[Premium-Rx] Premium RX Strong Signal Performance

[Carcia, Frank A. HS]

    Hi All,
    I have simulated John's test before I owned a second HP8640B. I
connected the antenna through a step attenuator to one port of my power
combiner
and the 8640 to the other port, I found a steady signal and increased the
step attenuator to reduce
the input level. Then I tuned across the signal to see the effect of the
8640. After each sweep I increased the level of the 8640 to observe the
effects. 
My power combiner was a copy of the one in the
ARRL Solid State handbook for measuring dynamic range. This shows the
combined performance of
dynamic range, phase noise and over load.   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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