[NLRS] SMA launch connectors

[Baker, Donn B]

Hi John,
Yup... its a problem.

First, get a large hammer.  Next, ....

Actually, its relatively simple, and you have the right idea. You'll have to make it fit.

First, get the cheapest GOLD PLATED on they have for 0.062 board.  Should be about $6. Stop at the hobby store, or a really good hardware store, and get piece of K&S copper (or brass) sheet (4x10x0.025 or so) or copper strip (1x12x0.025 or so). Don't go too thin (less than, say 0.010), or too thick (I'd guess >0.032 is to thick... hard to work with).

Cut off the BOTTTOM two legs flush with the body.  The distance from the bottom of the center pin to the bottom of the body is ~0.110.  That's REAL close to the thickness of the PC + heat spreader.  Solder the connector to the board (center pin and TOP legs).  Take a 1" long piece of the copper/brass strip and lay it on the bottom of the heat spreader so that it overlaps the body of the connector (which is only 0.060 wide).  Solder.  Obviously, you'll need a good sized gun. iron, etc.  The spreader will take a lot of heat.  Clean the spreader well, use rosin flux, etc.  This will support the connector much better than just the top legs, and it will also carry the RF ground from the connector to the bottom spreader.

Now, you'll note that this will cause a "bump" of ~0.025 at each end of the heat spreader, which will make mateing to the heat sink a minor problem.  Milling/cutting out a small pocket on the heat sink shouldn't be a problem.

Good luck.

73 Donn
WA2VOI/0

> -----Original Message-----
> From: nlrs-bounces at mailman.qth.net
> [mailto:nlrs-bounces at mailman.qth.net]On Behalf Of tosca005
> Sent: Monday, April 10, 2006 1:09 PM
> To: nlrs at mailman.qth.net
> Subject: [NLRS] SMA launch connectors
>   
> Hello, all.
> 
> If necessary, I'll guess and/or improvise.  But I figured I 
> might as well
> make at least one attempt to use the "right" part for the job. . .
> 
> I need to install two SMA launch connectors on a PyroJoseph 
> 60 watt power
> amplifier board (pulled from a Spectrian 180 watt amplifier 
> that used three
> of them.)  The instructions he provides say that the board 
> will mate up to
> "a standard SMA or N launch connector", and that's about it on that
> subject.  I figured that "standard" was "standard", and it would be
> reasonably easy to find the parts I needed.
> 
> The parts listings at Digi-Key are surprisingly less helpful 
> than I would
> have expected.
> 
> They list part numbers: (Digi-Key / Johnson Components)
>   J502-ND / 142-0701-801 Gold plated   0.062" board thickness
>   J716-ND / 142-0701-806 Nickel plated 0.062" board thickness
>   J629-ND / 142-0711-821 Gold plated   0.062" board thickness
>   J657-ND / 142-0701-881 Gold plated   0.031" board thickness
>   J658-ND / 142-0701-851 Gold plated   0.062" board thickness
>   J630-ND / 142-0701-841 Gold plated   0.042" board thickness
>   J610-ND / 142-0701-871 Gold plated   0.062" board thickness
>   J631-ND / 142-0721-881 Gold plated   ??     board thickness
> 
> They also list a bunch of part numbers in the range of J797-ND through
> J807-ND that are also board edge launch connectors, but they 
> provide no
> description of how they differ from one another or from the 
> other parts
> listed above.  On these, I tried looking directly on the 
> Johnson Components
> web site, and the "Johnson Part Numbers" listed by Digi-Key 
> are not found
> on the Johnson web site.
> 
> These listings come from "Catalog Page 294" on the Digi-Key web site,
> augmented with some information obtained from the Johnson 
> Components web
> site.
> 
> Further adding to my dilemma is that the board plus its 
> integral copper
> heat spreader are 0.100" thick (according to my digital 
> caliper), which
> appears to be too thick for any of the parts listed for which I can
> determine the design's board thickness design rating.
> 
> If you've put one or more of these boards into service, what 
> did you use
> for SMA connectors?  Did you have to hack up some of the copper heat
> spreader or bend the SMA "legs" to make it fit, or did you 
> find a part that
> is actually made for this board thickness, or . . . ?
> 
> Thanks in advance.
> John (W0JT)
> 
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