Shield the reclocker unit or not?

Oli · 28th June 2004, 11:08 PM

My current DAC project:

CS8412 receiver
Kwak Asynchronous reclocker
AD1865N-K DAC
OPA627 I-V conversion (I like this- I know some do not)

Whilst doing a PCB design I have the opportunity to shield the entire reclocker circuit (crystal, coils, flip-flops etc.) using a steel rf shielding can from Farnell.

My question...

Should I do it?

Can anyone give provide reasons for or against shielding the circuit?

BrianL · 28th June 2004, 11:25 PM

I don't think it would hurt as one wants to keep digital hash
out of the analog.

Oli · 29th June 2004, 12:09 AM

Thanks for your opinion- I share this view, although there are folk out there who believe shielding is a bad thing (NVA amplifiers)

Andypairo · 29th June 2004, 10:21 AM

Do it, I had some troubles with RF emissions from the canned oscillator I used in the ASR of my last DAC...

Cheers

Andrea

Pitch254 · 30th June 2004, 01:46 PM

Prefferably use cupper and or tinned metal. Steel doesn´t shield much when it concerns mHz or higher frequencies.

Jocko Homo · 1st July 2004, 07:55 PM

Old copper-clad works good.

I would build it without it......and use a TV set as a cheap spectrum anaylser to see how much it really radiates.

Wouldn't hurt to leave room on the PCB if it does............

Jocko

Elso Kwak · 1st July 2004, 09:32 PM

Quote:

Originally posted by Jocko Homo
Old copper-clad works good.

I would build it without it......and use a TV set as a cheap spectrum anaylser to see how much it really radiates.

Wouldn't hurt to leave room on the PCB if it does............

Jocko

Hi, I would shield it as Jocko does recommend.
I could receive the reclocker to back in the garden on my Walkmen. And I have a deep garden!

Oli · 1st July 2004, 10:50 PM

Jocko, Elso and others...

Thanks for your recommendations. With my prototype I see an inteference pattern whilst watching TV! The reclocker also serves as a powerful r.f. transmitter. It seems all agree that shielding is a good thing. The r.f. boxes from Farnell are steel with a solder coating, making them easy to solder. I suppose I should solder all the way along the joint with the PCB to ensure good screening and ensure a short ground loop (as per Guido Tent's ideas).

Fact: Steel is magnetic

and does not conduct as well as copper.

Q. Would copper really offer a significant improvement, since a drop-in solution is readily available in steel?

Ideally I should try both copper and steel, but the box will be soldered all the way along the joints, making it nearly impossible to remove from the PCB.

Jocko Homo · 1st July 2004, 10:59 PM

But your clock.

The harmonics of the SPDIF usually are not strong enough to see on a TV set. But the clock harmonics are. Try using coax for the clock feed, and see what happens. Bypass the DC coming into the unit, as the DC lines can also radiate clock harmonics.

Jocko

Oli · 1st July 2004, 11:27 PM

Just reading an interesting link on TNT-Audio...

Wood is good!

Clearly wood is no good for a reclocker box, but perhaps I should avoid steel and build a copper box?

More work!

28th June 2004, 11:08 PM	#1
Oli diyAudio Member Join Date: May 2003 Location: London	Shield the reclocker unit or not? My current DAC project: CS8412 receiver Kwak Asynchronous reclocker AD1865N-K DAC OPA627 I-V conversion (I like this- I know some do not) Whilst doing a PCB design I have the opportunity to shield the entire reclocker circuit (crystal, coils, flip-flops etc.) using a steel rf shielding can from Farnell. My question... Should I do it? Can anyone give provide reasons for or against shielding the circuit? __________________ Oli

28th June 2004, 11:25 PM	#2
BrianL diyAudio Member Join Date: Mar 2002 Location: USA	I don't think it would hurt as one wants to keep digital hash out of the analog. __________________ bel

29th June 2004, 12:09 AM	#3
Oli diyAudio Member Join Date: May 2003 Location: London	Thanks for your opinion Thanks for your opinion- I share this view, although there are folk out there who believe shielding is a bad thing (NVA amplifiers) __________________ Oli

30th June 2004, 01:46 PM	#5
Pitch254 diyAudio Member Join Date: Nov 2003 Location: The Netherlands	Shield Prefferably use cupper and or tinned metal. Steel doesn´t shield much when it concerns mHz or higher frequencies.

1st July 2004, 10:50 PM	#8
Oli diyAudio Member Join Date: May 2003 Location: London	A drop-in solution is available in steel! Jocko, Elso and others... Thanks for your recommendations. With my prototype I see an inteference pattern whilst watching TV! The reclocker also serves as a powerful r.f. transmitter. It seems all agree that shielding is a good thing. The r.f. boxes from Farnell are steel with a solder coating, making them easy to solder. I suppose I should solder all the way along the joint with the PCB to ensure good screening and ensure a short ground loop (as per Guido Tent's ideas). Fact: Steel is magnetic and does not conduct as well as copper. Q. Would copper really offer a significant improvement, since a drop-in solution is readily available in steel? Ideally I should try both copper and steel, but the box will be soldered all the way along the joints, making it nearly impossible to remove from the PCB. __________________ Oli


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29th June 2004, 10:21 AM	#4
Andypairo diyAudio Member Join Date: Sep 2002 Location: near Milano , Italy	Do it, I had some troubles with RF emissions from the canned oscillator I used in the ASR of my last DAC... Cheers Andrea

1st July 2004, 07:55 PM	#6
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	Old copper-clad works good. I would build it without it......and use a TV set as a cheap spectrum anaylser to see how much it really radiates. Wouldn't hurt to leave room on the PCB if it does............ Jocko

1st July 2004, 10:59 PM	#9
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	Probably not the reclocker....... But your clock. The harmonics of the SPDIF usually are not strong enough to see on a TV set. But the clock harmonics are. Try using coax for the clock feed, and see what happens. Bypass the DC coming into the unit, as the DC lines can also radiate clock harmonics. Jocko

1st July 2004, 11:27 PM	#10
Oli diyAudio Member Join Date: May 2003 Location: London	Interesting link Just reading an interesting link on TNT-Audio... Wood is good! Clearly wood is no good for a reclocker box, but perhaps I should avoid steel and build a copper box? More work! __________________ Oli

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