Re: Sbitx high swr on a 1 to 1 antenna
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Usually?those power meters actually measure VOLTAGE, and presume 50 ohms, then use the equation P = V*V / R to find the "power"
If the impedance they are looking into jumps way UP, then the transmitter output voltage may go significantly higher?(because it isn't being loaded down by 50 ohms any more) so then V*V is much much larger, but the meter is still calibrated for R=50 and hence reads a much higher impedance.? ??
In this case your power tripled or quadrupled, suggesting that your voltage went up by 2 times.? ? And your measured SWR by the bitx also went up.? ?Those make sense together.?
We have experienced all manner of poor connections in PL-259 / SO-239 connectors; there is always the possibility that you are experiencing a poor connection that is variably changing.? ?We have switched to certain types of connectors as a result to reduce bad connections, which are really really difficult to troubleshoot during contests, etc.? ? Something is weird?and connectors are often the problem.
Gordon KX4Z
On Sat, May 17, 2025 at 10:58?AM W1WCI via <timothy.macdonald= [email protected]> wrote: Will open things up later this weekend.? Also notice another change, on 20 meters getting more power out for a give drive setting, a (FT8) setting of 65 was good for 2 watts, now 7 to 8( measured on the out board meter). Sent from me and my iPad ? Have you made any progress?
Scotty On Thu, May 15, 2025, 12:40 PM W1WCI via <timothy.macdonald= [email protected]> wrote: Sbitx - antenna switch - swr/power coupler - antenna
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Previously radio showed power and 1.0 swr on 15, 20, and 40 meters with similar readings on the off board meter.
As of this morning swr on the radio and the off board meter show high SFR 2 to 3:1.
Removed the radio from the antenna line and replaced it with an antenna analyzer, it shows a perfect 1:1.?
Another radio shows 1:1 on the radio and the off board meter.
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Previously, maybe a month ago I had the same problem, spent time chasing down the antenna to no avail. Then one day all was well with no intervention at or in the radio.
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All bands that were workable for the antenna show the same behavior today.
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Trouble shooting help welcomed.
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Tim
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