R.V.R. Elettronica TEX20-NV User manual

Manufactured by R.V.R. Elettronica - Italy
TECHNICAL AND MAINTENANCE MANUAL
TEX20-NV

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 2
TEX20-
NV 20W FM EXCITER 87.5-
108 MHz RANGE
Technical and Maintenance Manual

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 3
INDEX
Preliminary Instructions and Warranty Information Pag. 5
Safety Regulations Pag. 7
CHAPTER 1
General Description Pag. 10
Technical Specifications (Table A) Pag. 12
Dimensional & Environmental Specifications (Table B) Pag. 15
CHAPTER 2
Electrical Description Pag. 16
"Europa" Version Front Panel Description Pag. 19
"Europa" Front Panel View (Fig.1A) Pag. 20
"USA" Version Front Panel Description Pag. 21
"USA" Version Front Panel View (Fig.1B) Pag. 22
"Europa" Version Rear Panel Description Pag. 23
"Europa" Version Rear Panel View (Fig.2A) Pag. 24
"USA" Version Rear Panel Description Pag. 25
"USA" Version Rear Panel View (Fig.2B) Pag. 27
"Europa" Version Top View Description Pag. 28
"Europa" Version Top View (Photo 1) Pag. 29
"USA" Version Top View Description Pag. 30
"USA" Version Top View (Photo 2) Pag. 31
Block Diagram (Fig.3) Pag. 32
Recommended Test Equipment (Table C) Pag. 33
CHAPTER 3
Installation Procedures Pag. 34
CHAPTER 4
Maintenance Pag. 40

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 4
CHAPTER 5
Calibration Procedures Pag. 41
APPENDIX A
Circuit Diagrams, Layouts and Bill of Material Pag. 47
Wiring Diagram Pag. 48
Main Card Pag. 51
Power Supply Pag. 64
CON-PA Card Pag. 69
R.F. Power Amplifier Pag. 73
Frequency Selector Card (Mod. TSW-1) Pag. 78
Frequency Selector Card (Mod. TSW-3) Pag. 82
USA Audio Input Card Pag. 86
Euro Audio Input Card Pag. 90
Clipper Card Pag. 94
TCXO Card Pag. 98

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 5
PRELIMINARY INSTRUCTIONS
AND WARRANTY INFORMATION
WARNING: This is a "CLASS A" equipment. In a residential place this equipment
can cause hash. In this case can be requested to user to take the necessary
measures.
Please observe safety precautions when handling this unit. This equipment
contains dangerous currents and high voltages.
This manual is written as a general guide for those having previous knowledge
and experience with this kind of equipment. It is not intended to contain a
complete statement of all safety warnings which should be observed by personnel
in using this or other electronic equipment.
R.V.R. doesn’t assume responsibility for injury or damage resulting from
improper procedures or practices by untrained/unqualified personnel in the
handling of this unit.
Please observe all local codes and fire protection standards in the operations
of this unit.
CAUTION: always disconnect power before opening covers or removing any
part of this unit. Use appropriate grounding procedures to
short out capacitors and high voltage points before servicing.
Any damage to the goods must be reported to the carrier in writing on the
shipment receipt.
Any discrepancy or damage discovered subsequent to delivery, shall be reported
to R.V.R. within five (5) days from its receipt.
R.V.R. extends to the original end-user purchaser all original manufacturers
warranties which are transferable and all claims are to be made directly to
R.V.R. per indicated procedures.
All manufacturers warranties will be supported by R.V.R. to ensure precise
and speedy service where possible.
R.V.R. shall not be liable for any damage of whatsoever nature, arising out
of or in connection with the product or its use thereof.
R.V.R.'s warranty shall not include:
1) Re-shipment of the unit to R.V.R. for repair purposes
2) Any unauthorized repair/modification
3) Incidental/consequential damages as a result of any defect
4) Nominal non-incidental defects
5) Re-shipment costs or insurance of the unit or replacement
units/parts
Warranty shall come into force from invoice date and for the period of the
manufactures warranty.

