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FLEX-6000 Signature Series – Maestro User Guide

25.10 SETTING THE RF GAIN/PREAMPLIFIERS

Each Spectral Capture Unit in a FLEX-6000 receiver includes an RF preamplifier with adjustable gain.

The RF gain selector is in the ANT menu on the left side of the screen. The gain range is selectable

in 10 dB steps from -10 dB to +40 dB on the FLEX-6700, 8 dB steps from -8 dB to +32 dB on the

FLEX-6400 and FLEX-6600, -10 dB to +20 dB on the FLEX-6500 and 0dB to +20dB on the FLEX-6300.

The default setting is 0 dB. For typical HF operations below 12m, the 0 dB setting provides the

highest dynamic range and is recommended for most locations. Even in quiet rural locations, gain

is not needed or desired unless a low gain/low noise antenna is utilized.

The best way to determine the amount of gain needed for a given antenna and band condition is to

disconnect the antenna and measure the receiver noise floor with the Slice Receiver’s signal level

meter, then connect the antenna. If the band noise measurement without a signal present in the

passband is 8 dB or more than that with no antenna, additional gain is not needed. If a directional

antenna is used, it should be pointed toward the band opening for this measurement because noise

propagates with the opening.

Note: Although the RF gain slider is present in every Panadapter, the gain setting controls the

RF preamplifier associated with SCU. If you adjust the preamp settings for one Panadapter, all

other Panadapters associated with that SCU will also be changed since the change is made to

the SCU. For operational purposes, this equates to a “per antenna” basis. In the case of the

FLEX-6500 and FLEX-6300 with a single SCU, the preamplifier settings affect all Panadapters

and receivers.

The preamp indicator in the upper right corner of each Panadapter will be lit whenever the

preamp/attenuator is turned on for the band. It will show the requested gain for a FLEX-6500 or

FLEX-6700 (such as +20dB). On the 6300, the preamp provides different levels of gain by frequency.

If there is a net +5dB or better gain, the indicator will show PRE. If there is a net -5dB or less gain

(attenuation) then the indicator will read ATTN. If it is in between these two values, it will read ----

to indicate that the preamp is on, but not providing much change in the band of interest. This

means on a 6300 that one Panadapter could have PRE and the other ATTN.

FlexRadio Signature FLEX-6000 Series User Manual

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