[S&DWS] Foundation Course Material in PDF Format
Sheffield & District Wireless Society /////////////////////////////////////////// Foundation Course Material in PDF Format Posted: 18 Aug 2017 04:04 AM PDT http://sheffieldwireless.org/2017/08...in-pdf-format/ PDF File versions for the Foundation Course Fslide01-Introduction and Registration Fslide02-Nature-of-Amateur-Radio Fslide03-Safety Fslide04-Licence-Conditions Fslide05-Transmitters-and-Receivers Fslide06-Propagation Fslide07-Feeders-and-Antennas Fslide08-EMC Fslide09-Technical-Basics Fslide09-Technical-Basics Fslide10-Repeaters-and-CTCSS |
[S&DWS] Foundation Course Material in PDF Format
In message , S&DWS via
rec.radio.info Admin writes Sheffield & District Wireless Society /////////////////////////////////////////// Foundation Course Material in PDF Format Posted: 18 Aug 2017 04:04 AM PDT http://sheffieldwireless.org/2017/08...in-pdf-format/ PDF File versions for the Foundation Course Please may I offer one correction: In 'Antennas & Feeders', the information about BNC connectors, you are warned "Take care not to mix incompatible 50 and 75 Ohm versions which have different inner pin sizes". This is NOT totally correct. While the profile of the pins are slightly different (the 50 ohm usually has a somewhat stubbier point), the diameters are the same. The difference in characteristic impedance is achieved by the amount of PTFE dielectric. As a result, you CAN physically mate 50 and 75 ohm BNC connectors (both sexes). -- Ian |
[S&DWS] Foundation Course Material in PDF Format
On 19/08/2017 09:32, Ian Jackson wrote:
Sheffield & District Wireless Society /////////////////////////////////////////// Foundation Course Material in PDF Format Posted: 18 Aug 2017 04:04 AM PDT http://sheffieldwireless.org/2017/08...in-pdf-format/ PDF File versions for the Foundation Course Please may I offer one correction: In 'Antennas & Feeders', the information about BNC connectors, you are warned "Take care not to mix incompatible 50 and 75 Ohm versions which have different inner pin sizes". This is NOT totally correct. While the profile of the pins are slightly different (the 50 ohm usually has a somewhat stubbier point), the diameters are the same. The difference in characteristic impedance is achieved by the amount of PTFE dielectric. As a result, you CAN physically mate 50 and 75 ohm BNC connectors (both sexes). This is far too technical for a 'training scheme' that produces Fulls who have to ask the question "USB/LSB? I'm confused!". -- Spike |
[S&DWS] Foundation Course Material in PDF Format
In message , Spike
writes On 19/08/2017 09:32, Ian Jackson wrote: Sheffield & District Wireless Society /////////////////////////////////////////// Foundation Course Material in PDF Format Posted: 18 Aug 2017 04:04 AM PDT http://sheffieldwireless.org/2017/08...aterial-in-pdf -format/ PDF File versions for the Foundation Course Please may I offer one correction: In 'Antennas & Feeders', the information about BNC connectors, you are warned "Take care not to mix incompatible 50 and 75 Ohm versions which have different inner pin sizes". This is NOT totally correct. While the profile of the pins are slightly different (the 50 ohm usually has a somewhat stubbier point), the diameters are the same. The difference in characteristic impedance is achieved by the amount of PTFE dielectric. As a result, you CAN physically mate 50 and 75 ohm BNC connectors (both sexes). This is far too technical for a 'training scheme' that produces Fulls who have to ask the question "USB/LSB? I'm confused!". Don't worry - I can also confirm that both impedances of BNC connectors are totally compatible with both USB and LSB. -- Ian |
[S&DWS] Foundation Course Material in PDF Format
"Ian Jackson" wrote in message ... In message , S&DWS via rec.radio.info Admin writes Sheffield & District Wireless Society /////////////////////////////////////////// Foundation Course Material in PDF Format Posted: 18 Aug 2017 04:04 AM PDT http://sheffieldwireless.org/2017/08...in-pdf-format/ PDF File versions for the Foundation Course Please may I offer one correction: In 'Antennas & Feeders', the information about BNC connectors, you are warned "Take care not to mix incompatible 50 and 75 Ohm versions which have different inner pin sizes". This is NOT totally correct. While the profile of the pins are slightly different (the 50 ohm usually has a somewhat stubbier point), the diameters are the same. The difference in characteristic impedance is achieved by the amount of PTFE dielectric. As a result, you CAN physically mate 50 and 75 ohm BNC connectors (both sexes). when I was newly licensed and poor I used 75 ohm TV coax and belling lee connectors on HF and got away with it ....... |
