PHILIPS 8FZ 513

GENERAL DESCRIPTION

25 kW AM SHORT-WAVE TRANSMITTER TYPE 8FZ 513 continuous tuning

General

In short-wave broadcasting stations a need frequently exists for a powerful transmitter which can be tuned rapidly to any frequency in the 2.3-26.1 Mc/s band. This modern 25 kW air-cooled transmitter fills the bill and does so economically.

Description

The transmitter consists of 4 cabinets housing: the driver stage — the output stage — the modulator — the power supply unit. The driver comprises a crystal-controlled exciter unit, while a special continuously tunable exciter unit is also available as an optional extra. With either of these exciters the transmitter fully meets international requirements as to frequency stability. If the tuning tables supplied are used, the transmitter can be fully tuned by hand to any desired frequency inside four minutes.

All the modulator stages are connected in push-pull, which, together with the negative feedback employed, ensures excellent modulation characteristics.

The power supply unit comprises only 3 rectifiers, so that a simple and effective protection system is possible. This system also includes a quick-trip circuit which switches off the HT for several seconds in the event of faults or disturbances of short duration. The system simultaneously ensures great reliability and renders operation extremely simple.

Modern air-cooled transmitting tubes give great electrical efficiency. This combination of excellent characteristics results in low running and maintenance costs.

Mechanical design

The four cabinets have doors which, in the case of the modulator and drive unit, conceal pull-out panels. Separate HT components such as mains and modulation transformers, etc. are arranged behind the transmitter or, if desired, in another room. In either case they can be placed in an enclosure composed of dummy panels harmonizing with the transmitter.

There are three separate fans for cooling the driver stage, the modulator and the output stage. The cooling air is filtered at the intake and the exhaust air can, if desired, be taken to an outlet outside the building.

Logical lay-out of components and sufficient doors make for a high degree of serviceability. All necessary precautions have been taken against HT hazards. The cooling system and the carefully chosen components make the transmitter suitable for the tropics.

Detailed manuals give full instructions as to installation, operation and maintenance of the transmitter. Installation is very simple and no special tools or highly skilled labour are necessary.

Transmitter name-plates and instruction manuals are normally supplied in English. Other languages (e.g. Spanish) are available on request.

TECHNICAL SPECIFICATIONS
Frequency range	2.3-26.1 Mc/s, continuously tunable
Frequency selection	one of up to ten crystal-controlled frequencies
Frequency tolerance	±20.10^-6 (2.3-4 Mc/s); ±15.10^-6 (4-26.1 Mc/s)
Power output	25 kW (carrier)
Output impedance	600 ohms balanced
Standing wave ratio	max. 1.4:1
Spurious radiation	as per CCIR recommendations
AF input impedance	approx. 600 ohms balanced
AF input level	adjustable between +5 and 0 dBm for 100% modulation in 10 steps of 0.5 dB, ref. 1000 c/s; 0 dBm = 1 mW into 600 ohms
Linear distortion	within ±1 dB from 30-10,000 c/s, reference 1000 c/s at 60% modulation
Non-linear distortion	less than 3% from 50-10,000 c/s at 90% modulation
Noise level	-60 dB unweighted; reference 1000 c/s at 100% modulation
Modulation capability	100%
Power supply	3 x 380 V ±5%, 50 or 60 c/s ±5%, four-wire mains (adaptation to other voltages by means of an optional separate auto-transformer)
Power consumption	at 0% modulation approx. 50 kW at 30% modulation approx. 56 kW at 100% modulation approx. 80 kW
Power factor	approx. 0.81
Ambient temperature	at sea level: +10° to +45° C under tropical conditions; at 6000 ft: +10° to 35° C
Relative humidity	up to 95%
Dimensions	driver + modulator: height 212 cm (84 in.); width 142 cm (56 in.); depth 90 cm (36 in.); final stage: height 212 cm (84 in.); width 102 cm (40 in.); depth 90 cm (36 in.); power supply: height 212 cm (84 in.); width 102 cm (40 in.); depth 90 cm (36 in.)
Minimum floorspace	450 x 420 cm (15 x 14 ft)
Weight	approx. 8000 kg (17,600 lb.) unpacked

TUBE COMPLEMENT
RF stages		AF stages and modulator		Rectifiers
Number	Type	Number	Type	Number	Type
4	TBL7/8000 (6961)	4	TBL7/8000 (6961)	6	DCG5/5000GB (872A)
2	QBL5/3500 (6076)	6	QE08/200	3	DCG7/100
3	QQE06/40 (5894)	4	QE06/50 (807)
1	OA2
4	E80L (6227)

THIS TYPE OF TRANSMITTER IS INSTALLED IN THE FOLLOWING COUNTRIES
	ITU	Country	ITU	Country
	MOZ	MOZAMBIQUE