[hpsdr] hardware question ( Mercury HPSDR)

[Don - ki6fom]

Note that it is very easy to accidentally put pressure on the relay
with your thunb when removing the antenna BNC connector,
partially dislodging it from the board in the process. I know this
from personal experience :-)

Don - ki6fom


On 07/18/2010 07:11 AM, Graham / KE9H wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Gedas:
>
> It is much more likely to be the relay that runs the 20 dB attenuator
> than a defective A->D converter.  I would change the relay, first.
>
> --- Graham / KE9H
>
> ==
>
> Gediminas Kasparaitis wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Hi,
>>
>> so many people responded, thank you my friends. Pdf  is so nice.
>>
>> No, I do not have RF source with known level, but I got good advice 
>> from where to get one
>> not too big , not too expensive ( Elecraft).
>>
>> Today I did some aditional testing, now I have no doubt,  my board 
>> has that instability,
>> sometimes everything is OK, sometimes a bit bigger noise
>> ( very hard to understand if it is bigger than it should be)
>> , sometimes terrible noise increase.
>>
>> When it works good, sensitivity is close to that of my radio, when it 
>> has
>> problems, then  base line just goes up  ( 10-30 db) and weakest 
>> signals dissapear,
>> strongest became weak... It takes time to duplicate this.
>>
>> The idea to put heatsing on top of the chip ( on my board at least) 
>> turned to be totally wrong.
>> On the opposite side it doesn't hurt at least and helps somewhat with 
>> cooling.
>> It seems to me, that  the best thing is keep everything away from 
>> that A/D, then it ( or front end ) is the most stable.
>> Strange, but it becomes apparent only after few hours of warm up......
>>
>> In CW skimmer  problem is  very visual..., but I misplaced somewhere 
>> cable from camera, so can't share
>> screen shots.
>>
>> For a while I will play with extra fan, mightbe I still can get it 
>> more reliable ....If that won't help,
>> I don't know...will try to look for the best A/D  ( -40 - 85 C) and 
>> try to replace with it.....
>>
>> 73, Gedas, nx2px
>>
>>
>> ----- Original Message -----
>> Subject: Re: [hpsdr] hardware question ( Mercury HPSDR)
>>
>>
>>> Hi,
>>>
>>> The basic shape of the noise looks OK but the base line is high - 
>>> have you calibrated PowerSDR against a known signal level?
>>>
>>> 73's Phil...VK6APH
>>>
>>
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