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MORE 2m questions.........

Discussion in 'Communication & Navigation' started by 450 DUDE, Feb 24, 2007.

  1. 450 DUDE

    450 DUDE

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    Couple Questions here:

    1. How do I know what a good antenna is ( 2m - 440)

    2. What can a dumb guy do with 440Mhz ?

    3. If an antenna states 2m/70cm will it do 440 Mhz ?

    4. How much compromise is a dual band antenna ? Will a newb care or notice?



    And 5.
    Im planning on the FT-7800r with either a comet sbb-1 or diamond rhf40 Using a rear hatch mount.
    Mistake ..??


    Any help / advise welcomed.

    thanks,
    ken
     
  2. aim

    aim

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    1. Good for what? Do you live on a plain? In the mountains? Where are you installing the antenna? I live in hilly terrain and had no trouble reaching local repeaters with a 1/4 wave magnetic mount antenna. On 2m. On 70cm, the 5/8 antenna maybe gets me 10 miles on transmit, 30 miles receive, which is to be expected.

    2. Umm. Listen, I guess. If you talk, most people will figure out the truth ;p

    3. frequency = speed of light/wavelength = 3x10^10(cm/s)/70(cm) = 428MHz
    giving you the 420MHz to 450MHz "70 cm" band. So yes, the 2m/70cm antenna is designed for the 440MHz frequency.

    4. Not enough to matter, unless things are otherwise marginal. Currently I'm very happy with my Comet AX-75 moutned on the lip of the hood. It's short, so ice buildup or tree branch clearance is less of an issue than a full 5/8. Good range, fine voice quality.

    5. The diamond is rated for 10W max and is therefore probably a lousy match for the 7800r. The sbb-1 is on the short side and will have somewhat more limited range. Mechanically, I found Comet antennas to be superior to Diamond and the Diamond mounts (K-400C) to be superior to the Comet ones.
    Realistically speaking, though, you are looking at line-of sight FM transmission. Realistic antennas will make a difference, but only within a limited range. For a goodly distance (on 2M), any antenna will work fine. Go far enough, and no antenna will work. This, of course, assumes repeaters. Mobile-to-mobile is different...
     
  3. Kofoed

    Kofoed

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    I assume it is a mobile application.

    1. The major manufacurers put out good unit.

    2. The repeater activity around the LA is low. It is mostly closed machine that run their weekly DCS etc nets. You can join a system and do that if desired.

    3 yes

    4. A dual band antenna is not a compromise that will be noticed.


    5. I would avoid a high gain antennas that use phase inductors (loading coils) this are damaged by trees, garage doors, etc. I run a Diamond 770. Very durable
     
  4. 450 DUDE

    450 DUDE

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    Good stuff Gents!

    To clarify,Back hatch mount, Hill/mountain terrain, No tech opperator.

    5. :doh: I just realized the rhf40 is a HT antenna.


    I forgot Question # 6-----

    -- Mounts,NMO, SO ,3/8 ?? What one do I go with? Does one get you more techy points
    I guess as long as I match the antenna base Im good.

    # 7. you think the K400 mount is better than the CP-5 ?

    Thanks again guys that actually cleared up a lot.


    ken
     
  5. ginericLC

    ginericLC Wagon Wheeler! SILVER Star

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    Ken,

    I'm sort of new at this HAM thing but you might want to consider going to the 8800. It has a lot more features. The cross band repeat feature is the one I'm most interested in. I know it is a little more, but if you use the extra features it would be worth it. I have an old Icom 2M I'm using in my Cruiser now but someday I'll have the 8800.
     
  6. 450 DUDE

    450 DUDE

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    That thing is definitely super sweet!

    I think Im all ready over my head with options,money,the wife..................

    Can you tell me about cross band repeat, If it informs you on good shoe sales im good with wife.

    Thanks,

    ken
     
  7. aim

    aim

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    Or the 8900. Since the morse code requirement went away, you can use 10M with just a written.
     
  8. ginericLC

    ginericLC Wagon Wheeler! SILVER Star

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    The crossband repeat allows you to use a HT in camp and use your mobile to reach out further. I've been reading about it some but I've never tried. Heck I've never seen a radio that can do it in person. It isn't like you can run down to the local Best Buy and check stuff out. In Idaho there are zero dealers, everything has to be mail order.
     