[S&DWS] Foundation Course Material in PDF Format
In message , Jimbo
writes "Ian Jackson" wrote in message ... In message , S&DWS via rec.radio.info Admin writes Sheffield & District Wireless Society /////////////////////////////////////////// Foundation Course Material in PDF Format Posted: 18 Aug 2017 04:04 AM PDT http://sheffieldwireless.org/2017/08...aterial-in-pdf -format/ PDF File versions for the Foundation Course Please may I offer one correction: In 'Antennas & Feeders', the information about BNC connectors, you are warned "Take care not to mix incompatible 50 and 75 Ohm versions which have different inner pin sizes". This is NOT totally correct. While the profile of the pins are slightly different (the 50 ohm usually has a somewhat stubbier point), the diameters are the same. The difference in characteristic impedance is achieved by the amount of PTFE dielectric. As a result, you CAN physically mate 50 and 75 ohm BNC connectors (both sexes). when I was newly licensed and poor I used 75 ohm TV coax and belling lee connectors on HF and got away with it ....... For 43 years, my day job was cable TV - so I've rarely used anything other than 75 ohm coax! Some cable TV trunk coax used to be (as one of my bosses put it) "as thick as a horse's prick". Unfortunately, it was not too convenient for home use. But as for BNC connectors, they are essentially the same as the innards of 50 ohm N-connectors. You can mate a female BNC with a male 50 ohm N. However, note that you can't inter-mate 50 and 75 ohm N-connectors, as the 75 ohm has a much thinner pin. A 50 ohm female in a 75 ohm male won't make contact (unless you put a bit of wire inside the female receptacle). A 50 ohm male fully mated with a 75 ohm female will splay the receptacle, and cause usually permanent damage. -- Ian |
[S&DWS] Foundation Course Material in PDF Format
On 19/08/2017 09:32, Ian Jackson wrote:
This is NOT totally correct. While the profile of the pins are slightly different (the 50 ohm usually has a somewhat stubbier point), the diameters are the same. The difference in characteristic impedance is achieved by the amount of PTFE dielectric. An interesting snippet, Ian, thanks. Perhaps time to remind all that BNC is Bayonet-Neill-Concelman and not Bayonet Navy Connector, as M3s and M6s past and present and other similar CBers maintain. |
[S&DWS] Foundation Course Material in PDF Format
On 19/08/2017 09:52, Ian Jackson wrote:
Spike writes On 19/08/2017 09:32, Ian Jackson wrote: Sheffield & District Wireless Society /////////////////////////////////////////// Foundation Course Material in PDF Format Posted: 18 Aug 2017 04:04 AM PDT http://sheffieldwireless.org/2017/08...aterial-in-pdf -format/ PDF File versions for the Foundation Course Please may I offer one correction: In 'Antennas & Feeders', the information about BNC connectors, you are* warned "Take care not to mix incompatible 50 and 75 Ohm versions which have* different inner pin sizes". This is NOT totally correct. While the profile of the pins are slightly* different (the 50 ohm usually has a somewhat stubbier point), the* diameters are the same. The difference in characteristic impedance is* achieved by the amount of PTFE dielectric. As a result, you CAN physically mate 50 and 75 ohm BNC connectors (both* sexes). This is far too technical for a 'training scheme' that produces Fulls who have to ask the question "USB/LSB? I'm confused!". Don't worry - I can also confirm that both impedances of BNC connectors are totally compatible with both USB and LSB. I doubt knowing that would help the woodentop Full. -- Spike |
[S&DWS] Foundation Course Material in PDF Format
On 19/08/2017 10:34, Jimbo wrote:
sexes). when I was newly licensed and poor I used 75 ohm TV coax and belling lee connectors on HF and got away with it ....... And it was standard on 145MHz. (QQV03-10 anyone?) |
[S&DWS] Foundation Course Material in PDF Format
In message , Jeff writes
However, note that you can't inter-mate 50 and 75 ohm N-connectors, as the 75 ohm has a much* thinner pin. A 50 ohm female in a 75 ohm male won't make contact (unless you put a bit of wire inside the female receptacle). A 50 ohm male fully mated with a 75 ohm female will splay the receptacle, and cause usually permanent damage. The 50 & 75 ohm BNCs that I have in front of me at the moment have identical pin dimensions. Also the spec sheets on Amphenol's website show the pins as being the same dimension. Are there any drawings? If so, do they show the 50 ohm pin being somewhat 'bull-nosed', while the 75 is more pointed - and the differences in the PTFE dielectric 'sleeve'? -- Ian |
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