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 6
The warranty for a period of 12 months is referred to any R.V.R.
product, while for products as Transistors, Mos-Fet and Tubes of the
final stages is applied the manufacture's warranty of these devices.
To claim your rights under this warranty:
a. Contact the dealer or distributor where you purchased the unit.
Describe the problem and ask if he has an easy solution. Dealers
and Distributors are supplied with all the information about prob-
lems that may occur and usually they can repair the unit quicker
than what the manufacturer could do. Very often installing errors
are discovered by dealers.
b. If your dealer cannot help you, contact R.V.R. in Bologna and explain
the problem. If it is decided to return the unit to the factory,
R.V.R. will mail you a regular authorization with all the necessary
instructions to send back the goods.
c. When you receive the authorization, you can return the unit. Pack
it carefully for the shipment, preferably using the original packing
and seal the package perfectly. The customer always assumes the
risks of loss (i.e., R.V.R. is never responsible for damage or loss),
until the package reaches R.V.R. premises. For this reason, we sug-
gest you to insure the goods for the whole value. Shipment must be
effected C.I.F. (PREPAID) to the address specified by R.V.R.’s ser-
vice manager on the authorization.
DO NOT RETURN UNITS WITHOUT OUR AUTHORIZATION AS THEY WILL BE
REFUSED.
Be sure to enclose a written technical report where mention all the problems
found and a copy of your original invoice establishing the starting date of
the warranty.
Replacement and warranty parts may be order from the following address. Be
sure to include the equipment model and serial number as well as part
description and part number.
R.V.R. Elettronica S.r.l. -
Broadcasting Equipment -
Via del Fonditore, 2/2c
40138 Bologna - Italy
Telephone [phone]
Fax [phone]
R.V.R. reserves the right to modify the design and specifications of the
equipment in this manual without previous notice.

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 7
WARNING!
The currents and voltages in this equipment are dangerous!
Personnel must at all times observe safety regulation!
This manual is intended as a general guide for trained and qualified personnel
who are aware of the dangers inherent in handling potentially hazardous
electrical and electronic circuits.
It is not intended to contain a complete statement of all safety precautions
which should be observed by personnel in using this or other electronic
equipment.
The installation, operation, maintenance and service of this equipment
involves risks both to personnel and equipment, and must be performed only
by qualified personnel exercising due care.
R.V.R. ELETTRONICA S.r.l. shall not be responsible for injury or damage
resulting from improper procedures or from the use of improperly trained or
inexperienced personnel performing such tasks.
During installation and operation of this equipment, local building codes and
fire protection standards must be observed.
WARNING!
Always disconnect power before opening covers,
doors, enclosures, gates, panels or shields.
Always use grounding sticks and short out high
voltage points before servicing. Never make
internal adjustments, perform maintenance or
service when alone or when fatigued.
Do not remove, short-circuit or tamper with interlock switches on access
covers, doors, enclosures, gates, panels or shields.
Keep away from live circuits, know your equipment and don’t take chances.
WARNING!
In case of emergency ensure that power has been disconnected

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 8
Treatment of electrical Shock
1) If victim is not responsive follow the A-B-C's of basic life support.
PLACE VICTIM FLAT ON HIS BACK ON A HARD SURFACE
A AIRWAY B BREATHING
IF UNCONSCIOUS, IF NOT BREATHING,
OPEN AIRWAY BEGIN ARTIFICIAL
BREATHING.
LIFT UP NECK, TILT HEAD,
PUSH FOREHEAD BACK, PINCH NOSTRILS,
CLEAR OUT MOUTH IF NECESSARY, MAKE AIRTIGHT SEAL,
OBSERVE FOR BREATHING 4 QUICK FULL BREATHS.
REMEMBER MOUTH TO MOUTH
RESUSCITATION MUST BE
COMMENCED AS SOON AS
POSSIBLE.
C CIRCULATION
CHECK CAROTID PULSE DEPRESS STERNUM 1 1/2" TO 2"
IF PULSE ABSENT, APPROX. 80 SEC. : ONE RESCUER, 15 COMPRESSIONS,
BEGIN ARTIFICIAL 2 QUICK BREATHS.
CIRCULATION APPROX. 60 SEC. : TWO RESCUERS, 5 COMPRESSIONS,
1 BREATH
NOTE: DO NOT INTERRUPT RHYTHM OF COMPRES-
SIONS WHEN SECOND PERSON IS GIVING BREATH.
Call for medical assistance as soon as possible.
2) If victim is responsive:
a. Keep them warm.
b. Keep them as quiet as possible.
c. Loosen their clothing (a reclining position is recommended).

