Rebuilding R-390A Power Supply Caps. Step by Step With Photos

Discussion in '"Boat Anchor" & Classic Equipment' started by KC8VWM, Apr 16, 2016.

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  1. W9GB

    W9GB Ham Member QRZ Page

    IF you are cutting that low on the old "FP" style electrolytic can capacitor, THEN use painter masking tape (build-up equivalent of that "lip") to "level" the small pipe cutter.
    KC8VWM, KC4DYM and AF6LJ like this.
  2. KC8VWM

    KC8VWM Ham Member QRZ Page

    I sent this video of the "almost" fully restored R-390A to shortwave radio station WTWW as an attachment in an email.

    This video was originally intended as a signal report.

    A short time later after making and sending in this video, I was hearing the radio announcer (Ted Randall) talking about this video recording I made on the air.

    I guess he really liked this radio, because he was telling everyone on the air about this video I sent in. I should have recorded his response.

    It's a funny feeling to hear your name and callsign being broadcast over a 100,000 watt shortwave radio station. :)

    Last edited: Jul 31, 2016
  3. AF6LJ

    AF6LJ Ham Member QRZ Page

    Your video's settings are set to private.
  4. KC8VWM

    KC8VWM Ham Member QRZ Page

    Guess I didn't hit "publish" ooops. :) lol...
  5. AF6LJ

    AF6LJ Ham Member QRZ Page

    Nice, you get them better than I do. :)
  6. KC8VWM

    KC8VWM Ham Member QRZ Page

    Of course you already know it's all about the antenna. :)

    The R-390A is connected to this 170 foot long trapless "flat top" EDZ at around 55 feet off the ground.

    It works everything from 160m -10m

    AF6LJ likes this.
  7. AF6LJ

    AF6LJ Ham Member QRZ Page

  8. KM1H

    KM1H Ham Member QRZ Page

    How long is the OWL and is the VP critical to the length? What sort of VSWR does it have.....I dont use tuners and Im going to be needing something simple for 160-20 on another bench soon.
  9. KC8VWM

    KC8VWM Ham Member QRZ Page

    This antenna requires a tuner but works well from 160 through 10m. It can be used with the R-390A as an exceptional SWL receiving antenna with out any antenna tuner at all.

    This is a horizontally polarized, broadside collinear antenna array.

    Element wavelength is .64 at it's design frequency of 7.175 mhz.

    599/Freq in Mhz = .64 wavelength.

    The VSWR is less than 1.5:1 between 7.100 - 7.250

    The antenna elements are center fed in phase using a section of 450 ohm transmission line which functions as a matching stub. Then it terminates into a 1:1 balun at the feed point where it's fed with 50 ohm coax cable.


    40m dimensions using 12-16 AWG bare wire. (These dimensions work well from 160-10m with an antenna tuner)

    Elements each side = 86' 4.9"
    450 ohm matching stub section = 14' 4.3"

    Final tuning is achieved by trimming the matching stub length.

    Total antenna length is 172' 9.8" and not everyone has the room for one of these, but if you don't have a Yagi for 40m, then this is the next best thing. Exhibits approx. 3 dB gain over a dipole at it's design frequency. Pattern and take off angle on 40m is optimal when installed at approx. 50' above the ground and it breaks DX pileups on 40m like crazy without working a sweat. :)

    It's a very good performing NVIS antenna on both 80 and 160m simply because it's a long antenna. Easy to tune with an antenna tuner and demonstrates good bandwidth characteristics.

    During A/B comparisons, it's typically about 2 S-Units down from a Mosley "Classic" Tribander when used on the 10m band.
    Last edited: Aug 6, 2016
    KM1H likes this.
  10. W2VW

    W2VW Ham Member QRZ Page

    Not long enough ago and not far enough away I worked overnights in an industrial park.

    Had an R-390A for entertainment.

    I found out that a square loop of THHN on the ground, broken in center of one side, hooked to TV twinlead made a fantastic receiving antenna .Used about 1,000 feet of wire before I stopped increasing the thing.

    All the nearby crud was reduced and one could hear lots of great stuff across the pond on lower H.F. and M.W.
    KC8VWM likes this.

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