[BC] Our Wild TECH Youth - more memories

[Charles Lewis]

    I wonder if I am the only person who ever used the local oscillator
    of an "All American Five" tube radio for a "wireless broadcaster?" 
    When I was about 12 years old, I discovered that the local
    oscillator in the converter stage would radiate a fairly strong
    signal if I clipped a good length of wire to the plate.  (Yes, I
    know the screen acted as the oscillator plate, but hooking an
    antenna to the screen caused problems.)  I also found that a high
    impedance, high output source like a crystal phono pickup would
    usually modulate the signal very nicely when hooked to the grid that
    normally was connected to the loop antenna.  The success of this
    varied from radio to radio, but it usually worked quite well.  I had
    an aunt living next-door and another who lived around the corner
    behind me.  This worked so well that I would play sacred music
    albums for them to listen to on their radios while they worked
    around the house, which they enjoyed.

    Usually, the radio's speaker could be pressed into service as a
    fairly sensitive microphone if desired.  I would disconnect the
    primary winding of the audio output transformer. Then I would ground
    one lead and connect the other to the RF input grid of the converter
    tube.   Using four old plastic table radios, two for receiving and
    two for transmitting, I once set up a duplex communications link
    with my cousin who lived a few hundred feet from my home.  I broke
    up the audio feedback loop by wearing headphones at my end.  We
    could sit and chat as though we were in the same room. 

    If connected to my 80 meters dipole, fed against a minimal ground as
    a T and resonated with a loading coil, I could hear this rig for
    about a half mile on on 1610 kHz on my father's car radio.  That was
    despite the fact that this loaded antenna hookup caused some
    reduction in modulation depth.  (The car radio would just hit 1610
    when tuned to the high end stop.)

    Such fun!  I later did some more daring on air deeds involving a
    good bit more power with a two stage transmitter of a few watts.  I
    think the output stage was a 6AQ5.  I would make a quick dash down
    the road to see how far the signal (on 1610 kHz again) could be
    heard and then dash back home to turn it off.  I once had a trusted
    friend who lived a few miles away across town to listen for a brief 
    transmission, and he heard it very well.  That was really exciting
    for me as a kid. 

    Even later I went into competition with the NCSU campus carrier
    current station with a home brewed 6AG7 & 6L6 carrier current setup
    in my room that covered two large dorms that were fed from a single
    transformer vault.  I built it to look as crummy as possible. The
    object was to show the campus system's "chief engineer" that an
    absolute piece of junk could be made to sound much better than the
    campus system.  (I must have been a real smart alec nerd back then!)
      I modulated it using a very large reverse connected audio line to
    voice coil transformer driven by a Heathkit Williamson mono hi-fi
    amp (KT-88s?).  What happened to that pile of junk after it proved
    its point at NCSU is another long story.

    Regards,
    Charles Lewis - S9SS

    Station Manager
    IBB Sao Tome Transmitting Station (VOA)
    Sao Tome Island, West Africa


    P.S. I'll bet some of you young fellows don't know what an "All
    American Five" refers too.
    -----------------------------------------------------------------------------------------------------------------------------------------------

Willie wrote -

>>I said "Hi, Sue!" and she just about jumped out of her skin! He laughed 
>>hysterically, and I explained to her what we were doing via the radio. We all 
>>had a good laugh. (I wonder how many, if any, other people heard those 
>>broadcasts!)
>  
>
>>That was back in the late 70's, early 80's, so thankfully, the Statute of 
>>Limitations has long ago expired on that stuff! Heh heh!
>  
>

That would have been really cool to have a station like that. Our middle school had a Lafayette
AM transmitter which had been slightly modified. 

Randy Shaffer
Harrisburg, PA