[hpsdr] Hermes/ANAN-10 RX spurious signals?

[Dick Lichtel]

Using a bit of brass to make a 2" deep shield placed in the slot above 
the Hermes board reduces the 10MHz signal to about S3. The shield has to 
be grounded.

I fashions a smaller piece to fit precisely over the 10MHz area of the 
board  and that reduced the signal to about an S3, however with this 
attempt had holes for the the 3 jumper to fit thru, so they were  not 
covered.This shield also has to be grounded.

I then  covered the jumpers  with foil tape (grounded to the shield) and 
the signal was reduced to  less than S1.

I am using double sided tape for an insulator between the brass and the 
board ( I'm not sticking the tape to any components). I am using a thin 
piece of brass shim material from ACE hardware. The shim material is 
easy to work with since it can be cut with scissors or an knife.

Now that I know what the shape of the shield needs to be, it should be 
easy to use a piece single sided PCB as well.

Once I get this cleaned up, I'll see if the same approach will work on 
the 25MHz oscillator.

Dick KD4JP

On 11/12/2012 6:17 AM, Bruce Beford wrote:
> Thanks, Dick.
> I am glad you have had a chance to experiment with this a bit. I won't be
> able to work with mine for a week. Please keep us posted on your
> progress/observations.
> 73,
> Bruce, N1RX
>
> ________________________________________
> From: Dick [mailto:dick221z at gmail.com]
> Sent: Sunday, November 11, 2012 10:11 PM
> To: Bruce Beford
> Cc: hpsdr at lists.openhpsdr.org
> Subject: Re: [hpsdr] Hermes/ANAN-10 RX spurious signals?
>
> Since the position of the Hermes board in the case seems to affect the 10MHz
> spur, I tried putting the Hermes back in position and sliding bit of
> shielding over the A/D  area, about 1/2 spacing above, not grounded. This
> reduced the 10MHz spurs by about 2 S units. So it looks  like some shielding
> is needed over the analog section.
>
> I'll look into making something more practical that can be grounded later on
> in the week.
>
>
>
>
>


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