I have an older I max that will not tune below a 1.5 swr no matter what I do. It's the full length version but it wont tune lower no matter what I've done to it. I've used different coax, added and subtracted the top whip length, raised the antenna and lowered it, reset the rings, even swapped radios and meters. Nothing changes.
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Older 2015 i max wont tune
- Thread starter Staybolt
- Start date
With an SWR of 1.5, 96% of your power is getting on the air. Most good coax cables have that much loss. And adding 4% to your signal won't make any difference on the other side.
If you want perfection, you will need a VNA to take an impedance measurement (with the reference plane at the antenna feed point) to know what to change at the feed point to get a better match. If the adjustments and positioning on the antenna can't tune it out, you may need something external. Problem is, with only 4% loss, its not worth introducing more connections and components (that can be lossy themselves) to tune out such a minor mismatch. Just my opinion.
However, with the VNA, it would be possible to monitor what adjustments do what to the feed point impedance, and with that, it may be easier to find a winning combination between height, ring positions and tip length. Its just a lot of F-ing around for 4%....
If you want perfection, you will need a VNA to take an impedance measurement (with the reference plane at the antenna feed point) to know what to change at the feed point to get a better match. If the adjustments and positioning on the antenna can't tune it out, you may need something external. Problem is, with only 4% loss, its not worth introducing more connections and components (that can be lossy themselves) to tune out such a minor mismatch. Just my opinion.
However, with the VNA, it would be possible to monitor what adjustments do what to the feed point impedance, and with that, it may be easier to find a winning combination between height, ring positions and tip length. Its just a lot of F-ing around for 4%....
VNA stands for "Vector Network Analyzer", think of it like an advanced antenna analyzer. Most tend to be pretty pricey but you can get a nanoVNA for around $50 or $60 these days, which is amazing based on what antenna analyzers cost not to long ago (and really still even today).
If you already have an antenna analyzer, that will work fine as well, they do very similar things, although a VNA is typically a step up in capability, this often comes at the price of an additional learning curve if your not used to using said devices.
The DB