1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

Texas star 1200 or 1600

Discussion in 'General CB Services Discussion' started by dxing440, Mar 27, 2012.

  1. Robb

    Robb Yup

    Joined:
    Dec 18, 2008
    Messages:
    11,139
    Likes Received:
    2,876
    One thing to keep in mind, is that those spec sheets were written with a 12v reference voltage. Now, no one runs their amp or radios @12v. Most run them @13.8v or higher. When keyed, that voltage will drop according to the quality of the power supply - be it a vehicle's electrical system or the AC to DC supply. Think it is fair to say 70 watts @ 14.1v isn't much of a stretch with a stout supply.



    I agree with you about amp mfrs will give watt ratings with no consideration at all as to the cleaniness of the output. An 8 pill 2290 amp with decent biasing (al la Texas Star) @14.1v (voltage drop estimate) should put out ~560 watts with a clean input source. But who considers having a clean signal? Yes; any operator that has been around awhile at this sort of thing - should certainly know better than being satisfied with over-driving the amp! I prefer to put out 120 watts of clean output rather than 240 watts of nasty harmonics and a crappy sound when transmitting. But that - is me . . .
    :mellow:
     
    1 person likes this.

  2. AudioShockwav

    AudioShockwav Extraterrestrial Admin
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    5,817
    Likes Received:
    1,844
    I just made this post in the other thread, and I will re-post it here as well

    I agree.

    73
    Jeff
     
  3. Eastside

    Eastside Well-Known Member

    Joined:
    Apr 29, 2011
    Messages:
    1,730
    Likes Received:
    132
    My bad....I thought you were talking about the sweet 16 and the 8x2879. :)
     
  4. AudioShockwav

    AudioShockwav Extraterrestrial Admin
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    5,817
    Likes Received:
    1,844
    I wanted to show you guys what the difference is between AVG ( average ) watts and Peak Watts.
    The Bird 43 is a well know watt meter, and Bird makes a Peak reading kit for it.
    So you will have a meter that will read AVG and then you flip the switch and use the same meter to read Peak.


    This Video is about a cobra 29 with a RFX kit on it, i am using it just to show the difference in reading with the same meter on the 2 different settings.

    Cobra 29 LX with RFX-75 for Pallet Burner - YouTube


    You will note the guy making the Vid, uses the term RMS....this is not what the Bird reads when it is not in the peak mode, it is a term often used in error when talking about RF power measurments.
    RMS or Root Mean Square is a way to measure voltage and current.
    Not a way to measure RF.
    ( see links at the bottom of post)

    The Bird only reads 2 ways...Avg or Peak.
    There is another way to read RF power, it is called PEP
    Or Peak Envelope Power.
    The Bird watt meter will not read PEP power, to do that you need a Oscilloscope.

    If you have ever wondered why in the Radio world there is so much difference in My radio does this, or my amp does this on my meter and that on his meter or something....well you get the Idea.
    Then toss 5 or 10 different kinds of meters, not just a Bird, maybe a dosy, or a radio shack, or a astatic, or a heathkit, or a Yaesu meter....

    73
    Jeff






    for more Information about RMS, please click this Link, and read up on the subject.
    http://www.eznec.com/Amateur/RMS_Power.pdf

    For those that do not want to read the entire article...
    (I would recommend that you Do read it, it has some good info in it.)
    It can be summed up at the end.
    For More Info about how to make PeP measurements Click this link
    A Simple PEP Measuring Procedure


    For some Good reading about a summary or overview of the different types power level measurements that can be made - average power, pulse power, peak envelope power, PEP power.......
    Click this link
    RF average, pulse and peak envelope power measurements :: Radio-Electronics.Com
     
  5. unit_399

    unit_399 EL CAPO

    Joined:
    Jun 17, 2008
    Messages:
    1,449
    Likes Received:
    827
    EXCELLENT POST JEFF

    - 399
     
  6. psycho

    psycho Running a special on our rooms!

    Joined:
    Aug 25, 2006
    Messages:
    3,440
    Likes Received:
    1,262

    The actual gain difference between a 4 pill and an 8 is 1/2 of an S unit.
    Half an s unit is big when have a mobile keydown or when you are trying to talk long groundwave.....other than that, not noticeable.
    The TNT 1500 is a nice piece!
     
    Capt Crunch and gamegetter like this.
  7. Keikiokalani

    Keikiokalani New Member

    Joined:
    Nov 2, 2019
    Messages:
    42
    Likes Received:
    2
    you need 15 watts dead key
     
  8. Onelasttime

    Onelasttime Well-Known Member

    Joined:
    Aug 3, 2011
    Messages:
    884
    Likes Received:
    418
    Not if you plan on using it every day for a decade or more with out letting the smoke out. Also do you want a clean signal or to sound like you just came from the dentist or a a splatter box?

    I can almost guarantee that rfx75 has impedance matching problems since it's big brother's always did. So you have a driver with impedance issues going into questionable coax and then into a 12-16 transistor amp of questionable design with questionable transistors that have not been beta matched? What could go wrong?

    Only a moron operates their gear at the limit or even near it. That would be like driving your car around at redline every place you go! What gear you buy and how you operate it is an IQ test if you know it or not! It also affects your pocket book.

    In vest in a modern LDMOS amp. Under drive it and 20 years from now when it is still kicking butt you can thank me! Do not invest in technology that is 3-4 decades obsolete. Not unless you have a stock pile of parts and such your sitting on.
     
  9. Onelasttime

    Onelasttime Well-Known Member

    Joined:
    Aug 3, 2011
    Messages:
    884
    Likes Received:
    418
    If you get a TS and want it to last you would need to redo the input tuning, narrow down it's band width with tuned input and output more like a tube amp and think about changing the combiner network. 99% of people in the builder world wont do it right because they are starting from a bad design and copying that as if it is correct. You do not want to have a transformer coupled amp that has .3 to 50Mhz bandwidth. Not if you like efficiency and thermal control. You also should think about a low impedance transistor bias feed instead of sandbars for bias but that is just me. Clean is mean and cool runs for a long long time!
     
  10. Onelasttime

    Onelasttime Well-Known Member

    Joined:
    Aug 3, 2011
    Messages:
    884
    Likes Received:
    418
    Either buy a Henry SS-750 or have someone build you an amp like it. Do the maintence and 20 years from now thank me!
     
  11. AudioShockwav

    AudioShockwav Extraterrestrial Admin
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    5,817
    Likes Received:
    1,844
    Good luck finding a Henry Solid State amp now days.
    Not to often will you find one for sale.
    And there are not many solid state builders around now that have the skill to build a properly biased amp with electronic voltage regulation, temp tracking, over heat protection, overdrive protection, overvoltage protection and proper input / output tuning.
    I can only think of one person off the top of my head, and you are going to have to pay him well for his expertise.
    Most CB guys will not spend that kind if money.
    And then they will not be happy with the numbers they see, because there buddy has a 8 pill class c amp running on high volts that will do 600 watts more regardless of the signal quality.
    Along with getting pissed off when they overdrive it and it keeps shutting down.
    Honestly, lots of guys that have the skill to build a very nice amp will not do it anymore because they have had to put up with the Bullshit from operators that don't run there equipment properly or think they should be getting more power out for the money they spent.
    73
    Jeff
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!