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 9
FIRST-AID
Personnel engaged in the installation, operation,
maintenance or servicing of this equipment are urged
to become familiar with first-aid theory and practices.
The following information is not intended to be a
complete first-aid procedure, it is brief and is only
to be used as a reference. It is the duty of all
personnel using the equipment to be prepared to give
adequate Emergency First Aid and thereby prevent
avoidable loss of life.
Treatment of electrical Burns
1) Extensive burned and broken skin.
a. Cover area with clean sheet or cloth.
(Cleansed available cloth article).
b. Do not break blisters, remove tissue, remove adhered particles of
clothing, or apply any salve or ointment.
c. Treat victim for shock as required.
d. Arrange transportation to a hospital as quickly as possible
e. If arms or legs are affected keep them elevated.
NOTE
If medical help will not be available within an hour and the victim is conscious
and not vomiting, give him a weak solution of salt and soda: 1 level teaspoonful
of salt and 1/2 level teaspoonful of baking soda to each quart of water (neither
hot or cold).
Allow victim to sip slowly about 4 ounces (half a glass) over a period of 15
minutes.
Discontinue fluid if vomiting occurs (Do not give alcohol).
2) Less severe burns - (1st & 2nd degree)
a. Apply cool (not ice cold) compresses using the cleansed available
cloth article.
b. Do not break blisters, remove tissue, remove adhered
particles of clothing, or apply salve or ointment.
c. Apply clean dry dressing if necessary.
d. Treat victim for shock as required.
e. Arrange transportation to a hospital as quickly as possible.
f. If arms or legs are affected keep them elevated.

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 10
CHAPTER 1
DESCRIPTION OF THE TEX20-
N.V.
1.1 GENERAL DESCRIPTION
The TEX20-N.V. is housed in a 2U, 19" rack-mounting container comprising
a number of interconnected modules mounted internally on the bottom of the
equipment, facilitating removal and substitution.
On the front panel there are: the power output control PWR ADJ, the PWR/DEV
selector to select the power or deviation measuring on the analog meter, the
switch on selector with its relative led and the analog meter for the measuring
of main operating parameters.
For EUROPA version there are two BNC connectors too, one for MONO input and
other for MPX input.
On the rear panel there are: the BNC connector for mains voltage input, the
R.F. TEST -30dB BNC connector, the INTERLOCK BNC connector to block R.F. power
output from external equipment, the R.F. Output N-type connector, and only
for USA version, a EXT. REF. 1KHz BNC connector and audio inputs BNC connectors.
1.2 ELECTRICAL DESCRIPTION
The TEX20-N.V. is an exciter working in the 87.5 to 108 MHz band,
programmable in steps of 10 KHz. Its power output is continuously adjustable
from 2 to 20W into a 50 Ohm load.
It also accepts three SCA signals through the connectors placed on the rear
panel (only for USA version).
The specification features low audio distortion and intermodulation figures
(typ. 0.05%) and a high signal-to-noise ratio (typ. -72 dB).
A voltage selector on the transformer primary allows a variety of supply
voltages to be used.
1.3 METERS AND INDICATORS
The operating parameters of the exciter can be monitored using the analog
multimeter (1 Fig.1A EUROPA ver. and 1 Fig.1B USA ver.) situated on the front
panel.
The parameter to be measured is selected by the selector
(10-11 Fig.1A and 3-5 Fig.1B).
The frequency control (8 Fig.1A and 6 Fig.1B) allows frequencies to be selected
in steps of 10 KHz.
Two red alarm leds indicate VCO unlock (12 Fig.1A and 7 Fig.1B) and the mains
voltage line presence (13 Fig.1A and 9 Fig.1B).
Three green leds indicate the presence of +12V, +15V and +20V (2 Fig.1A
and 1B) voltages which are used to power the various cards inside the exciter.
There are a trimmer (7 Fig.1A and 4 Fig.1B) too that allows to choose the level

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 11
of the output power level and the switch ON selector (9 Fig.1A e 8 Fig.1B).
1.4 AUTOMATIC FREQUENCY CONTROL
The operating frequency is governed by a thermally-compensated, reference
oscillator working within a phase-locked loop (PLL).
The TEX20-N.V. reaches frequency lock within a maximum of 30 seconds.
1.5 CONTROL CIRCUITS
The control circuits allow automatic control of output power, maintaining
the chosen power level across the entire operating band. Furthermore another
circuit protects the final stage against excessive VSWR or short circuits.
1.6 RF AMPLIFIER
The RF amplifier is a wide-band design and guarantees an adjustable power
output of 2 to 20 watts across the entire band.
A low-pass filter enables the TEX20-N.V. to be used as a low power transmitter,
connected directly to an antenna.
1.7 SPECIFICATIONS
Please refer to Table A for the electrical specifications and
Table B for the mechanical specifications.

