K7DYY 80/40 Super Senior Transmitter

Discussion in 'Chat' started by WD5JKO, Jul 11, 2015.

  1. WD5JKO

    WD5JKO Member

    There are a few pre release K7DYY Super Senior transmitters appearing around the country. This is a follow up to the 160/80 meter version that is on Bruce's web page. He also has a followup to the D-104 base preamp that was once evaluated on this board.

    The transmitters are class D RF, and the modulator is the power supply. With class D, the RF Fet's feed a band specific low pass filter. This differs from class E that uses a high Q resonant output circuit.

    Think about this for a second...a 10 pound 4U rack mount chassis, and a 120V line cord. Runs 1500 watt PEP output with a carrier level up to 375 watts. Most users throttle back to 250-300 watts carrier, and let the positive peaks fly a bit over 100%.

    http://k7dyy.com/

    The announcement, and updated schematics are on the Index Labs AM Transmitter Yahoo group.

    Jim
    Wd5JKO

    K7DYY.png
     
  2. W5HRO

    W5HRO Administrator

    Where are the press releases or that Yahoo group? I can't find anything about a 40/80-meter model and there is nothing on his webpage about.

    I'd be tempted to buy one myself if it worked on 40-meters.

    My favorite bands have always been 160, 80 and 10-meters, but 160 is always an issue due to available antenna real estate so 40-meters is a must. I mainly work only on 80, 40 and 10-meters now-a-days.
     
  3. WD5JKO

    WD5JKO Member

    Brian,

    I'd email Bruce, K7DYY. There is a link on his website to check for availability. The Yahoo group is closed to all but members. Here is the URL I have, but I am a member:

    http://groups.yahoo.com/neo/groups/IndexLabsAMXmtrs/info

    There is a review of this rig by fellow AM'er Janis AB2RA. This is mostly about her 160/80 meter version, but she does mention the 80/40 version:

    http://wireless-girl.com/Projects/AMTransmitters/K7DYYtransmitter.html

    The Yahoo group posts the schematics. They include the early schematics, and the current ones. It looks like Bruce beefed up certain areas dealing with carrier level set, and SWR protect. Also some of the RF output capacitors got changed around as well. Overall this seems to be a rather simple transmitter in concept, and the price for a legal limit transmitter is below $1 / PEP watt. The RF FET's used can be had for less than $5 apiece.

    Jim
    Wd5JKO

    Attached are 2 of the 5 sections
     

    Attached Files:

  4. W5HRO

    W5HRO Administrator

    Jim,

    Did you ever hear what NQ5T's sounded like? Also attached below are all 5 PDFs in one file.
     

    Attached Files:

  5. WD5JKO

    WD5JKO Member

    Well I worked him once on 7160 but noontime propagation was so bad I could not hear much of his audio. I have been working others on 7290 in the evenings though. I just finished with Ed N5AEA and Bob K9EID. Those 811A's are hanging in there at 150 watts RF out. I am sure that the 12V bias is helping bump up the efficiency. I should redo that matrix of tests on my class BC thread, but I am getting lazy...being content that it works.

    Jim
    Wd5JKO