Daniels Electronics Ltd. VR-3H User manual

DANIELS
ELECTRONICS LTD.
TM
MT-3 RADIO SYSTEMS
VHF ENHANCED
EXTRA WIDEBAND
RECEIVER
INSTRUCTION MANUAL
V
R
-3H 29 - 50 MHz
Covers model: VR-3H035-SWA, VR-3H045-SWA
Converted for 50 kHz Channel spacing
Copyright ©2003 Daniels Electronics Ltd. All rights reserved. No part of this publication may be reproduced, stored
in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or
otherwise, without the prior written consent of Daniels Electronics Ltd.
DE™ is a registered trademark of Daniels Electronic Ltd. registered in the U.S. Patent and Trademark Office.
Daniels Electronics Ltd.
Revision Date: Aug 2003 Victoria, BC
Revision: 1-1-0
Document No.: IM10-VR3H040-AB PRINTED IN CANADA

DANIELS
ELECTRONICS LTD.
TM
ii VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB
DOCUMENT CONTROL:
This document has been produced, verified and controlled in accordance with
Daniels Electronics’ Quality Management System requirements.
Please report any errors or problems to Daniels Electronics’ Customer Service
Department.
NOTE:
The user's authority to operate this equipment could be revoked through any
changes or modifications not expressly approved by Daniels Electronics Ltd.
The design of this equipment is subject to change due to continuous
development. This equipment may incorporate minor changes in detail from
the information contained in this manual.

DANIELS
ELECTRONICS LTD.
TM
VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB iii
TABLE OF CONTENTS
Page
1 GENERAL................................................................................................................. 1-1
1.1 Introduction........................................................................................................ 1-1
1.2 VR-3H040 Extra Wideband Receiver Family Models...................................... 1-1
1.3 Manual Organization ......................................................................................... 1-2
1.4 Performance Specifications ............................................................................... 1-3
1.4.1 General........................................................................................................... 1-3
1.4.2 Enhanced Front End Performance Specifications ......................................... 1-5
1.4.3 Enhanced Synthesizer Performance Specifications....................................... 1-5
1.4.4 Physical Specifications .................................................................................. 1-6
2 SYSTEM OVERVIEW ............................................................................................. 2-1
2.1 Receiver Operation ............................................................................................ 2-1
2.2 Frequency Selection........................................................................................... 2-2
2.3 Receiver Assembly and Adjustment.................................................................. 2-3
2.3.1 Complete Receiver Alignment....................................................................... 2-3
2.3.2 Frequency Change ......................................................................................... 2-4
2.3.3 Minor Frequency Change .............................................................................. 2-5
2.3.4 Major Frequency Change .............................................................................. 2-5
2.4 21.4 MHz IF/Audio Main Board ....................................................................... 2-6
2.5 Enhanced Front End .......................................................................................... 2-6
2.6 Enhanced Synthesizer........................................................................................ 2-7
2.7 Receiver Front Panel Illustration ....................................................................... 2-8
2.8 MT-3 Receiver Case – Exploded View............................................................. 2-9
2.9 VR-3H040 Family Enhanced Receiver Block Diagram.................................. 2-10
3 THEORY OF OPERATION ..................................................................................... 3-1
3.1 21.4 MHz IF / Audio Main Board ..................................................................... 3-1
3.1.1 General........................................................................................................... 3-1
3.1.2 Power Supplies .............................................................................................. 3-1
3.1.3 IF Buffer Board.............................................................................................. 3-1
3.1.4 First IF Amplifier........................................................................................... 3-2
3.1.5 Second IF / Demodulation ............................................................................. 3-2
3.1.6 Received Signal Strength Indicator (RSSI) ................................................... 3-2
3.1.7 Audio Processing ........................................................................................... 3-3
3.1.8 Post Discriminator Filtering .......................................................................... 3-4
3.1.9 Squelch Circuitry ........................................................................................... 3-5
3.1.10 COR Outputs.................................................................................................. 3-6
3.1.11 Channel Selection .......................................................................................... 3-7
3.2 Enhanced Front End .......................................................................................... 3-8
3.2.1 General........................................................................................................... 3-8
3.2.2 Power and Interconnection ............................................................................ 3-8
3.2.3 Preselector Filter............................................................................................ 3-8

