low MHz connector design consultant
in [Design]
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From: Joerg on 30 Apr 2010 21:48 mpm wrote: > 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! > Actually I used RG-8 and RG-58 outdoors extensively, all with PL-259 connectors. But I applied the regular precautions like trying to seal stuff and preferably not running a cable in a way that rain water would creep towards the connector. I never had any coax go bad. Ok, one, but that was my own fault for not watching the SWR meter and running full bore into an antenna that had just burned out ... *PHOOMP* -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Michael A. Terrell on 30 Apr 2010 22:56 mpm wrote: > > Then again, many coaxes used with PL-259's aren't rated for outdoor > use in the first place! Well, it does date back to W.W.II which is the 'Model T' days for connectors. It was a simple design that could be assembled with few tools, and repaired quickly in the field by soldiers with little training. Those RG- coax numbers were military, as well. RG = "Radio Guide". -- Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge.
From: mpm on 30 Apr 2010 23:57 On Apr 30, 8:48 pm, Joerg <inva...(a)invalid.invalid> wrote: > mpm wrote: > > 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! > > Actually I used RG-8 and RG-58 outdoors extensively, all with PL-259 > connectors. But I applied the regular precautions like trying to seal > stuff and preferably not running a cable in a way that rain water would > creep towards the connector. I never had any coax go bad. Ok, one, but > that was my own fault for not watching the SWR meter and running full > bore into an antenna that had just burned out ... *PHOOMP* > > -- > Regards, Joerg > > http://www.analogconsultants.com/ > > "gmail" domain blocked because of excessive spam. > Use another domain or send PM.- Hide quoted text - > > - Show quoted text - Trust me on this: Many RG-type jackets are indeed water permeable. I know this as the former Vice President of Engineering for Pinnacle Towers (Now Crown Castle). We had over 10,000 tower sites and rooftops in inventory at one point (pre Ch-11), mostly in the US, but some in Canada and the UK as well. I'm pretty certain I've seen everything imaginable when it comes to coaxes and antennas. And the "fun" doesn't stop there: I've even seen the occasional dual Motorola Mitrek mobiles placed back to back to make a UHF repeater. For that matter, I once ran across a Motorola T1414 used as a crossband repeater with a GE Master Exec II 35-watt mobile. I've seen 9" continuous coax run 3 Class-C FM's (New Orleans). Pressurized with Freon, and then later, sodium hexaflouride (when Freon became unobtanium) I helped engineer the first ever 3-FM and 1 Full Power Analog TV (later DTV) on a single coax. (Fountain, FL) I was involved with the original HDTV tests in Charlotte (Ch-6, WCNC-36) and Washington DC (Ch-4, WRC) Then there's the 8 Class-C FM's (each 100kW, H&V) on a dual stack Harris panel antenna (St. Louis). Note: That later blew up (badly!) when they tried to add C-3 station #9. (I had since moved on.) More terrestrial microwave & uplink/downlink than I can remember. (Typically with quad-shield RG-6 - also not waterproof jacket) ....and more leaky RG-type cables, and even Andrew SuperFlex (both RF and water intrusion) than you can imagine. I've seen a few instances where the fire department had to be called to put out the transmitter, and cellular monopoles that collapsed (or bent badly), or caught on fire during tower re-strengthening attempts (i.e., welding structural sleeve or plate reinforcements.) Generally speaking, it is never a good day when the Fire Dept arrives. I think the worst installation I EVER came across - the Grandaddy of them all - was an AM station using (and I am NOT KIDDING!), sawed-off metal garden shovel parts used as their main AC power / genset disconnect! And believe it or not, this baby was a close tie for the entire town of Bayou Sale, LA. (Don't ever go there!!!) You are free to form your own opinions of course about the survivability (including UV protection) of RG-type cables. From direct experience over the course of many years, I probably can't be easily swayed. Even if the datasheets say otherwise. -mpm
From: krw on 30 Apr 2010 23:58 On Fri, 30 Apr 2010 18:39:21 -0700 (PDT), mpm <mpmillard(a)aol.com> wrote: >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.) "infinite length" <> "independent of length"
From: mpm on 1 May 2010 00:01
On Apr 30, 10:57 pm, mpm <mpmill...(a)aol.com> wrote: > On Apr 30, 8:48 pm, Joerg <inva...(a)invalid.invalid> wrote: > > > > > > > mpm wrote: > > > 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! > > > Actually I used RG-8 and RG-58 outdoors extensively, all with PL-259 > > connectors. But I applied the regular precautions like trying to seal > > stuff and preferably not running a cable in a way that rain water would > > creep towards the connector. I never had any coax go bad. Ok, one, but > > that was my own fault for not watching the SWR meter and running full > > bore into an antenna that had just burned out ... *PHOOMP* > > > -- > > Regards, Joerg > > >http://www.analogconsultants.com/ > > > "gmail" domain blocked because of excessive spam. > > Use another domain or send PM.- Hide quoted text - > > > - Show quoted text - > > Trust me on this: Many RG-type jackets are indeed water permeable. > I know this as the former Vice President of Engineering for Pinnacle > Towers (Now Crown Castle). > We had over 10,000 tower sites and rooftops in inventory at one point > (pre Ch-11), mostly in the US, but some in Canada and the UK as well. > I'm pretty certain I've seen everything imaginable when it comes to > coaxes and antennas. > > And the "fun" doesn't stop there: > I've even seen the occasional dual Motorola Mitrek mobiles placed back > to back to make a UHF repeater. > For that matter, I once ran across a Motorola T1414 used as a > crossband repeater with a GE Master Exec II 35-watt mobile. > I've seen 9" continuous coax run 3 Class-C FM's (New Orleans). > Pressurized with Freon, and then later, sodium hexaflouride (when > Freon became unobtanium) > I helped engineer the first ever 3-FM and 1 Full Power Analog TV > (later DTV) on a single coax. (Fountain, FL) > I was involved with the original HDTV tests in Charlotte (Ch-6, > WCNC-36) and Washington DC (Ch-4, WRC) > Then there's the 8 Class-C FM's (each 100kW, H&V) on a dual stack > Harris panel antenna (St. Louis). Note: That later blew up (badly!) > when they tried to add C-3 station #9. (I had since moved on.) > More terrestrial microwave & uplink/downlink than I can remember. > (Typically with quad-shield RG-6 - also not waterproof jacket) > > ...and more leaky RG-type cables, and even Andrew SuperFlex (both RF > and water intrusion) than you can imagine. > I've seen a few instances where the fire department had to be called > to put out the transmitter, and cellular monopoles that collapsed (or > bent badly), or caught on fire during tower re-strengthening attempts > (i.e., welding structural sleeve or plate reinforcements.) Generally > speaking, it is never a good day when the Fire Dept arrives. > > I think the worst installation I EVER came across - the Grandaddy of > them all - was an AM station using (and I am NOT KIDDING!), sawed-off > metal garden shovel parts used as their main AC power / genset > disconnect! > > And believe it or not, this baby was a close tie for the entire town > of Bayou Sale, LA. (Don't ever go there!!!) > > You are free to form your own opinions of course about the > survivability (including UV protection) of RG-type cables. > From direct experience over the course of many years, I probably can't > be easily swayed. Even if the datasheets say otherwise. > > -mpm- Hide quoted text - > > - Show quoted text - Oops - obviously meant so say "Sulpher Hexafloride" Probably got solar power on my mind... :) |