1. NV Series Transmitters Theory of Operation
The following presentation uses the NV40 as a reference; refer to the last slide of this presentation for an NV Series Transmitter Comparison table which highlights some key differences between the NV40 and other NV transmitters.
This module covers the Theory of Operation. We’ll review how the functional stages of the transmitter work independently and together.

2. NV40 Block Diagram See page 1-9 of Operation & Maintenance Manual
NV40 Shown for Reference
Explain diagram.
See page 1-9 of Operation & Maintenance Manual

3. System Overview Functional Stages
Ac/Dc Power Stage
Converts the ac power source to a positive dc voltage (PA volts) for the
transmitter’s intermediate (IPA) and RF power amplifiers.
Also provides power for:
cooling fans (ac for power supply fans, dc for RF power module fans)
low level dc voltages (±15 V and +5 V) for use throughout the transmitter
+12 V dc power supplies for the SBC (single-board computer) and AUI.
NOTES:
Read information on slide.

4. System Overview Functional Stages
Control/Monitor Stage monitors critical signal samples and
status/alarm signals from the ac-dc power stage, RF drive stage and RF
power stage.
Contains monitoring and protection circuits to prevent transmitter damage.
Provides the remote control/monitor interface for the transmitter.
Provides local transmitter controls via an advanced user interface.
Read information on slide.

5. System Overview Functional Stages
RF Drive Stage converts the exciter's RF output to the intermediate RF level needed to drive the RF power modules.
RF Power Stage accepts the intermediate RF drive inputs from the RF
drive stage and generates the final RF output.
The output power probe (A13) monitors the transmitter's forward and
reflected power and generates the forward and reflected power sample
signals.

6. AC/DC Power Stage The ac-dc power stage comprises:
See SD1-A, SD1-B, SD1-C, SD-2 & SD-3
The ac-dc power stage comprises:
Ac input terminal block TB1, and distribution terminal blocks TB2 and TB3
“Ac Present” Lamps (3)
Ac distribution assembly (2x 3-way)
Power supply distribution PWB
SBC/AUI power supply A and supply B (+12V)
LVPS module A and B (+5V, +/-15V)
Fan supply module A and B (nom. +48V)
IPA power supply modules A, B, & C (3 for NV30/NV40)
Dual PA power supply modules for each of the RF power modules (2 per)
PS interface PWB associated with each power supply module (Fan, IPA & PA).

7. AC/DC Power Stage – AC Entrance
TB2/TB3
TB1
AC Present Lamps
Station Reference Ground

8. AC/DC Power Stage – Power Supply Modules
Power supply modules convert the ac input voltage to a regulated dc
supply (IPA volts and PA volts) to all RF power modules.
Each power supply provides up to 2000 W output, at max levels of 50 V and 40 A.
The modules regulate the output voltage based on a PA (or IPA) Control Voltage input from the control/monitor stage. Control input command is 0-5V.
Test points on the associated PS interface PWB allow monitoring of module
presence and ac input status.
Each module has a built-in cooling fan. PS Fail and PS Temp alarm signals are applied to the associated RF power.
PS Fail and PS Temp alarm signals are applied to the control/monitor stage.

9. AC/DC Power Stage – Power Supply Module
RF Power Module
Power Supplies
Fan PS (A & B)
IPA PS (A & B)
Ac Distribution
Assy (2x 3-way)
AUI/SBC PS (+12V)
LVPS (+5V, +/-15V)

10. AC/DC Power Stage – LVPS Modules
See SD-1
LVPS modules A and B (U1 and U2) convert the ac input voltage to the regulated low voltage dc supplies.
The +5 V, +15 V and -15 V regulated outputs of the LVPS supplies are paralleled (via power supply distribution PWB A7) and applied throughout the transmitter.
The 2x 3-way Ac Distribution assembly (A6) distributes the ac power to the LVPS (A & B), +12V PS (A & B) and exciters (A & B). It offers the advantage of the customer having a convenient location to supply power from an external UPS to those devices.
Read information on slide.

