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class e rigs

Discussion in 'Amplitude Modulation' started by N2DTS, Oct 23, 2017.

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  1. KB3OUK

    KB3OUK Ham Member QRZ Page

    Biggest class E rig I have heard of is 24 FETs, Steve has a schematic for one on the class E website, and I am pretty sure that is how many the particular guys in question are running. Going off of that design, and using the values for curent and voltage on that schematic, it is very possible that by running 70 volts at 40 amps on that RF deck you could get 2.5 kw out and still be within the ratings of the FETs, if you also choose to ignore any of the safety factors on the voltage and current limits of the FETs. That mess on the bottom end of the AM window is the reason why I've been sticking to 40 meters lately, besides the fact that that is the only band I have an antenna for at the moment. The taunting from those particular individuals gets the sidebanders all stirred up and just draws them in, like flies to a cowpie.

    Shelby
     
  2. WA1QIX

    WA1QIX Ham Member QRZ Page

    I would say that I am reasonably authoritative on my designs, and I can say with absolute certainty, the system will not function with 70 volts of carrier unless there is VERY little modulation. Furthermore, the overload system would require modification along with a whole lot of other circuits. Furthermore, the devices would overheat, and the cores in the output transformers would also be permanently damaged by heat.

    You may not like certain operators, their habits, politics, etc., however engaging in defamation of character or putting forth false (possibly slanderous) information is not helpful.

    I would like to request that the moderator remove this thread since it has degraded to personal attacks.
     
  3. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    There are practical limits and I believe a 24 FET rig is about the limit for most homebrewers.

    In Broadcast, we build separate Class E circuit boards and then combine through Combiners. Power Splitters feed the individual circuit boards. Say you need 10kW output, we may use 5 boards at 2.1kW each, or 10 boards at 1.1kW each and then combine them.

    QIX: You may not like certain operators, their habits, politics, etc., however engaging in defamation of character or putting forth false (possibly slanderous) information is not helpful.

    I would like to request that the moderator remove this thread since it has degraded to personal attacks.

    Now hold on partner. :)Unless I missed a post, I haven't seen any call letters or names mentioned, only that an operator or certain operators seem to have wide bandwidths.


    Phil
     
    Last edited: Nov 18, 2017
    WA3VJB and KA0HCP like this.
  4. WA3VJB

    WA3VJB Ham Member QRZ Page

    Phil I would like to associate myself with your remarks, to suggest this thread should remain posted because it has been very useful for several reasons:

    • shows an interested pursuit of a polite and reasonable query (Brett's original post)
    • provided a forum for respectful discussion of factors ranging from technical to behavioral
    • demonstrates the attributes of peer pressure and self-policing to ensure responsible operating
     
    AC0OB likes this.
  5. WA1QIX

    WA1QIX Ham Member QRZ Page

    Unfortunately the realities of normal AM operation for all types of transmitters have been ignored, in favor of picking on one technology because the accusers don't like some of the people using it, their politics or whatever.

    Fact: The widest AM transmitters on the air are tube transmitters. I experience this all the time up here in the north east, and can easily provide waterfall and panadapter displays as backup. These rigs usually have NO filtering, and overmodulation causes severs splatter. This is just a fact.

    I won't get into the power thing (I'm not trying to be a jerk) - suffice to say that pairs of 4-400s, 4-1000s and 15kW of plate dissipation in linears are out there, and if I check the max ratings....well.... no further discussion needed at this time.

    And of course there are guys are running modulated oscillators! Wide ? Terrible sound? Distorted?
     
  6. N1BCG

    N1BCG Ham Member QRZ Page

    It sounds like we all agree that any transmitter can be operated irresponsibly much in the same way that any vehicle can be driven irresponsibly. Those who do so intentionally, for whatever reason, are unlikely to change their ways.

    Two productive discussions might include ways to assist responsible ops in improving their signals and ways to set a good example for them to follow. There is evidence of a growing interest in AM and each new op will represent the mode. What are the best ways for new AM operators, or established operators with a renewed interest, to keep their modulation and bandwidth in check?
     
