Tuner confusin

Discussion in 'General Technical Questions and Answers' started by KE0WXN, Dec 11, 2019.

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  1. RANCH55

    RANCH55 QRZ Member

    This info is straight from my Icom 7300 Full Manual ........

    "Using an external antenna tuner"
    When you use a non-Icom external antenna tuner,
    be sure to turn
    OFF the internal antenna tuner.
    Otherwise, the tuning may fail because both antenna
    tuners (internal and external) will simultaneously start
    tuning.
     
    WB5YUZ likes this.
  2. KD0CAC

    KD0CAC Ham Member QRZ Page

    So we have to assume that you " be sure to turn OFF the internal antenna tuner " .
     
  3. N3PM

    N3PM Ham Member QRZ Page

    Yes, I believe that's true if you use an external tuner that is not connected to the 7300 tuner jack. If the external auto tuner "looks like an AH-4 tuner to the 7300", the radio recognizes an external interfaced autotuner.
    This article concurs with my findings.
    https://www.k0pir.us/ldg-at-600proii-autotuner/
    Mike N3PM
     
    W9FL likes this.
  4. W9WQA

    W9WQA Ham Member QRZ Page

    how does it "look like" an icom tuner?

    meantime my sg230 is wired like an ah4 icom so it probably "looks like" an icom tuner.
    i still routinely use both with great results, no trouble.
    work fine together..
    i first tune the sg with the internal off,sg tunes itself.

    i use the icom cable to power the sg230
    then tune internal into the sg230. works fine...

    could icom be wrong?
     
    Last edited: Dec 12, 2019
  5. N3PM

    N3PM Ham Member QRZ Page

    I'm going with, the radio senses when the AH-4 is connected, and bypasses the internal tuner. You SGC apparently does this, as does my LDG. When I short press the radio's tune button, the LDG goes into by pass. Longer press goes to tune.
    Chances are if your SGC is wired like an AH-4 , it'll look like an AH-4. Only a guess here.
    How does it know if something is connected? Maybe current draw?
    Mike N3PM
     
  6. N3PM

    N3PM Ham Member QRZ Page

    W9FL likes this.
  7. W5DXP

    W5DXP Ham Member QRZ Page

    That will work FB because both autotuners are NOT tuning at the same time (the ICOM is not sensing the SG230).

    No, ICOM is assuming both tuners are trying to tune at the same time and they are saying to avoid that condition. You are avoiding it by doing the two tunings at separate times. But the ICOM autotuner is not accomplishing much since the impedance looking into a tuned SG230 is in the ballpark of 50 ohms. You might as well disable the ICOM autotuner.
     
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  8. K7TRF

    K7TRF Premium Subscriber QRZ Page

    I second that notion.

    It's not that you 'cannot' run two tuners in series without troubles, it's that you shouldn't really have to and if you do it implies the antenna system impedance you're trying to match is pretty extreme which at least in coax fed systems implies relatively high losses. IOW the external wide range tuner should be able to deliver a decent SWR50 to the rig and you shouldn't need the rig's internal tuner. If the external tuner cannot achieve a decent tuning solution and still has relatively high SWR50 then the system you're trying to match is likely presenting a fairly extreme impedance.

    If the external tuner gets the SWR low enough such that the rig can deliver full power without using the rig's tuner then switching in the extra tuner just adds a bit of extra loss to the system as every tuner adds some losses. If you don't need it I wouldn't use it and if you do need both tuners then there's likely a pretty big problem with your antenna system on the bands you're having trouble and I'd recommend solving that issue at the antenna itself.
     
    W9FL, W9KEY and KD0CAC like this.
  9. W9WQA

    W9WQA Ham Member QRZ Page

    sg cable just has grnd,+12 and key so no sensing.
    long wire needs tuning everywhere. sg does good,2:1 or less, internal tunes that to zero.
    i only make an issue because guys who dont know get scared to try stuff when others are adamant about something that may not be true.
    its silly not to use both if it cannot hurt anything
     
  10. K8JD

    K8JD Ham Member QRZ Page

    I could not find what kind of "multi band" antenna this is in the many postings,
    If it is a trap vertical (you mentioned tuning the antenna), the manual shows how to set it up by changing the length between traps on each band while checking for lowest SWR. Using a tuner for this antenna is counterproductive and may insert extra losses in power going to the antenna .
    The only use I can see for a tuner is when you want to operate on the extreme high or low end of a band like 80 or 40 M when the ant is tuned for center band.
    I always tweak the antenna lengths for the end of the band I operate on (for me its the low end for CW)...that way I don't need any tuner.
     

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