GLOBE ELECTRONICS GLOBE KING 500C (01) PDF DOCUMENT

FINAL POWER INPUT	540 watts CW and Phone 700 watts SB Peak Envelope Power (with external SB exciter).
POWER REQUIREMENTS	115 VAC. 50/60 cycles 1300 watts phone, 820 watts CW.
OUTPUT	Coaxial into 52-300 ohm antenna.
FREQUENCY CONTROL	Xtal or VFO.
DIMENSIONS	31 inches high, 15 inches deep, 22 inches wide.
SHIPPING WEIGHT	270 pounds.

BAND COVERAGE:

160 meters	1750-3000 KC
80 meters	3200-4800 KC
40 meters	6600-9000 KC
20 meters	13-19 MC
15 meters	13-24 MC
10 meters	16-31 MC

OSCILLATOR: Tunes oscillator plate circuit to fundamental, second or third harmonic of crystal or VFO frequency.

EXC. BAND SW: Selects proper amount of inductance in both oscillator and buffer plate circuits.

BUFFER: Tunes buffer plate circuit to oscillator frequency or selected harmonic.

METER SW: Places EXCITER meter into any one of the following four circuits: OSC. PLATE, BUFF. PLATE, FINAL GRID or FINAL SCREEN.

FUNCTION SW: Serves three purposes. Inserts high resistance in power amplifier screen grid circuit for tune-up, shorts modulation choke for CW operation, inserts modulation choke into power amplifier screen grid circuit for AM operation.

F. GRID DRIVE: Controls screen voltage of buffer stage, thereby, controlling power amplifier grid current and RF drive.

ANT. COUPLING: Inserts added inductance or capacity into the output circuit for proper antenna match.

FINAL PL. TUNE: Tunes plate circuit of power amplifier stage to resonance. Must be retuned after any adjustment of either ANT. LOAD control or ANT. COUPLING control.

FINAL BAND SW: Inserts proper amount of inductance into the pi-network to resonate on selected band.

ANT. LOADING: Varies amount of loading by matching power amplifier plate circuit to antenna circuit. Always start with this control in the “MIN” position. This corresponds to maximum capacity of condenser, and at this setting, will match lowest impedance.

SB-AM SWITCH: Changes class of operation of the power amplifier tube from class “C” to class “B”. Also removes all low B plus voltages from oscillator and buffer stages for SB operation of the power amplifier.

GAIN: Controls level of modulation in AM operation.

MODE: Serves three functions. In phone position, applies AC filament power to the modulator, applies AC plate power when TRANSMIT switch is turned on, removes short from modulation transformer secondary. In CW position, removes AC power to filament and plate circuits, shorts the modulation transformer secondary.

FILAMENT (Power supply panel): Applies AC power to the entire transmitter.

EXCITER: Applies AC power to low B plus plate transformer for the exciter section and to the VFO switching relay.

TRANSMIT: Applies AC power to plate transformer for high B plus voltage for the power amplifier tube. Also applies AC voltage to the exciter plate transformer. Push-to-talk switch on the microphone stand will also energize the complete transmitter by relay control.

XTAL-VFO: In VFO position, connects VFO to input of crystal stage.

COMPRESSION: Switches speech compression circuit in or out as desired.

BANDSWITCH: Selects proper band of operation for VFO with the transmitter. Must be set to same band of operation as the EXCITER BANDSWITCH and FINAL BANDSWITCH. Located on power supply panel.

VFO TUNING: Tunes the VFO to the desired frequency of operation.

PATCH IN: This jack is wired to the top of the audio GAIN control so that an external audio signal, such as from a phone patch, may be fed into the speech stages independently of the microphone.

KEY: Closed circuit type wired in the grid circuit of the keyer stage for sequential keying.

XTAL: Insertion of proper 160-80-40 meter crystal allows operation on all amateur bands, 160 meters through 10 meters.

INPUT: Input socket for use of external SB exciter. SB exciter must deliver SB signal of 15-20 watts. Located on rear apron of RF section chassis.

MIC: Located on the front panel of the modulator section. Audio input is between pin 1 and ground. Push-to-talk connections are from pin 2, through push-to-talk switch and to ground.

