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Help a new ham go /MM

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KB0ATY, Feb 18, 2021.

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  1. KB0ATY

    KB0ATY XML Subscriber QRZ Page

    Hello, I am a new ham and I am trying to obtain my first radio + antenna. I've been reading and reading but I am probably beyond my limited understanding. I wonder if anyone would be willing to double-check a summary of what I've learned and what I'm planning. Tell me if I'm crazy or where I've made mistakes!

    My shack will be on a steel trawler operating on the Great Lakes and St. Lawrence Seaway. There is the potential for future travel on the Atlantic or Gulf.

    My goals are:
    • relieve boredom when underway by providing something to fiddle with
    • communicate when out of VHF/cellular range -- note this means an antenna must be sturdy enough that it can be used while underway (some marine hams on the forums say they hoist an antenna only when docked at a marina, that's not my goal)
    • use digital modes via a connected laptop
    • buy/build something simple first to be sure it works and I like it before investing a lot of money
    • be able to communicate on the marine nets, particularly MMSN (14.300 MHz) and Waterway/Hurricane Net (14.325 and 7.268 MHz).
    • avoid extensive boat modifications
    Just to be clear about what I hope to do, at this point I am LESS interested in contesting, DXing, DIY experimentation with different antennas/radios, building my own system, and I really don't need an additional distress/emergency system (although an extra radio is always better than not). I'm more interested in communicating at least for now.

    Here is my crude drawing of the rigging.

    [​IMG]

    From what I can tell the **non-ham** marine people in my situation almost always do the same thing: they buy a marine SSB radio and equip a Shakespeare 23' whip or a backstay antenna. It's easily possible to spend $5000+ doing this, but I guess yacht owners have a lot of money. A lot of them later complain on the forums that they get poor HF performance.

    In contrast to the non-ham mariners, there are frequent posts by experienced marine hams saying that they have years of personal experience that you can do just as well -- or better -- with a cheaper ham radio and either a simple homemade random-wire antenna hoisted up a mast or a dipole whose high point is the mast. There is even one guy who swears by energizing his own rigging (no antenna).

    After a lot of reading I think the best way for me to get started would be to buy a 20W Xiegu G90 and hoist a simple wire antenna and see how it goes.

    I looked at the "Random Wire Antenna Lengths" page and it looks like my best option is probably an end-fed bent vertical that is 35' long hoisted up the signal mast (the main mast) for 20' then bent down the forestay or backstay for the remaining 15' and is grounded to the hull. It is certainly possible that a 68' sloper dipole with the feed at the highest point of the mast would be better -- not sure how to decide between these two.

    Some people who seem experienced in antennas on the forums seem to always prefer verticals and claim they produce better over-the-water propagation. But maybe the "bent" part of the bent vertical is going to eliminate this advantage.

    This is about as far as I've gotten and I could use a sanity check.

    Things I haven't figured out yet:
    • what to actually buy aside from the G90 to make/get the antenna. I have to get the RF away from the helm as much as possible or I'm pretty sure I'll mess up the compass, so I need an insulated feed line I guess. I'm obviously not "Mr. Electrical." Trying to learn here.
    • there is a chimney along part of the signal mast, I'm not sure how hot it gets... there is some electrical wiring up there now so it may be fine but OTOH it doesn't seem great to run an antenna along a hot chimney does it? I don't know.
    • will grounding to the hull cause stray current corrosion on the steel hull? The boat has a bunch of stray current protection stuff (zinc sacrificial anodes, galvanic isolator, bonding system) and I don't want to mess it up but I'm not sure how to find out more about this.
    • does using this antenna raise my risk of damage from a lightning strike? Thunderstorms are frequent and the mast is the highest thing around!
    • will all of the boat's systems make my new radio worthless? Many mariners complain about heavy interference from their own refrigerators, winches, and pumps.
    • The G90 has a note in the specification that says "(voltage must be in 13.8-15V if need 20W)" ... not sure where I would get that extra voltage! I guess I won't? The boat has 12V DC so I expect the best I could possibly get is 12.9V if I operate from the engine room, which isn't feasible.
    Any thoughts? Reactions? I am really hoping someone can help me get closer to getting this going. Thank you so much in advance.

    P.S.
    I was not sure where to post this as it is about my whole system not just the antenna, but it is MOSTLY about the antennas I think, so I've opted for this forum. I hope it was the correct choice!
     

    Attached Files:

    Last edited: Feb 18, 2021
  2. N1EBC

    N1EBC Ham Member QRZ Page

    Is this your ship or do you have permission from the captain?

    jason
    N1EBC
     
    K2CAJ, AK5B, K0UO and 2 others like this.
  3. PU2OZT

    PU2OZT Ham Member QRZ Page

    Maybe you could get in touch with https://www.qrz.com/db/IU1DUB
    Not that I know him, also, a trawler is a rather challenging ship for operating.
    Sure knew your callsign Q-code, shouldn't be misinterpreted?

    Oliver
     
  4. KC3PBI

    KC3PBI Ham Member QRZ Page

    The G90 has a little trouble developing full output when fed less than full voltage. This is pretty common among many radios and if anything the G90 will hold a cleaner output down to a lower voltage, but for some reason everyone reacts strongly to that note in the specs.

    I have found success in feeding my G90 with a voltage regulator meant for a golf cart. It takes 18-42V in and makes a perfect 13.8V out of it. It cost me about $30 on amazon and is RF-quiet. I feed it with 40v lithium battery bricks from my lawnmower since they're already paid for and usually charged up. I have seen different versions of the same regulator with different input voltages, you may find an appropriate buck converter to get from 12 up to 13.8.

