Radio sees something completely different...

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K2QI, May 23, 2020.

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  1. K2QI

    K2QI Ham Member QRZ Page

    I redid my antenna's ground this afternoon. Analyzer shows bands 10-80 all below 1.5:1 with reactance (X) as close to zero (most between 7-13) ohms on the analyzer, and impedance (R) anywhere from 40 to 60 ohm.

    I tested both at the antenna feed point and at the antenna coax in the shack. I did not however test from the coax from the rig, going into the linear, then to to the SWR meter, and out to the antenna. That's 2 extra pieces of coax which I believe are good.

    Furthermore, the working assumption being the amp's input circuits are all tuned correctly (which they are), and show 1.5:1 or less at the radio when the amp is keyed. That said, when the amp is not keyed and RF is simply passed through, the rig sees 1.5 to 1.6 on a band that the analyzer says should be around 1.3:1 on a given frequency.

    The rig is a Flex 6600M. Amp is a Heathkit SB-220. Antenna is a ground-mounted Tarheel 100HP (deed restrictions, bleh).

    Thoughts on what I should be looking at?
  2. WJ4U

    WJ4U Subscriber QRZ Page

    That's what you should be looking at.
    PU2OZT likes this.
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I'd be looking at ignoring this.

    You have a problem with a VSWR of 1.5 or 1.6?

    The difference between 1.3 and 1.6 is commonly called "measurement error.":)
    KI5WW and AI3V like this.
  4. K2QI

    K2QI Ham Member QRZ Page

    LOL.. how did I know that's the first answer I'd get? I guess I'll test the coax into a dummy load later.
    Would it be measurement error if the finals start folding back? There's gotta be some weird reactance thing going on between the radio, amp, and watt meter. Only thing I can think of. I guess I'll pull the patch cords later tonight and test them.
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The Flex folds back at 1.5-1.6:1 VSWR?

    No wonder I sold mine and never wanted another one.:p
  6. K2QI

    K2QI Ham Member QRZ Page

    I'm using a T/E rig. Determining if this is something my club station wants to move towards. I've had the radio for about 3 weeks now. I used to own a K3, and still have a 756 Pro III. I'm seeing according to SmartSDR, forward losses amounting to up to 20% in some cases. It's significant when driving an amp at lower power, say 25 watts. That's the reason I went and redid the ground plane earlier today; added new radials, trimmed existing ones, adjusted the matching shunt coil for lower bands, etc. The analyzer is usually spot on, but what the radio sees doesn't match; hence the question.

    To be honest, after years of only using analog radios, I have to admit that SDRs have their place; especially for remote ops or when you can't be right in front of the rig - as in the case of my club. That's not to say they're without fault though. I've already submitted a number of technical tickets and feedback to Flex's engineering team regarding strange nuances that shouldn't really exist (in my opinion). I just want to make sure that my QTH's equipment isn't at fault here before I file another one.
  7. AI3V

    AI3V Ham Member QRZ Page

    That's some special antenna if at any frequency between 80 and 10 meters the vswr is below 1.5:1

    Do tell us more.

  8. K2QI

    K2QI Ham Member QRZ Page

    It's a Tarheel 100HP screwdriver. I've got a shunt coil for anything 10 Mhz or below which works once you have the coil spacing properly set. I also have 24 untuned radials at ground level along with antenna. The rest of the tuning is done by extending or contracting the antenna's electrical length via control box. And it's not any frequency between 80-10, it's for any given tuned frequency within those bands I mentioned. What else is there to say?

    As for my initial problem; found it. Bad patch cable between rig and amp.
  9. AI3V

    AI3V Ham Member QRZ Page

    Start by telling us just what was wrong with your "jumper" that turned a 1.3:1 vswr into a 1.6:1 vswr over that same 80-10 range.

    I have been repairing transmitters for 45 years, and your posts indicate that you have very little tecnical knowledge, as they- the posts- are fragmented and describe measurments that are little more than guesses.

    In fact, it seems that its mostly a post about how much you $pent on your gear.

  10. K2QI

    K2QI Ham Member QRZ Page

    Hello Rege,

    Not quite sure what your particular issue with me or my post is, and why you'd need to resort to backhanded insults, but to answer your question - the center conductor on the PL259 has what appears to be a cold solder. Swapping the cable solved the problem.

    I simply asked question; I mentioned the rig (which is a test and evaluation unit that I did not spend any money on) because I felt if it could be an issue with the radio, then someone might let me know.

    It's wonderful how people lose all sense of decorum when speaking to each other on the internet. Now I have better things to do than continue this pointless discussion with you moving forward. Have a nice weekend.


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