115V AC: Terminal strip, located on rear of power supply chassis. Provides 115 VAC to operate relay when TRANSMIT switch or push-to-talk is in ON position.

ANTENNA CONNECTORS: Located on rear of RF section. Two coax connectors marked ANT. and RECEIVER.

WARNINGS & PRECAUTIONS

Before making any external connections to the transmitter, remove the AC line cord plug from the AC outlet. Also, place all power switches in the OFF, or down position and ground cabinet.

Operation of this equipment involves the use of high voltages which are dangerous to life. Observe all safety precautions! Do not attempt to make adjustments inside the equipment, or change tubes with any power on. Disconnect the main power line before touching any high voltage components.

All meter readings should be noted occasionally. Should the readings deviate considerably from that listed in the typical readings, operation should be suspended until the cause is determined. Failure to do this may result in damage to the equipment, or, in any event, cause a poor signal to be transmitted.

Use extreme caution when taking voltage readings. High voltages, dangerous to life, are involved.

CAUTION

DO NOT operate Telegraph (CW) with MODE switch of the modulator in PHONE position. The FUNCTION switch should be in the CW position.

OPERATING HINTS

Proper tune-up is necessary for optimum performance of the Globe King 500-C transmitter. Attempted operation of the transmitter without proper tune-up may result in damage. Dial settings in Table III are typical for frequencies and resistive loads indicated. A deviation of more than 10% from these readings indicates a reactive load presented to the transmitter, causing improper tuning. When the loading control is advanced from the minimum position to obtain loading, the final plate tuning control should NOT have to be retuned more than a small amount.

TABLE II. CRYSTAL CHART

Band	Crystal
160 meters	1800-2000 KC
80-75 meters	3500-4000 KC
40 meters	7000-7300 KC
20 meters	7000-7175 KC
15 meters	7000-7150 KC
10 meters	7000-7425 KC

a. Place all power and control switches in the OFF position. Place EXCITER switch to XTAL OPERATE.

b. Insert AC line cord plug into a 110-115 volt, 60 cycle, single phase current source.

c. Connect antenna feed line to coax connector marked ANT. (Rear of RF chassis).

d. Select the proper crystal for the frequency from the crystal chart, TABLE II, insert into XTAL socket. Place XTAL-VFO switch in XTAL position.

e. Place FILAMENT switch (power supply panel) to the ON position, and allow three minutes warm-up time.

f. Set EXC. and FINAL bandswitches to the desired band.

g. Place FUNCTION switch to the TUNE position.

h. Set ANT. COUPLING switch to position indicated in TABLE III for band in use and load expected. Set ANT. LOAD control to minimum (counter-clockwise).

i. Rotate F. GRID DRIVE control to position 5.

j. Place SB-AM switch in AM position. (On panel of RF section).

k. Place METER switch in OSC. position. Place MODE switch on the MODULATOR section to the CW position.

l. Place EXCITER switch to XTAL TUNE position and adjust OSCILLATOR tuning control for minimum current indication of the meter. Note the tuning chart for approximate dial reading for band in operation.

m. Place METER switch to BUFF. position.

n. Tune BUFFER plate control for minimum current reading. (Check TABLE III for typical dial readings, as a wrong harmonic can be tuned in some instances).

o. Place METER switch to F. GRID position and note the amount of grid current. A reading of approximately 13 Ma should be obtained. If not, tune OSC. and BUFF. for maximum F. GRID current, adjust the F. GRID DRIVE control until a reading of 13 Ma is obtained.

p. Place EXCITER switch in XTAL OPERATE position and TRANSMIT switch to ON position. Carefully adjust FINAL PL. TUNE for minimum final current. This indicates resonance in the final plate circuit, dial setting of FINAL PL. TUNE control should correspond closely with the setting in TABLE III.

q. Advance the ANT. LOADING control slowly clockwise, final plate current should increase. When plate current has increased to 190 Ma, re-tune the FINAL PL. TUNE control for minimum plate current again. Repeat the procedure of advancing ANT. LOADING control and re-tuning the FINAL PL. TUNE control to resonance until the minimum plate current dip is 190 Ma.

