Re: DUO-ART: How do I change the CoaxRTX to RX+TX? #duo-art


Jim AJ8S
 

John,

To change from CoaxRTX to CoaxRX+TX go to menu #31 on the FDM-DUO and change it from Antenna #1 to Antenna #2.  Why?  One might assume that the #2 antenna connector is for a second receive only antenna such as a receiving loop and it can be used this way with the FDM-DUO as a stand-alone QRP rig. But when you are using it with the ART amplifier, it serves a different purpose. If you look at the block diagram of the ART you will see that the receive preselector filters are routed to the radio via antenna connection #2. The ART does not come with filters but you can order them. I have 7 of the 8 slots filled with ham band filters. The 8th slot comes with a "bypass" card so that frequencies not in these ham bands will go through. When you say, "the receive level drops" you may be trying to pass a signal where there is no filter. Anyway, again take a look at the block diagram and I think things will come together for you. The filters are not necessary but help to improve receiver performance by attenuating undesired strong signals from over driving the A/D converter.

73, Jim AJ8S

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