13ULNA
SPECIFICATIONS
Noise Figure: < 0.7 dB
Gain: > 15 dB
Frequency Range: 2300 - 2450 MHz
Input Voltage: 7 - 16 VDC
Current Drain: < 25 mA.
DESCRIPTION:
The 13ULNA is a low noise amplifier designed by W5LUA and Down East Microwave Inc.
using the latest PHEMPT technology. This LNA was designed for receive only purposes including
Phase IIID, EME, and other standard weak signal reception between 2300 and 2450 MHz. The
LNA is assembled in a weatherproof enclosure and has the option of two connector types, either
SMA or Type “N” that is specified when ordering. This new design can be biased either through
the coax or through a external DC feed through connector in its standard form. There is no need
to specify. Custom models are available to cover band segments from 2100 - 2500 MHz.
INSTALLATION and USE:
Depending on your application, the LNA may be installed anywhere in your system to
increase gain. To maintain or improve the systems noise figure requires the LNA to be installed as
close to the systems antenna as possible. If you are using this LNA in a transceive system with
transmit bypass relays, be sure of their isolation characteristics and transmit power handling
capabilities before transmitting. Use only interconnecting cables and adapters that are rated for
use at or above 2.5 GHz. Inadequate cabling or cables with poor shielding may cause system
instabilities, signal loss, or undesirable intermittent operation.
The connector marked INPUT, is to be connected to the antenna. The OUTPUT is
connected to the receiver. The output connector accepts only DC bias between +7 and +16 volts.
This may be supplied by the receiver or a DC power inserted located between the LNA output and
the receiver input. If using coaxial transfer relays in the system with DC bias on the coax, be sure
that shorting type relays are not used in the receive path in a way that the DC is connected to
ground when the LNA is switched out of line.
The input circuit of the LNA is DC shorted for static protection. This a useful feature when
using antennas such as a dish with a wave guide fed or a helical type antenna that are DC open to
ground. This DC short will protect the LNA when it is installed in a remote location but will degrade
the noise figure by 0.1dB. The LNA will not withstand a direct lightning hit. Other precautions will
need to be made for such an instance.
/Built/13ULNA.doc 1 Rev. A 8/12/07
OPERATING:
Expected performance should be overall improvement in gain and noise figure of the
receive system with the LNA correctly installed. The proper installation of a LNA becomes more
and more important at these frequencies and because of the developments in the ISM bands,
interference will increase in the future. The gain bandwidth of the LNA design is wide to obtain a
low noise figure. Therefore, certain conditions may cause overloading of your receiver producing
intermodulation. It is always suggested to use adequate filtering between gain stages and to
practice gain management by not cascading amplifiers to solve system noise problems. Use of
directional antennas will also increase desired signals and aid in elimination of undesired signals in
the 13cm band.
For use in EME or weak signal type systems, the elimination of the shorted line on the input
circuit may be desired. If so, open the lid by removing the 4 screws, and with a sharp knife, cut the
printed inductor line as close to the RF input circuit as possible. This may only slightly improve the
noise figure and may not be worth giving up the static protection in a tropo only system. If you are
not biasing the LNA through the coax, eliminating the printed inductor on the output connector will
only net you a maximum of 0.1dB gain.
If you are biasing the LNA through the coax, there is no need to insulate the DC feed
through connector. There will be no measurable voltage on the Feed through and it will not disable
the LNA if shorted accidentally.
COMPONENT LIST
All resistors are 1206 size chips unless indicated. The white band is positive on the Tantalum chip
capacitors. All other capacitors are various sizes.
C1 0.1µF C6 10.0 µF Tant.
C2 8.2 ρF ATC C7 0.1µF
C3 0.1µF C8 8.2 ρF ATC
C4 10.0 µF Tant. C9 8.2 ρF ATC
C5 1.0 µF Tant. C10 8.2 ρF ATC
CR3 MMBD914 R1 15 R5 1K pot
CR4 MMBD914 R2 51 R6 100
IC1 7660 SMD R3 5.1K VR1 78L05
L1 0.4” Strand R4 51 PC Board
Q1 ATF36077
/Built/13ULNA.doc 2 Rev. A 8/12/07
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