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slightly higher than normal receive antenna input RF levels, the Receiver Guard has a specially designed
mechanism of limiting that reflects higher than normal levels of RF energy while generating minimal harmonics
and noise. That, plus it has extremely low insertion loss are the most important differences between the Receiver
Guard and other protection devices.
What happens if the receive antenna is extremely close to the transmit antenna, or there is an antenna support or
other system failure that causes a high RF level to enter the receive antenna input? The
DX Engineering
Receiver Guard
can save the day!
Some Amateur Radio Operators have an antenna installation arrangement where their Beverage wire antenna, or
other receive antenna, is installed in close proximity to the transmit antenna. With the Receiver Guard installed,
when RF signal levels on the receive antenna line rise above the -10 dBm level, the specially designed circuit
limits the output signal, with a resulting rise in the input SWR. The Receiver Guard 5000HD can dissipate a
continuous 3 watts input, while only allowing only a 76 dB over S-9 signal out to the receiver. Ultimately, the
Receiver Guard 5000HD can handle a continuous 10 watt input, allowing no more than +10 dBm (0.010 watts)
output, which is only 83 dB over S-9 (The Receiver Guard 5000HD is +14 dBm [0.025 watts] output, which is
over 87 dBm over S-9) to the receiver front-end, preventing damage, while the reflected energy at the Receiver
Guard input is nearing 100%. To help prevent catastrophic damage to the receive input from an extremely high
RF level, the Receiver Guard contains a modern gas discharge tube, a fast acting clamp component at the antenna
input connector.
This is a
Receive Only
Accessory - Do not connect the DXE-RG-5000HD Receiver Guard
to a transmitter output
DO NOT TRANSMIT through the Receiver Guard
The Receiver Guard is is NOT a filter. - The Receiver Guard operates by clamping or limiting very
strong RF signals
Some good scenarios:
Separate Receiving Antennas
(a Beverage receiving antenna, for example): If a receiving antenna is located too
close to the transmitting antenna, RF power can flow back into the receiving line during transmit. The Receiver
Guard will limit stray RF energy presented to the receiver (or other sensitive devices such as a preamp).
Contest Stations:
There are many different configurations of contest stations. If it is possible to be receiving on
one radio while another is transmitting, a Receiver Guard would make good sense to use. If the radios are on
different bands, and if there is substantial filtering on each band, then the Receiver Guard might not be necessary.
The Receiver Guard is a good ‘insurance policy’ to have in case one of the filter/band/antenna settings is
incorrect, and high levels of RF energy is accidentally applied to a receiver.
Skimmer Antennas:
Many stations run a CW skimmer, where bands are monitored for CW activity and
automatically decoded by the skimmer software running on a PC. The skimmer antennas are usually located in the
same area as all of the normal station antennas. If a transmitter is keyed, the receiving antenna can pick up
substantial RF power, especially if resonant. The Receiver Guard will protect the skimmer receiver. The Receiver
Guard
would be installed between the antenna and the SDR antenna input.
High Power AM Station Nearby:
The Receiver Guard is not a filter. If the bothersome RF source is a constant
high power broadcast station, the Receiver Guard will reduce the AM energy, but it will also reduce all desired
signals as well. The limiting is not frequency specific. Therefore, if a strong signal on 1 MHz causes 20 dB of
