For FUNcube Dongle Pro Plus users - IF to USB all in one small package that enumerates as a
sound card - the Configure dialog has extra settings, illustrated left.
The LNA Enable and Mixer Gain can be set as shown for good low noise performance but the
IF Gain is not needed. The FCDP+ needs DC Block set on the Input tab to mimimise the
centre hump and the Set Gain control adjusting appropriately. In the author's setup needed
reducing by ~7dB compared to the E-MU 1212m. The actual value in any setup will depend
upon the total gain between the rig antenna connector and the IF output. As with quality sound
cards the channels are already close to balance by default.
The FUNcube Dongle Pro Plus is particularly useful for those with an IF in the VHF region but can be
used at almost any frequency.
There are a couple of snags: the 'dc hump' in the middle of the display may make manual image cancellation (see
Menu/Configure/DSP)
necessary. The dynamic range of the Dongle is less than the LP-Pan but it takes large signals to observe this. If a FUNcube Dongle Pro Plus
muts connected to the system *before running NaP3* to appear in the Input/Device dropdown. It will appear first with internal defaults but a
Reset enters the settings needed for a K3 IF. Others will need to adjust this. All the settings are saved.
FUNcube DP+ dialog
FUNcube on 40m at night in Europe.
In the picture above right, When that 9+40 signal gets just a few dB higher, the FUNcube Dongle clips hard,
filling the display with
intermodulation. A 10dB rig attenuator pushes this threshold a bit further away, but this device may not be suitable for some stations;
transmitters on adjacent bands should be well down by the time they emerge from the rig IF but very strong local signals can give trouble.
A 'DC Hump' will be evident but enabling DC Block will reduce it; the author's 'before and after' are shown
below.
To avoid the 'dc hump' further the FUNcube Frequency can be offset 6kHz or so like the LP-Pan and the Global
Offset in the Rig tab used to
compensate for this.
Tests have shown that the IF Gain does not improve the sensitivity and in a large signal environment it may
be necessary to remove Mixer
Gain. With the above settings in the author's setup the Dongle has about 7dB more gain than an E-MU1212m card, compensated for by the
new Set Gain control.