[DSP-10] Mixers under the board

[Ron Meiring]

Hi Courtny,

Thanks for the confirmation and the links.
Must have read it some about the ground problem with the mixers, but 
could not find it any more.
Thanks for that Courtny.

Documentation is very chaotic.
I have seen that with many good engineers ... Hi.
I am just a new guy on the block, bought my DSP10 6 weeks ago.
Smoke test is done, and tests are looking good so far.
Waiting on new IC for U7 (got it in upside down...)

Keep my fingers crossed .....

73 Ron VK6KDD

On Sat, 02 Apr 2005 22:40:18 +0000, Courtney Duncan wrote:
>Ron,
>
>Mounting the mixers under the board is a good thing and is
>recommended
>for "new kit construction" at the diagnostic page
>
>http://www.proaxis.com/%7Eboblark/u15_mod.htm
>
>When I got to this step in my post-assembly testing (see
>
>http://home.earthlink.net/%7Ejccool3/dsp10.html
>
>at 2005 March 10)
>
>I did not want to take the board out of the box and risk the mixer
>by
>removing and reinstalling it, so I just did the ground-braid mod.
>In
>the process I got the part so hot that I could smell it, but it
>still works.
>
>By the way, I don't really understand the explanation for the
>problem
>that I fixed with this test.  It says that phase noise from the
>19.68
>MHz oscillator gets into the mixer washing out everything upstream.
>How
>come phase noise from the mixer doesn't just go through the
>amplifier
>chain and cause the problem anyway then?  I can see how other hash
>inside the box could get onto the mixer, however, and the extra
>grounding did yield the expected improvement in my case, so it is in
>fact a lot quieter now.
>
>Good luck as you continue,
>
>Courtney, n5bf/6
>
>
>
>From: Ron Meiring <rmeiring at iinet.net.au>
>Date: Mon, 21 Mar 2005 05:38:59 +0800
>To: Yamamoto Jiro <jyamamoto at katch.ne.jp>
>Subject: Re: DSP10 question
>X-Mailer: PocoMail 2.63 (1077) - Licensed Version
>
>To all replying to this topic.
>
>Thank you for the ideas and tips on how to remove the IC.
>I decided to sacrifice the IC, because I don't rely on them after
>removal. (and the value of the board is more than the component ...)
>
><snip>
>
>I mounted the Mixers under the board, had the feeling that this 
would
>give better isolation and grounding to the mixer ... Any feedback
>here ?
>
>
>
>
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