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New TL-922 Owner

Discussion in 'Amateur Radio Amplifiers' started by G3YRO, Dec 14, 2016.

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  1. W1QJ

    W1QJ Ham Member QRZ Page

    Not true, the HW-101 had a CW/MIC gain control. This control acts much like an RF Power control on a solid state radio. In the CW mode this control adjusted the drive to the final amplifier, to be legal all one had to do was to advance the drive level using this control and peak the load and tune for maximum power output at a given level that related to whatever drive power the SB-220 needed to produce a legal limit output. It wasn't like it was impossible to use the two and no way to be legal. The issue is if anyone ever heeded to the rules.
    WA7PRC likes this.
  2. SM0AOM

    SM0AOM Ham Member QRZ Page


    My own HF setup in the early 70's was an HW-100 and an homebrew gg 2x813 amplifier.

    The power limit in SM at that time was 500 W DC, and the SSB interpretation was literally taken from the FCC definition
    including the 250 ms time constant of the meter and all.

    The memories are quite foggy, but when I tried to stay legal, the procedure was to first tune up for 500 W indicated input on key-down,
    increase the loading slightly and the speak so the meter kicked-up to approx. 200 mA at 2.8 kV.
    I also had an inline wattmeter (copy of Heath IM-102), an RF ammeter and an oscilloscope connected to the amplifier output.

    This combination taught me important lessons for the future about the actual relationships between peak and average power ratings, both input and output. Without any direct speech processing, it was possible to reach peaks of about twice or three times the deflection of the oscilloscope when it was tuned for 500 W DC at key-down, and still staying within 500 W indicated peak. This meant that sometimes a kW or more PEP was emitted. The thermocouple meter however showed the long-term average.

    When an antenna tuner was used, it was first tuned up using only low power from the HW-100 driver.
    Fortunately enough, no combination of frequency or tuner settings resulted in flash-overs.

    Unlike the rig at my Uni radio club SK6AB, where the 2xQB4/1100 or 7527 tetrode amplifier (named "Pripps BlÄ" after its sea-blue front panel colour and the trademark of a local brewery that sponsored the radio club) delivered an unspecified amount of RF.
    It was however sufficient to damage a Drake W-4 and blow up the balun and loading coils of a Hy-Gain 40m yagi...

    WA7PRC likes this.
  3. AI3V

    AI3V Ham Member QRZ Page

    And there you have it.

    Peak the plate and load controls.


    It's dip the plate, and adjust the load for desired plate current.

    And good luck keeping Your CW power constant with the drive control on a hot water 101. And let's not even talk about the folly of changing SSB pep with that knob.

  4. G3YRO

    G3YRO Ham Member QRZ Page

    Yes, in the old days we KNEW how to tune things up properly . . .

    1. Tune PA on valve transmitter into dummy load at low power

    2. Switch to ATU, and adjust the Antenna tuning for 1:1 VSWR

    3. Increase transmitter power to desired level, and adjust Loading

    4. If using an Amplifier, feed rig into Amp at low power into dummy load, then switch to Antenna, increase drive power to desired level, and adjust Loading

    As someone said, it's not following the proper way of using equipment that causes flashovers !

    Roger G3YRO
  5. W1QJ

    W1QJ Ham Member QRZ Page

    WRONG: Rege, you are batting 0 (ZERO) today. HW-101 manual page #141 step #8 Read it and weep.
  6. K9AXN

    K9AXN Premium Subscriber QRZ Page


    Interestingly, after installing the QSK feature or properly adjusting the TX/RX timing those problems almost disappear. The results are repeatable.

    Regards Jim
  7. SM0AOM

    SM0AOM Ham Member QRZ Page

    We had to know what we were doing, and it was learned by mistakes mixed with listening to those that knew better. There were no "instant hams" during these times.

    I had some guidance in high-voltage practices from a neighbour "pro", but some self-preservation instincts probably also saved me from killing myself with the HT in the same way they saved me from crashing with my motorbike.

    "Dipping and peaking" became almost second-nature, and was acquired by practicing on our home-brew 10W input crystal controlled Novice transmitters, for a year or so before coming of age for the higher class licences.

    Regarding the adjustment of the PEP with the MIC/CW Control, it worked very well. This was used in my first 144 MHz operation with the HW-100 and an homebrew transverter, that previously had been driven by a low-power SSB exciter with a 6CL6 in the output stage.

    Pure laziness made me run the power control down until the HW-100 produced 2 or 3 W to drive the QQE 03/12 in the mixer.
    The only "caveat" (my Latin teacher now smiles in her heaven...) was that reducing power this way degrades the carrier suppression.

    Finally, I forgot to reduce power one day after some "DC-band" operation and blew the cathode resistor in the transverter. This prompted the installation of a proper RF tap-off in the driver, and a switch-box that disconnected both HT and screen voltages for the 6146's.

    To summarise, when radio amateurs had to learn their trade properly, and there were no "instant hams", the building, tuning and loading of even high-power amplifiers could be done [relatively] safely even by teen-agers.

    WA7PRC likes this.

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