Simplest Transmitter

Discussion in '"Boat Anchor" & Classic Equipment' started by KL7AJ, May 29, 2020.

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  1. KL7AJ

    KL7AJ Ham Member QRZ Page

    I acquired a "Pastime Projects" reproduction of W1DX's simplest transmitter...a single 6V6 transmitter. Cute lil thing. Just for jollies...I wanted to see just how much power I could get out of this. I got a whole 18 watts with 400V on the plate. I wouldn't do that for very long, though. At 200V, it puts out a comfortable 4.5 compliance with the actual specs.

    Check out December 1946 QST for Byron's original article
    PU2OZT, WA1GXC, WN1MB and 1 other person like this.
  2. W9WQA

    W9WQA Ham Member QRZ Page

    a friend made an am xmtr from one 6a8 converter section was the oscillator. another grid took mic audio in. he ran a phono in and you could get him in the neighborhood. this on am bcst band,find a dead spot...!
    he inspired me to build with a 6bq6 final. we could take a drive around town !!
    my mother would flip the record stack !! plate modulated with pp 7c5.
    way back in the 50's
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  3. KL7AJ

    KL7AJ Ham Member QRZ Page

    My brother and I built a phono oscillator back in the early 60s, as well. Ran about a thousand feet of wire around the property, and we could be heard nearly a mile away. :)
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  4. K9STH

    K9STH Ham Member QRZ Page

    Growing up, I was around several "olde tymer" amateur radio operators who talked about running over 1000 VDC on the plate(s) of 6L6 tubes. They said that they had to send CW at pretty high speeds because a short "dah" would turn the plate(s) red hot and a long "dah" would melt them!

    Glen, K9STH
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  5. N2EY

    N2EY XML Subscriber QRZ Page

    "The Most Inexpensive Transmitter", pages 33-35. Note that W1DX doesn't take credit for the idea. It originated with W9JVI.

    To get the full effect, it needs to be used with a receiver that has a suitable audio output stage.

    The Southgate Type 1 was inspired by this design. However, it used the grid-plate circuit rather than the Tri-Tet.
    WA1GXC likes this.
  6. KL7AJ

    KL7AJ Ham Member QRZ Page

    Yep. The original design "stole" filament and B+ from a common receiver
  7. N2EY

    N2EY XML Subscriber QRZ Page

    Not so much "stole" as "utilized unused".

    W9JVI's brilliant trick was to remove the audio output tube of the receiver and use it in the transmitter. This required using 'phones, but most CW ops of the time used them anyway. In many receivers of the era, the headphone jack was in the grid circuit of the audio output stage, so that stage did nothing when using 'phones.

    So the transmitter borrowed power and the tube from the receiver.

    The transmitter itself uses a pair of octal sockets, a variable capacitor, a resistor, an RF choke, two bypass and one mica capacitor. The chassis is some wood and a few bits of hardware, the coils and wiring all come from a roll of bell wire. Power plug is made from the base of a worn out tube.

    In those times they didn't count the crystal cost because you had to have it anyway.

    The whole thing cost well under $5 (1946 prices) if you bought everything new.
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  8. KL7AJ

    KL7AJ Ham Member QRZ Page

    Here's my Pastime Projects transmitter. Built it in about 2 hours. 6v6.jpg
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  9. K1APJ

    K1APJ XML Subscriber QRZ Page

    I'd imagine that the hardest part is finding a crystal that will be happy with the current. I would expect that you need a genuine FT-243 or larger.

    What does it sound like on the air?
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  10. KL7AJ

    KL7AJ Ham Member QRZ Page

    I have piles of FT-243s. However, most of them are outside the ham bands. :(

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