SWR spikes with Palstar AT1KP

Discussion in 'Becoming a Ham - Q&A' started by AB2YS, Dec 9, 2008.

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  1. AB2YS

    AB2YS Ham Member QRZ Page

    I've been dealing with an odd problem with a new tuner and I'm looking for some ideas as to why this is happening.

    I have an IC-718 that will tune 80M-10M with a LDG AT-100Pro auto tuner with no problems. When I use my AT1KP I can no longer tune up on 10M, and I'll get SWR spikes that show infinite SWR while attempting to tune on certain bands, 10M and 17M (with less than 10W). There are no SWR spikes when connected to a dummy load through the AT1KP. When I activate the 160M relay switch in the Palstar tuner (it bypasses a 10uh torroid after the inductor, to ground) I can find a match, but that shouldn't work nor is it advisable according to Palstar.

    I've tried two different antennas, a Cobra UltraLite Jr. and a 135' wire dipole, both fed with 450 Ohm window line into a 4:1 Palstar current balun. Both antennas tune fine with the LDG tuner, but give me SWR spikes with the Palstar.

    I've checked all of my patch cables and I can find no shorts. I've switched patch cables around one at a time and I've also run the window line into the house directly to the AT1KP and used the tuner's internal 4:1 balun but I get the same SWR spikes. All I need to do to make the problem disappear is switch to the LDG tuner.

    I already sent the AT1KP tuner back to Palstar and it was checked out and found to be fine after being tested with their antenna, but it just doesn't make sense to me that my LDG autotuner can find a match for my antennas and my Palstar tuner can't. Also odd is that bypassing the torroid works when it shouldn't. Everything points to the tuner as far as I'm concerned, but I'm wondering if there are any other specific tests I should do before I send it back once again.

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