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Coax Loss vs Connector Loss

Discussion in 'Amateur Radio News' started by VK6FLAB, Mar 15, 2018.

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  1. K7JEM

    K7JEM Ham Member QRZ Page

    But I think the UHF connector is just not that "bad". So, manufacturers will be unwilling to change to something else that is just not clearly superior in most ways.

    I think the TNC connector is the way to go, at least on LMR equipment. But at frequencies below 450MHz or so, there just isn't a real clear advantage, when all things are considered. In my experience, I have had more problems with mechanical problems with mini-UHF connectors (percentage wise) than their big brothers. I just don't see anyone gaining a huge advantage, or even a small one, by switching connectors used on equipment that operates at VHF or lower frequencies. Probably equivalent to shortening the feedline by 5 inches, just won't be seen.
     
    N8EKT and NL7W like this.
  2. KR3DX

    KR3DX Ham Member QRZ Page

    Attitudes like this are EXACTLY why manufacturers still use UHF connectors on ham equipment. They don't want to hear the whining and crying from people who want to keep on using what they are used to using, people who make excuses like "it's not that bad", or "it's good enough".
     
  3. K7JEM

    K7JEM Ham Member QRZ Page

    But the truth is that it isn't that bad, and it is good enough. If no noticeable improvement can be had, why change things?

    And it's not just ham equipment. It is almost all LMR mobile equipment used on VHF, and a lot of it used on UHF. The truth is, there is really nothing wrong with the connectors when used at these frequencies, and at power levels up to 100 watts or more. Up to more than 1500 watts at HF.
     
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  4. KR3DX

    KR3DX Ham Member QRZ Page

    By your own admission in your post #41, the mechanical mating of the UHF and Mini-UHF connectors IS INFERIOR to the other connectors (TNC) that YOU prefer. To quote W1YW in post #5 "The problem arises when they loosen and/or oxidize (which is inevitable). Then you --may--suffer from intermod, which can raise the noise floor". The other problem with the UHF series is its total lack of weather resistance. I think that noticeable improvement can be made, and this is enough reason to change things. BOTH of these problems are solved by N connectors and they are good to at least 12 GHz. Wouldn't it be nice if ALL ham gear used one type of RF connector that would have a constant impedance and minimal loss at ALL frequencies, and would be weather resistant when used in outdoor applications like fixed station or mobile antennas? Wouldn't it be nice if we didn't have to worry about the number of connectors in our antenna feed systems because they have a constant 50 ohm impedance and mechanically and electrically reliable contacts that don't rely on the torque of the locking ring? How about a connector for which you don't have to make excuses?
     
    Last edited: Mar 20, 2018
  5. KM1H

    KM1H Ham Member QRZ Page

    The PL-259 connector is fine when properly crimped or soldered by a well trained installer. Some of my soldered ones, (indoor or out) are well on their way to 40 years in use.

    Silver plated BNC's are at the top of my list for intermittents.

    Heath used the RCA type on the SB-200 input and is the first thing I toss in favor for a SO-239 or "good" BNC.

    Carl
     
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  6. DF5VAE

    DF5VAE Premium Subscriber QRZ Page

    Interestingly, "UHF" connectors (Amphenol 83-1SP) have slightly less insertion loss at 450 MHz than type N (UG-21D/U) connectors do.

    I've measured both many times.

    But going above 500 MHz, Type N, as well as C, BNC-TNC-SMA etc. are a better match and lower loss.[/QUOTE]


    Well, I eliminated PL259 & SO239 long time ago - may be they are ok for DC up tp 100MHz or so, but measurable mismatch (even if small losses are measurable with a good NA)
    Properly assembled N-connectors are better -
    However I have seen many N-connectors poorly assembled - and their quality and tolerance highly depends on their manufacturer -
    Proper N connectors are good to 18 GHZ - but lousy ones may have poor performance on upper UHF bands.
    Still prefer to minimise number of connectors as it avoids losses.
     
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  7. K1FBI

    K1FBI Ham Member QRZ Page

    Don't worry, sooner or later you'll make the connection.;)
     
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  8. K7JEM

    K7JEM Ham Member QRZ Page

    What you say is essentially true, however, there is a lot of inertia built into connector choice and usage. The PL259 connector is somewhat more robust that a type N connector, and that counts for a lot. If you install connectors outside, you will do a good job of weatherproofing them anyway, whether it be a PL259 or a type N connector. That weatherproofing will also prevent the connector from coming loose. These connectors have been successfully used for decades. For the most part, people don't have problems with them.

    The TNC would be a good choice for LMR and other situations where the attaching cable is primarily RG58 size, since those connectors are readily available. However, RG214 cable will put an unusual stress on TNC or BNC connectors, so you don't see them used a lot on base station equipment, where RG213/214 size cables are the norm. So, type N connectors are used a lot on modern base station equipment, but SO239's are predominant on VHF mobile equipment. The center pins on both the male and female type N connectors are more subject to breakage, due to their construction. I think that may be a primary reason that the UHF connectors are so popular.
     
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  9. AK4QR

    AK4QR XML Subscriber QRZ Page

    love the L4B's in the back ground
     
  10. KK6FTD

    KK6FTD XML Subscriber QRZ Page

    NL7W, N9PBD, WA7PRC and 2 others like this.

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