r. Place FUNCTION switch to the CW position. This should cause an increase in final plate current up to approximately 300 Ma. Re-tune OSC. and BUFFER controls for maximum final grid current, then re-adjust the F. GRID DRIVE control so that 11 Ma of grid current is indicated. When the full voltage is applied to the final stage, normal loading will decrease grid current 10 to 20%, so re-adjusting of the BUFFER and F. GRID DRIVE control is necessary.

s. Repeat the loading procedure by advancing ANT. LOADING control and re-tuning the FINAL PL. TUNE control, until the minimum plate current dip of 300 MA is obtained. This is full load for the final stage and it should not be exceeded or a reduction in power output will result. Do not exceed 11 Ma grid current or shortened tube life will result. The ANT. LOADING control may be advanced until sufficient final loading is obtained. Should the dial indications differ greatly from the typical table readings, a defective antenna or a high reactance is indicated and should be corrected.

t. Re-check all meter readings for safety sake. The screen grid current of the power amplifier has the widest allowable tolerance as its value depends on the plate current. A reading of 15-50 Ma is reasonable. Also, if the final is loaded below 500 watts, the screen grid current will be considerably higher.

Tune-up procedure for VFO operation varies somewhat from crystal operation tune-up. Proper procedure is as follows:

a. Place all power and control switches in the OFF position. Place the power supply EXCITER switch to VFO OPERATE.

b. Insert AC line cord plug into a 110-115 volt, 60 cycle, single phase current source.

c. Connect antenna feed line to coax connector marked ANT. (Rear of RF chassis).

f. Feed a steady tone into the audio input of the SB exciter, in the range of 1,000 to 1,500 cycles. An audio signal generator is excellent for this purpose. Should no generator be available, the operator may whistle into the microphone, holding the tone as steady as possible. Final amplifier grid current should NOT exceed 3 Ma. (A grid current of about 1 Ma on PEAKS is excellent).

g. The final plate current swing for full input should not exceed 260 Ma PEAK. The resting current will be approximately 50-80 Ma. In SB operation, the power amplifier grid and plate current swings are entirely controlled by the amount of excitation from the SB exciter. Heat dissipation at the resting current of 50-80 Ma on the final plate will be evidenced by a slight color on the plate of the tube, however, this will disappear under modulation.

h. Settings of the tuning controls will hold over a slight frequency shift. For large frequency excursions, the transmitter should be retuned.

The best way to tune any SB amplifier for maximum efficiency is to use a RF current indicating device in the antenna system, along with a scope to monitor linearity. Using the two tone test, adjust drive to the final for about 1 Ma. Load the final for maximum RF output, as indicated by the RF indicator so long as the wave-shape stays linear.

For emergency shut-off, place filament switch (power supply panel) in OFF position. This action removes all voltages.

OSC. PLATE	BUFFER PLATE	P.A. GRID	P.A. SCREEN	P.A. PLATE
15-25 Ma	40 Ma	11 Ma	15-50 Ma	300 Ma
SB Operation
		PEAK 1-3 Ma	0-30 MA PEAK	50-260 Ma PEAK

The Globe King 500-C uses a PI-NET final tank circuit which has the capability of matching a considerable range of non-reactive load impedances. As the reactive component increases in the antenna and feed line, the range of match possible is reduced, as the PI-NET has to compensate with an opposite reactive component, thereby, reducing its capability to match higher impedances. In some cases where the reactive load may be large enough, as compared to the resistive load, the matching range may be reduced to as little as 50-100 ohms. It is to the operator’s advantage to correctly measure the impedance at the transmitter end of the feed line and to correct a large reactance at the antenna, rather than trying to tune it out with the PI-NET. Many low power transmitters have a greater capability to tune out reactance from an antenna system than is possible with the 500-C. This is due to the fact that components in the average low power transmitter can have a high capacity, etc., and still have only a very low power rating. These same components will stand a very high power loss without failure in most cases. In a 500 watt transmitter, these components are impractical as they become too large physically, so the compromise consists of not being able to handle as large a reactive load. The capability of handling a LARGE RESISTIVE LOAD is, however, still present in the 500-C transmitter. There are numerous antenna configurations that will give excellent all band results, however, in nearly all cases the impedance presented to the transmitter on one or more bands will not be within the capabilities of the PI-NET, and an antenna tuner will be required. The simple DIPOLE or FOLDED DIPOLE will most likely be easiest to match. While the free space impedance of the dipole, at the center, is approximately 72 ohms, this may vary from 10-600 ohms, depending on height above ground and surrounding objects.

