Re: Low cost coax connectors
- From: Jeff Liebermann <jeffl@xxxxxxxxxx>
- Date: Sat, 27 Oct 2007 11:29:49 -0700
Joerg <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> hath wroth:
Jeff Liebermann wrote:
On Fri, 26 Oct 2007 21:24:44 GMT, Rich Grise <rich@xxxxxxxxxxx> wrote:
How about those coaxial, "power" types, like this?
(mind the wrap)
http://www.radioshack.com/product/index.jsp?parentPage=search&pg=3&summary=summary&cp=&productId=2103612&accessories=accessories&kw=plugs&techSpecs=techSpecs¤tTab=techSpecs&custRatings=custRatings&sr=1&features=features&origkw=plugs&support=support&tab=summary
You might have to modify the plug and socket a bit, and impedance might be
interesting...
That will probably work fine until someone plugs a live AC wall wart
into the plug and vaporizes your radio. I think they call that an
"attractive nuisance" or "warranty magnet".
Can be remedied by a wee component: A series capacitor :-)
Too easy. I thought this was a low cost design, where every extra
component saved is important. I've seen designs with DC on the
antenna jack in order to save the cost of the capacitor. However, the
power jack as an antenna connector does present another problem. If
the antenna is part of the FCC type certification, the FCC sometimes
requires a "unique" coax connector to prevent users from substituting
the antenna and violating the type certification. The reason I say
"sometimes" is that there have been various rulings and variances that
allow the use of not so unique connectors or connectors that were at
one time unique, but are now commonly available. Anyway, using the
power jack as a coax connector would certainly not qualify as unique
as one could easily obtain one at Radio Shock. Same problem with the
3.5mm earphone jack.
Incidentally, don't forget to perform the basic antenna field test.
That's where the customer grabs the unit by the antenna and swings it
around while walking. It's a very common problem with HT's (handie
talkies) and seems to be spreading to wi-fi wireless access points and
other devices with rubber duckie antennas. If the connect can't
support the unit when held by the antenna, it will fail this all
important field test.
About 25 years ago, my employer embarked on yet another bean counting
cost reduction adventure. Someone decided that all the coax cables
connectors going between boards was too expensive. So, I contrived a
stamped, board mounted, receptacle. That by itself wasn't very
interesting as those were already being sold by AMP. I eliminated the
coax plug by simply tinning the coax cable braid and the center wire.
We were using RG188a/u, which is the PTFE dielectric version of
RG174a/u. Cut the end off squarely and remove the outer jacket. Tin
the outer braid being carful not to let the braid bluge. Then run it
through a rotary blade stripper to trim the tinned braid to length,
expose some dielectric, and strip the center conductor. Tin the
center conductor, trim, and you have the world's cheapest coax plug.
<gasp> Oh man, I haven't gone that far yet...
Well, you asked for something cheaper than an RCA phono connector pair
and tinning the coax is certainly cheaper.
--
Jeff Liebermann jeffl@xxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.
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