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Screwdriver auto controllers - thoughts?

Discussion in 'Mobile Radio Systems' started by KC8QVO, Feb 24, 2019.

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  1. W9CLL

    W9CLL Ham Member QRZ Page

    I had the original Turbo Tuner and it was a piece of crap and they went out of business, TennaTronix picked it up and hopefully fixed all the problems.
  2. K0BG

    K0BG Ham Member QRZ Page

    I could postulate on this subject, and fill a page or two. However...

    NONE (!) of the current, screwdriver antenna controllers properly detect two issues: Stall current and SWR. Everyone detects stall current by measuring the voltage drop across a resistor. That is the correct (simplest, really) way to do it. The question is, WHEN they measure it. We need to understand, that weather conditions often dictate the stall and running current. As a result, most controllers develop issues during cold weather, especially so if snow and ice are present. The question remains, when do you detect stall current? That is almost a trade secret! Remembering that the stall and run current are dynamic in nature, the answer is just after the motor starts to turn as detected by the reed switch. If you do it correctly, there will be no weather-related issues.

    Ah! SWR! Almost no one correctly adjusts the SWR of their screwdriver antenna. The preferred method is to use a shunt coil, but only if the antenna is mounted correctly (with lots of metal mass under it). Done correctly (both mounting and shunt coil adjustment), the SWR will always be under 1.6:1 across the 80 through 10 meters. That level of SWR can easily be detected, IF the detection methodology is correct. Of the four, currently popular, screwdriver controllers, only one does it correctly. In other words, measuring only the V-SWR (simple SWR bridge circuitry) isn't accurate enough.

    The only screwdriver controller which did these things correctly, was BetterRF. Alas, they are out of business, and we are all diminished.
    WW2PT, K0UO and AJ5J like this.
  3. WQ6N

    WQ6N Ham Member QRZ Page

    I could be in error, but I believe the newer TurboTuner-2 uses the radio SWR function as part of the tuning. I am speaking to the current R7 firmware and the 7000 ICOM series radios. The older models R3 and R5 still had to go through the tuner which limited them to 100w. The ICOM 700 series also needs the RF coax tuner in line. The Kenwood KTT-480 uses the radio control which allows full HX power 200w pep which is the spec for the Little Tarheel-II. I have never had a problem with auto tuning either the the ICOM's 7100 & 7200 or Kenwood 480HX with the latest firmware revisions. I did have a problem with an older "purchased used" TurboTuner-2 ITT-1 with the older R5 firmware as it would not tune the antenna. it's on the way back to TennaTronics for the R7 upgrade and hopefully a functional controller.
    I have seen older firmware revisions on eBay/QRZ/QTH. Hopefully one does their homework first before purchasing. Hind sight, I should of just purchased a new one and end up with a 1 year warranty instead of trying to save a few dollars. Lessons learned
  4. WA4SIX

    WA4SIX Ham Member QRZ Page

  5. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    I have run screwdriver antennas for years and tried tuners in the past.

    My question is why do you need something that's automatic???

    Screwdriver antennas, like most mobile antennas are very narrow banded, so all you do is move them up and down till you start to hear more noise on the radio also look at the S meter coming up. Then you're very close to the proper frequency.

    If you're moving to a higher frequency you shorten the screwdriver, if you moving to a lower one you lengthen it, that might take all of 10 to 15 seconds.

    So why make things complicated????

    With all the RF in the vehicle it's likely to screw up the controllers on most devices anyway, and drive you crazy!!!!! My experience with trying to use auto tuning on screwdrivers just creates more problems and eventually fails, put the money that you're spending on the controller into a better antenna.

    I use an inline SWR meter, tune for maximum noise, then bump it up or down to get best SWR. In 10 seconds you have jumped from 20 to 40 meters!!!!!

    It's called the KISS solution

    A Simple double pole double throw switch will do it, just move the antenna up or down, and use your eyes and ears, EASY. Then get on the AIR and make some contacts.

    I must add one more thing,
    you never try to tune a screwdriver antenna while driving, I don't care if it's automatic or not. If it's automatic and your driving by metal objects such as electrical lines, buildings, street signs, and other vehicles your tuner is likely to go crazy and you'll be distracted.
    If it's done manually you will definitely will be distracted, so you must stop to tune it. So my Point, why do you need an automatic tuner???? Spend your money and time on a better antenna with proper grounding and strapping in your vehicle.

    Last edited: Nov 30, 2019
    AJ5J likes this.
  6. AJ5J

    AJ5J Ham Member QRZ Page

    I couldn't agree more with K0UO's excellent post above! I gave up trying to tune while mobile and am more than happy to tune up or down while parked, safe and sound. A split second of a distraction is all it takes to lose one's life or cause a disastrous accident that can kill or injure others.

    Kudos to you Steve, especially for reminding all of us that tuning while within an ever-changing mobile involvement is folly!


    K0UO likes this.
  7. WQ6N

    WQ6N Ham Member QRZ Page

    I must admit, one touch and the antenna is tuned. Two touches parks the antenna while pulling into the garage.
    A split second could be a swallow of coffee or those greasy french fries. My control head is up where I can see both it and the road.
    I can change bands and re-tune while enjoying one of the many local traffic jams on the fly. So auto-tuning works for me. I do carry a manual switch and do use it while the remote CI-V port is being used by another device mostly for the RV. Common mode chokes are not that hard to make. So to each their own process. It's all good.
  8. N3UML

    N3UML XML Subscriber QRZ Page

    im using a target tuner with a dismond screwdriver and it works flawleesly but i have been told that running the control cable with the coax together has been known to cause failure according to a couple people i talked to and ran the control cable down the right side of the vehicle and 8 other coax cables down the opposite side just to be sure. have had no failures glitches of any kind have worked greece and spain on 75 at 80 watts from a 706 mkII and the diamond screwdriver and target tunner./ i love it unless something happens i may be purchasing a second one. Happy Dxing Allan N3UML
  9. KN2U

    KN2U Ham Member QRZ Page

    I gave lots of thought to auto controllers. My Yaesu rig has a way to give a low power CW carrier with the push of a button (remaining on SSB mode), which I installed in the antenna's manual switch box. I can get very close by listening for the noise level, which is very noticeable. Then a button poke while glancing at SWR gets it right in. Very little time is spent looking away from the road. After that, most of my bands are wide enough that no more tuning is required, except for 75m, but I don't go there often. I love the simplicity. More complex systems can be a PITA.
  10. WW2PT

    WW2PT Ham Member QRZ Page

    I tried the Targetuner. Mixed results. I went back to my original tuning method: use an MFJ SWR analyzer set to my QSY frequency, then manually tune the antenna until the SWR dips. I have an A/B switch to select either radio or analyzer. It takes a few extra seconds to tune the analyzer to the target frequency, but I often run 500w without an ATU and I really like to keep the reflected power to a minimum so it’s worth the effort. I also like that it lets me tune the antenna without putting a signal on the air. Wish more people would do it! :D
    AJ5J likes this.

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