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 12
TABLE A
ELECTRICAL SPECIFICATIONS
Power Supply 110-130V ±10%, 50-60Hz
198-250V ±10%, 50-60Hz
Power Consumption approx. 130 W
Cooling Forced Ventilation
Frequencies from 87.5 to 108 MHz in steps of
10 KHz, microprocessor-controlled
Output power adjustable from 2 to 20 W cont.
Output impedance 50 Ohm
Output Connector N-type standard
Harmonic suppression > -65dB
Spurious Signal Suppression > -80dB
Frequency stability ±500Hz (typ. ±300Hz) from 0° to
50°C
Modulation type Direct frequency modulation of the
RF oscillator at fundamental freq.
Frequency deviation ±75KHz nominal
Harmonic distortion < 0.10% (typically 0.05%)
Residual AM (asynchronous) approx. 0.05% = 65 dB RMS
Residual AM (synchronous) 0.1% = 55 dB
Pre-emphasis 50µs ±2% or 75µs ±2% selectable
Composite Operations
Composite Inputs 4 total, 1 for MPX and 3 for SCA
for USA version

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 13
1 for MPX for EUROPA version
MPX Input BNC connector, balanced
MPX Input Impedance 10 KOhm
MPX Input Level 0dBm (775mVrms / 2,2Vpp) for
±75KHz of adjustable deviation
Composite FM S/N Ratio > 75dB measured with ±75KHz
deviation at 400Hz in a 30Hz to
15KHz band RMS.
Composite Intermodulation Distortion 0.1% or less (typ.0,05%), measured
at 1KHz and 1.3 KHz, ratio 1:1 at
100% modulation
Composite Frequency Response ± 0.5dB from 30Hz to 100KHz
Stereo Separation > 50 dB
Crosstalk better than 55dB (typ. 60 dB)
SCA Inputs 3 BNC Connectors, unbalanced only
for USA version
SCA Input Impedance 10 KOhm
SCA Input Level 0dBm (775mVrms / 2,2Vpp) for
±75KHz of adjustable deviation
SCA Frequency Response ± 0.5dB from 40KHz to 100KHz
Crosstalk 67KHz, 65dB
92KHz, 70dB
Mono Operations
Mono Input Impedance 600 Ohm balanced for USA vers.
1 KOhm unbalanced for EUROPA vers.
Mono Input Level 0dBm (775mVrms / 2,2Vpp) for
±75KHz of adjustable deviation
Mono FM S/N Ratio > 75dB measured with ± 75KHz

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 14
deviation at 400Hz in a 30Hz-20KHz
band RMS.
Mono Frequency Response ± 0.5 dB from 30 Hz to 15 KHz
Mono Intermodulation Distortion 0.1% or less (typ.0,05%), measured
at 1KHz and 1.3 KHz, ratio 1:1 at
100% modulation

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 15
TABELLA B
DIMENSIONAL AND ENVIRONMENTAL SPECIFICATIONS
Cabinet dimensions 483mm (19") W
83mm (3,26") H
327mm (13,7") D
Panel Dimensions 483mm (19") W
88mm (3.46") H
Operating temperature -10°C to 50°C
Humidity 95% max. non-condensing
Weight 15 1/2 Lbs (7 Kg)

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 16
CHAPTER 2
ELECTRICAL DESCRIPTION
2.1 INTRODUCTION
This section describes, in detail, the operating theory behind the TEX20-
N.V..
To aid understanding, the unit has been subdivided into blocks, each of which
is fully described below.
A Block Diagram is shown in Fig.3.
2.2 POWER SUPPLY
This circuit comprises a board, mounted on a heat sink, which is fixed
to the central part on the bottom of the unit (5 Foto 1-2).
The power supply generates the various stabilized voltages necessary for each
of the various modules that make up the TEX20-N.V..
After having undergone filtering for mains-borne interference, the supply is
transformed into lower voltages, rectified, smoothed and stabilized to the
following values: +12V, +15V and 2 to 24V variable (+20V upstream of the voltage
control stage).
The +15V supplies the EURO Audio Input card and the contraves card. The +12V
supplies the RF power amplifier driver and the 2-24V variable supplies the
final power stage of the same module.
The variable voltage of the final stage is controlled by the PWR ADJ control
which determines the RF power output of the exciter.
The automatic control of output power guarantees the power level set by the
PWR ADJ control right across the frequency range and independently of other
variables such as temperature, load variations etc.
The system works by comparing the value set by the PWR ADJ control with the
actual power output of the unit and compensating accordingly.
A power limiting circuit intervenes in the event of excess SWR on the output,
thus protecting the final stage.
2.3 EURO AUDIO INPUT CARD
This card (2 Foto 1-2) is situated on the front panel of the exciter.
This card, only for EUROPA version, filters all audio signal inputs to the
unit, removing R.F. interference, before supplying them to the main card.
This card works too as measures card allowing the measuring of forward and
reflected power or deviation.
2.4 MAIN CARD
The main card is situated internally, on left of the unit’s bottom (1 Foto
1-2).
The circuit includes a voltage-controlled oscillator (VCO) which generates

