这两天有空去野架，拉了一个20m端馈天线，先用nanoVNA测，显示4个主要业余波段的驻波比均在3-4之间，而在891上面按PTT显示驻波比不到1.5，究竟哪一个更有参考性，新手请教。

是我会比较相信电台，然后校准一下网分试试，你想想，一个几千块一个200块。

1. 网分没校准吧，或者是坏的。 2. 电台在SSB模式下测的驻波吗？按下PTT大声喊了吗，不大声喊的话SSB没有功率输出，驻波当然不准。FM、AM模式下才准

@"BI4IUI"#p20098 喊不科学，科学的应该是小功率，在无人频率使用fm按住ppt

@"BI4IUI"#p20098 当时是在SSB模式下按住PTT正常说话，并没有喊。现在知道了，下次在FM、AM模式下测😃

@"BA7MTH"#p20100 感谢补充🤭

过后看了下，自己的nanoVNA确实没有好好校准😳下次野架再测

@"BD4UNH"#p20119 整理一下上边的答案： AM 是调幅模式，单边带模式（SSB）是 AM 保留下一个边带，同时去掉载波，并且 SSB 是语音模式，故输出的射频功率取决于调制前的语音信号的强度，不提倡大声喊，一是喊破喉咙可能也不会到巅峰功率，二是可能会干扰到别人 FM 调频即使没有音频信号，也是恒定的最大功率，不需要说话因为 FM/AM 有载波，所以功率稳定，可以测量如果有电键用 CW 测量也可以，如果有电脑，用各种数据模式测量（FT8 之类）也是可以的

@"BG2ELG"#p20160 感谢分析和总结😀

The SWR, nanoVNA, and Yaesu FT-891 built-in measurement values show significant differences. Which one is correct?

BD4UNH

I've had some free time lately and went to the field to install a 20m end-fed antenna. I initially used a nanoVNA to measure it, which showed an SWR of around 3-4 across the four main amateur bands. However, when using PTT on 891 MHz, the SWR was below 1.5. Which one is more reliable for reference? Please advise beginners.

BA7MTH

I would trust the radio more, and then calibrate the network to see if that helps. Think about it – a device costing several thousand yuan for just 200 yuan.

BD4UNH

BA7MTH Thank you.

BI4IUI

The network division seems to be misconfigured, or it might be faulty.
Does the radio measure standing wave in SSB mode? Does it loudly announce using PTT, or does it not make a loud announcement? If it doesn't make a loud announcement, there is no power output in SSB mode, and the standing wave measurement will be inaccurate. FM and AM modes are accurate.

BA7MTH

BI4IUI "Shouting isn't scientific; it should be about low power, using FM on a specific frequency for drones."

BD4UNH

BI4IUI Previously, I was using the SSB mode and pressing PTT to speak normally without calling. Now that I know this, I will use FM or AM mode next time.😃

BH1AYY

BA7MTH That's correct!

BD4UNH

BA7MTH Thank you for the additional information.🤭

BG2ELG

BD4UNH

Let's organize the answers above:

AM is in amplitude modulation (AM) mode, single-sideband (SSB) mode.（SSB）This leaves a sideband for AM, while removing the carrier. Since SSB is in voice mode, the output RF power depends on the strength of the pre-modulated voice signal. It's not recommended to shout loudly because: firstly, shouting too loud might not reach peak power; and secondly, it could interfere with others.

Even when there is no audio signal, FM modulation maintains a constant maximum power output, without requiring speech.

Because FM/AM uses a carrier wave, it provides stable power, which allows for accurate measurement.
If a keyer is available, you can also measure with CW; and if you have a computer, you can use various data modes (such as FT8) to measure.

BD4UNH

After checking it myself, I realized that my nanoVNA hadn't been properly calibrated.😳Please re-measure the wild card next time.

BD4UNH

BG2ELG Thank you for your analysis and summary.😀

dovesky

This is essentially the same situation; do you believe what your family tells you, or what someone else tells you?😹

BI1JNP

In some cases, exceptional talent can lead to inaccurate readings, while readings taken internally are generally more accurate.

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