[hpsdr] Mercury Level Cal

[Steven Doyle]

Hi Alex,

50uV(-73dBm)  is S9

Regards

Steve
G1YLB


----- Original Message ----- 
From: "Alexander Geckeler" <alexander.geckeler at gmx.de>
To: <hpsdr at hpsdr.org>
Sent: Saturday, February 28, 2009 7:00 PM
Subject: Re: [hpsdr] Mercury Level Cal


> ***** High Performance Software Defined Radio Discussion List *****
>
> Hello Ben,
>
> thanks for your suggestions.
> I bought an Elecraft XG-2 and will use it as a signal source.
> At what what output level it should be used - 1microV or 50 microV to 
> calibrate Mercury?
>
> Alexander
>
>
>
> -------- Original-Nachricht --------
> Betreff: [hpsdr] Mercury Level Cal
> Datum: Sat, 28 Feb 2009 13:42:31 -0500
> Von: W4sc <www4sc at alltel.net>
> An: HPSDR Reflector <hpsdr at hpsdr.org>
>
>
>
> ***** High Performance Software Defined Radio Discussion List *****
>
> All,
>
> In level calibration of Mercury RX, be aware of the following that may
> leave you with a less than optimal calibration. A good, consistant
> calibration could not be obtained while attempting on 14.2MHz at -70dbm.
>
> If you use a signal generator connected via a cable, make sure the
> inter-connecting cable is of good quality and condition and no longer than
> required.  In the specific case, it was determined that the interconnect
> cable (RG-58)  had a bad connector, and the shielding effectiveness was 
> not
> good enough. Leakage into the setup from external sources (ie computer
> clocks, and general
> electrical noise, external radio signals ect, ect.) should be eliminated.
> Level calibration was being attempted on 14.2 MHz, and in this particular
> case the 20M band seems rife with computer and other external noise.
> Possibly due to the 14.314MHz crystal osillator within the host itself.
>
> Level calibration was eventually performed at 15MHz, first at -70dbm, then
> at -90dbm.
>
> The following is suggested to mitigate this leakage problem:
>
> 1) Use a good quality inter connect cable, such as a double shielded 
> RG-142
> This can give about 20db better isolation over RG-58 type cable.
> 2) Use the Elecraft signal generator (XG1 or XG2) connected directly to
> Mercury.. This will eliminate the interconnect. Be sure of the SGx output
> level.  This setup may also benefit from having a shield around the
> generator.
> 3) Find and use a "quiet" frequency.
>
>
> de Ben W4SC
>
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