PRELIMINARY

a. Disconnect all cables from the rear apron of the power supply section and remove this section of the transmitter from the cabinet.

b. Place all power and control switches in the OFF position.

c. Insert the AC line cord plug into a 110-115 volt, 60 cycles, single phase current source.

d. Place the power supply section EXCITER switch to the VFO OPERATE position.

e. Place the power supply FILAMENT switch to the ON position and allow a ten-minute warm-up period.

f. Elevate the power supply section chassis to provide convenient access to the VFO slugs and trimmers located on the bottom side of the chassis. It is very important that the power supply section and the VFO remain in their normal operating position or else the compensating capacitors will not function properly and calibration may be off as much as 5-10 KC.

ALIGNMENT PROCEDURE

a. Place the EXCITER switch to the VFO TUNE position.

b. Place the VFO BANDSWITCH to the 160-80 M position.

c. Tune your receiver (using a 100 KC crystal calibrator) to 1800 KC.

d. Tune the VFO dial to 1800 KC.

e. Adjust the slug-in coil L-8 for zero beat with the receiver.

f. Tune the VFO and receiver to 2.0 MC.

g. Adjust trimmer condenser C-68 for zero beat with the receiver.

h. Repeat steps c, d, e, f and g as many times as necessary until the 1800 KC and 2.0 MC points on the VFO dial correspond with these same points on the receiver.

i. Place the VFO BANDSWITCH to the 40-10 M position.

j. Tune the VFO and the receiver to 7.0 MC.

k. Adjust the slug-in coil L-7 for zero beat with the receiver.

l. Tune the VFO and receiver to 7.4 MC.

m. Adjust trimmer condenser C-62 for zero beat with the receiver.

n. Repeat steps j, k, l and m as many times as necessary to make the VFO track with the receiver.

o. Place the VFO BANDSWITCH to the 20-15-11 M position.

p. Tune the receiver to 7.1 MC and the VFO to 14.2 MC.

q. Adjust trimmer condenser C-61 for zero beat with the receiver.

PEAKING THE VFO OUTPUT COILS

The VFO alignment is now completed. The VFO output coils should now be peaked for maximum drive to the crystal stage of the transmitter. Proceed as follows:

a. Place all switches on the power supply section to the OFF position.

b. Place the power supply section as close as possible to the RF section of the transmitter.

c. Insert the VFO output cable into power and RF section sockets labeled VFO. They are located on the rear apron of each of the two chassis.

d. Insert the 6-prong power plug from the power supply section into the socket on the RF section labeled POWER.

e. Place the power supply section FILAMENT switch to the ON position.

f. Place the EXCITER switch to the VFO TUNE position.

g. Place the VFO BANDSWITCH and the RF section EXCITER BANDSWITCH to the 80 M position, the frequency to approximately 3.8 MC.

h. Adjust the slug of coil L-10 for maximum drive to the oscillator stage of the transmitter as determined by the maximum amount of oscillator plate current dip.

i. Place the VFO BANDSWITCH and the RF section EXCITER BANDSWITCH to the 15 M position, the frequency to approximately 21.3 MC.

j. Adjust the slug of coil L-9 for maximum drive to the oscillator stage as in step h.

VFO alignment and peaking is now completed and the transmitter may be reassembled for normal operation.

CONDITIONS: Typical voltage readings Globe King 500-C. 80M band-VFO control-115V AC line-72 ohm dummy antenna 20,000 ohm/volt meter.

