[hpsdr] Neat front end from Phil

[Eric Ellison]

Folks!

Any one "dead buggin'" this board? Looks pretty good to me! Like Bob says!
"Saddle up, let's ride"!< note different emphasis! Also Bob's comments seem
to echo the sentiment of the posters on the reflector re the layout for
Horton or Phoenix! Leverage!


Eric




-----Original Message-----
From: hpsdr-bounces at hpsdr.org [mailto:hpsdr-bounces at hpsdr.org] On Behalf Of
rwmcgwier at comcast.net
Sent: Saturday, July 29, 2006 12:28 AM
To: hpsdr at hpsdr.org
Subject: [hpsdr] Neat front end from Phil

***** High Performance Software Defined Radio Discussion List *****

I believe the naturally balanced view, lower noise, and wider gain bandwidth
of 
the OPA1632, which I believed is needed will  make this right.   The LT1128
has 
higher noise at 4.2 nv/Hz than the OPA1632 and it has 1/4 the gain bandwidth
of the OPA.

 I believe we should prototype this and work out the kinks.  It is my
opinion 
that Phil has figured out all of the relevant features in making this mixer
work 
if they are born out in implementation details:

The return loss from the sampler circuit, in band and out of band will
present 
the filters and preamp/antenna in front of the circuit with proper
termination.   I suspect the  return loss will be good over the entire set
of amateur bands below 54 MHz.

The switching approach seems right in that it removes the need for inverted 
pulsing and I am only trying to work out in my head how the grounding or 50
Ohm  termination of these parts and the variants does the right thing.  It
is long 
days and late nights here at Central States VHFS meeting so my mind is a bit

foggy.  It was 100+ degrees on the antenna range this morning.  The
measurements  went on for hours!

But in my opinion,  this is the approach to take and we have a prototype
heart 
for Horton and all we need are the LO's and a few parts selections to be
there.

Saddle up, let's ride.

Bob


 
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