Ten-Tec 238 Tuner and the Mysterious R-30

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by W6FG, Apr 14, 2016.

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  1. W6FG

    W6FG Ham Member QRZ Page

    Hey all you TT owners...

    My Model 238B tuner's pwr meter really needs to be calibrated. I have the manual and it explains that to calibrate the wattmeter, you simply adjust the meter to match the known-standard meter that you have in line. To do this, you "adjust R30". Well, I've searched for that R30 and I just can't find it. It is NOT in the schematic in the manual, nor is it listed in the "MASTER PARTS LISTS" in the back of the manual. I've looked at all of the markings I can see on the boards with no luck.
    Anyone out there that can direct me to the illusive R30??


    REASTON QRZ Member

    If you look at this schematic for a TT229 tuner, R30 is at the bottom of the page near the meters. It's 10K pot in series with the forward power position. Its probably the same pot but may be marked differently in the TT238.

  3. G3TXQ

    G3TXQ Ham Member QRZ Page

  4. KA9JLM

    KA9JLM Ham Member QRZ Page


    Does it have the 80911 board ?

    Good Luck.
  5. W6FG

    W6FG Ham Member QRZ Page

    Oh Brother....

    Thanks guys for your help!!!

    Unfortunately, I've goofed again and put the wrong model number in the title of this thread. What I have (and should have said in the title) is the Model 238B, which has no 80911 board. It appears to be a whole different tuner with a more complete and different manual. I thought the *B* designation simply referred to the color of the unit being Black; live and learn...
    If I knew how to edit the title, I would do so now. I'll keep fumbling around here, trying to change the title.

    Again, thanks for your help!

  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The 238A and B are identical except for color, but are different from the regular 238.

    The internal calibration controls are:

    R4 200W power range adjustment
    R10 2000W power range adjustment
    R9 SWR adjustment

    Their locations are shown in the manual, Figure 3-3.

    The reference in the text to "R30" is an error.
  7. W6FG

    W6FG Ham Member QRZ Page

    Most EXCELLENT Steve, thanks Pal! Now I've got it fixed...


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