11. AC/DC Power Stage – Power Supply Distribution PWB
The power supply distribution PWB (A7) interfaces between:
fan supply modules U7 and U8
cooling fans for the RF power modules
reject loads
SBC/AUI power supplies U1 and U2
the control/monitor stage
A nominal 48 VDC fan voltage sample and a nominal 12 V sample A (U1) & B (U2) is applied to the control/monitor stage for metering and fault detection.
Read information on slide.

12. Control/Monitor Stage
Explain diagram.

13. Control/Monitor Stage
See SD-4, SD-5 and SD-10 through SD-17 (Control/Interface PWB)
The control/monitor stage monitors critical signal samples and status/alarm signals from the ac-dc power stage, RF drive stage and RF power stage.
It produces the appropriate control signals for the RF power stage to ensure the proper operation and protection of the transmitter.
It provides the remote control/monitor interface for the transmitter.
The control/monitor stage comprises:
a control/interface PWB (A1)
a remote interface PWB (A2)
an LCD touch monitor (U5) and a single-board computer/SBC (U6)
Note: The transmitter will continue working if the user interface or single-board computer fails.
The control/interface PWB contains push-button switches that provide backup control for the RF On/Off, Power Increase/Decrease, Reset and Local/Remote functions. It also has Summary Alarm status LEDs and a Forward Power Meter LED bar.
Read information on slide.

14. Control/Monitor Stage
Remote Interface PWB
Control/Interface PWB

15. Control/Monitor Stage – Remote Interface PWB
See SD-18
The remote interface PWB (A2) (NAPI115) performs the following
functions:
Provides an interface between the remote control/monitor facility and the transmitter.
Provides momentary contact activation switches for each of the 24 digital inputs.
Provides configurable status or alarm indicator LEDs for each of the 24 digital outputs.
Read information on slide.

16. Control/Monitor Stage –
AUI
Features a 17 inch Color LCD touch-screen with a wide range of configurable displays.
The AUI can be controlled by touch-screen, or via a mouse and keyboard.
Features:
Advanced Instrumentation
Configurable meters
- Exciter control
- Linux OS
You must put the tx into remote at the tx.

17. RF Drive Stage See SD-6 and SD-19 (exciter)
The RF drive stage splits the exciter's RF output with the proper phase
and amplitude for the RF power modules.
It consists of exciter A (A3), exciter B (A4, optional) and RF drive splitter/changeover assembly (A5).
The exciters are an integrated design and part of the transmitter. Exciter control is through the transmitter’s AUI.
Exciters A and B (if purchased) are the RF drive sources for the transmitter. They accept the external audio program and/or IBOC information.
The RF drive outputs from exciters A and B are applied to the splitter/changeover PWB (A5A1).
The RF drive stage selects the active exciter via an RF coaxial relay.
Read information on slide.

18. RF Drive Stage NVE300 Block Diagram
NVE300 Shown for Reference (HP)
See page 1-10 of Operation & Maintenance Manual

19. RF Drive Stage – NV Exciter
Two power levels:
NVE50 (50 watts FM)‏
NVE300 (300 watts FM)‏
The NVE exciter is built with the following components:
Digital FM Exciter PWB
Power Amplifier
Power Supplies (+48V/+27V and LVPS)
Exgine (optional, for HD Radio operation)‏
LED PWB (Status and Power)
Fan
Read information on slide.

20. RF Drive Stage – NV Exciter
Rear View
Internal View (Top Cover Removed)

21. RF Drive Stage
The exciters’ main/standby operation is controlled locally using the AUI, or remotely.
The exciter outputs are applied to the RF drive splitter/changeover assembly (A5).
For the NV30 / NV40 the exciter provides an RF drive signal of 130W (in analog mode).
Read information on slide.

