[hpsdr] Alex - Do I need it

[Graham / KE9H]

Gordon:

Alex provides multiple functions that you will need to consider.

You may or may not need them, and you may have other ways
to get the same functions. 

In the case of Alex, they are all enclosed in one compact metal housing.

It provides a transmit - receive antenna relay.

It provides a low noise 6 Meter preamp.

It provides a series of switchable step attenuators up to 30 dB that
are ahead of everything in the receive path.

It provides switching/connection for a VHF/UHF transverter.

It provides for switching/selection for up to three external antennas.

It enables splitting the receive input apart from the transmit output for
special receive antennas.

It provides a transmit Low pass harmonic filter function, up to 100 
watts peak power.

It provides a receive bandpass filter function, by pairing the high pass 
filters on
the receiver card with the low pass filters on the transmit card.  To 
get the receive bandpass
filter function, both the receive and transmit cards must be present. 
These receive bandpass
filters do not degrade the +50dBm IP3 of the basic Mercury receiver.

Mercury by itself is an extremely robust receiver.  But it has its 
limits.  If you have
broadcast transmitters or other hams nearby, you may need the extra 
selectivity.

Penelope by itself does not need a transmit harmonic filter, but it is 
only 1/2 watt.
Any amplifier that you add to Penelope will need such a filter.  
Sometimes they
are built into the amplifier, or for something like PennyWhistle, the 
filters are external
to the amplifier, and are required.

I hope this helps.

--- Graham / KE9H

==

Gordon & Lois Duff wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>   
>
> ------------------------------------------------------------------------
>
> I recently saw a post on another site from Phil Covington, I believe.  
> He described the benefits of having front end filtering for his QS1R 
> and this gave some insight into my need.
>
>  
>
> It would be helpful to me, and probably others, to see a similar 
> discourse on the benefits with Mercury and Penny.  Also, is one needed 
> for Penny and another for Mercury?  If so, this becomes a pretty 
> significant part of the overall HPSDR package.
>
>  
>
> Gordon, KA2NLM
>
>
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