[DSP-10] DSP-10 C203-C219—Feed-through capacitors

[Courtney Duncan]

The way I read Figure 11., the ferrite beads went on the wiring on the 
inside of external connectors J205, J206, and J211-J213, two each.  I 
did not put any on the feedthroughs to the DSP box, C203 - C219, either 
on the inside or on the outside.

I have a couple of not-very-good pictures of this on my website

http://home.earthlink.net/%7Ejccool3/dsp10.html

Scroll down to the two pictures between February 24 and February 26, 
2005 text entries.  These are reduced in size in the web page 
representation, but in my browser I can right click on the image, select 
"View Image", then when the image is the whole view, the cursor becomes 
a "+" which will magnify it so much that it doesn't entirely fit on my 
screen.  In this huge view, I can see one of the ferrites on one of the 
yellow coaxes in the middle and around the power inputs at the upper 
left on the top picture.  In the bottom picture you can see a bead 
around each of the coaxes, one on the BNC and one on the "TX Out" (red) 
phono jack.

This was the only way to put the beads that I had around the coaxes that 
I had.  I wound each power lead through each ferrite twice because I 
could and this would lead to more isolation.  I think it is best to have 
these ferrites as near the wall / connector as possible.  I think mine 
ended up being trapped there by the wiring arrangement in the final 
assembly and if I had thought there would be a problem with them staying 
put, I would have tacked them with a little RTV, but I don't think I 
thought or did this.

By the way, the rat's nest of internal interconnects pictured is not 
well made up.  Most of the DSP-10s built on this list (I bet) have well 
bundled and routed harnesses, such as those pictured in QST, which is 
generally a better approach, and which I would recommend.

ve3ytz at sympatico.ca wrote:

> Greetings to the group
> 
> I am in the process of constructing the PC-board box and looking down the line I see I have to mount some feed-through capacitors. There are some ferrite beads that also come into play. In the Oct 1999 QST article describing the DSP-10 project, Bob wrote:
> 
> In some cases,there are bypasses right where a connector
> is mounted and ferrite beads are placed over the connecting wires. These beads are shown in Figure 11, the interconnection
> schematic. It is best to err on the side of extra shielding and filtering than having to add parts later on.
> 
> I must admit it is not very clear to me how these beads should be mounted: are they just loose and and hang between the PC box and the connecting wire, or are they soldered /glued? The fit is very snug, but they will pop off. Are the beads on the outside of the PC-box or inside or are they both side (inside and out)? 
> 
> I have searched through the discussion forum (found nothing) and looked closely at a number of pictures (including the said QST article) and it isn't clear to me how this is done.
> 
> As always, I appreciate the help.
> 
> 73
> 
> Greg/VE3YTZ
> 
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