2 meter amplifier

Discussion in 'General Technical Questions and Answers' started by KD8HQY, Nov 9, 2008.

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  1. KD8HQY

    KD8HQY Ham Member QRZ Page

    looking to see if there is any information on building a home brew 2 meter linear amplifier. i know they are readily available and pretty cheap to buy already built, but i am wanting to do some experimenting and playing around to see what i am capable of building.

    more or less looking for something to "tinker" with in my spare time. plus i like the fact that i can actually say i built it, if it works.
     
    Last edited: Nov 9, 2008
  2. W0IS

    W0IS Ham Member QRZ Page

    I'm sure there are many designs out there. But if you're going to be using it for FM (and not AM or SSB), then it doesn't need to be "linear".

    Keep this in mind as you search for designs. You will probably find a lot more designs if you search for "two meter amplifier" than if you search for "two meter linear amplifier", because most of them are for FM and not linear.
     
  3. KD8HQY

    KD8HQY Ham Member QRZ Page

    thank you for the heads up. and yes it will be for FM. i have seen a few out there but figured i would ask around to see if one design is better than the next, or if someone has tried and successfully built one off of an internet design.
     
  4. WB3BEL

    WB3BEL Ham Member QRZ Page

    What output power level are you trying to achieve?
    What power supply voltage is available?
     
  5. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    For a newer builder who hasn't homebrewed such a project before, starting out with a semi-kit that has a solid, proven design is sometimes the best thing:

    http://communication-concepts.com/875a.htm

    That's an example of one. It can be purchased as a full kit, a semi-kit, just parts, or just instructions: Up to you.

    WB2WIK/6
     
  6. KD8HQY

    KD8HQY Ham Member QRZ Page

    not looking for anything crazy maybe something like 200 to 300 watts. mainly just a little help while talking simplex due to the fact all the folks i talk to are around 30 miles away (as the crow fly's)
    and we don't like tieing up the repeaters for our long winded conversations.

    as far as power supply i have 2 to choose from. a 10 amp and a 35 amp, i am pretty much covered on what i would need i would think.

    thanks for the link. this is another route that i have though about taking. more or less trying to weigh my options on what would be the best for me as a beginner to making these things
     
  7. KA1MDA

    KA1MDA Ham Member QRZ Page

    "not looking for anything crazy maybe something like 200 to 300 watts. mainly just a little help while talking simplex"

    That's pretty funny. Would hate to see the wattage required if he needed a lot of help while talking simplex!

    Seriously- if you need 300W to talk 30 miles on simplex, I would be looking into finding a better antenna.

    Tom, KA1MDA
     
  8. KD8HQY

    KD8HQY Ham Member QRZ Page

    ok so you got me there, but there's no need to be an ass about it.

    and as far as the antenna goes i am using all that i can right now. space is limited and do to restrictions i am not able ot put up a out side antenna due to the apartment community that i live in.



    and as far 200 to 300 watts to me isnt much when you take into consideration that 1500 watts is legal limit.
     
  9. KA1MDA

    KA1MDA Ham Member QRZ Page

    "i am not able ot put up a out side antenna"

    This is just asking for trouble.

    First off, yes, the legal limit is 1500W. On VHF though, few people (outside of contest or moonbounce stations) run over 100-200W.

    Second, 300 watts to an indoor antenna is just insane. You will most likely create so much RFI to your neighbors electronic devices (not to mention your own) that you will become very unpopular. I also doubt such an installation would meet RF exposure limits.

    Although the desire to not tie up repeaters and go simplex is commendable, the end result of such an installation does not make good neighbors. You would be much better off investing in a better antenna. Even a small 3-4 element beam mounted on a camera tripod inside the apartment could offer an improvement without resorting to excessive power levels.

    Tom, KA1MDA
     
  10. KD8HQY

    KD8HQY Ham Member QRZ Page


    well i didnt give RFI a thought so i appreciate the reminder there.

    as far as the beam, i do have home brew 5 element that is not being used, i just might have to try it out and see how well it will work.

    my question with that is tho, with only being about 5 foot above my balcony seem like it would have a decent amount of reflect due to the close proximity of the buildings and railings.

    i am able to put an antenna up for a brief amount of time, usually during the dark hours due to the fact that i have no on site management to turn me in. so the beam just might work for my application.


    but altho i still would like to build an amplifier. if i use it then ok but even if i dont i at leas want ot try my hand at building more items, i have a few antennas under my belt and getting kind of bored with those so i am in wanting to move to something else now.
     
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