[time-nuts] GPSDO module connections
Hello, I am looking for the advise: what will be the better method to connect GPSDO module by short extension cable to put its antenna input on front or back panel ? Lets say, GPSDO module has female “F” connector. And I would like to have BNC connector on back panel of my project. Manufacturer of GPSDO recommend to use RG-59 cable for antenna connection. Is it OK if I'll take some RG-59 from CCTV, cut 6 or 12 of it, connect one end to GPSDO (let say this cable has compression type connector) and solder other end to BNC on the panel ? Or its better to use adapters and no soldering ? Like F connector-to-BNC adapter , then short BNC-to-BNC cable connected to BNC panel connector ? And other question: is it worth to use RF cable to connect 1PPS output from GPSDO to distribution amplifier ? Or regular AWG-22 could do that job ? Thanks ! -- WBW, V.P. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO module connections
RG-59 cable is fine but soldering wires is not a good idea for 1.6GHz. Use a panel-mount BNC crimp connector made for RG-59 such as the Amphenol 31-343-RFX. I presume you want to use regular 50 ohm BNC types rather than the 75 ohm variant. It is preferred to use coax for the 1 PPS as any reflections will degrade its risetime. Good luck, David On 3/3/14 1:01 PM, d0ct0r wrote: Hello, I am looking for the advise: what will be the better method to connect GPSDO module by short extension cable to put its antenna input on front or back panel ? Lets say, GPSDO module has female “F” connector. And I would like to have BNC connector on back panel of my project. Manufacturer of GPSDO recommend to use RG-59 cable for antenna connection. Is it OK if I'll take some RG-59 from CCTV, cut 6 or 12 of it, connect one end to GPSDO (let say this cable has compression type connector) and solder other end to BNC on the panel ? Or its better to use adapters and no soldering ? Like F connector-to-BNC adapter , then short BNC-to-BNC cable connected to BNC panel connector ? And other question: is it worth to use RF cable to connect 1PPS output from GPSDO to distribution amplifier ? Or regular AWG-22 could do that job ? Thanks ! ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO module connections
Is it OK if I'll take some RG-59 from CCTV, cut 6 or 12 of it, connect one end to GPSDO (let say this cable has compression type connector) and solder other end to BNC on the panel ? Or its better to use adapters and no soldering ? Like F connector-to-BNC adapter , then short BNC-to-BNC cable connected to BNC panel connector ? The fewer adapters the better, and it is best to avoid solder-type panel connectors entirely (if what you mean is a non-coaxial connection with the center conductor soldered to the center pin and the shield separated and attached to the panel or the connector body). Best to keep it coaxial all the way. So, the best solution would be a piece of RG-59 with a male F connector on one end and a female, rear-mounting, panel mount BNC on the other end. If you do not have the facilities to make up your own coaxial cables with crimp or compression terminations, there are a number of ebay vendors who will do it for very reasonable cost (or you may well find the pigtail cable you need already made). Alternatively, you could use a cable with a male F connector at one end and a male BNC at the other end, connecting to a female-to-female bulkhead connector at the panel. But that is one more connection, which is better avoided. One further consideration is whether the shield of the panel-mount connector should be galvanically connected to the panel, or insulated from it. If you have problems with ground loops, insulating it may help. If you do insulate it, the shield should be bypassed to the panel right at the connector with (for example) a 0.01uF capacitor paralleled by, say, a 1k ohm resistor. is it worth to use RF cable to connect 1PPS output from GPSDO to distribution amplifier ? Or regular AWG-22 could do that job ? The PPS signal has a tendency to leak everywhere because it is a short pulse with fast edges. If you bring it out of the box you definitely need to use coax. Good, quad-shielded coax. Really, you should use triaxial cable, but that is enough hassle that few people do it. If you don't have a pressing use for the PPS signal, it is best to leave it inside the box. You can mitigate the leakage by slowing down the edges, but that may compromise the utility of the pps by increasing jitter in the trigger circuitry of whatever you feed with it. If you bring the PPS out of the box, you will need to make sure it is properly terminated to preserve the pulse shape. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO module connections
