My first days with a MOSLEY PRO-67-C3

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by OE4KSF, Jul 10, 2021.

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  1. OE4KSF

    OE4KSF Platinum Subscriber Platinum Subscriber QRZ Page

    I have so far used a Spiderbeam 5 band - HD on my little tower (at a total some 15m over the ground) - and have been very happy with the performance.

    However, missed 30m and 40m opportunities. I was therefore very excited after swapping it for a PRO-67-C3 and over what it could give me.

    The antenna came very well packed and everything was well color coded.
    My only challenge was that it was a wrong packing when it comes to the boom itself. It was 2x # 1 and 2x # 2 instead of 1 to 4.
    I managed to assemble them after a little tricking with the drill, and measured everything again - when it came to the placement of the elements.
    Marked this again on the boom and recalculated and measured several times just to be sure before I started the assembly.
    Everything else was absolutely perfect.

    I tried to be extra careful during the assembly of the elements, and checked and checked that everything was correct during the whole process.

    On the whole, there were few challenges during the entire process. I had read the installation instructions many times even before I received the antenna to be prepared.
    I use a lot of digital modes, so I tried to calculate the length of the 40m end pieces to fit this and used tape to keep them in place temporarily.

    Took the first SWR test while the tower was still in the lower position - only to see that there was nothing totally wrong, but was pleasantly surprised by the result.
    Then raised the tower to its full height and checked the SWR. To my good surprise, 40M was just fine to 1.2 in SWR - and the rest of the bands to 1.1 to 1.25 - EXCEPT from 12m - it was / is 2.3. 12m was far too high in the resonance.

    Then took down the tower and fastened the 40m end elements with screws and checked everything I could think of had something to do with 12m - without finding anything wrong ?? .
    Then hoisted the tower again and checked my measurements - and everything except 12m was still perfect.

    Then it was to try the antenna on the air, but was first surprised at how few stations I heard, but now the bands are pretty quiet during the day.
    Had a few laps with FT8 on all bands and followed on pskreporter.

    There I was surprised to see that the antenna was very little directional - then in relation to my Spiderbeam.

    And with the 25W output effect, I got a lot more people who could receive me than I could receive - and on pskreporter I see that those who could hear me were just as happy 90 degrees to the side as from behind.

    Hmm - not as I expected. Since I do not have both antennas up at the same time, it is impossible to compare, but my feeling is that my receiving possibilities did not get any better with this antenna.

    Took a round at night of 40m and had several FT8 contacts to South America. However, there was very little difference between the beam and my vertical, but to some extent the beam.

    By listening to some weak SSB stations and then turning the antenna in different directions - I find that there was almost no difference on the front or back of the antenna.
    On the whole, it is very little dependent on direction. Slightly better at 10m to 20m, but still.
    So my first tests give me a feeling that if it had not been for 40m - then I would have mounted my Spiderbeam back.

    Dos it work - yes it dos, but not as I had expected - and or hoped for.

    So disappointed - yes - in relation to my Spiderbeam

    But will continue my testing, and I will take down the tower again - to once again go over my measurements of positions of elements on the boom and again make a full length measurement of all elements according to the manual.
    All the measurement are there - and that's a good thing.

    IMG_6981 2.jpeg
    N4FZ and W9FL like this.
  2. K8DO

    K8DO Ham Member QRZ Page

    Myriad possibilities.
    1. The belief by many hams that a good swr means a beam must be right.
    (resistors have a good swr all the way across the band)
    2. The belief by many hams that one can put 7 competing resonances on multiple elements and have a killer beam with world class FB ratio and gain on all 7 bands.
    3. The belief by many hams that one can have loaded elements and cover the entire 40 meter band with a low swr.
    (I can't do that on a full size dipole at 70 feet)
    4. Bad coils.
    5. Bad Karma.
    6. Coupled to nearby wires/metal destroying the pattern.
    (Those solar panels right underneath are one of the usual suspects to round up)

    Have someone else (without you hovering over their shoulder) take the instructi0ns and measure the beam and confirm the coils.
    It is well known that you can be positive it is right and measure it again and again and it is right - except that it is wrong.
    Well, at least well known by me - not that I ever made such a silly mistake!
    (Not MY fault - I cut it off 3 times and it's still too short)