DANIELS
ELECTRONICS LTD.
TM
iv IM10-VR3H040-AB VHF Enhanced Extra Wideband Receiver Instruction Manual
3.2.4 RF Amplifier.................................................................................................. 3-9
3.2.5 Image Rejection Filter ................................................................................... 3-9
3.2.6 Local Oscillator Filter.................................................................................... 3-9
3.2.7 Double Balanced Mixer................................................................................. 3-9
3.3 Enhanced Synthesizer...................................................................................... 3-10
3.3.1 Internal Power and Control (Digital Board) ................................................ 3-10
3.3.2 Common Analog Board Circuitry................................................................ 3-10
3.3.3 29 - 71.4 MHz Analog Board Circuitry....................................................... 3-12
3.3.4 Synthesizer Digital Circuitry (Digital Board) ............................................. 3-13
3.4 Frequency Control ........................................................................................... 3-13
3.4.1 BCD Switch Frequency Control.................................................................. 3-13
3.4.2 Synthesizer Base and Frequency Increment Table...................................... 3-14
3.4.3 5.0/6.25 kHz Channelization. ...................................................................... 3-14
4 RECEIVER ALIGNMENT ....................................................................................... 4-1
4.1 General............................................................................................................... 4-1
4.2 Repair Note........................................................................................................ 4-1
4.3 Printed Circuit Board Numbering Convention .................................................. 4-2
4.4 Recommended Test Equipment......................................................................... 4-2
4.5 Synthesizer OS-3, OS-3H)................................................................................. 4-3
4.5.1 VHF OS(R/T)-3H 29 - 71.4 MHz VCO Alignment ...................................... 4-3
4.6 Front End Tuning............................................................................................... 4-5
4.7 Main Board Tuning............................................................................................ 4-6
4.7.1 IF Amplifier Bias Current Adjustment .......................................................... 4-6
4.7.2 21.4MHz ........................................................................................................ 4-6
4.7.3 Audio Levels.................................................................................................. 4-6
4.7.4 Distortion and Sensitivity .............................................................................. 4-7
4.7.5 Second IF / Demodulation ............................................................................. 4-7
4.7.6 Squelch Window............................................................................................ 4-8
5 RECEIVER CONFIGURATION AND TEST POINTS........................................... 5-1
5.1 21.4 MHz IF / Audio Main Board Factory Settings .......................................... 5-1
5.1.1 The 21.4 MHz IF/Audio Main Board Configuration: ................................... 5-1
5.1.2 The 21.4 MHz IF/Audio Main Board Configuration Jumper Settings.......... 5-1
5.1.3 Test Points ..................................................................................................... 5-2
5.1.4 Power Supplies .............................................................................................. 5-3
5.1.5 21.4 MHz IF / Audio Board Interconnect Pin Definitions ............................ 5-4
5.2 Enhanced Front End Test Points....................................................................... 5-4
5.3 OS(R/T)-3(A/H) Synthesizer Factory Configuration ........................................ 5-5
5.3.1 Jumper Configuration .................................................................................... 5-5
5.3.2 Synthesizer Test Points.................................................................................. 5-6