It might also be worth noting that whilst manufacturers such as Trimble do recommend the use of RG59 or similar 75 ohm cable for GPS module antenna connections this is based on its lower loss compared with 50 ohm equivalents such as RG58. The connector itself on the GPS module, in most cases if not all, will still be a 50 ohm connector but it's considered that the lower cable attenuation will more than compensate for any mismatch effects. In overall cable loss terms it isn't going to make any difference whether 75 ohm RG59 pigtails are used for the internal connections or whether 50 ohm RG58 is used instead, it will just shift the position of the mismatch we're planning to ignore anyway:-) However, RG58 does tend to be better quality, particularly when it comes to the braided screen, some RG59 has a very open weave indeed, and this does generally make the RG58 easier to work with and might also ensure a more reliable connection. If it were me I would maintain the 50 ohms impedance within the unit and then switch to 75 ohms externally, assuming of course that's what I chose to do rather than stay with 50 ohms right through. Regards Nigel GM8PZR In a message dated 03/03/2014 19:42:38 GMT Standard Time, n1...@dartmouth.edu writes: RG-59 cable is fine but soldering wires is not a good idea for 1.6GHz. Use a panel-mount BNC crimp connector made for RG-59 such as the Amphenol 31-343-RFX. I presume you want to use regular 50 ohm BNC types rather than the 75 ohm variant. It is preferred to use coax for the 1 PPS as any reflections will degrade its risetime. Good luck, David On 3/3/14 1:01 PM, d0ct0r wrote: Hello, I am looking for the advise: what will be the better method to connect GPSDO module by short extension cable to put its antenna input on front or back panel ? Lets say, GPSDO module has female “F” connector. And I would like to have BNC connector on back panel of my project. Manufacturer of GPSDO recommend to use RG-59 cable for antenna connection. Is it OK if I'll take some RG-59 from CCTV, cut 6 or 12 of it, connect one end to GPSDO (let say this cable has compression type connector) and solder other end to BNC on the panel ? Or its better to use adapters and no soldering ? Like F connector-to-BNC adapter , then short BNC-to-BNC cable connected to BNC panel connector ? And other question: is it worth to use RF cable to connect 1PPS output from GPSDO to distribution amplifier ? Or regular AWG-22 could do that job ? Thanks ! ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO module connections
As a rule I'd say to minimize the number of connectors. The ideal is to use one long cable but you can't do that. Soldering to connectors is fine but it is really hard to do correctly with that double shielded cable. The compression fitting are very good and even water proof. I would use those. Custom cables that have the correct ends on them minimize the number of adapters. Note that there are TWO TYPES of BNC connectors, 50 and 75 ohm. Use whatever matches the cable you are using. Also think again if you really plan to connect and disconnect the antenna more then once every few years. A rubber grommet might be better than a BNC. It would save two connectors. All that said It may not matter at all, the antenna has an amplifier in it and you may have dBs to spare. Trimble even says in their manual that impedance mis matches between 50 and 75 oms don't matter. For the PPS it hardly matters if we are talking about a 12 to 18 inch cable. But if you are going 50 or 100 feet you want the coax AND you want to properly terminate it. On Mon, Mar 3, 2014 at 10:01 AM, d0ct0r t...@patoka.org wrote: Hello, I am looking for the advise: what will be the better method to connect GPSDO module by short extension cable to put its antenna input on front or back panel ? Lets say, GPSDO module has female F connector. And I would like to have BNC connector on back panel of my project. Manufacturer of GPSDO recommend to use RG-59 cable for antenna connection. Is it OK if I'll take some RG-59 from CCTV, cut 6 or 12 of it, connect one end to GPSDO (let say this cable has compression type connector) and solder other end to BNC on the panel ? Or its better to use adapters and no soldering ? Like F connector-to-BNC adapter , then short BNC-to-BNC cable connected to BNC panel connector ? And other question: is it worth to use RF cable to connect 1PPS output from GPSDO to distribution amplifier ? Or regular AWG-22 could do that job ? Thanks ! -- WBW, V.P. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
