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BevFlex-4X Installation Manual Rev 2.23 November 2019
antenna system. It is known that the SPE Expert linear amplifier internal antenna switch will not adequately protect
the BevFlex-4X.
TESTING AND OPERATION
An antenna analyzer can be useful to determine that the antenna is correctly installed and functional. By connecting the
analyzer to the “RX” port on the
Switch Unit
and sweeping the frequency from 1.8 to 10 MHz, you should see a relatively flat
and non-fluctuating (but not necessarily extremely low) VSWR that is less than approximately 2:1 (referenced to 50 Ohms).
Listening to various signals, you should observe lower atmospheric and man-made noise levels than on your transmit
antenna as well as a significant (sometimes more than 20 dB) front to back ratio when switching directions.
Spend time listening to signals from several directions on different frequency bands and compare the signal to noise ratio to
your other antennas. There are several HF broadcast signals that can be helpful in determining the performance of your
BevFlex-4X receiving antenna system.
For example, in the eastern USA:
Gander and New York aviation weather broadcasts on 3,485kHz and 10,051kHz (USB mode)
CHU Canada time and frequency references on 3,330 kHz and 7,850 kHz
WWV time and frequency reference on 2,500, 5,000, and 10,000kHzThese are all reliable and predictable HF sources that
can aid in understanding the performance of your antenna.
Also, try listening to AM broadcast stations in known directions relative to your BevFlex-4X
’s favored directions. Listen to
both daytime ground wave and night time skywave. Note that F/B measurements should be made during daylight hours. At
night, stations off the back end will pop in and out quickly, making accurate F/B measurements difficult.
You will notice that all received signal levels will generally be more than 10dB lower than on your transmit antenna, but the
signal to noise ratio on the BevFlex-4X will typically be much better than on your transmit antenna for signals coming from
the favored direction of the BevFlex-4X antenna. The lower overall received signal strength is not usually a problem since
the sensitivity and excellent noise figure of modern receivers/transceivers are good enough to make up for this difference in
strength. The signal and noise levels on the lower HF bands below 10 MHz are far above the receiver signal to noise
thresholds even when using the BevFlex-4X antenna system.
We hope you will find the BevFlex-4X receiving antenna system a highly useful and satisfying tool for digging signals out of
the noise to hear what you could not hear on your other antennas.
