500.0 KHz, through IF amplifiers V7 and VB.

In the Product Detector, V9A, the IF signal is heterodyned

With the carrier frequency generated by Carrier Oscillator,

Q3. The resultant audio is then amplified by V9B, which

then couples to the AGC amplifier, VIO, and the audio out-

put stage, VII.

The Siltronix 1011B is capable of 180 watts, P.E.P. input

under steady state two-tone test conditions. The peak

envelope power, when voice modulated, is considerably

greater, typically 260 watts, or more.

The built-in power supply produces a no-load plate voltage

of approximately 880 volts. Under TUNE conditions, or

CW operation, this voltage will drop to approximately 680

volts. Under steady state two-tone modulation, the voltage

will drop to approximately 710 volts. If the power ampli-

fier idling current is 40 ma.,' and the two-tone current, just

before flat-topping, is 200 ma., the peak two-ton. current

will be 300 ma. Under these conditions, the P .E.P. input

will be 710 volts times 300 ma..= 213 watts. Under voice

modulation, because average power is considerably less, the

power amplifier plate and screen voltages will be maintained

higher, even during voice peaks, by the power supply filter

capacitors. Peak plate current will therefore also be higher

than with two-tone test conditions. Under typical operating

conditions, peak plate current before flat-topping will be

350 ma. at 800 volts, to result in an input of 280 watts

P.E.P. Readings of cathode current will not reflect this

power input, however, because of the damping in the cath-

ode current meter. Cathode current readings under normal

voice input should not average more than 100 to 120 ma.

FREQUENCY CALIBRATION

Frequency calibration of the Model 10 II B is in 5 KHz in.

crements. Dial accuracy and tracking are quite good, but

caution must always be observed when operating near band

edges. Measuring the frequency with the 100 KHz cali.

brator when working near band edges is recommended.

DIAL SET

POWER AMPLIFIER PLATE DISSIPATION

A DIAL SET control has been provided so that dial adjust-

ment can be made at any 100 KHz point on the dial. With

calibrator on, set the dial to any loa KHz point closest to

the frequency you wish to work. Now adjust DIAL SET

control to zero-beat the VFO with the 100 KHz Calibrator.

This provides greater accuracy of dial readout.

There is often a misunderstanding about the plate dissipa-

tion of tubes operated as ABI amplifiers under voice modu-

lation. In the Siltronix 1011 B, while in the transmit mode,

and with no modulation, the plate voltage will be approxi-

mately 830 volts, the plate current 40 ma., and the power

input 33 watts.

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