ZS6BKW 80 M help

Discussion in 'General Technical Questions and Answers' started by K7HN, Jun 8, 2019.

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  1. W5DXP

    W5DXP Ham Member QRZ Page

    Is there no local amateur radio club where you could obtain some help from an elmer? With the help of an elmer with an antenna analyzer, the dimensions of your ZS6BKW system could be adjusted to obtain no-tuner resonance at the choke on 40m and maybe 20m with those same dimensions.
    K7HN likes this.
  2. KD5RKO

    KD5RKO Ham Member QRZ Page

    What is a good source for these doorknob capacitors?
    If I do all the mods for this antenna, I would need 44.5 pf, 104 pf, 128 pf, 700 pf 920 pf
    I did some looking around with not much success. Will other types of caps work for this? Power will always be 100W or less in my setup.
  3. K7HN

    K7HN XML Subscriber QRZ Page

    Thank you again for your assistance on this. Because of my current disability situation, I totally agree. I’m going to look at getting not only the analyzer but a matching system installed into the system as well. So that will be my first addition to my ham shack LOL! That’s no joke! That’s the first one LOL thanks for recommending the MFJ.

    Thank you for sharing what you did! I don’t have anything like that in my shack yet (just a radio, power supply antenna and 2 computers. Thanks. I’ll look into it.

    What do you think of the ICOM AH4 and since I already have an ICOM 7300 it should work really slick. Especially with the Cord provided for the rear of the radio as well as memory tuning it sounds like a nice workaround for me until I can get up and make the changes that you have taken such an incredible amount of your time to help me with. And believe me I’m very grateful for it!

    Would plug right into my 7300, make things not so difficult as most things would be done automatically. Any suggestions there my friend? Because of your great pictures you’ve helped explain exactly what to do. I’ll get that done once I can be mobile again.
  4. W7CJD

    W7CJD Ham Member QRZ Page

    ceramic transmitting capacitors:

    eBay UK

    Max Gain Systems

    ICA Manufacturing

    High-Power RF Capacitors

    RF Parts

    Allied Electronics

    Dan's Small Parts?

    ..any ceramic transmitting capacitor will do?

    W5DXP, What are the requirements?
    K7HN likes this.
  5. K7HN

    K7HN XML Subscriber QRZ Page

    I’m thinking what I’ll do is the first addition I’ll make to my ham shack after the radio/power supply/antenna will hopefully just be an analyzer/matching system for now since The extra coax didn’t work. I learned from it though... and learning is what this is all about.

    I’m going to try the ICOM AH4 as it’ll plug right into my radio and he’ll with the impedance mismatch automatically. Any thoughts on that work around?
  6. K7HN

    K7HN XML Subscriber QRZ Page

    Not sure if I asked you this yet my friend and I appreciate so much you putting so much time into this thread. You were the one that did the research on the door knob capacitor into the ZS6BKW what an incredible resource you are and a great help you are to many of us. Thank you.

    What do you think about in the meantime, since I can’t climb my roof, Using the ICOM AH4 Antenna matching system? I know it won’t work as well as correcting the problem as your capacitor does, but in the meantime it appears as though it would be a great workaround in the meantime until I can get up on my roof and would be great for field day operations to it seems.

    Thanks again and 73!

  7. K7HN

    K7HN XML Subscriber QRZ Page

    Because I’m brand new into this, I haven’t joined the radio club yet. I will though. Check out my previous post about the ICOM AH4. It seems like it essentially would “plug-in play“ into my 7300. Any thoughts on that my friend?
  8. W7CJD

    W7CJD Ham Member QRZ Page

    Congratulations, K7HN on you new callsign.

    ..getting better SWR will only "placate" the transmitter.

    My questions are to the other respondents.

    I know some answers, however my only communication method is Q&A. (I have dysphasia, in the long list of neurological impairments after injury.)

    I am eager to see answers to the questions, here, because the K7HN's dilemma is typical:

    1. purchase antenna, the antenna does not perform as advertised, why not?

    2. not correctly deployed?

    3. coax length? need better antenna tuner?
    (what is better? why?)

    4. SWR is not the answer? How much SWR is too much, even if handled by the tuner?

    5. Adding a big amplifier is not quite the correct answer?

    6. Capacitors?

    I wish I could explain it, however "new communications" are in my disability rating report severe category.

    I understand the amount and placement of the "current" in the antenna provides the RF transmission we seek.

    If someone can do better, please do so.

    The antenna does not perform as advertised is an almost universal problem, and too many licensed radio amateurs throw money at the problem, and then, after a time quit.
    Last edited: Jun 9, 2019
    K7HN likes this.
  9. K7HN

    K7HN XML Subscriber QRZ Page

    This is very well stated my friend! Thank you for the congratulations! I’m very grateful for the call sign.

    I think the only way to get through the problem for me at least at this point is by using an external tuner to be able to make it work. I’m very grateful that it works on so many bands as it does. It’s just that sometimes we want more than what we originally hoped we would have. I need to remember that myself sometimes too.

    I’m thinking a tuner is the way to make it work for getting 75 and 80 m. Hopefully, that will take care of things.

    If people want to keep the conversation going, no worries from my end LOL!!
  10. W7CJD

    W7CJD Ham Member QRZ Page


    I am not at all convinced you will get a better transmit.

    I understand it, the capacitor moves the maximum current point on the antenna to a more favorable location on the band.

    ..and this provides the better SWR at the desirable location you seek on the amateur radio band from the antenna, rather than applying "a fix" from an "antenna tuner" for what the transceiver "sees".

    The "antenna tuner" isn't applying the change to the maximum current point at the transmit point on the 80-meter band antenna.

    re: W5DXP, The capacitor does that job, without adversely affecting the other bands transmit frequencies "higher up" the antenna.


    Is this a good explanation?
    Last edited: Jun 9, 2019

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