low MHz connector design consultant
in [Design]
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From: Jan Panteltje on 30 Apr 2010 19:05 On a sunny day (Fri, 30 Apr 2010 12:58:48 -0700) it happened John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in <15dmt55o7eom6860il9q0hfil1a80h4uvd(a)4ax.com>: >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 I have never used those, I use SMA, BNC. That is a very nice board, but I do not like those IC sockets, I prefer the turned ones. I have had plenty of bad contacts with that sort of IC sockets. Oxides I suppose, my old Epson R460 inkjet as example.
From: Paul Keinanen on 30 Apr 2010 19:29 On Fri, 30 Apr 2010 10:00:44 -0700, Joerg <invalid(a)invalid.invalid> wrote: >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. The main problem with the "UHF" PL-259 connector is that moisture will enter quite easily into the cable. With standard BNC/TNC/N connectors, this is not so much an issue. With UHF connectors, the reflection coefficient is reasonable in the whole VHF range and even partially in the lower end of the UHF range.
From: John Larkin on 30 Apr 2010 20:48 On Fri, 30 Apr 2010 16:43:54 -0400, Spehro Pefhany <speffSNIP(a)interlogDOTyou.knowwhat> wrote: >On Fri, 30 Apr 2010 11:54:23 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>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 > >You got one of these things to check them out with? > >http://cp.literature.agilent.com/litweb/pdf/5990-5271EN.pdf > >I wonder how long the sales guys would lend one for... might be fun. No, I'm using an old 11802/SD24 TDR rig. But we do have a 40 GHz sampling head for it, 1 THz equivalent-time sample rate, so I'm still theoretically ahead of the $200K Agilent monster. And my scope doesn't run Windows! Hey, the rental rate on the Agilent, with a couple of probes, would run about $25K a month. I can buy a nice 11801 and an SD24 for a tenth of that, and get TDR for free. John
From: mpm on 30 Apr 2010 21:30 On Apr 30, 6:29 pm, Paul Keinanen <keina...(a)sci.fi> wrote: > On Fri, 30 Apr 2010 10:00:44 -0700, Joerg <inva...(a)invalid.invalid> > wrote: > > > > > > >John Larkin wrote: > >> On Fri, 30 Apr 2010 09:41:13 -0700, RST Engineering > >> <jwei...(a)gmail.com> wrote: > > >>> On Fri, 30 Apr 2010 06:54:29 -0500, "mook johnson" <m...(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. > > The main problem with the "UHF" PL-259 connector is that moisture will > enter quite easily into the cable. With standard BNC/TNC/N connectors, > this is not so much an issue. > > With UHF connectors, the reflection coefficient is reasonable in the > whole VHF range and even partially in the lower end of the UHF range.- Hide quoted text - > > - Show quoted text - Then again, many coaxes used with PL-259's aren't rated for outdoor use in the first place!
From: mpm on 30 Apr 2010 21:39
On Apr 30, 4:31 pm, Wimpie <wimabc...(a)tetech.nl> wrote: > On 30 abr, 13:54, "mook johnson" <m...(a)mook.net> wrote: > > > > > > > "John Larkin" <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote in message > > >news:ql9kt5tg7s7e5q7pb460gcdig4r00jjmrj(a)4ax.com... > > > > On Thu, 29 Apr 2010 18:30:41 -0500, "mook johnson" <m...(a)mook.net> > > > 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 > > > > There are so many military connectors, including ones for wild > > > environments, hermetic, etc, some standard part might work. > > > > 20 MHz isn't very demanding. Most any mil connector will be "matched" > > > to any impedance at 20 MHz. Wavelength is 15 meters! > > > > John > > > The connector I need goes into environments that far exceed military > > applications but the physical concept is similar. We have an in-house > > connector company that makes these connectors for us but they have never had > > to deal with never greater than >200KHz signals before. 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. > > > There are some commercial plastic connectors that tested very well (just to > > validate our test setup) with good impedance match/stability (+/- 5%) and > > low insertion loss (.1dB/connector) but they won't take the environment.. > > > I'm looking for a consultant that can provide either of the following > > > 1) model a connector that is already designed but not made (basically review > > the in-house company proposed design) and simulate the high frequency > > response of the design. > > > 2) Give direction for the connector design based on constraints of material > > choices, physical size and geometry to meet the desired electrical signal > > characteristics while withstanding the environmental conditions. > > > The cut and try approach based on simple equations has a long cycle time. > > I'm looking to improve my chances of getting it right the first time. > > Hello Mook, > > When you have already a company that knows mechanical design and > reliability issues, you only need the EM-field guy. When you can > keep the mechanical guys and the EM-field guy in one room, this should > converge to a solution fast. > > One familiar with the concept of characteristic impedance, complex > propagation constant (contains both complex epsilon and permeability) > and know how to measure the material constants can do the job. > > What about: required Return Loss, characteristic impedance, Insertion > loss, propagation delay, size, cross section, (coaxial, square, > symmetrical, etc), peak and average power, etc? > > Kind regards, > > Wim > PA3DJSwww.tetech.nl > when you delete abc first, PM will reach me- Hide quoted text - > > - Show quoted text - I have a question for you: Do you believe that the characteristic impedance is dependent on the length of the coax? (For the ratio of transverse electric field to transverse magnetic field launched on a transmission line of infinite length.) -mpm |