SV1AFN has a nice preselector in his sales program. A nice addition to the HL2.
I've built it into an aluminium case and have added a 20dB attenuator as well as
a LNA from Nooelec.
The latter are easy to connect, two SMA connectors each (in and output) are provided.
I've used a Switchbox from Elad with the addition of a reed relay to disconnect the preselector when transmitting. You can also use the MFJ 1708B which has additional contacts avoiding the extra reed relay..
By the way the preselector can be used with any SDR by the use of a splitter.
I've not made any measurements at the moment but I estimate the reception to be
less sensitive to broadcast interference. Selectivity seems to be increased.
Measurements will follow later on.
Here some pictures . If you needed more info please contact me directly.
73 to all
Ezio F5MWA / K3EK