对U段的损耗有点兴趣，实测了一下。结果如下 [upl-image-preview uuid=ce06ff99-b88a-406a-9d2e-5d428599e638 url=https://storage.hamcq.cn/2026-01-24/1769267834-931395-20260124231039-28-73.jpg alt={TEXT?}] [upl-image-preview uuid=f4111684-c287-4be9-a7db-e145d5ac00c1 url=https://storage.hamcq.cn/2026-01-24/1769267835-133425-20260124231051-29-73.jpg alt={TEXT?}] 连接方式分别为 1. FT-1907->0.3m连接线->功率驻波表->5m 50-3线->电阻:表显功率18.61W (42.7dBm) 2. FT-1907->5m 50-3线->0.3m连接线->功率驻波表->电阻:表显功率4.1W(36.1dBm) 测试的损耗为：-6.6dB **5m** 但是搜了一下，50-3的 **10m** 435MHz的损耗是-3dB（https://www.bilibili.com/video/BV1dF411P7bZ/?vd_source=55d678116e899a55c4976b3620a4865c），我不确定为什么我这个损耗这么高？是因为M头的损耗吗？

功率开高多发射一会，看看哪里发热？6dB 的衰减转化成热量应该挺好找到的

昨天自己测试的应该有问题，今天又重新测试了一下，大概在0.7-0.8dB每米，和网上各种博主的测试还是差一点。我自己测的50-3镀银线也差一些，原因还没找到 [upl-image-preview uuid=66d33766-9687-472f-b557-dbaa259913c0 url=https://storage.hamcq.cn/2026-01-25/1769355903-553484-image.png alt={TEXT?}]

怎么说吧...你把馈线全展开测试下

建议用矢网较准后再测测

What is the reason for a 5-meter, 50-3 cable having a measured loss of -6 dB at 435 MHz?

BG2MKU

I was interested in the power loss of U-shaped components, so I performed some measurements. The results are as follows:

The connection methods are as follows:

FT-1907->0.3m connection cable ->Power Standing Wave Meter ->5m 50-3 line ->Resistance: Apparent power 18.61 W (42.7 dBm)
FT-1907->5m 50-3 line ->0.3m connecting cable ->Power Standing Wave Meter ->Resistance: Apparent power 4.1W (36.1 dBm)
The measured loss is: -6.6 dB 5m

However, after searching, I found 50-3. 10m The loss at 435 MHz is -3 dB.https://www.bilibili.com/video/BV1dF411P7bZ/?vd_source=55d678116e899a55c4976b3620a4865c), I'm not sure why my losses are so high. Is it because of the M-head?

bg7nzl

Substandard aluminum wire?

BI1XJT

Turn on the power and transmit for a while, then check where it's heating up. A 6 dB attenuation converting to heat should be easy to find.

BA4QBK

6 dB, remaining 1/4

BG2MKU

The results I obtained yesterday were likely incorrect, so I retested today and got values around 0.7-0.8 dB/m. This is slightly different from the results reported by various bloggers online. My own measurements with a 50-3 silver-plated wire also differ somewhat, but I haven't yet identified the reason.

Sunset

Well, let's say this: you should thoroughly test all the cables.

BI1NIZ

I recommend using the Y-net to measure it more accurately.

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