[Premium-Rx] Rhode Schwarz EK-07 vs. R390A

[Karl-Arne Markström]

My experience from the Rohde & Schwarz tube-type equipment
comes from the EK-07's close relative EK-11 (same receiver but used a decadic frequency synthesizer),
which was used in large numbers in the Swedish Air Force point-to-point networks.

This receiver is rated for a noise figure not exceeding 10 dB (corresponds to about 3.5 uV EMF 30% AM
in 6 kHz bandwidth) in the lower HF range. A sensitivity figure to be expected from a receiver with tubes and two loosely coupled resonant circuits (high selectivity) before the medium-gain RF stage.

Most receivers from the same era have noise figures in this frequency range of 4 - 7 dB, as they
usually only have one resonant circuit before the RF stage.

However, with an antenna of resonant size, the temperate climate antenna noise temperature in the lower HF range is in the order of  20000 K daytime and at least 200000 K nighttime, which makes a receiver noise figure of 10 dB (2500 K noise temperature) quite insignificant.

The advice to those who search for the ultimate sensitivity levels is to use a narrow-band preselector
and connect it before a low-noise and high-IP amplifier with only sufficient gain to mask the receiver noise.
Only RF selectivity can prevent receiver front end overload from adjacent channel signals, which quite often gives the same symptoms as low sensitivity.

73/

Karl-Arne
SM0AOM

----- Original Message ----- 
From: "Peter Gottlieb" <nerd at verizon.net>
To: <premium-rx at ml.skirrow.org>
Sent: Monday, January 24, 2005 3:44 PM
Subject: Re: [Premium-Rx] Rhode Schwarz EK-07 vs. R390A


> Can't help you in comparing these two, never seen a EK-07, but is sensitivity 
> itself what you are looking for?  I peaked up my Harris RF-590A and it is able 
> to pull a copyable SSB voice signal in the under 0.1 uV range yet rarely does 
> that help as the background noise - in the passband - is the limiting factor.
> 
> I suppose if your antenna is poor it might help but still you'll get the best 
> bang for the buck changing that rather than the receiver.
> 
> 
> 
> Aidehua at aol.com wrote:
> > Though these may not qualify in the premium category, I'm wondering if 
> > any experts on this list have compared these two?  Looking for the 
> > ultimate receiver in the sensitivity category, as I hunt for weak 
> > stations on the 60/90m bands and need a true and proven performer.
> >  
> > I have a Chuck Rippel R390A and it's hard to beat.  Not a whole lot of 
> > published info on the EK-07, though.  Your input is appreciated.
> >  
> 
> 
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