    Before I discovered my regulator, I used a different one that gave a 12V output... and the radio pretty much didn't care. The internal display would show the voltage sagging down to 10.5V or so when transmitting on full power, but that was the only indication- it never showed up in the signal or reports.

    I'm a new ham myself and haven't tried many other radios, but I'd think the small size and extremely capable antenna tuner in the G90 would be helpful with challenging space & improvised antenna conditions on a boat.

    As for the antenna? I guess I would want to pack parts. Rope, wire rope, antenna wire, plastic insulators, swaging couplers, rings & other hardware typically used for rigging, and I'd want it to be good marine grade stuff so it doesn't crust over and leave a smear of rust on the boat.
     
  5. WG7X

    WG7X Platinum Subscriber Platinum Subscriber QRZ Page

    Interesting post, and you're already getting good replies. But first things first: in order to use the frequencies you listed you'll first have to upgrade to General or higher. Maybe you've already done that and the QRZ data base has not yet updated?
     
    AK5B and K0UO like this.
  6. K6CLS

    K6CLS Ham Member QRZ Page

    I thought /MM was in international waters only. And I thought the great lakes are all in US or CA, not international.
     
  7. VE7BPB

    VE7BPB Ham Member QRZ Page

    Having lived on my own trawler yacht for a time I can help you with this.

    You have a very simple solution to covering the bands you are interested in.

    Hang a pulley at the top of the mast and use some dacron rope to pull up the center insulator and coax connected to a standard inverted-V wire dipole cut for 40 meters. The coaxial cable comes down along the mast, keep it away from any hot spots. Each side of the dipole will be around 30-33 feet long, so put an insulator at each end and use more rope to tie it fore and aft. Use an SWR meter to trim the length to resonate where you want in the 40m band.

    You could just stay with that by itself and do quite well if you either use a radio with an automatic antenna tuner built in, or an external manual or automatic tuner to tune not only 40m but also the higher bands.

    Alternatively, you can add another dipole right to the same center insulator and run it parallel to the 40m dipole, like a 20m dipole, which would only be about 16.5 feet long on each side. You can space the two parallel dipoles a short distance apart (4-6 inches is fine) with whatever non-conductive spacer you can come up with.

    This known as a fan dipole ( look it up )and the big advantage is that if you tune the two dipoles properly to the two bands of interest you will be able to get by without using an antenna tuner for your maritime nets.

    First tune the 40m dipole with the SWR meter to resonance, then tune the 20M dipole. The two dipoles interact a little bit so you may have to go back and forth a bit in tuning.

    I would use something like #14 stranded wire for the antenna wire, insulated or not, your choice. It's quite cheap, so if it is ever damaged it doesn't cost much to replace.

    As for radios, more transmit power is always a better option for these kinds of options. There are any number of 100 watt radios out there. You don't need to get the latest, newest one. Look for some older HF mobile radios like the venerable Icom 706 or Yaesu FT-100D, or Yaesu 857, all of which also cover VHF and UHF, as a good example for something that would be easy to mount at the helm.

    There is no need to overthink this, it is a quite easy installation and will work very well for you.

    regards, Roy
     
    KA0HCP and AK5B like this.
  8. VE7BPB

    VE7BPB Ham Member QRZ Page

    You thought wrong.

    regards, Roy
     
    AK5B likes this.
  9. KB0ATY

    KB0ATY XML Subscriber QRZ Page

    Thanks so much @VE7BPB !!! I think you've got my vibe. Let's start simple. Nothing too complicated to start. I will check out the fan dipole thanks for that tip. It sounds interesting.

    On various forums I did see some marine ham proponents of verticals on metal boats vs. dipoles because they reported better performance with the metal of the deck as the ground plane (I think -- if I understood them correctly). That's why I was thinking of trying the vertical first. But there were lots of happy people with dipoles too. I was just thinking they might be fiberglass hull people. It also felt like hoisting a single wire up would be even easier than the dipole. But I am definitely open to persuasion here and I appreciate your thoughts.

    I did look at the used radios you mention and I know 100W would be better than 20W but this was my thought process: I was alarmed by the power draw stats on these radios. e.g. 23 amps on transmit seems like a lot. I was also concerned that if I wanted to do digital modes it might be better to use a more modern radio. The price point for the G90 is lower new than some of the used listings I see for the radios you mention on eBay. Plus the G90 has a built-in antenna tuner. And the rafts of positive G90 reviews sure are persuasive. However, if you are saying I'm going to need 100W that is very important. I have not been able to find any /MMs with a G90 so far, maybe they all have 100W radios.

    @KC3PBI thanks so much for that tip, I have not put thought into voltage regulators -- I will get to reading. I was assuming I would wire this into the boat's electrical system but maybe I should re-think that.

    The other stuff: Haha, yes @PU2OZT my callsign was sequentially assigned by the FCC, I wasn't trying to make a reference to QOD! I have put in a vanity request to change it.

    I do have a general license. I do have permission.

    Thank you so much for your helpful comments I'd love to hear any other thoughts.
     
    PU2OZT likes this.
  10. W0MSN

    W0MSN XML Subscriber QRZ Page

    I have G90 and love it. Great antenna tuner too. I would still suggest a 100 watt radio. Possibly something like the a Yaesu 891. You will not be drawing as much current as you think when using SSB voice and you can turn the power down if using digital modes. Good luck on your project. Sounds like a fun install.
     
    PU2OZT likes this.

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