Author Topic: G5RV Junior or Carolina Windom  (Read 10675 times)

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ghrit

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Re: G5RV Junior or Carolina Windom
« Reply #15 on: August 21, 2016, 07:05:13 AM »
"That would indicate that the antenna was not tuned properly causing the foldback circuit in the radio to decrease power due to a high swr.  With a G5RV you must use a tuner to get a good match and when I used one, I could get a 1:1 match on all bands 10 thru 80 meters using a simple MFJ-949D manual tuner and always got full power out."

Ummm, no. That would be losses in the tuner matching circuit converting RF energy to heat. The 99 watts into a tuned fan dipole is easily explained by hysteresis in the meter. And if you used a tuner did not get full power out, unless you figured a way to circumvent the laws of physics. You may have made your radio happy because it saw the 52 ohm load it was looking for, but once that tuner was put inline you didn't put out full power.
Said another way, the radio might have been putting out rated power, but it wasn't getting past the tuner.  The tuner, in the case of a mismatch simply uses some of the power in to correct the impedance, and makes heat in doing so.  To prove this to yourself, power meters on the input and output should show you the difference.

Perhaps stating the obvious, but everything in the signal path is a loss to one extent or another.  It's termed "insertion loss" and has to be accounted for in the design.
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Lamewolf

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Re: G5RV Junior or Carolina Windom
« Reply #16 on: August 23, 2016, 11:05:56 AM »
You may have made your radio happy because it saw the 52 ohm load it was looking for, but once that tuner was put inline you didn't put out full power.

If your radio is only doing 90 watts out when it is capable of 100, then it is not seeing a 52 ohm load is what I am saying.  At 52 ohms the foldback circuit is satisfied and will allow full output, but as the load changes which causes the swr to rise the output will drop on most modern rigs.  I've seen some modern rigs that would drop to around 70 watts with as little as 2:1 swr !