22. RF Drive Stage – RF Drive Splitter/Changeover Assembly
The RF drive splitter/changeover assembly (A5) controls the routing of the main and standby exciters and provides the RF drive signals for the 16 RF power modules.
The assembly is comprised of the following:
splitter/changeover PWB (A5A1)
two 4-way RF drive splitter PWBs (A2 and A3)
two attenuator PWBs (A4 and A5)
eight 3 dB hybrid couplers (U1 through U8).

23. RF Drive Stage – RF Drive Splitter/Changeover Assembly
Exciter drive splitter
The RF drive source (A or B) is applied to the ISO port of A5A1U1.
The signal is split into two equal amplitude signals that are 90° out-of-phase, at the 0˚ and -90˚ ports.
These split signals are applied to 4-way RF drive splitter PWB A5A2.
Read information on slide.

24. RF Drive Stage – RF Drive Splitter/Changeover Assembly
4-way RF drive splitter
The 4-way RF drive splitter PWB (A5A2) accepts the signals from A5A1U1 and splits them into four equal amplitude signals.
The outputs of the 4-way RF drive splitter are applied to the final RF drive splitters.
Final RF drive splitters
3 dB hybrid couplers (identical to A5A1U1) are connected as splitters.
Each coupler accepts an output of the 4-way RF drive splitters and splits the signal into two equal amplitude signals that are 90° out-of-phase.
These split signals are applied to attenuator PWB A5A4 and A5A5.
Attenuators
The attenuator PWB’s (A5A4 and A5A5) accepts the outputs from the 4-way RF drive splitter PWB’s and attenuate each of the signals for application to the RF power modules.
Read information on slide.

25. RF Power Stage See SD-7, SD-8 and SD-9
The RF power stage accepts the intermediate RF drive inputs from the RF drive stage and generates the final RF output.
The RF power stage consists of the following components:
16 RF power modules
Four module backplane PWBs (A17, and A32, A50 and A65)
Four 10 kW combiner/filters (A16, and A31, A49 and A64)
Two 20 kW combiners (A30 and A63)
One 40 kW combiner (A48)
Output power probe (A13)
Three reject load assemblies
A (A14, 8-input)
B (A45, 4-input)
C (A46, 4-input)
Two reject load interface PWBs A (A15) and B (A47).
Read information on slide

26. RF Power Stage – RF Power Modules
See SD-21 through SD-26
Each RF power module provides up to 3000 W of RF output power and is comprised of:
one IPA PA PWB (A9)
eight PA PWBs (A1 through A8)
a power module interface PWB (A10)
a module splitter PWB (A11)
a combiner PWB (A12).
Read information on slide.

27. RF Power Module

28. RF Power Stage – RF Power Modules
Cooling air for the module is provided by six internal fans (B1 through B6).
An RF Drive output from the RF drive stage is applied to each RF power module via its power module interface PWB (A10).
Within each RF power module, the RF drive signal is amplified through an IPA (A9) and then split to drive the module's eight PAs (A1 through A8).
The IPA Volts input from the associated power supply modules controls the RF output of the IPA, while the PA Volts A and B inputs from the associated power supply modules controls the RF output of the eight PA’s. Both output voltage levels are controlled by the control/monitor stage.

29. RF Power Stage – RF Power Modules
Protection for the RF Power modules
Alarm signals (PS Temp, PS Fail and PS AC Fail) from the ac-dc power stage are used to inhibit the PA’s.
The power supply is responsible for its own monitoring and protection and inhibits itself when an internal fault is detected. The RF power module only provides a Power Supply Inhibit signal to the ac-dc power stage to inhibit its associated power supplies when the control/monitor stage informs it to do so (e.g. via the PA Volts Inhibit signal for RF Off, Shutback, etc…).
A PA V Sample and IPA V Sample from each RF power module is applied to the control/monitor stage.
Read information on slide.