DANIELS
ELECTRONICS LTD.
TM
VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB v
6 ILLUSTRATIONS AND SCHEMATIC DRAWINGS ............................................ 6-1
6.1 21.4 MHz IF/Audio Board Component Layout (Bottom) – Extra Wideband... 6-1
6.2 21.4 MHz IF/Audio Board Component Layout (Top) – Extra Wideband......... 6-2
6.3 21.4 MHz IF/Audio Board Schematic Diagram – Extra Wideband.................. 6-3
6.4 21.1 MHz FM IF Buffer Component Layout .................................................... 6-5
6.5 21.1 MHz FM IF Buffer Schematic Diagram.................................................... 6-5
6.6 Enhanced Front End Block Diagram................................................................. 6-6
6.7 BandPass Filter Component Layout .................................................................. 6-6
6.8 BandPass Filter Schematic Diagram ................................................................. 6-6
6.9 Enhanced Front End Schematic Diagram – Extra Wideband............................ 6-7
6.10 Enhanced Front End Component Layout – Extra Wideband ............................ 6-9
6.11 Synthesizer Analog PCB Component Layout (Bottom) – Extra Wideband.... 6-10
6.12 Synthesizer Analog PCB Component Layout (Top) – Extra Wideband ......... 6-11
6.13 Synthesizer Analog PCB Schematic Diagram – Extra Wideband................... 6-12
6.14 Synthesizer Digital PCB Schematic Diagram – Extra Wideband ................... 6-13
6.15 Synthesizer Digital PCB Component Layout (Bottom) – Extra Wideband .... 6-14
6.16 Synthesizer Digital PCB Component Layout (Top) – Extra Wideband.......... 6-15
7 PARTS LISTS ........................................................................................................... 7-1
7.1 Electrical Parts Lists .......................................................................................... 7-1
7.1.1 21.4 MHz IF/Audio Main Board ................................................................... 7-1
7.1.2 IF Buffer Board.............................................................................................. 7-8
7.1.3 Enhanced Front End ...................................................................................... 7-8
7.1.4 FE BandPass Filter ...................................................................................... 7-10
7.1.5 Enhanced Synthesizer Analog Board .......................................................... 7-11
7.1.6 Enhanced Synthesizer Digital Board ........................................................... 7-14
7.2 Mechanical Parts.............................................................................................. 7-16
7.2.1 21.4 MHz IF/Audio Main Board ................................................................. 7-16
7.2.2 Enhanced Front End .................................................................................... 7-17
7.2.3 Enhanced Synthesizer.................................................................................. 7-17
8 CHANNEL DESIGNATION TABLES .................................................................... 8-1
8.1 Channel Designation Table: 29-50 MHz, 5kHz Increments ............................. 8-1
8.2 Channel Designation Table: 29-50 MHz, 6.25kHz Increments ...................... 8-13
9 REVISION HISTORY .............................................................................................. 9-1

DANIELS
ELECTRONICS LTD.
TM
vi IM10-VR3H040-AB VHF Enhanced Extra Wideband Receiver Instruction Manual
This Page Intentionally Left Blank

DANIELS
ELECTRONICS LTD.
TM
VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB 1-1
1GENERAL
1.1 Introduction
The VR-3H040 Enhanced Extra Wideband Receiver family provides high performance
synthesized FM reception in 50 kHz channels in one of two frequency bands: 29 to 38 MHz or
38 to 50 MHz. A modular design allows each of the receiver's three internal modules; 21.4 MHz
FM IF/Audio Main Board, FE3H Enhanced Front End, and OS-3H Synthesizer to be
individually assembled and tested. This facilitates construction, tuning, and general receiver
maintenance. The internal synthesizer module may be programmed with up to 16 channels for
remote frequency control applications.
The VR-3H040 Receiver family combines state of the art performance in a compact modular
enclosure for applications ranging from remote mountain top repeaters to congested urban radio
environments. Each receiver module is characterized by dependable, low maintenance
performance under the most severe environmental conditions.
The VR-3H040 modular receiver family is compatible with all Daniel’s subrack and base station
enclosures.
1.2 VR-3H040 Extra Wideband Receiver Family Models
There are two distinct receiver models in the VR-3H040 Extra Wideband Receiver family
covering 29 to 38 MHz and 38 to 50 MHz bands respectively while operating in 12.5 kHz or
20/25 kHz occupied channel bandwidths. The two models are as follows:
• VR-3H035-SW- synthesized, 29-38 MHz band, Converted for 50 kHz Channel spacing
• VR-3H045-SW- synthesized, 38-50 MHz band, Converted for 50 kHz Channel spacing

