[Premium-Rx] Premium RX Strong Signal Performance

[Carcia, Frank A. HS]

    Hi John,
    I wonder what your first IF bandwidth is in Racals
    compared to the RF590? I have found the weak link in the Racal design is
the second mixer when
you are inside the first IF band pass. I wonder what  signal level the RX
sees at 1450 KHz?
I'm surprised about the RF590.  fc

-----Original Message-----
From: John Reed [mailto:jreed at alum.mit.edu]
Sent: Thursday, May 29, 2003 1:30 PM
To: Premium RX
Subject: [Premium-Rx] Premium RX Strong Signal Performance


I recently moved to a new location and discovered that there is a meduimwave
broadcast station on 1450 KHz about 1/2 mile from my location with 5000
watts of power.  This has given me the opportunity to test various receivers
in the strong field of this station.  For an antenna I'm using Dallas
Lankford's Ultralinear whip with push-pull second stage.  There is a weak
station on 1460 KHz and the test is based on how well this station can be
heard.
 
Here are some results, in order of best to worst:
 
Racal RA6793A - good readability.  I used USB and manual AGC.  RF gain was
turned down to give the best signal.
 
Racal RA6772E - essentially the same performance as the RA6793A.
 
WJ DMS-105R - more splatter.  I used 20 dB of input attenuation and the gain
controls for best signal.  This receiver is single conversion so there is no
roofing filter, also analog tuned so phase noise is minimal.  Still not as
good as the Racals.
 
NRD-525 - more splatter and noise than the above receivers.  This is not a
stock 525.  It has the ESKA roofing filter and PLAM board with post IF
filters.
 
Harris RF-550 - Very noisy and splatter was bad.  Just pieces of the
received signal could be made out.  USB was used, manual gain and RF and
audio gain were adjusted for best reception.
 
Harris RF-590 - about the same as the 550, but not as much signal made it
through.
 
I am surprised at the wide range in performance between these receivers.
The published specs don't indicate to me that much of a difference should
exist.  I'm curious as to what specs would be most important in quantifying
this test?
 
John Reed
 
 

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