FW: RE: Linrad Questions (Leif Åsbrink Oct 11 2002)

[Leif Åsbrink <leif.asbrink@xxxxxxxxxxxxxxxxxxxx]

-----Original Message-----
From: owner-linrad@xxxxxxxxxxxxxxxxxxxxx
[mailto:owner-linrad@xxxxxxxxxxxxxxxxxxxxx]On Behalf Of Leif Åsbrink
Sent: Friday, October 11, 2002 5:42 PM
To: linrad@xxxxxxxxxxxxxxxxxxxxx
Subject: RE: [linrad] Linrad Questions


HI, Ermannoand Roger!

> I got two at Dayton this year and have used them on VHF (after
> downconversion), on HF, and on VLF.  Currently one of them is monitoring
> from 300-390 KHz (using AMRAD upverter as front end), in IQ mode.
> 
> I have not heard EME signals with it although I tried one weekend.  This
> surprised me, as I use my homebrew receiver with Linrad as my main EME
> receiver, with excellent results.  I thought the Time Machine would do
> just as well.  
The Time Machine will equally good as any other receiver if the
144 MHz preamplifier lifts the noise floor adequately. I like
the noise floor to be lifted by 20 dB when the pre-amp is switched on, 
but if dynamic range is a problem somewhat less is ok.

There is only one possible source for lower sensitivity and that is
mirror image responses in the conversion process that shifts 144 to 
the frequency where the TimeMachine operates. Very unlikely.

The Time Machine will run into dynamic range problems at modest
signal levels, but it will probably be good enough for the majority
of the 144 MHz EME'ers.


73

Leif  /  SM5BSZ

 



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