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 17
the selected operating frequency.
This signal is amplified to drive the phase-locked loop (PLL) control circuit
and also the final stage.
The audio signal supplied by the Euro Audio Input card (for the EUROPA version)
or from USA Audio Input card (for USA version), is amplified and processed
in order to compensate for distortion caused by the varicap diodes; it is then
injected into the VCO to provide modulation.
The operating frequency generated by the VCO is divided down before being
compared to a reference frequency, generated by a high stability oscillator
(standard 5 ppm). The error voltage is filtered and used to compensate the
VCO frequency and guarantees its stability.
An indicator (situated on the front panel signals the "unlocked" condition.
Three trimmers are present on this card for adjustment of deviation, distortion
and pre-polarization of the varicaps.
2.5 R.F. POWER AMPLIFIER
The final power stage is mounted on a heat sink to dissipate waste heat
and is enclosed in a totally screened, metal container, fixed to the middle
part of the unit’s bottom (6 Foto 1-2).
The R.F. signal coming from the Main card at a power level of about 150-200
mW, reaches the driver stage (MRF237 in Class C) and is amplified to a level
of about 2W before being further amplified by the final stage (BLW86) to a
level of upto 20W.
The resultant signal is then filtered by a low-pass filter which removes any
harmonic content.
A directional coupler allows the direct and reflected power levels to be
measured and displayed on the analog multimeter and also feedback to the power
supply for automatic control of the output power (see Power Supply sec. 2.2).
A BNC connector situated on the rear panel provides a power signal at -30dB
of the amplifier output power.
2.6 FREQUENCY SELECTOR CARD (CONTRAVES)
This card (3 Foto 1-2) is fixed to the left-hand side of the front panel.
The operating frequency selected by the frequency control is represented by
a signal which is supplied to the frequency dividers that form part of the
PLL circuits found on the Main card.
2.7 USA AUDIO INPUT CARD (only for USA version)
This card is situated on the left part of the rear panel of the exciter
(7 Foto 1-2).
This card, only for USA version, filters all audio signals that input to the
unit, removing RF interference, before supplying them to the main card.
In addition to three SCA input connectors and MPX input connector, there is
a 10 poles socket that .

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 18
"EUROPA"VERSIONFRONTPANELDESCRIPTION(FIG.1A)
1 METER Analog meter used to display the

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 19
following operating parameters of the
exciter: Direct and Reflected power, and
Deviation
2 VOLTAGES Led indicators that indicate the
presence of the +20V, +15V and +12V
3 MONO LEVEL Trimmer for the adjustment of MONO input
level
4 MONO INPUT MONO input connector, BNC type
5 STEREO (MPX) LEVEL Trimmer for the adjustment of MPX input
level
6 STEREO (MPX) INPUT MPX input connector, BNC type
7 PWR ADJ Trimmer to regulate the power output of
the exciter. AGC maintains the level set
by this control
8 MHz/KHz Rotary frequency selector
9 POWER ON/OFF Power switch
10 PWR/DEV The measurement made by the meter
corresponds to the position of this
selector: POWER or DEVIATION
11 FWD/RFL The measurement of the FORWARD or
REFLECTED power are selected from the
correspondent position of this selector
12 L.O. UNLOCK Indicates that the VCO is not locked to
the reference frequency. The output
power will drop to zero in this
condition
13 LED ON Led indicator that indicates the
presence of the mains voltage
"USA"VERSIONFRONTPANELDESCRIPTION(FIG.1B)
1 METER Analog meter used to display the

TEX20-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 20
FIG. 1A