DANIELS
ELECTRONICS LTD.
TM
1-2 IM10-VR3H040-AB VHF Enhanced Extra Wideband Receiver Instruction Manual
1.3 Manual Organization
The organization of this document reflects the modular construction of the VR-3H040 family of
products. Each Section (e.g. Theory of Operation, Alignment, etc.) contains “subsections”
specific to each electronics module.
In general, this instruction manual includes the following information for the VR-3H040
Receiver and for each of its electronics modules:
1. A functional description and specifications summary.
2. A detailed technical description (Theory of Operation).
3. Assembly, setup and alignment procedures.
Along with a system overview of the entire receiver, information for the following electronic
modules is contained within this document:
21.4 MHz FM IF / Audio Main Board Instruction Manual: This manual provides complete
information on the operation of the 21.4 MHz FM IF / Audio Main Board. The bulk of the
material relating to receiver operation and installation can be found within this manual. The
majority of receiver options, including channel selection, are accessed through the FM IF /
Audio Main Board. In addition, most of the external receiver connections are made through the
FM IF / Audio Main Board.
FE3H Front End Instruction Manual: This manual provides information on alignment and
operation of the FE3H Front End Module. The Front End module provides filtered low level RF
signal amplification and down conversion to the IF frequency of 21.4 MHz.
Enhanced Synthesizer Instruction Manual: This manual provides information on alignment and
operation of the Enhanced Synthesizer Module. The synthesizer module provides the low noise
first local oscillator signal to the FE3H Front End module.
VR-3H 29 - 50 MHz Channel Designation Tables: This manual provides tabular frequency /
channel number assignment.

DANIELS
ELECTRONICS LTD.
TM
VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB 1-3
1.4 Performance Specifications
1.4.1 General
Type: MT-3 Series Synthesized Receiver.
Family: VR-3H040 Converted for 50 kHz Channel spacing
Compatibility: MT-3 Series Radio Systems
Frequency Range: 29 to 38 MHz or 38 to 50 MHz.
System Impedance: 50 Ω(Type N connector).
Frequency Generation: Synthesizer Module (Internal).
Channel Spacing: Converted to 50 kHz
System Deviation: ± 15 kHz
Channel Selection: In 5.0 or 6.25 kHz increments selected through four
internal BCD rotary switches.
Number of Channels: Preset capability for 16 channel memory selectable through
four external logic control lines.
Channel Switching Range: ±1 MHz. (38 - 50 MHz, No tuning adjustment)
±0.5 MHz. (29 - 38 MHz, No tuning adjustment)
Reference Sensitivity: -114 dBm (typically -116 dBm) for 12 dB SINAD.
Local Oscillator Frequency Stability: ±5 ppm; -30°C to +60°C. Provision for external 10.0 MHz
reference input.
First IF 21.4 MHz, 8 pole crystal filter.
Second IF 455 kHz
Adjacent Channel Selectivity: 90 dB; 50 kHz channel.
Conducted Spurious + Harmonics: 95 dB
Intermodulation Rejection: 75 dB (typical 80 dB); as per TIA/EIA 603
Hum and Noise: 60 dB; 20 kHz LPF

