low MHz connector design consultant
in [Design]
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From: Joerg on 30 Apr 2010 13:00 John Larkin wrote: > On Fri, 30 Apr 2010 09:41:13 -0700, RST Engineering > <jweir43(a)gmail.com> wrote: > >> On Fri, 30 Apr 2010 06:54:29 -0500, "mook johnson" <mook(a)mook.net> >> wrote: >> >> . We tried using our >>> regular connectors for this application and the impedance mismatch and >>> insertion loss were extreme at 5 - 20MHz. The Zo mismatched by 50% and was >>> not stable above 1MHz and had several resonant modes. Insertion loss >>> something on the order is 6dB/connector and we'll have a couple dozen in >>> series on this line. The number of series connection is the is the rub and >>> it is unavoidable, non negotiable. >> A PL-259 will do that, y'know. >> >> Jim > > At 1 MHz, an ordinary wall plug and outlet has excellent specs. > Actually, ye olde PL-259 as well. It used to be called the shielded banana-plug. I have used these up to >100MHz and under 30MHz at over a kilowatt. Up to 100W I even used 1/4" phono plugs and the VSWR didn't move one bit. For the PL-259 you could get very rugged ones, gold plated and with ceramic inner body. This was in my ham radio days. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: John Larkin on 30 Apr 2010 14:54 On Fri, 30 Apr 2010 09:43:06 -0700, RST Engineering <jweir43(a)gmail.com> wrote: >On Thu, 29 Apr 2010 20:42:20 -0700, Robert Baer ><robertbaer(a)localnet.com> wrote: > > >> An RCA phono type connector is almost good enough, a BNC certainly fits. > > >RCAs work quite well up to about 100 MHz. > >Jim BNCs are pretty good at 6 or 7 GHz. I just did sampling head, TDR step 8" sma coax sma-BNC male BNC female-SMA 8" sma coax other channel of head and got a pretty decent step response with 52 ps rise time, using the cheapest Jameco sma-bnc adapters on the planet. John
From: Jan Panteltje on 30 Apr 2010 15:50 On a sunny day (Fri, 30 Apr 2010 10:00:44 -0700) it happened Joerg <invalid(a)invalid.invalid> wrote in <840gm6Fnk8U2(a)mid.individual.net>: >Actually, ye olde PL-259 as well. It used to be called the shielded >banana-plug. I have used these up to >100MHz and under 30MHz at over a >kilowatt. Up to 100W I even used 1/4" phono plugs and the VSWR didn't >move one bit. > >For the PL-259 you could get very rugged ones, gold plated and with >ceramic inner body. This was in my ham radio days. I use them today, a lot: http://panteltje.com/panteltje/pic/swr_pic/swr_box_rear_img_0976.jpg
From: mpm on 30 Apr 2010 15:53 On Apr 29, 10:42 pm, Robert Baer <robertb...(a)localnet.com> wrote: > mook johnson wrote: > > Gents, > > > I looking for a consultant that can assist in the design of a custom > > military style connector with controlled characteristic impedance and > > insertion loss between two terminals in the 1MHz - 20MHz frequency range. > > > This connector is special because is the application so an off the shelf > > component will not work. > > > Any leads where I can start looking for such a consultant? > > > thanks > > Am a bit confused; just because an application is special does not > mean that a special connector needs to be mickey moused. > Doesn't everyone absolutely *hate* it when a maker of a widget > purposely with malice and forethought design something that cannot be > fixed or repaired unless the user treks back to the evil maker? > An RCA phono type connector is almost good enough, a BNC certainly fits.- Hide quoted text - > > - Show quoted text - I don't know if it applies in this circumstance, but.... You do know that the FCC REQUIRES special connectors on Part-15 equipment (low-power, unlicensed) if the device has user replaceable antennas? Right? And by "special connector", it is meant types that are not commonly avaialble to consumers for purchase -- though over time, this definition has always been a moving target. See the first paragraph of FCC Rule 15.203. Link: http://www.gpo.gov/fdsys/pkg/CFR-2009-title47-vol1/pdf/CFR-2009-title47-vol1-part15.pdf Several years ago, the FCC released an update of what it now considers to be user available. Of course, the directive is forward-looking only, so if you're already manufacturing something that uses a connector formerlly considered "special", and is now commonplace, you are free to continue flooding the market with devices using those older connectors. In other words, this whole Part-15 notion of special connectors isn't really well thought out. (Big shocker there!). Some manufactuers go overboard of course, and specify a connector so esoteric (perhaps unique only to them), that they will never run afoul of Part-15, even has periodic updates occur. This allows them to freely standardize on a specific connector -- which in some markets, and on some products, is an advantage in the marketplace. -mpm
From: John Larkin on 30 Apr 2010 15:58
On Fri, 30 Apr 2010 19:50:09 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Fri, 30 Apr 2010 10:00:44 -0700) it happened Joerg ><invalid(a)invalid.invalid> wrote in <840gm6Fnk8U2(a)mid.individual.net>: > >>Actually, ye olde PL-259 as well. It used to be called the shielded >>banana-plug. I have used these up to >100MHz and under 30MHz at over a >>kilowatt. Up to 100W I even used 1/4" phono plugs and the VSWR didn't >>move one bit. >> >>For the PL-259 you could get very rugged ones, gold plated and with >>ceramic inner body. This was in my ham radio days. > >I use them today, a lot: > http://panteltje.com/panteltje/pic/swr_pic/swr_box_rear_img_0976.jpg I'm a great fan of SMBs. They are small, easy to mate and unmate (no screwing around!) and are almost as good as SMAs for speed. ftp://jjlarkin.lmi.net/DSC01786.JPG There are tons of SMB cables on ebay, too. John |