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Thread: zetagi b150 linear amp

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  1. #1

    Smile zetagi b150 linear amp

    Hi Guys And Girls
    Would a Zetagi B150 linear amp cover 40 meters even though its only meant for cb as they say as some of the rm models are similar and work the full spectrum 1.8-30 and would i need a filter inline if i did as my radio is qrp 10 watts kenwood ts 670 and am strugling getting out on antron 99 tuned up with vectronics vc300dlp any info would be most apreciated as i dont have alot of money and would like to make some qso's soon. thanks

  2. #2
    Join Date
    Jan 2000
    Location
    Ridgefield, Washington
    Posts
    2,227

    Default

    No. I hope you were only thinking about buying that zetagi b150 amp. If you already own it, you can save yourself grief if you never mention it again. If you do mention it in amateur radio circles, never call it a linear amplifier. Class C amplifiers are not "linear", and will create all sorts of splatter & crud if used for SSB operation. Even if used only for CW operation - say on 10 meters - it is unlikely to meet the spectral purity requirements for the amateur radio service. It might be a good idea to go wash your mouth out with soap right now. I plan to do the same, shortly.

    Suggestion: Change your user name to reflect your amateur radio call sign. Mucho expertise lurks here at the zed, but many will remain silent on certain questions about equipment (like yours) unless they know it is coming from a licensed amateur radio operator.

    Your Kenwood TS-670 has a good reputation among users that don't expect the world. It is designed to cover 6, 10, 15, and 40 meters, and I understand there is a mod to add 12 meters.

    Your Antron 99 may work effectively on 10 & 12 meters, but those bands are mostly silent at this point in the solar cycle. When they do open up (usually sporadic E), your 10 watt rig will do just fine. Your Antron 99 will not work effectively on 40 meters or other HF bands (including 15 meters), even with a tuner . . . and even with a good amplifier designed for amateur radio operation.

    If you want to make some QSO's, please consider making a simple 40 meter dipole antenna. That band is open almost every day, with lots of activity. With just 10 watts on 40 meters, you will be able to make some contacts.

    If you are at least a general class licensee, you should be able to make some SSB contacts on 40 meters when conditions are good. If a technician licensee, you can use CW on 40 meters, and contacts would be very easy with 10 watts and even a low dipole. BTW, that 40 meter dipole will also work on 15 meters, although your vectronics vc300dlp may have to help a bit to get a good impedance match.

    No room for a 40 meter dipole? You could probably find room for a 15 meter dipole, and that band opens a little bit on many days. I enjoyed a CW contact into Illinois (from Southern California) this afternoon, and heard many other signals. In recent weeks, I've even made contacts into the Midwest with just 5 watts CW on 15 meters.

    Bottom line: Don't be discouraged by low power. A good antenna is far more important than high power for making contacts. The Antron antenna is used by many hams on 10-12 meters (with some dubious claims that it also works on 15 meters), but the most success comes from adding some radials for the intended band of operation. But that's a subject for another whole thread.

    Once you get an antenna for either 40 or 15 meters, I'd be happy to schedule a contact with you. My email addie is good at the zed look-up. 73

    Gary, K9ZMD/6
    Palmdale, CA
    Last edited by K9ZMD; 12-21-2009 at 04:50 AM.

  3. #3
    Join Date
    Apr 2002
    Location
    Rochester, MN
    Posts
    19,893

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    Here's an inexpensive amplifier kit you could build that would take you to the 35 watt level. That's about an S-unit stronger than what you have now:
    http://site.hfprojectsyahoo.com/hf_packer-amp

    You will need to reduce the power from your 10 watt rig into this amp. You can simply turn the power down on the Kenwood, or, a much better idea would be to build a 6 dB pad into the input of this amplifer, so the full output of the Kenwood doesn't overdrive the amp. If you overdrive the amp, the results will be distorted garbage.

    In general, the CB amplifiers are junk. Oh, they may work, but since they're 100% illegal anyway, why do you think the makers might be inclined to spend the extra money to make sure that it has a clean output? Why? With a lot of work, you might be able to make it work, but it depends on how bad it is to start with.

    K9ZMD's comments about your antenna are correct. The Antron is designed to work the higher ham bands - 17, 15, 12, and 10 meters. But on 20, 40, 80, etc.., it's going to present a very high SWR and it's also too short physically to work well. The high SWR means that a lot of your power is being wasted as heat in the coax. The short size means that it's less efficient than a full sized antenna. I would wager that you're radiating less than 1 watt for 10 in .

    A 40 meter dipole is 66' feet long. Let's assume a reasonable SWR. You would now be radiating 10 watts. It will still be a challenge to make contacts on 40 meters, but you certainly should be able to make some, particularly in the daytime with a dipole. When 15 is open, you should be able to work North America about as easily as somebody running 100 watts.

    If you simply can't do a horizontal dipole, look into larger verticals on the ground with lots of radials or on the roof with a few tuned radials.
    EchoLink, IRLP, Allstar and DSTAR linking - adding interest to repeaters worldwide 24X7

  4. #4
    Join Date
    Jan 2000
    Location
    Clearwater, FL
    Posts
    4,927

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    Don't even think about using this on 40 meters, or 10 meters for that matter.

    ..........Bob
    ex-W4DFW Ham since 1970. ARRL Life Member and Volunteer Counsel

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