  9. spressomon

    spressomon glutton Moderator

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    8800 will do it...
     
  10. jonb96150

    jonb96150

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    Like generic says: The cross-band repeat allows you use the mobile radio as a repeater. You park the mobile somewhere and enable that option. You carry a 440 mhz (or 2m/440) handie talkie. You can transmit on the h.t. to the mobile which receives your 440 transmission and re-transmits it on 2m at whatever power setting you set it to. Then the person who answers you is transmitting on 2m to your mobile which re-transmits it on 440 and you hear it on your h.t., does that make any sense? The above scenario can be reversed ie; 2m h.t. to the mobile which re-transmits on 440.

    When I got my first ham rig it had cross-band repeat because I figured that it would be good for the back-country and I used it a bit in that mode.

    On mine I was able to enable a PL tone lock so that it would only re-transmit if it heard the correct tone. This keeps it from re-transmitting someone elses transmission. I left the 2m side unlocked so anyone responding to me would be re-transmitted on 440 to me, but nobody else on 440 could trigger the re-transmit. This is not limited to h.t.'s hitting your mobile, it can be other mobiles.

    This could be useful on an organized run. You park the cross-band mobile on a high spot where the trail leaders can hit it on their 2m radios (but they can't reach base camp). The cross-bander re-transmits that back to base camp on 440 where it is received on a dual-bander at base camp. Base camp talks to the cross-bander on 440 and it is re-transmitted to the trail leaders on 2m.

    Long answer to a short question, and I've probably muddied it up completely!
     
  11. 450 DUDE

    450 DUDE

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    isn't like you can run down to the local Best Buy and check stuff out. In Idaho there are zero dealers,

    Not necessarily a bad thing :)



    Update: I went ahead with the 7800. along with comet sbb-5nmo and
    a k400cnmo mount.
    I purchased used on ebay. the radio came with a bunch of extras.
    Im looking forward to installing this stuff. The plan is to mount the radio in the rear cargo area behind the panel. the Ant. mount comes with 6.5ft of lead and should work good. Remote mounting the face up front somewhere (haven't figured exactly where) .

    Anyone have opinion on this?

    Thanks,

    ken
     
  12. Cruiserdrew

    Cruiserdrew SILVER Star

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    Sounds good Ken. The only problem I see is how are you going to hear the radio? You will need to mount a remote speaker as well. Talk to the guys at AES Electronics in Las Vegas. They are very helpful, knowledgable guys, and take the radio thing seriously-meaning they are not just sales droids.

    It might be easier to mount the radio under the front seat. Then the power and remote leads are shorter, and it simplifies the speaker mounting as well. I would like to see your set up whan complete.
     
  13. 450 DUDE

    450 DUDE

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    Thanks guys.

    First the rig has a second aux buss (7 circuts) in the rear so getting power shouldnt be an issue .
    Second the radio came with sepration kit , speaker, software ,mount .
    Is there something else ?
    I just rather not have anymore s***e up front and I cant install electrical components on the floor (no likey)



    Jon thanks for that explanation . May be someday ill get to that level.

    ken
     
  14. Mark W

    Mark W

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    Mounting an expensive radio undder the seat (or any other low location) n an off road rig?

    One water crossing that doesn't go as planned would make you regret that choice.

    Okay for you desert guys I guess, but a bad idea in these parts.

    I'm dealing with a lot of pre-season maintenance and minor mods right now. Including moving ALL of my radios and electronics in the '40 to one of those over the windshield shelves. (CB, amp, 2M, stereo, FRS and CB and 2M handhelds, GPS, chargers... EVERYTHING)


    Mark...
     
  15. 450 DUDE

    450 DUDE

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    Found some time and installed the stuff.
    The pics are kinda lame. the set up is working well. One thing Im not sure of is I did not ground my antenna/base ???? not sure If It would make a difference.

    Pics..


    Thanks again for everyones help.

    ken
    P1010004.jpg P1010001.jpg P1010010.jpg
     
  16. 450 DUDE

    450 DUDE

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    Some more............
    And a pic of the #2 aux buss with things and the remote speaker.

    ken
    P1010009.jpg P1010002.jpg P1010006.jpg