    This is a beam with a good reputation. Get another set of eyes on the beast.
    You have my sympathy after that much expenditure and effort.
    PU2OZT likes this.
  3. W2AAT

    W2AAT XML Subscriber QRZ Page

    Mosley is a good company and you have credible concerns about the antenna's performance. I recommend that you contact them and tell them all that you have written here in the ZED. If you choose to do this, please let us know the outcome of your discussion with them..
    K9XR and PU2OZT like this.
  4. WS4K

    WS4K Ham Member QRZ Page

    I have been using Mosley beams for 40 years. I never had a Spider Beam but my Mosley has been fantastic.

    I will also tell you Mosley techs are the best in the industry. I have contacted them a few times over the years. They are responsive and they know their products.

    Contact Mosley. I bet they will help you solve your issues.
    K9XR and W4LJ like this.
  5. WN1MB

    WN1MB Ham Member QRZ Page

    How tall is the tower it's mounted on?
    K9MRD likes this.
  6. OE4KSF

    OE4KSF Platinum Subscriber Platinum Subscriber QRZ Page

    Many good words in that
  7. OE4KSF

    OE4KSF Platinum Subscriber Platinum Subscriber QRZ Page

    The tower is only 12 meters + top unit + about 1m on top of that.
    Its to low for 40m - I know - But should work for 10..20m - as my Spiderbeam did work great from there.
    I did not have to much of expectation for 40m that height - and the solar panels under , but as now - the 40m is the only one somewhat working ;-)
  8. OE4KSF

    OE4KSF Platinum Subscriber Platinum Subscriber QRZ Page

    Yes I will. I have been in contact before - before I decided on this antenna - and they have always been responsive
  9. OE4KSF

    OE4KSF Platinum Subscriber Platinum Subscriber QRZ Page

    A few words more .....

    Yes - the solar panels under will influence on the pattern - for sure , but again - I was more than happy about how the Spiderbeam did work from there - and that is my only reference .

    And yes - it is a big possibility that I have made a mistake under my mounting - and that the 12m is not where it suppose to be is a good indication of that.
    It now resonates on 25.200MHz and not at 24.950 as indicated in the manual.
    All the other bands have the resonance spot on looking at the manual.
    I will take the antenna totally apart - and have a close look, but first I will do the total length measurements of the elements again.
    As the color coding is now hidden inside other tubings - I need to take it totally apart.

    Under mounting I did sort every element after color marking - and checked a zillion of times that every part of an element did have the right color.
    The brown and red color marking was not the easiest to sort :)
    Then assembled one element at the time - and measured the total length of each element according to manual .
    One thing is that every measurement in the manual are using inches , and I have to recalculate into metric - meter , cm and mm
    But when I did measure the total length of every element - they was spot on - so I can not see that there should be anything wrong with the inch->metric calculation.
    I was able to mount the elements on the boom, by first mount the boom in lowest possible position on the mounting tube and then using only 1 U bolt over the boom.
    Then I could turn the boom and lower it over the roof - using ropes - and do all mounting of the elements standing on the roof.
    This way I had good control of everything.
    At the end I balanced the antenne in horisontal - and mounted the rest of the U bolts to the plate.
    Another thing was the missing boom parts #3 and #4 - so I had to measure the element position - and remark on the boom for that side of the antenna.
    I did measure from both sides of the boom - and as the marking for the #1 and #2 boom tube did align with my markings - I was confident that it was done correct.
    And looking at pictures from other ones found on the net - it "looks" similar in position of elements - Not far off anyway.

    But it can be that this antenne is more influenced by the solar panels and the metall roof of the garasje than my Spiderbeam - fully possible.
    This position is the only one I can use - due to the way my garden is situated etc etc.

    If I'm not able to make it work better, I will probably remount my Spiderbeam again - and use my 26meter vertical for 30m and 40m - as before - that one do work great (And no traps - hehe):

    More updates later on .....

    IMG_6930.jpeg IMG_6933.jpeg IMG_6394.JPG
    KA3BQE and PU2OZT like this.
  10. KO4LMA

    KO4LMA Ham Member QRZ Page

    Really interested in seeing how this turns out i have a Pro 67-b-3 on order.

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