30. RF Power Stage – RF Power Module Block Diagram
Wilkinson Combiner
3dB combiner
50 ohm reject load

31. RF Power Stage – Power Amplifiers (PA and IPA)
Each power amplifier PWB [IPA (A9) and PA (A1 through A8)]
contains an identical, broadband, push-pull, RF power amplifier (PA).
Each PA provides 375 W (nominal) of RF power in the FM band (87.5 to 108 MHz).
The RF Drive, PA V and Bias voltages are provided by the power module interface PWB (A10).
Read information on slide.

32. RF Power Stage – Power Module Interface PWB
The power module interface PWB (A10) monitors and distributes
the RF drive and the dc supply current to the individual power amplifiers of
the IPA or RF power module.
Main functions are:
Monitoring the current supplied to each PA and cause an alarm condition if a PA stops drawing current.
Providing a low level dc signal, proportional to the intermediate RF drive power, for monitoring.
Providing each PA's dc bias voltage.
Inhibiting the associated switching power supply module when the appropriate transmitter/RF module fault occurs.
Communicating with the control/monitor stage on module specific status and alarm parameters.
Read information on slide.

33. RF Power Stage – Module Splitter PWB
The module splitter PWB (A11) splits and impedance matches the
intermediate RF drive power to each PA.
The RF drive signal is passed through the module splitter PWB to the IPA (A9).
The IPA output is then applied to the combiner PWB (A12), where the RF drive is split into two equal signals.
For each of the signals applied, the module splitter PWB provides four equal amplitude PA drive signals to drive the eight PA’s.
For final combining purposes, half of the PA Drive signals are at 0°
and the other half are at -90°.
The PA outputs are applied to the combiner PWB.
Read information on slide.

34. RF Power Stage – Combiner PWB
The combiner PWB (A12) contains the first stage quadrature splitter for the IPA.
It also combines the PA outputs to provide the final RF output for each RF power module.
The PWB has Wilkinson combiners for the first and second stage of combining. The final stage is a 3dB quadrature combiner that is located off the PWB.
An IPA Pwr Sample is applied to monitoring and protection circuits in the module interface PWB and the control/monitor stage.
Read information on slide.

35. RF Power Stage – Module Backplane PWB
See SD-7
Each set of four RF power modules (1-4, 5-8, 9-12, 13-16) has an associated module backplane PWB which interfaces with all module inputs and outputs, except for the RF output.
It also provides the fan voltage connections for the module's cooling fans.
Read information on slide.

36. RF Power Stage – Combiner/Filters
See SD-8
There are various stages of combiners used in the transmitter.
10 kW combiner/filters
Each 10 kW combiner/filter (A16, A31, A49 and A64) is a 2-stage combiner that accepts the RF outputs from four RF power modules.
Each 10 kW combiner/filter uses three 3 dB hybrid couplers in a corporate/binary structure (Outputs of first stage feed inputs of second stage, and so on).
Read information on slide.
PWR Module Inputs
10kW Combined Output
3dB Couplers

37. RF Power Stage – Combiner/Filters
10 kW combiner/filters continued
The combined RF output is applied through two 10 kW low pass filters before being applied to the 20 kW combiners.
Any amplitude and phase imbalances between the inputs of any 3 dB hybrid coupler causes a proportional signal to be applied to the reject load assemblies.
The amplitude of the 5 kW Rej Ld Pwr signals is representative of imbalance between the combined outputs of the first stage of combining.
The amplitude of the 10 kW Rej Ld Pwr signal is representative of imbalance between the combined outputs of the second stage of combining.
Read information on slide.

38. RF Power Stage – Combiner/Filters
20 kW combiners
The 20 kW combiners (A30 and A63) which are also 3dB hybrid couplers, accept the RF outputs from the two 10 kW combiner/filters.
Any amplitude and phase imbalances between the inputs of the 20 kW combiners causes a proportional signal to be applied (via J1) to the reject load assemblies.
The amplitude of the 20 kW Rej Ld Pwr signal is representative of imbalance between the combiner inputs.
Read information on slide.

