DX Engineering DXE-RPA-2 Instruction Manual

RPA-2 HF Modular Receive

1200 Southeast Ave. - Tallmadge, OH 44278 USA

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Preamplifier

DXE-RPA-2

DXE-RPA-2-INS Rev 2a

U.S. Patent No. 7,319,435

© DX Engineering 2019

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Introduction

The DX Engineering DXE-RPA-2 Modular Receive Preamplifier is a high-performance broadband
LF through HF receiver preamplifier that features exceptional immunity to overload. It also has an
excellent noise figure and a low input SWR, optimized
for the 300 kHz to 35 MHz range. Meticulous
craftsmanship and durable, robust components allow this
50-ohm preamplifier to withstand high signal levels
while providing superior dynamic range and third-order
intercept performance that equals or exceeds most
receiver and transceiver front-ends. Unlike other external
preamplifiers and many transceiver internal
preamplifiers, the RPA-2 enhances the readability of
weak signals without artificially increasing the noise. On low bands and beyond, weak signals
become more intelligible using this preamplifier in conjunction with proper adjustment of the RF
Gain and Attenuator in the transceiver.

The RPA-2 is a combination of a redesigned aluminum shielded enclosure chassis with the DXE-
RPA-2-PM Receive Preamplifier Plug-in Module factory installed. The DXE-RPA-2-PM module
retains the essential characteristics of the milestone product, the original DX Engineering RPA-1.

Featuring one internal optional module slot, the RPA-2 allows the use of the optional DXE-IT-PM
75 to 50-ohm Impedance Transformer Plug-in Module or the optional DXE-RG5000HD-PM
Receiver Guard Plug-in Module or optional filter. See DX Engineering Receive Filters.

While many other common preamplifiers suffer from harmonic distortion, the DXE-RPA-2 low­noise preamplifier features an advanced push-pull design that eliminates harmonic distortion. High
quiescent current increases its ability to handle strong signals without distortion or overload. This
high performance device must be powered with a well filtered and regulated DC power supply and
offers maximum performance at +13.8 Vdc to +18 Vdc input. Never use an inexpensive, poorly
performing wall transformer to power this top-of-the-line preamplifier.

Features

 Internal circuit impedance of 50-ohms for direct connection to 50-ohm receive systems and

antenna feedline BNC connectors with no transformer required

 Internal slot accommodates the optional 75 to 50-ohm Impedance Transformer Module to

accomplish transition from a typical F connector 75-ohm receive antenna feedline to 50-ohm
equipment, without losses

 Input and output connectors BNC and F types, prevent accidental connection to transmitting

devices

 Automatic RF bypass relay also turns the preamp off when the dc power is removed
 Green LED indicates when DC power is present and the preamplifier circuit is engaged
 An ingenious positive-capture threaded-sleeve 2.1 mm power connector that ensures the DC

power cannot be accidently disconnected from the RPA-2

 A simple internal jumper allows the RPA-2 to be powered by DC on the feedline for use on

antenna types that require a preamplifier at the antenna such as Pennants, Flags or K9AY Loops

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Additional Requirements

Please note you will need to consider the following requirements (parts not included in this
package) to install and operate the RPA-2 HF Preamplifier:

The RPA-2 requires a well-filtered, negative ground, +13.8 to +18 Vdc @140 mA power source.
Depending on the supply current, you should use an inline fuse. Alternatively, powering the RPA-2
through the coax feedline requires a voltage injector circuit (not included) and an internal jumper
(HD5) change. See the section “Powering Through the Coaxial Cable”.

Installation outdoors at the antenna is not normally needed or recommended. However, some antenna
types such as Pennants, Flags or K9AY Loops require a preamplifier at the antenna. If you are
mounting the unit outdoors, you will also need to mount the RPA-2 in such a manner as to prevent
moisture entering the unit.

Specifications of the DXE-RPA-2 Receive Preamplifier:

 Input and Output Connectors, female: BNC and F
 Frequency Range: 300 kHz to 35 MHz
 Gain: 16 dB, +/- 1.5 dB (over entire frequency range)
 Output Third Order Intercept: 43 dBm
 Noise Figure: 3.5 dB
 One dB Compression Point: +26 dBm (400 mW output)
 Dynamic Range, IM3: 110 dB or greater (500 kHz BW)
 Power Requirement: +13.8 to +18 Vdc, 140 mA max.
 Operating Temperature Range: -10°F (-23°C) to 150°F (65°C), non-condensing

The following are simplified explanations of information highlighted above.

Third Order Intercept - A
standard measure of how well a
receiving system performs in
the presence of strong nearby
signals. The higher the third
order intercept (TOI), the less
likely adjacent strong signals
will cause interference. The
RPA-2 offers substantially
improved TOI over competitive
preamplifiers and
communication receivers. The
figure to the right illustrates a
typical RPA-2 output third
order intercept measurement.
The RPA-2 is significantly more immune to overload than the best commercial amateur
receivers. Third order products are 50 dB below +18 dBm output.

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