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Ham Radio Magazine article six 572Bs on 160 meters

Discussion in 'Amateur Radio Amplifiers' started by KU7I, Jan 10, 2019.

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  1. KU7I

    KU7I Ham Member QRZ Page

    There was an article in Ham Radio Magazine from the late 1970s, early 80s. The builder had six 572Bs in parallel on 160 meters. An extensive internet search has not found this article. I had a copy for the longest time but 14 moves while in the Navy contributed to me losing the only copy I had. Trying to find this article. Thank you. Lane Ku7i
  2. W1VT

    W1VT Ham Member QRZ Page

    If you remember the author or title the ARRL Periodical Archive and Search should be of help, even though it is only an index for ham radio articles and not a depository of scans. CQ magazine holds the copyright so downloads would require their permission.
  3. W1QJ

    W1QJ Ham Member QRZ Page

    You can build a unit with only 4 tubes that will easily do 1500 watts with no sweat. I converted a Dentron Clipperton L to a 160 meter monoband amp and it does 1600 watts output and I ran out of drive power. The plate current was only 800ma. 4 of them can take an amp.
  4. N8CMQ

    N8CMQ XML Subscriber QRZ Page

    Do you remember why the author used so many tubes?
    Was it to reduce the output impedance, or increase the drive required, or some other reason?
    It seems strange to use so many tubes when two would do a good job, especially at MF rather than HF, unless it was the 1.21 GW output requirement...
  5. WA2CWA

    WA2CWA Ham Member QRZ Page

    Last edited: Jan 10, 2019
  6. N8CBX

    N8CBX Ham Member QRZ Page

    I agree Lou, really don't need 6 tubes, especially the cost of new tubes today.
    I homebrewed a 4-tube 572B amp and benefited from buying some key parts from Ameritron's AL-572 to speed up construction. Power transformer, socket assembly (comes with neutralizing circuit), meters and some tank parts. Everything else was homebrewed, and works great.
    Jan N8CBX
  7. W1QJ

    W1QJ Ham Member QRZ Page

    Jan, I used a Clipperton L for a mono band 160. Amazing results with only 4 tubes. I ran out of drive power at around 100 watts and could still have driven anther 200ma of plate current which would have been quite a bit over 1500 watts.
  8. KD8DEY

    KD8DEY Ham Member QRZ Page

    6 Tubes??...
    I remember reading somewhere that the answer was bigger, not more tubes...
  9. N2EY

    N2EY Premium Subscriber QRZ Page

    There was an article in ham radio magazine in August, 1975 by W2BP, "A 500 Watt Power Amplifier For 160".

    My uneducated guess is that it used 6 sweep tubes or similar - not 572Bs. In 1975, tubes like 6LQ6s and 6KD6s were plentiful and inexpensive, and the high combined C of 6 tubes in parallel would not be a problem on 160.
  10. WA2CWA

    WA2CWA Ham Member QRZ Page

    The article was modification of the Heathkit HA-14 or SB-200 for 160 operation.
    N2EY likes this.

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