39. RF Power Stage – Combiner/Filters
40 kW combiner
The 40 kW combiner (A48) is also a 3dB hybrid coupler which accepts the RF outputs from the 20 kW combiners.
The output is passed through the output power probe.
Any amplitude and phase imbalances between the inputs of the 40 kW combiner causes a proportional signal to be applied (via J1) to the reject load assemblies.
The amplitude of the 40 kW Rej Ld Pwr signal is representative of imbalance between the combiner inputs.

40. = RF Power Module Output
NV40 Combining
40kW
3dB
= 3dB combiner
20kW
20kW
3dB
3dB
= RF Power Module Output
10 kW
10kW
10 kW
10kW
filter
Each level of 3dB combining has an associated reject load assembly.
This is a corporate or binary combining scheme (1 comes from 2, 2 comes from 4, 4 comes from 8, etc…).
10 kW
3dB
10kW Block
X 4
5kw
5kw
3dB
3dB
2500w
2500w
2500 w
2500w

41. RF Power Stage – Reject Load Assembly
See SD-9
Reject load assemblies provide 50 ohm terminations to dissipate reject power from the outputs of the combiner/filter's 3 dB hybrid couplers.
Reject load assemblies contain power resistors to dissipate reject power and cooling fans to regulate temperature.
There are three different reject load assemblies (A, B and C) used in the transmitter:
8-input reject load assembly ‘A’
4-input reject load assembly ‘B’
4-input reject load assembly ‘C’

42. RF Power Stage – Reject Load Assembly
8-input reject load assembly ‘A’
Reject power generated from the 1st level module combining (5kW) is dissipated by resistors in 8-input reject load assembly A14.
4-input reject load assembly ‘B’
Reject power generated from the 2nd level module combining (10kW) is dissipated by resistors in 4-input reject load assembly A45.
4-input reject load assembly ‘C’
Reject power generated from the 3rd level module combining (20kW) and final stage combining (40kW) is dissipated by resistors in 4-input reject load assembly A46.

43. RF Power Stage – Reject Load Assemblies
RF sample voltages from the reject load assemblies that represent the reject power in each specific load are applied to the control/monitor stage via reject load interface PWBs ‘A’ (A15) and ‘B’ (A47), if applicable.
The reject load interface PWB provides an interface between the ac-dc power stage’s Fan Volts supply and the reject load assembly’s cooling fans.
The reject load interface PWB also acts as the interface between the cooling fans’ Rej Fan Tach signals and the control/monitor stage.
Read information on slide.
Debrief:
ASK: Are there any questions?
Do written exercise and review answers when finished.

44. RF Power Stage – Output Power Probe
See SD-8
The output power probe (A13) couples a small sample of the transmitter's forward and reflected power and routes those sample signals to the control/monitor stage for protection and monitoring.
RF monitor PWB A3 provides a nominal 4.5V rms (NV40 at 40kW) signal for use with a modulation monitor or spectrum analyzer.
RF sample PWB’s A4 and A5 provide samples which are applied to exciters A and B (if used) for use by the exciters' adaptive pre-correction circuitry [for all-digital (HD) or hybrid (FM+HD) IBOC modes of operation only].
Read information on slide.

45. NV Series Transmitter Comparison (Key Differences Only)
Model
Max Analog Power
# of PM
# of PA
# PA PS
# IPA
# Fan
Exciter
RF Drive
(W)
Dimensions
(in)
Weight
(lbs)
Air Flow
(CFM)
NV40
44kW 16
128 32 3 2
NVE300
130
72.5" H x 65" W x 32" D
1600
3000
NV30
33kW
NV20
22kW 8 64 65
72.5" H x 36" W x 32" D
850
1500
NV15
16.5kW
NV10
11kW 4
NVE50 25
72.5" H x 23" W x 32" D
415
500
NV7.5
8.25kW
NV5
5.5kW 11
300
250
NV3.5
4.13kW
NOTE: Each PM has + 1 IPA; there is up to 4 PM per Module Backplane PWB
Read information on slide.
Debrief:
ASK: Are there any questions?
Do written exercise and review answers when finished.