1
$\begingroup$

I have purchased a high quality ZS6BKW from the U.K. I have it suspended up about 40' between 2 trees. There is 30' of coax from the ladder line to the radio (Kenwood TS-870).SWR on the MFJ269 shows below 1.5 from 80m all the way up to 10m. SWR on the radio shows below 1.5 too.

However, I cannot hear anything on any band. Nothing whatsoever. On 40m I get some voice VERY faint on 7.070.00 and 7.095.00. As far as I have read on google I can use any length of coax from the ladder line (which is a specific length) to the radio.

Any ideas?

| improve this question | |
$\endgroup$
  • $\begingroup$ Please look at the information at the bottom of G3TXQ's G5RV page. "An antenna 93ft long fed with 39.8ft of 400 ohm ladderline (Vf=0.9) provides a reasonable match on five bands." Are the dimensions of your antenna and feedline the same? Regardless, there is something very wrong if the SWR is low across the entire HF band! It indicates very high losses. Do you have a link to a website that describes this antenna? $\endgroup$ – Mike Waters♦ Feb 7 at 15:51
  • 1
    $\begingroup$ Yeah, because you know what else has a very low SWR across all the HF frequencies! (Yes, it’s a dummy load) $\endgroup$ – Scott Earle♦ Feb 9 at 2:42
  • 1
    $\begingroup$ Have you tried a different antenna? The problem could be in your radio, or propagation could be really bad. If you haven't, try something simple like a dipole cut for 20m. $\endgroup$ – rclocher3 Feb 11 at 0:17
  • $\begingroup$ Here is the link to the antenna ebay.com/itm/HF-ZS6BKW-Multi-Band-Antenna/… $\endgroup$ – Danny Mar 2 at 9:44
4
$\begingroup$

I have a homemade ZS6BKW antenna so I might be able to provide some insight, even though I've only used it for a few weeks now. I get good reception on 40m and 20m with it (when conditions are favorable), and have not spent much time on the other bands. No tuner except for the built-in one on the IC-7300. With it in a less-than-ideal inverted V formation, and with my QTH laying between mountains in Colorado, USA, I've still reached Antarctica and Australia on WSPR, and around North America on FT8 and SSB.

The first thing that makes me think something is wrong is that you're seeing a 1.5:1 SWR on 80m. The ZS6BKW is not an 80m antenna without a tuner. Mine shows 5.5:1, and the "standard" design should be north of 4:1 unless you've got some relay-controlled stuff going on. I think you're seeing some kind of fake resonance (akin to a dummy load), unless perhaps your feedline is resonant which is also not good. You also should see very, very high (> 5:1) SWR on 60, 30, and 15m. If you're seeing low SWR on those bands, I guarantee you something is wrong with the antenna or your feedline.

I would recommend picking up a NanoVNA and adapters or some other antenna analyzer. You should see clear dips below 3:1 for 40, 20, 17, and 12m, with part of 10 and 6m bands covered, and a slight dip for 80m that would require a tuner.

If you do see the proper dips in SWR, and you've tested your feedline, then I would try doing something like WSPR and see who reports you on the other bands, or trying to reach a friend at an agreed upon time and frequency, or tune in to a nearby WebSDR to listen for yourself.

If it helps, here is what the NanoVNA shows as SWR for my ZS6BKW antenna, as measured at the feedpoint, when I was in the process of trimming it (it was a little long here for 20m). Notice the 80m dip on the far left edge of the chart is about 6:1 (each horizontal line is about 1 SWR with the bottom edge being 1:1). ZS6BKW NanoVNA

Edit: I missed from your question that the MFJ-269 is an antenna analyzer, I assumed it was some kind of inline SWR meter in the shack. I would confirm with it that you have high SWR at the feedpoint on 80/60/30/15, and that you do not have a short (low-Z). I think it might be possible that a short at the end of the ladder line where it meets the dipole legs might result in a false low SWR reading, but someone with more experience with antenna modeling might be able to confirm or deny that.

| improve this answer | |
$\endgroup$
  • 1
    $\begingroup$ Thank you for the reply. I understand the antenna much better now from your explanation. Turns out the (brand new) coax was defective. I replaced it and checked again as you suggested. Now it works perfectly. $\endgroup$ – Danny Mar 2 at 9:57
  • $\begingroup$ @Danny Great to hear! Since I posted this a few weeks ago, I've made FT8 contacts as far away as Indonesia and Belarus. I'm still not impressed with the noise floor of this antenna for SSB, but I don't have any others to compare it to, just comparing it to videos I've seen on YouTube and how quiet their noise floors are with other antennas. Might try rigging up a simple 20m dipole soon to compare. But it works fine for digital modes and CW for me. 73! $\endgroup$ – Paul Mar 2 at 16:41
  • $\begingroup$ I am experiencing the same noise floor level. 73's $\endgroup$ – Danny Mar 3 at 18:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.