Question Number One...

Discussion in 'Amateur Radio Amplifiers' started by KI6GEA, Nov 19, 2021.

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  1. KI6GEA

    KI6GEA Platinum Subscriber Platinum Subscriber QRZ Page

    How do I hook this thing up? I have an ACOM 1200S incoming, as well as an LDG 600 ProII tuner. I'm brand new at this and have a lot to learn obviously, and I really appreciate your help.

    Currently my FTDX10 is being powered by a Samlex 1235. The very helpful dude at DX Engineering tried to give me the rundown of how these will all go in series but I didnt write it down and I'm not clear on it.

    Does the tuner go between the amp and the radio, or between the amp and the antenna?

    I also called LDG, and they tell me I don't need any interface cable between the antenna. But I should put the amp in "Standby mode" before hitting the tune button on the tuner.

    Also, I recall DX engineering said I will still use the Samlex to power the FTDX10, and I will also need to use it to power the tuner, connecting both devices simultaneously to the power pole outputs on the Samlex. Does that sound right?

    Thank you so much in advance for your help.


  2. VK4TUX

    VK4TUX Ham Member QRZ Page

    The LDG 600 ProII tuner goes between AMP and antenna.
    Do not use the int ATU on the FTDX10 to match its RF connection to the amp input.
    The amp input should already be 50 ohms on each band for low input swr.
    Yes put amp in standby before LDG tune, and also set drive power for lowest power
    initially for first operate use at lowest amplified power after standby tune.
    When all looks good you can increase drive to obtain 600w or less at amp output.
    N3RYB, AK5B, KI6GEA and 1 other person like this.
  3. K7TRF

    K7TRF Premium Subscriber QRZ Page

    The tuner goes between the amp and the antenna. Your amp is designed to provide a good near 50 ohm match to the rig, the tuner (aka trans match) helps adjust for antenna systems that do not provide the ideal 50 ohm match. So the tuner definitely goes between the amplifier and the antenna.

    Based on the model numbers listed above you purchased a 1000 watt amplifier and a tuner rated at 600 watts. You really should run a tuner that's rated for at least if not more power than the amp you're running unless you are very careful never to drive the amp to its full power output.

    And yes, modern amps do not need an interface box for use with modern or even older rigs as they just switch a low voltage and low current to enable the amp unlike some vintage amps that switched very high positive or negative voltages that could cause damage to newer rigs.

    And yes your Samlex supply is rated at 30 amps which is more than enough to power the rig and the antenna tuner but of course the amplifier needs its own power supply.

    The biggest concern is probably running a 1000 watt amp from a rig capable of generating 100 watts into a tuner rated at 600 watts. If you're very careful about limiting your transmitter's power so you stay below the tuner's maximum power rating, for instance setting the transmitter to 50 watts or less, you should be OK but personally I'd want a higher power antenna tuner in that lineup.

    [edit] looks like I doubled with Adrian above...
    K0UO and K4YNZ like this.
  4. KI6GEA

    KI6GEA Platinum Subscriber Platinum Subscriber QRZ Page

    Thank you. I didnt realize the amp also needed it's own power supply. I actually have two Samlex 1235's.. The second one is powering an IC-9700.. Would that also be able to power the amplifier?

    I have the 120VAC version of the 1200S, which is 500 watts. Hence the 600w tuner.

    Thanks again for your help, I really appreciate it.
  5. KA2BLG

    KA2BLG Ham Member QRZ Page

  6. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Well that takes care of both issues.

    The power supply is built into the 120V version of the amp so no worries about supplies and if you have the 500 watt version then all is good on the antenna tuner power rating.

    Sounds like you're good to go.
  7. KI6GEA

    KI6GEA Platinum Subscriber Platinum Subscriber QRZ Page

    Ahh sweet, thank you so much, really appreciate the help. 73,
  8. K7GQ

    K7GQ Subscriber QRZ Page

    No such thing. The ACOM 1200S runs on anything between 100 and 240 VAC, and below 200 VAC it does run in a reduced power mode. Nevertheless, you should know that driving the amp to full power usually only requires 10-12 watts from the transceiver, and often only 5 watts results in 600-700 watts output. You're going to need a higher power-rated tuner eventually (or sooner).
    AK5B likes this.
  9. AK5B

    AK5B Ham Member QRZ Page

    If it's not too late I would return the LDG and order a Stockcorner JC-4S 1 KW tuner (antenna matching device). If you read all the reviews of both on you'll soon understand why (besides the fact you could damage or destroy the LDG in a forgetful moment).


    N3RYB likes this.
  10. KI6GEA

    KI6GEA Platinum Subscriber Platinum Subscriber QRZ Page

    The 1200S-120 is a separate model with max 500w from what DX Engineering told me:

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