Drake L7 vs Amp Supply LK-500

Discussion in 'Amateur Radio Amplifiers' started by N8FVJ, Nov 20, 2019.

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  1. N8FVJ

    N8FVJ Ham Member QRZ Page

    Which amp is better in your opinion? I understand a Drake L7 can be driven to 1500 out PEP like the Amp Supply LK-500, but needs more drive power.
  2. WB7TDG

    WB7TDG Ham Member QRZ Page

    have a drake L7...100 watts drive will get ya about 1100-1200 out the door. When mine was in line, I typically drove it with 50-60 watts to give me 10 to 11 db of gain, depending on frequency.
    BTW getting ready to list the L7 for sale, down sizing the station a bit.
  3. W1QJ

    W1QJ Ham Member QRZ Page

    That's about right. The 2600vdc that amp uses is a little anemic for 3-500 tubes. They play much better with higher plate voltage, they love that. Henry runs some of their 3-500 amps at 4000v. Ameritron runs the Al-82 at around 3600. The L7 RF deck will handle 1500 watts on SSB but watch the tubes for enough cooling. It will require more than 100 watts drive with only 2600 volts. The LK-500 runs up close to 3000 volts and it can tickle 1500 pep all things being good.
  4. N8FVJ

    N8FVJ Ham Member QRZ Page

    I figure 120 watts in to get full 1500 watts PEP out on the Drake L7. Transformer is large enough for 1500 watts PEP. Amps like the older Swan MKII & Heathkit SB-220 can not produce 1500 watts PEP, but some state the SB-220 will produce 1500 watts PEP (generous meter).
  5. W1QJ

    W1QJ Ham Member QRZ Page

    The CBer's drive the SB-220 with a two "pill" driver SS amp that can make around 250+ watts. They will run it like that and get 2500 watts output of them but obviously not for long. In the real world you can probably push a "tweaked" SB-220 to 1500 watts with no problem. That would be PEP output on SSB. The average stock unit probably won't do that but a tweaked one could.
  6. N8FVJ

    N8FVJ Ham Member QRZ Page

    SB-220 has weak 23lb transformer. Even an AL80B single 3-500z has a 26lb transformer.

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