Interesting amplifier comment heard on the air

Discussion in 'Amateur Radio Amplifiers' started by W7UUU, Apr 11, 2021.

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  1. K7JQ

    K7JQ Ham Member QRZ Page

    ....or tune nothing if your antenna(s) are *reasonably* resonant. Most SS amps won't trip out until SWR hits around 2:1. No tuner needed. If you reduce drive to get the amp's output below its maximum rating, perhaps it will tolerate higher SWR's (although I don't recommend it). And then there are (motorized) automatically tuned antennas to less than 1.5:1 across all frequencies, like the SteppIR series. Or SS amps with built-in automatic tuners. More than one way to achieve your intended "no-tune" results.

    Bob K7JQ
  2. K7JOE

    K7JOE Subscriber QRZ Page

    Hi Dave. Hope your ham shack is returning to normal after the fire! I lost the thread / updates, but trust you're accumulating a few boat anchors and other goodies again.

    Just a note that some of the big west coast contest stations have done something similar as far back as the late 1950's / early 1960's. Rush Drake W7RM's mega station on Foul Weather bluff near Seattle and then later when he relocated to La Center WA just north of Portland OR had a bunker with legal limit amplifiers - one (or more) for each band. There was no band switch on them it as I recall ...all custom designed for each band. I'm told W6AM had similar capabilities in the heyday of 1960's and 1970's in southern Caliornia. I know many of the top honor roll guys in that era especially before life with "packet spots" and "solid state anything" had separate RF amplifiers tuned up and ready to go (along with a set of twins, usually Collins but sometimes Drake) this was actually fairly common. No need for time consuming band changes to work the DX or chase mults on multiple bands. The old DX column in QST etc would often comment about this -- i only remember it because as a teen age ham, I wondered how anyone could afford one, let alone multiple stations at once !

    With the relatively inexpensive price for certain old green HF amplifiers that run a pair of 572B tubes, one could see this being done on the very cheap today - especially when things like replacement band switches and genuine Eimac or Cetron tubes almost exceed the total value of the amplifier. Being resonant, tuned up and ready to go means no boo-boo's and less likelihood of damage.

    Then again, with modern technology, it's just so easy to QSY almost instantly with the advent of auto tuners, solid state amplifiers, and band following that looks to the radio for data, it's probably not much of an advantage now days vs in the past when a "band change" of yesteryear could take several minutes.
  3. ZS6US

    ZS6US XML Subscriber QRZ Page

    As already said there's nothing wrong with having 2 amps in use, especially if you have different antennas. If you have the money and it makes operating easier for you whether you contest or whatever, then why not.
    K8PG likes this.
  4. W1BR

    W1BR Premium Subscriber QRZ Page

    Wrong. My ALS1300 is far more sensitive to SWR than that. Even my retired KMA1330 LPA would trip the SWR unless a tuner was used. I do have a MF998RT mounted at the tower; but needing to spend an extra 1000 to 4000 bucks to circumvent a manually tuned amp is a bit of a financial stretch for many hams.
  5. VE3PP

    VE3PP XML Subscriber QRZ Page

    I have a friend who has a radio and amp for every HF band :) He just changes stations and operates!
  6. K1APJ

    K1APJ XML Subscriber QRZ Page

    Well, setting aside practicality (!) is it emotionally or spiritually or psychologically different from having 6 or 8 or 25 rigs that all do about the same thing?

    I have-

    Drake Twins
    Flex 6300

    All the above rigs are practically interchangeable, but I keep them all. As well as a few CW-only positions. And, that is a small collection compared to many TRUE hams, which, I am frequently reminded, I am not.

    Some people are turned on by having lots of stuff. God bless 'em. That's the American way.

    Oh, my 1967 RAH describes separate kilowatt amps for each band as the ne plus ultra of transmitter construction.

    So there! ;)
  7. W7UUU

    W7UUU Principal Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Exactly. Then those scary knobs never have to be turned and mess things up ;):D

  8. KA9JLM

    KA9JLM Ham Member QRZ Page

    The knobs should not scare you. The high voltage should. :)
  9. K7JQ

    K7JQ Ham Member QRZ Page

    Not wrong...I did say *most* SS amps won't trip until around 2:1 SWR. I have no experience with your ALS-1300, but my previous ALS-600 and THP HL-1.5KFX wouldn't trip until 1.9 and 2.0:1 respectively at their maximum ratings. My current Acom 1200S is programmed to trip at 1.5:1 if you exceed its rated 1KW output. I haven't tested it further, but I can run up to 999W continuous at 1.9:1 without tripping. Apparently, each manufacturer has their own protection thresholds programmed into their amps.
  10. W4NNF

    W4NNF XML Subscriber QRZ Page

    Guess he never thought of the idea of writing down the settings (or taking a cell phone picture) of the load/tune controls for different bands, spots on the bands. ;)

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