DANIELS
ELECTRONICS LTD.
TM
1-4 IM10-VR3H040-AB VHF Enhanced Extra Wideband Receiver Instruction Manual
Audio Output: 600 Ωbalanced or unbalanced line output;
De-emphasis output, +3 dBm maximum level;
Flat response output, +3 dBm maximum level;
Audio Distortion: Less than 3.0% (typical < 2%) THD at +25°C;
less than 3.5% THD, -30°C to +60°C.
De-emphasized Audio Response: +1, -2 dB; (500 Hz to 2.8 kHz)
+1, -3 dB (300 Hz to 3 kHz
Flat Audio Response: +1, -1 dB; (300 Hz to 3 kHz)
Squelch Hysteresis: Adjustable from 2 dB to 20 dB.
Squelch Threshold: Adjustable from -123 to -105 dBm.
Squelch Operation: Noise based (standard) or optionally configured RSSI
controlled.
Front Panel Controls: Receiver power On (Norm) / Off.
Squelch Disable (Push-button).
COR Interface: 2 amp, 50 V open drain power MOSFET;
100 mA, 30V opto-isolator (optional);
2 amp, form C electro-mechanical relay (Optional).
Supply Voltage: +9.5 Vdc (Supplied by SR-3 Subrack or SM-3 System
Monitor Supply).
Supply Current: Normal programmed options less than 385 mA.
Operating Temperature Range: -30°C to +60°C Standard;

DANIELS
ELECTRONICS LTD.
TM
VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB 1-5
1.4.2 Enhanced Front End Performance Specifications
Frequency Range: 29.0 MHz - 38.5 MHz (FE3H035)
37.5 MHz - 50.0 MHz (FE3H045)
IF Frequency: 21.4 MHz
3 dB Bandwidth: > 5 MHz (Preselector Filter)
Conversion Gain: 12.5 dB
Third Order Intercept Point: > +18 dBm
Impedance: 50 Ωat RF, LO, and IF ports
Temperature Range: -30˚C To +60˚C
Power Requirements: +9.5 Vdc @ 160 mA
1.4.3 Enhanced Synthesizer Performance Specifications
Frequency Range: 29 MHz - 38 MHz [±0.5 MHz] (OST-3H035)
(Tuning range with no adjustment 38 MHz - 50 MHz [±1.0 MHz] (OST-3H045)
is shown in [ ] brackets.) 50.4 MHz - 71.4 MHz [±1.0 MHz] (OSR-3H061)
Output Power: +5 dBm ±2 dBm into 50Ω
External Reference Input: ●External reference input signal via SMB
connector J1
●Input level 0 dBm ±3 dB
●Input impedance 50Ω
●Input frequency 10.0 MHz or 9.6 MHz
(selectable through digital board jumper JU1)
Power Requirements: Normal Configuration:
+9.5 Vdc @ 160 mA for FM
Low Current Standby Mode (TCXO enabled):
+9.5 Vdc @ 14 mA for FM

DANIELS
ELECTRONICS LTD.
TM
1-6 IM10-VR3H040-AB VHF Enhanced Extra Wideband Receiver Instruction Manual
1.4.4 Physical Specifications
Physical Dimensions: Width: Height: Depth:
7.1 cm (2.8 in) 12.8 cm (5.05 in) 19 cm (7.5 in)
Module Weight: 1.0 kg (2.2 lbs)
Corrosion Prevention: Anodized aluminum construction. Stainless steel
hardware. Selectively conformal coated glass epoxy 2 and
4 layer printed circuit boards. Gold plated module
connectors.
Module Design: Compact Eurostandard modular design. Plug-in modules
mate with Daniels standard M3 repeater subrack. Subracks
/ modules comply with IEEE 1101, DIN 41494 and IEC
297-3 (mechanical size / modular arrangement).
External Connections: RF Connection: type N connector located on the receiver
module front panel. Motherboard Connections (Audio,
Power, and Control) are made through a 48 pin, gold
plated, type F connector on the rear of the transmitter
module. User connection made through mated "mother
board" assembly of the repeater subrack. Type F standard
connector complies with DIN 41612 Level 2 (200 mating
cycles, 4 day 10 ppm SO2gas test with no functional
impairment and no change in contact resistance).
Handle Text Colour: Orange.

