[hpsdr] Comparison

[Scott Cowling]

Hi Jose,

Hermes has two antenna connectors, one for RX and one for TX. There 
is no on-board T/R antenna switching.

Antenna T/R switching must be done externally. Both Apollo and 
Anan-10 provide this. In addition Anan-10 provides three antenna 
inputs, but they are used to select a transceive antenna, not an 
RX-only antenna. With Anan-10 you could switch the antenna to a 
different (RX-only) antenna during receive, but you cannot select any 
antenna but the TX antenna during transmit. This might work for you 
unless you want to listen on an RX antenna (such as a Beverage) while 
you are transmitting.

You could use Alex-RX to perform this function. I don't think that 
you will get anything close to 100dB of isolation any way you do it, 
since Alex, Apollo and Anan all use standard relays.

Take a look at the schematics for all three boards, and you can see 
if you can hook it up to do what you want it to.

73,
Scotty WA2DFI





At 02:51 PM 7/15/2012 -0400, N4IS wrote:
>***** High Performance Software Defined Radio Discussion List *****
>
>Roger
>
>I'm new on this list and I ordered the Hermes board; now I'm concerned how
>it handles the RX antenna. I'm very active on 160m and external RX antenna
>is a must, the complication is the isolation between TX and RX port. My Rx
>antenna has low gain and weak signals is just above noise level near -130
>dBm, standard relay isolation near 60db is not enough to hold the strong
>signals from the TX antenna leaking into the RX port.
>
>Today I'm using high speed high isolation SMA switches with 100 db
>isolation.
>
>My question for the group it is possible  to select external RX antenna on
>Hermes/ANAN-10 for HF bands?
>
>Regards
>Jose Carlos
>N4IS
>
>-----Original Message-----
>From: hpsdr-bounces at lists.openhpsdr.org
>[mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of Roger W2REO
>Sent: Sunday, July 15, 2012 2:35 PM
>To: HPSDR
>Subject: [hpsdr] Comparison
>
>***** High Performance Software Defined Radio Discussion List *****
>
>
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