  7. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page


    Hey Steve, I have always enjoyed a QSO with you and your audio is always FB.

    I like Class E technology and have worked with it a lot, but I also like Boat Anchor vacuum tube technology as well.

    I disagree that it is the Class E technology that has been singled out.

    In fact, I am confident it has been shown that Class E is an excellent AM technology with excellent audio response and we have demonstrated that to the OP.

    The main focus has not been the technology the individuals are using nor the individual(s') politics in question, but to their "behaviour."

    As a child, we learned not poke a Hornet's nest. We also learned that we don't take the Hornet's nest and put it on the neighbor's front porch if we still want to be neighbors.

    At this very point in time, myself and one other individual in the AM community has written to the FCC's "TAC" group requesting a more equitable AM power rule be enacted:

    https://www.fcc.gov/ecfs/search/filings?proceedings_name=17-215&sort=date_disseminated,DESC

    So it would be advantageous at this time that no monkey wrenches be thrown into the gearbox to impede a return to equitable AM power rules.

    Regards,


    Phil


     
    Last edited: Nov 18, 2017
  8. K4KYV

    K4KYV Premium Subscriber QRZ Page

    The only one I know is the (in)famous SBE rig (Slop Bucket Eliminator). Unreadable with my synchronous detector; I must put it in envelope detector mode and open up the selectivity to 16 kc/s to understand what he says.

    Modulated oscillators used to be illegal, but the FCC deleted the rule that prohibited simultaneous amplitude and frequency modulation, along with the rule that a transmitter could be modulated no more than 100%. Maybe inadvertent, or else someone at the Commission ASSumed that amateur radio AM would soon die out and thus no longer be any need for either rule.

    It was never completely clear if the 100% modulation rule in the amateur regs applied to positive peaks as well as negative. The AM BC service limits positive peak modulation to 125%. But the FCC seemed unable to use the 100% rule against W3PHL when he ran his upside-down tube circuit (high level plate modulated, partially unbalanced, balanced modulator) to run 600 watts DC input to the final, modulated with 5 kw of audio. They ended up citing Fred, who usually operated on 7290 kc/s, for having detectable sideband products outside the top edge of the 40m band, even though those products were down tens of dB, well within the limits of good engineering practice.
     
  9. WA1QIX

    WA1QIX Ham Member QRZ Page

    That is fantastic that perhaps we might get a more reasonable way to measure AM power ! Just great!!

    Perhaps we should abandon this thread which IS called "Class E Rigs" and start a new one called - Good and Bad Operating Practices. That portion of the conversation has much merit.

    Phil, do keep us informed about your efforts with the Commission ! No monkey wrenches PLEASE to impede this excellent effort (including perhaps the possible monkey wrench of this thread?)??

    Interference at the edges: The "AM Window" (notice the quotes) border wars have, unfortunately, been going on at least since I became a ham which is around 1970 and perhaps longer. That is a long time! They are not NEARLY as bad as they were back in the 70s and early 80s, that is for sure, however they are still there. There is the group on 3892 that sometimes decides to operate on 3888.888 and causes problems on 3885. There is the so-called "magnolia net" on 3878 and their minions. They are a REAL problem and should go back down the band where they came from. Then there is the 3868 group who regularly runs double side band just to cause interference. Of course, I forgot to mention the so-called "Texas traffic? net" which NEVER has any traffic on 387-something - they move between 3873 and 3875.

    And Yes - No ham or group of hams has exclusive rights to any frequency, and of course we can use AM everywhere - please, do spare all of us those arguments - we know them well.

    From a practical standpoint, the so-called "window" is a good gentleman's agreement and when gentlemen are involved, it works. Much like the DX window and other "windows" on various bands. It is convenient; a hang out; a well known place to look for your AM compatriots. Love it or hate it - it more or less works :cool:.

    Regards, Steve
     
  10. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

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