DANIELS
ELECTRONICS LTD.
TM
VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB 2-1
2SYSTEM OVERVIEW
2.1 Receiver Operation
A VR-3H040 Receiver family is constructed using three primary modules; the FE3H Front-End
module, the MT-3 Receiver FM IF/Audio Main Board and the OSR-3H061 local oscillator
synthesizer (refer to section 3.3, VR-3H040 Family Enhanced Receiver Block Diagram).
Two Front-End modules, FE3H035 and FE3H045 provide frequency coverage from 29 - 38
MHz and 38 - 50 MHz respectively. Tuning within each frequency band is provided through
five ferrite core slug adjustment points. The FE3H Front-End (FE3H035, FE3H045) combines a
low noise BJT amplifier with a cascaded, multiple pole, high selectivity coupled resonator filter
structure. A high intercept point active mixer is also located within this module. The module
has inputs for the RF signal (Front Panel N connector), local oscillator input signal, and an
output for the 21.4 MHz IF signal which connects directly to the FM IF / Audio Main Board.
Interconnections are made using quick connect SMB style connectors.
The MT-3 Receiver FM IF/Audio Main Board accepts the IF signal of 21.4 mHz. The signal
passes through the following stages: selective crystal filtering, amplification, second IF
frequency conversion to 455 kHz, and final audio FM demodulation / amplification. The board
provides a high degree of receiver flexibility by providing a number of different audio paths,
audio levels, and control interconnect options.
The OSR-3H061 Synthesizer Module produces a low noise, high stability RF local oscillator
signal covering the frequency band of 50.4 - 71.4 MHz which translates to a receive frequency
range of 29 - 50 MHz. The internal TXCO is used for frequency stability, but an external
reference signal may also by used.

DANIELS
ELECTRONICS LTD.
TM
2-2 IM10-VR3H040-AB VHF Enhanced Extra Wideband Receiver Instruction Manual
2.2 Frequency Selection
Receiver channel selection is achieved by setting a decimal number on four BCD frequency
select switches, FSW1 through FSW4. These rotary switches are located on the FM IF/Audio
Main Board and are made accessible by removing the outer receiver cover. The switch settings
are scanned by the synthesizer module when the receiver is first powered up, and the desired
local oscillator frequency is generated. Refer to the following equations or the channel
designation manual for simplified channel number and frequency information.
VR-3H035-S and VR-3H045-S (29 - 50 MHz) with:
• 5 kHz channel increments (BCD settings from 0000 to 4999):
CHNL#= Rxfrequency
−
29 MHz
5 kHz






or
Rxfrequency = CHNL#
×
5 kHz
[
]
+
29 MHz
• 6.25 kHz channel increments (BCD settings from 5000 to 9999):
CHNL #= Rxfrequency
−
29 MHz
6.25 kHz





 + 5000
or
Rxfrequency = CHNL# -5000()
×
6.25 kHz
[]
+
29 MHz
Alternatively, a frequency and channel lookup table is available in the 'Channel Designation
Table' manual for the VR-3H040.
A channel can be selected from a set of 15 (maximum possible) factory programmed channels by
the four channel select lines available at the rear 'F' connector on the Receiver Main Board. A
single user selectable channel is set by switches located on the Receiver Main Board. See the
Receiver Main Board Manual for details.

