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Reducing Gain
If signals are overloading your receiver or if background noise is excessively high, there are two
solutions. The first solution involves adding a conventional attenuator pad either leading or
following the
DXE-RPA-1
. Addition of a pad on the input will reduce noise figure roughly by the
amount of the attenuation. This is usually not a problem with modest antenna efficiency. At the
same time noise figure decreases, input intercept (overload limits) will increase. Addition of an
attenuator pad on the
DXE-RPA-1
output reduces output intercept. Input intercept and noise figure
remain essentially unchanged.
As a general rule, reduction of gain with a pad at either spot will not compromise system performance.
This is because the
DXE-RPA-1
design has a very large performance margin in both noise figure and
intercept. You can also reduce gain about 3 dB, from 17 to 14 dB, by cutting one lead of
C3
and
C6
. Since
this is a push-pull circuit, both capacitors must be removed.(See
Figure 2
). If additional gain reduction
is still necessary, solder a 1,500 ohm 1/4 watt resistor in parallel with R1
and
another resistor of the
same value in parallel with R6 to reduce the gain to 10 dB. Be aware internal gain reduction
modifications will cause the upper frequency performance to fall at approximately 15 MHz or
higher.
Maintenance
The
DXE-RPA-1
requires virtually no maintenance as long as the unit is not exposed to direct
sunlight, moisture, or extreme temperatures. But as with any electrical device, lightning is a
concern.
Lightning
While most amateur radio installations rarely suffer damage from lightning (even though they never
disconnect their equipment); the best protection is to disconnect electrical devices during storms.
The key to proper lightning survival is proper grounding of feedlines and equipment, and
maintaining integrity of shield connections. A proper installation improves lightning protection and
enhances weak-signal receiving performance. The
DXE-RLP-75FF
Lightning Protector, 75 ohm,
DC Pass, Type F Connectors is one optional device that could be used.
Consult lightning protection
and station grounding information in the ARRL handbooks, the National Association of
Broadcasters (NAB) handbook or other reliable sources.
Optional Items
DXE-F6 - 75 ohm F-6 Style, Direct Bury Coaxial Cable - Full Spool or Custom Cable Assemblies
DX Engineering recommends using a high quality 75 Ω “flooded” F6 type coaxial cable. Flooded style cables have the
distinct advantage of automatically sealing small accidental cuts or lacerations of the jacket. Flooding also prevents shield
contamination and can be direct-buried. This low-loss cable features dual shields and an 85% Velocity Factor.
Custom cable assemblies are available, Call DX Engineering for details.
DXE-SNS6
Snap-N-Seal connectors are recommended for use with this coaxial cable to ensure a high quality
and weather resistant feedline connection. The proper tool
DXE-SNS-CT1
must be used to install these
connectors.
DXE-CPT-659 - Coax Cable Stripper for CATV F-6, RG-6 and RG-59 coaxial cable.
Coax Cable Stripper for CATV F-6, RG-6 and RG-59 coaxial cable. Includes 1 Replacement Blade - DXE-CPT-659.
Prepares CATV F-6, RG-6 and RG-59 coaxial cable for the installation of an "F" type connector - One-step cutting
motion. Precision cut . No nicks or scratches to conductor
