Let me make it perfectly clear that when I said INSERTION LOSS is less than 0.25 dB I did not say it would be anything like -0.25 dB for most connector pairs. Old gold plated connectors may have insertion losses that are less than 0.025 dB at 300 MHz. When dealing with high power applications where SWR may vary during tune-up of automatic antenna couplers there is a type H connector which can handle PIVs of 3,000 volts. Good RCA phono connectors use ceramic insulation and are a very low loss when coax shields are properly soldiered all around them. Network analysis arms used to use hermaphrodite (sexless) connectors at their ends. They were made by General Radio, which has been out of business for years. They just pushed together, rather than being screwed. They had polystyrene insulation. A network analysis station is not designed to handle high power when making RF loss tests. It is designed to make tests at low power levels. such as when testing rotary joints, fixed and variable attenuators, PIN diode attenuators, switches, etc. All of these tests can be made at low power levels. The RCA phono connectors were not initially designed for RF but they were selected for reasons other then being cheap. It is interesting that the 75 ohm Type F connector that feeds your TV sets has low loss and flat bandwidth. It is cheap, solderless and easy to crimp on to coax. The 75-ohm coax used has a solid center conductor wire that becomes the center pin of the connector. You can tell if a technician is a microwave technician. If so, his or her his fingers will be either raw or callused, depending on how many years he or she has spent screwing connectors. 73, W2ILP (Insertion Loss Professional)
I made similar tests several decades ago and confirmed my long held belief that the old wives tales were exactly that. And if swapping out a pl259 for a N connector helps you sleep at night more power to ya. Those of us who know better won't change a thing.
What I find interesting is that they do not make PL-259 connectors for hardline cable like AVA5-50 or even FSJ4-50b. They only make N and DIN. Why do you suppose that is?
Yes! An example being the massive 'Cigar Lighter' receptacle still being fitted in cars even though none of us can afford cigars any more....and whatever equipment you want to run from it has to be fitted with that great big clunky badly-made plug that never fails to fall out or break off just as you start to make that longed-for contact with the ISS !
Very interesting! I wonder if: a) homebrew copper plating the PL-259 / SO-239s would extend their efficiency further up the frequency range b) how silver plated ones would compare with the nickel-alloy plated ones you used in the experiment.
The "cigar lighter" is another excellent example of manufacturers resistance to change. Like the UHF connector, the cigar lighter "worked" for its original, intended purpose. It still "works" as a DC connector, but there are certainly better alternatives. A secure, RELIABLE DC connection is NOT its best quality. To quote post #5 regarding UHF connectors: "Connectors are reasonably lossless. The problem arises when they loosen and/or oxidize (which is inevitable). Then you --may--suffer from intermod, which can raise the noise floor. Each additional connector decreases the mean time between failures, and increases the probability of increased intermod noise. That's why people don't use 30 connectors" The PL-259 is very difficult to install correctly, and is inherently prone to a poor electrical connection due to the mechanical mating scheme of the shield. There are certainly better alternatives for it, also.
I guess its not "good enough" for that application. If you use quality feedline, why install a junk connector when much better ones are available?
Unfortunately, that is discontinued. So the only two options are N and DIN. So why discontinue the UHF connector if loss is minimal and the N type is not superior?
FSJ4-50B offers better flexibility than the standard LDF4-50, which makes it useful for short microwave jumper cables. I used a couple feet of it between a 5760MHz transverter and a prime focus dish feed. N connectors, of course, as UHF doesn't work up there. In fact, those N connectors designed to solder on similar to UHF connectors don't work up at 6GHz either. Products get discontinued because the demand falls off to the point where you can't sell full production runs. Inventory taxes penalize businesses that try to carry an inventory of useful products that don't have a high demand. Looks like someone figured out that they would make more money by discontinuing products.
Jim's videos are excellent, he's a great mentor for new hams as well as more experienced. Jim has a refreshing common sense approach to ham radio topics!