DANIELS
ELECTRONICS LTD.
TM
VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB 2-3
2.3 Receiver Assembly and Adjustment
All modules and the front panel are mounted on the Receiver Main Board which then forms a
single assembly. The FE3H Front End is attached with two front panel screws and one screw
through the rear F connector. Removal is required to access the Synthesizer for tuning. An
enclosure is formed by an extruded aluminum shell that slides over the Receiver Main Board as
illustrated in section 2.8). The enclosure is completed by the installation of side and front panel
screws (see section 7 in this manual for parts lists).
Receiver alignment is performed on a module by module basis and detailed steps are provided in
the respective manuals. Alignment is simplified by using an SR-3 Subrack, SM-3 System
Monitor, and RF extender cable to provide receiver power and signal interconnection.
Alternatively, +9.5 Vdc and +13.8 Vdc, as well as any required test signals, may be applied
directly to the individual modules. Refer to section 4.
Throughout the alignment procedure reference is made to a "standard signal". This refers to an
external generator signal source with FM modulation, 1 kHz tone, and 60% system deviation
connected to the receiver RF input type N connector (if a nominal receiver frequency is not
given, it can be assumed to be the selected receiver channel frequency).
2.3.1 Complete Receiver Alignment
A complete Receiver Alignment is performed at the factory and should not be required under
normal circumstances. A large change in operating frequency, as discussed in the next section,
may require a complete realignment operation. This operation requires that all the receiver
modules be aligned on a per module basis in the following order.
Sequence Module
(1) Front End
(2) Synthesizer
(3) Receiver Main Board

DANIELS
ELECTRONICS LTD.
TM
2-4 IM10-VR3H040-AB VHF Enhanced Extra Wideband Receiver Instruction Manual
2.3.2 Frequency Change
The receiver is initially aligned at the factory for the frequency stamped on the 'Factory Set
Operating Frequency' label (see section 3.1). This label should list the frequency at which the
last complete receiver alignment was performed. For a small frequency change, a simple channel
change (see section 2.2) may be all that is required. A larger frequency change may involve the
realignment of other modules. The frequency change in question is the accumulated frequency
change in relation to the frequency stamped on the label. For example, if the frequency is
changed by 0.5 MHz from that stamped on the label, then a second frequency change of 1 MHz
in the same direction would result in a total change of 1.5 MHz. The action taken would be on
the basis of the 1.5 MHz value. Failure to perform a realignment after a large frequency change
could result in unreliable receiver operation or operation that does not conform to the published
specifications.
Size of Frequency Change Modules to be Aligned
less than ± 0.5 MHz, 29 - 39MHz (minor) Receiver Main Board (Channel Change).
less than ± 1.0 MHz 38 - 50 MHz, (minor) Receiver Main Board (Channel Change).
greater than ± 0.5 MHz, 29 - 39MHz (major) Complete alignment.
greater than ± 1.0 MHz 38 - 50 MHz, (major) Complete alignment.

DANIELS
ELECTRONICS LTD.
TM
VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB 2-5
2.3.3 Minor Frequency Change
Changes less than ± 0.5 MHz (29 - 38 MHz) or ± 1 MHz (38 - 50 MHz) from a previously tuned
working receive frequency will generally not require any adjustment. Change the channel
frequency select switches (Section 2.2) and inject a standard signal at the new channel
frequency. Verify that the receiver sensitivity is ≈-114 dBm for 12 dB SINAD. Slight
adjustment of the Front End tuning slugs (5) may be performed to maximize sensitivity at the
new frequency. Be aware that the preferred Front End tuning procedure (Refer to sub-manual
IM10-FE3H040) requires swept frequency response measurement of the Front End filter in order
to provide a maximally flat response over a range of input frequencies, with the primary channel
frequency centered in the filter passband (5 MHz wide). This alignment approach is not
mandatory for single channel operation.
A quick check of the Synthesizer module PLL control voltage at TP4, accessible through the
synthesizer top cover, is advisable at all programmed frequencies. The voltage at TP4 should
range between +0.5 Vdc and +4.5 Vdc at all programmed frequencies. Measured voltages
outside this range indicate a possible "out-of-lock" condition and should be avoided. The Front
End module must be removed (but left connected) from the main receiver chassis in order to
access TP4. The synthesizer top cover foil label may have to be cut in order to access TP4. Fine
Frequency TUNE adjust trimmer capacitor C24 may then be adjusted to position the PLL loop
voltage (TP4) as close as possible to the nominal +2.3 Vdc for all programmed frequencies. For
single channel operation, TP4 should always be set to +2.3 Vdc.
2.3.4 Major Frequency Change
Changes greater than ± 0.5 MHz (29 - 38 MHz) or ± 1 MHz (38 - 50 MHz) from a previously
tuned working receive frequency will require complete FE3H Front End and OSR-3H061
Synthesizer alignment as per section 4 in this manual. Changing a high band receiver (VR-
3H045-S) to a low band receiver (VR-3H035-S) or vice-versa requires a complete change out
and alignment of the Front End module (FE3H035 or FE3H045) in addition to OSR-3H061
alignment.

