Why don’t VHF/UHF radios and antennas have N connectors?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KG4DYN, Dec 6, 2018.

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  1. WB5WPA

    WB5WPA Ham Member QRZ Page

    re: "Consider a typical ge or Motorola uhf repeater,"

    Interstage, inside these units, one finds "RCA phono plugs" in use too!

    Also, some of the Heathkits in past years utilized the venerable RCA phone plug as the "antenna connector" ...
    AI3V likes this.
  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Those RCA connectors are really quite good as RF connectors, the only downside for antenna connectors is the lack of screw or bayonet locking mechanisms but electrically they're quite good.
    KC8VWM likes this.
  3. WB5WPA

    WB5WPA Ham Member QRZ Page

    re: "Those RCA connectors are really quite good as RF connectors"

    I know; We even "TDR'd" them at Heathkit, and were pleasantly surprised ...
  4. WB5WPA

    WB5WPA Ham Member QRZ Page

    I wonder if you have noticed, as we have seen when running that particular Motorola duplexer, certain parts of the cable harness on the xmit side getting warm? Indicative of a mismatch and it manifests itself, it seems, with observable dissipation of RF energy as 'heat' in the coaxial cable harness and connectors ...
  5. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    The old ceramic dielectric ones that were popular from "the beginning" through the 1970s were amazingly good up through UHF.

    Unfortunately, most of them "today" are imports with an unidentifiable plastic dielectric and not nearly as good at VHF-UHF -- although at HF I think they're fine.
  6. W1GHD

    W1GHD XML Subscriber QRZ Page

    For what it's worth, some EF Johnson VHF mobiles do have an N connector.
  7. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    Collins Radio Company was the first major manufacturer to use the RCA connector as the r.f. output connector starting with the 32S-1 / 32S-2 in 1958 and then the KWM-2 / KWM-2A in 1959. Heath copied Collins in using the RCA as the r.f. output connector.

    Motorola and General Electric used the RCA connector extensively all the way to at least the 450 MHz band and Motorola even used that connector in some of the 960 MHz equipment. For many years, both Motorola and GE used the UHF series connectors for the r.f. output on their 450 MHz equipment.

    I have related this numerous times before:

    During the 1960s and well into the 1970s, the two major employers, here in Richardson, Texas, were Texas Instruments and Collins Radio Company. This resulted in a large number of amateur radio operators being employed by both companies. There was an operator who also was an engineer employed in the Texas Instruments r.f. laboratory. This operator kept making fun of the fact that Collins used the RCA connector for the r.f. output on the S-Line and KWM-2- series equipment. Finally, several Collins employees challenged him to prove that the RCA connector was a poor choice and the TI engineer accepted the challenge.

    The TI engineer acquired a large number of RCA, UHF, BNC, and Type "N" connectors and started testing those connectors on all amateur bands from 1800 kHz all the way to 1296 MHz. These tests were made in the TI r.f. laboratory using the best test equipment available.

    Several days later, the TI engineer came back, hat in hand, and announced the results of his tests. The UHF connectors (SO-239 / PL-259) were fine up through the 6-meter band and were marginal on 2-meters. On 70 cm those connectors started to show some significant problems (i.e. as was shown by the test referenced earlier - "SWR" starting to go high) and at higher frequencies were unacceptable. However, the BNC, Type "N", and the lowly RCA connectors all passed, with flying colors, all the way through 1296 MHz. Probably, all of these connectors would go much higher in frequency but the TI engineer did not make any tests above 1296 MHz.

    For most amateur radio applications through the 70 cm band, the UHF connectors perform satisfactorily and they are definitely less expensive than the Type "N" connector. My Motorola "B" amplifier, which uses a single 4CX250B tube, that I use on the 70 cm band, has a Type "N" connector for the output. It does have an RCA connector for the input!

    motorola linear-1.JPG

    The Type "N" output is on the other side.

    Glen, K9STH
  8. G3YRO

    G3YRO Ham Member QRZ Page

    Yes, but so are some PL259 connectors . . . the ones that have a barrell like on a BNC plug.

    But anyway . . . several rigs for the British market (like the Yaesu FT100) come fitted with a PL259 for the HF antenna, but an N Type for the VHF/UHF antenna.

    Roger G3YRO
  9. AI3V

    AI3V Ham Member QRZ Page

    I never noticed.

  10. W6KCS

    W6KCS Ham Member QRZ Page

    I think a lot of it is that hams are more familiar with the PL-259, and might be a little intimidated by the N connector.

    As far as waterproofing goes, when most people think of waterproofing, they are probably thinking of the rubber that is clamped around the cable jacket, but the part I like best about the N is the rubber washer in the plug that keeps water from entering the connector through the threads. It's easy to seal up the connector body where it meets the cable jacket, but harder where the threads mate at the base of an antenna, so I like having the gasket at that point.
    KC8VWM likes this.

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