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Date: Mon, 25 Mar 2002 08:45:13 +1200
From: Ron ZL1TW <ron_w at clear.net.nz>
Subject: Re: [Elecraft] 1SV149 mounting question
To: Rod N0RC <rod at n0rc.com>
Cc: Elecraft <elecraft at mailman.qth.net>

Hi Rod,
           I had the same concern, so to give me peace of mind I cut a 
small strip off a 5 thou steel feeler gauge, inserted it between the legs 
of the diode,and gently held the top down against the gauge while I 
soldered the legs. My reasoning being....5 thou  ain't much of a gap, but I 
knew I had a gap....just in case.
Be it the right or wrong method, or even nescessary, it seems to have 
worked anyway.
Cheers.....Ron ZL1TW

At 12:46 PM 3/24/02 -0700, you wrote:
.........<snip>........<snip>.....
>I'm concerned about the center lead of the diode, cut flush to
>the diode body, forming a bridge bridge between the PCB pads for
>the others lead.
>......<snip>......
>73, Rod N0RC
>Ft Collins, CO

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Reply-To: "Don Wilhelm" <w3fpr at peoplepc.com>
From: "Don Wilhelm" <w3fpr at peoplepc.com>
To: "Rod N0RC" <rod at n0rc.com>,
        "Elecraft-list" <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] 1SV149 mounting question
Date: Sun, 24 Mar 2002 19:32:57 -0500

Rod and all,
This has come up before several times, and the response from Elecraft seems
to be - put the diodes right down to the board - the mask on the RF board is
tough and is sufficient to prevent a short.

OTOH, if you want to space them up just a tad (like a few thousanths of an
inch) I would not think it to be a problem, but don't park them off the
board by any significant distance.  The thickness of a couple of pieces of
20# paper should not hurt (20# paper is about 0.002 inches thick).

73,
Don Wilhelm  - Wake Forest, NC   W3FPR home page: http://www.qsl.net/w3fpr/
  QRP-L # 485   K2  SN 0020   mailto: w3fpr at arrl.net

*** Life is what happens when you're making other plans -- Mike Cross  ***

----- Original Message -----
>
> "Install type 1SV149 diodes .... Keep them flat against the PC
> board, with no excess lead length."
>
> I'm concerned about the center lead of the diode, cut flush to
> the diode body, forming a bridge bridge between the PCB pads for
> the others lead.
>

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From: "Rod N0RC" <rod at n0rc.com>
To: "Elecraft-list" <elecraft at mailman.qth.net>
Cc: <ron_w at clear.net.nz>, <n4so at juno.com>,
        "Don Wilhelm" <w3fpr at peoplepc.com>
Subject: Re: [Elecraft] 1SV149 mounting question
Date: Mon, 25 Mar 2002 07:36:20 -0700

Thanks all who have responded so far.

Some have mentioned that the solder mask will protect things. Not
likely, the solder mask does not cover the pads on top of the PCB. See
figure below.



           #####
           #   #  <- diode body
           #####     U = lead trimmed flush to diode body
           | U |
      ____=|=_=|=____ "__" = Solder mask, "===" = solder pad
      *****|***|***** <- PCB
           |   | <--diode leads (2)

If the mechanical tolerances are not exact and proper the trimmed lead
"U" may bridge the gap between the pads "=". The pad edges do no
appear to be protected by solder mask.

I think for personal piece of mind I'll lift the part off the board
such that the trimmed lead is off the board a few thousands of an
inch.

NOT DON'T ALL GET CONCERNED THAT THIS IS A BIG PROBLEM, I'M SURE
THINGS ARE FINE. I tested each diode with a ohmmeter, no shorts were
found with the diodes mounted per Elecraft instructions. I am
personally looking for an EXTRA measure of reliability. (I once worked
as a manufacturing engineer for commercial and military avionics
equipment. It is indigenous for me to worry about such small detail
;-)

73, Rod N0RC
Ft Collins, CO

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