Message-ID: <4B8127D9.70602@online.fr>
Date: Sun, 21 Feb 2010 13:32:25 +0100
From: =?ISO-8859-1?Q?=22Jean-Pierre_M=E9r=E9_=28F1AFJ=29=22?=
 <jpm.f1afj@online.fr>
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Subject: Re: LF: SDR RX ideas for grabber...
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Hi Andy ,

Andy Talbot a =E9crit :
> Jean - Pierre...
>
> Is the circuit diagram correct ? =20
Yes my diagram  is correct
>  Your two final op-amps used as
> differential amplifiers both have their inputs taken from teh same ndes,=
 yet
> are labelled to deliver I and Q.  =20
No is not I/Q
> The first pair of op-amp do correctly
> take I and Q channels from the FST3253 mixer, but then their outputs are=
=20
> summed (differenced !)  together.=20
>  =20
Owing to the fact that it is not I/Q, that makes it possible to have the=
=20
OL /2 or /4, the two exits are for two separate PC! the rejection of the=
=20
frequency image is made by the selectivity of the filter of entry, the=20
IF is of 10kHz (spectrum lab)
>   As far as I can see,   I and Q outputs
> are the same signal.  Also, there is very littel audio gain in the circu=
it,
> so the receiver as shown requires plenty of RF input to deliver enough=
 audio
> for teh typical soundcard
>
> An ERA-5 is a rather exotic device to use in the preamp - it
> has considerable gain right up to 8Ghz and could be difficult to kep
> stable.   Better to use a MAR-3 at LF.
>  =20
The ERA-5 resists very well the strong signals, I am to 80 km of France=20
Inter (2MW on 164kHz) and 50km of HWU (200 KW on 22kHz) not of problems,=
=20
(see my grabber)

> Andy
> www.g4jnt.com
>  =20
73 Jean-Pierre f1afj
>
> On 21 February 2010 08:33, "Jean-Pierre M=E9r=E9 (F1AFJ)"
> <jpm.f1afj@online.fr>wrote:
>
>  =20
>> Hi Scott ,
>>
>> Please , loock at :     http://jpmere.online.fr/Grabber/Setup/Setup.htm
>>
>> It is my grabber on 2200m !
>>
>> 73 qro Jean-Pierre f1afj
>>
>>
>> Scott Tilley a =E9crit :
>>
>> Hi All
>>    =20
>>> I was wondering if there is a simple solution that is fairly well
>>> documented for converting a softrock type receiver over to 2200m use?
>>>
>>> Any other suggestions on how to get a SDR on 2200m with a minimum of
>>> effort would be greatly appreciated.
>>>
>>> Regards,
>>> Scott
>>>
>>>
>>>
>>>
>>>
>>>      =20
>
>  =20