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CB Whip vs Double Bazooka: 10M WSPR experiment

Discussion in 'Ham Radio Discussions' started by KM1NDY, Oct 12, 2021.

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  1. KM1NDY

    KM1NDY Ham Member QRZ Page

    I did a goofy little experiment with my CB whip vs. a 10M double bazooka dipole antenna to see if I could make out any difference between them. Both antennas had rather poor SWR for 10M. The CB whip is resonant at 12M**, and between 5 and 10 across 10M.

    [​IMG]

    The vertically hung double bazooka had an SWR between 2 and 3 across 10M.
    [​IMG]

    I conducted this while parallel parked in Boston. The antennas were in close physical proximity to each other. I tested then sequentially using a portable wspr unit transmitting 200mW. I tested each antenna within a few minutes of each other. I figured that the feedline loss would take care of any reflection in power back to the transceiver. It seems my wspr unit still works.
    [​IMG]
    These are the results, with 3 unique spots each.
    [​IMG]
    [​IMG]

    So, obviously there is not much I can conclude from this experiment. Except possibly why I have such trouble with my cb radios (given the lack of resonance on 11M). But it was fun to do. I did not have many spots. Looking at the world wspr data, it did not seem like anyone did at that particular time I transmitted. I wonder if FT8 would have shown more results.

    It was fun to try. Something I can do right in the middle of the city. Gets me using a lot of my ham radio gear. Gets my mind thinking (why did I get such similar results between the two antennas?) And helps me learn and explore the wonderful hobby of amateur radio.

    Just thought someone out there would enjoy this ugly little experiment.

    Mindy

    **EDIT: oops, I take it back. I did not realize the rigexpert has a blue band for CB. SWR actually looks good there!!
     
    Last edited: Oct 12, 2021
    KA0HCP, N1VAU, K7WFM and 3 others like this.
  2. K8XG

    K8XG XML Subscriber QRZ Page

    I like that!

    I always get an extra whip for the mounts. Most CB whips out of the box are too long and need cut down, a stone wheel on the other side of a wire wheel desk grinder works great to cut them. So does a Dremel tool with cutting disk, use eye protection and put the whip in a vice as you cut it down. 1/4" cuts at a time.

    Now once as you get the first whip cut for the CB part of the band you want [I cut for channel 29 as I want 19 and 36-40] the extra whip I cut for 28.400.

    Back in the days I worked at Jerry's CB, we used the stone grinder wheel on the desk stone and wheel, made things fast. Not having on of those today, the Dremel cut wheel has to do it but it is not as fast and really need eye and face protection as if that cutting disk breaks, it can hit your face. Ask me how I know , Hi Hi
     
    KM1NDY likes this.
  3. K4NWD

    K4NWD Platinum Subscriber Platinum Subscriber QRZ Page

    Art, get some of the fiber-reinforced disks. They can shed small bits (dust, mostly) but won't blast apart like the all-abrasive disks.
     
    W4HMB and K8XG like this.
  4. K8XG

    K8XG XML Subscriber QRZ Page

    I have used those and what I have now, they still can break but not as bad as the regular ones.
     
  5. K7WFM

    K7WFM Ham Member QRZ Page

    The propagation may have been affected by the intense solar storm activity we're experiencing lately.
     
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    To do such "side by side antenna tests" which actually are relevant if you can switch one to another very fast and do it repeatedly, I send CQ or TEST on CW (and of course ID with your callsign) and look at RBN reports. They have a lot of skimmers (often more than 100 listening) and report signal strength, time and frequency almost immediately.

    10m propagation is hit-and-miss these days, so a better band might be 17m or 20m, but that would require somewhat different antennas.
     
  7. K8XG

    K8XG XML Subscriber QRZ Page

    Mindy said she was moving between them in near real time FYI
     
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Yes, I know.

    But RBN (using CW) may provide more reports; that was the only point.
     
    K8XG likes this.
  9. KM1H

    KM1H Ham Member QRZ Page

    Comparing a full size hunk of whatever, I have no use for those lossy bazookas, and a mag mount on CB isnt much of a comparison.

    A 5/8 wave tuned CB or 10M vertical is a better comparison match.

    Carl
     
    KE0NSK likes this.
  10. KM1NDY

    KM1NDY Ham Member QRZ Page

    @K8XG Art, good tip! I have to admit, I just tin snipped the few metal whips I cut. This isn't actually the right way?

    @K7WFM I did it on Sunday, I think before the CME? I usually run my wspr unit from my qth all the time, but took it offline for this experiment. I was disappointed not to see how it performed during the event.

    @WB2WIK This was kind of a quickie video to demonstrate feasibility (just a pilot). I think an antenna switch, a timer, and several more 2 minute cycles would be better. FT8 or RBN, even as a comparison, would be neat. For any more serious antenna testing, I would use a dipole vs. X, and prefer it not be 10M.

    @KM1H I just used what I had. I have no real love for the double bazooka. I prefer to operate 10M off my 40ocf in real life. I just wanted a 10M comparison I could hang vertically.

    Mindy
     
    N1VAU, K7WFM and WZ7U like this.

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