Tube Type	Function	Pin 1	Pin 2	Pin 3	Pin 4	Pin 5	Pin 6	Pin 7	Pin 8	Plate Cap.
6AG7	Xtal Oscillator	0	0	0	Minus 5V	0	Plus 140V	6.3VAC	Plus 330V
6146	Buffer/Doubler	0	0	130V	0	Minus 50V	0	6.3VAC	0	Plus 480V
6156	Final	5VAC to Pin 5	Plus 400V	Minus 120V AM / Minus 65V SB	Plus 400V	5V AC to Pin 1	NC	NC	NC	Plus 1800V
6X5	Bias Rectifier	0	6.3VAC	Minus 140	0	Minus 140	190 VAC	0	190VAC
5Y3	Final Screen Rectifier	0	Plus 430V	0	360 VAC	0	360 VAC	0	5VAC to Pin 2
6SJ7	Mic. Amplifier	0	0	Plus 1V	0	Plus 1V	Plus 25V	6.3VAC	Plus 45V
6C5	Speech Amplifier	0	0	Plus 1.5V	0	Plus 140V	0	6.3VAC	0
6L6G	Mod. Driver	0	0	Plus 410V	Plus 325V	0	Plus 420V	6.3VAC	Plus 27V
811A	Modulator	6.3VAC to Pin 4	0	0	6.3VAC to Pin 1	NC	NC	NC	NC
5Y3	Mod. Speech Rectifier	0	Plus 410V plus 500V	0	390 VAC	0	390 VAC	NC	5VAC to Pin 1
816’s	Mod. Rectifier	Plus 1000V / 1300V	0	0	2.5 VAC to Pin 1	NC	NC	NC	NC	Plate 1150 VAC
6AL5	Comp. Rectifier	Minus .5V	Minus .5V	6.3VAC	0	0	Minus .3V	Minus .3V	NC
5U4G	RF Exciter Rectifier	0	Plus 520V	0	580 VAC	0	580 VAC	0	5VAC to Pin 1
866A’s	Final Rectifier	Plus 1800V / Plus 2500V	0	0	2.5VAC to Pin 1	NC	NC	NC	NC	Plate 2000VAC
6CB6	VFO Buffer	Minus 4V	Plus 1.5V	6.3VAC	0	Plus 185V	Plus 185V	0	NC
6AU6	VFO Oscillator	Minus 13V	0	0	6.3VAC	Plus 185V	Plus 150V	Plus .5V	NC
OA2	VFO Regulator	Plus 150V	0	0	0	Plus 150V	0	0	0

Notes:

* RF Choke in series with positive volt meter lead

1. Key open.

2. Key closed.

3. 100% modulation.

4. 0% modulation.

Symptom	Probable Cause
1. Main fuse blows when filament switch turned on.	1-1. Shorted capacitor C-55 or C-56. 1-2. Internally shorting tube or tubes.
2. Main fuse blows when high B plus turned on.	2-1. Shielding on M-2 or M-3 shorting to ground at meter connections. 2-2. Internally shorting tubes. 2-3. Insulators ST-1, ST-2, ST-3 or ST-4 punctured and shorting. 2-4. Shorted capacitors C-27, C-60 or C-53.
3. Buzzing relay or relays.	3-1. AC line voltage too low or too high. 3-2. Filings between armature and core of noisy relay.
4. No modulation.	4-1. Open coil on RLY-4. 4-2. Bad speech or modulator tubes.
5. Rough VFO note.	5-1. Weak 6AU6 tube. 5-2. Gassy 6CB6 tube.
6. Final screen current excessive or insufficient.	6-1. Weak 6156 tube. 6-2. Improper antenna loading. 6-3. Insufficient grid drive to final.
7. Exciter B plus goes on when filament switch turned on.	7-1. Shorted capacitor C-55 or C-56.
8. Excessive final plate current swing when modulating.	8-1. Excessive antenna reactance causing poor loading. 8-2. Capacity of the house wiring being exceeded. 8-3. FUNCTION switch on CW instead of PHONE position.
9. Push-to-talk provision inoperative.	9-1. RLY-3 requires adjustment or replacement. 9-2. Shorted capacitor C-40. 9-3. Defective rectifier SR-1.
10. Inoperative VFO.	10-1. Defective rectifier SR2 or SR3. 10-2. Defective 6AU6 or 6CB6 tube.