DANIELS
ELECTRONICS LTD.
TM
2-6 IM10-VR3H040-AB VHF Enhanced Extra Wideband Receiver Instruction Manual
2.4 21.4 MHz IF/Audio Main Board
The 21.4 MHz IF / Audio Main Board is the main board for all receivers up to 512 MHz. This
board provides interconnects for Daniels Synthesized and Crystal Controlled Oscillators, and
Daniels high performance and low current Front Ends. An F48 type connector plugs into
Daniels M3 Motherboard. The 21.4 MHz IF / Audio Main Board is configurable at the factory
for either narrow band or wide band channels. Different bands within a frequency range do not
require a configuration change.
2.5 Enhanced Front End
The FE3H040 Enhanced Front End is a highly integrated, frequency selective, down converter
used in Daniels Electronics standard MT-3 Low Band VHF FM receiver product line. The
FE3H040 Front End connects to the 21.4 MHz IF / Audio Main Board and the enhanced
Synthesizer to form a complete receiver.
The Enhanced Front End amplifies and down converts the RF signal to the IF frequency of
21.4 MHz. The FE3H035 and FE3H045 Front Ends use high side injection. The Enhanced
Front End consists of the following:
• Five Section L-C coupled Bandpass Filter
• Single Stage Low Noise RF Amplifier
• Image Rejection Filter
• Local Oscillator Low Pass Filter
• Double Balanced Active Mixer

DANIELS
ELECTRONICS LTD.
TM
VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB 2-7
2.6 Enhanced Synthesizer
The OS-3A/H Synthesizer is a compact, fully shielded and environmentally rugged frequency
synthesis module that is the nucleus of every MT-3 synthesized Receiver and Transmitter radio
module. The OS-3A/H generates a high stability, low distortion radio frequency signal in one of
several frequency bands, including 29 - 50 MHz. The OS-3A/H utilizes an internal temperature
compensated 9.6 MHz reference to produce a signal stable to ±1 ppm within the temperature
range of -40°C to +60°C. Alternately, the OS-3A/H can be disciplined by an external 9.6 MHz
or 10 MHz reference of higher stability. All synthesizer modules are designed to be easily
removed for programming, calibration and/or repair. The synthesizer circuitry is distributed
between two printed circuit boards (PCBs) which are isolated yet interconnected via photo-logic
optical transceivers that effectively eliminate residual electrical noise between digital and analog
circuitry. Further shielding of the synthesizer’s RF filter circuitry is provided by an internal
shielded enclosure.

DANIELS
ELECTRONICS LTD.
TM
2-8 IM10-VR3H040-AB VHF Enhanced Extra Wideband Receiver Instruction Manual
2.7 Receiver Front Panel Illustration
VR3H040SM1
SQ . DI SABLE
N
O
RMO
FF
RF NI
REFERENCE
INPUT
RECE VERI
SQUELCH DISABLE
ON / OFF SWITCH
TYPE N RF
INPUT JACK
SMA REFERENCE
INPUT JACK
FACTORY SET
OPERATING
FREQUENCY
RECEIVER
MODEL IDENTIFIER
FREQUENCY (MHz)
45.120
MADE IN CANADA
MADE IN CANADA
VR-3H045-SW
ORAN GE TEXT