各位好，我是本月刚拿 A 证的新火腿，QTH 上海，目前住在学校公寓，在尝试用手台上中继通联，距离中继大概跨市中心 15km 左右。公寓有开放式阳台，而且天台和高层窗户都是密封的（理由是保护学生安全），所以我想从自己房间阳台上直接通联。**接收中继很清楚**（甚至用拇指天线也能 59 听），但**怎么发射都没回波**。已经用两个手台互相验证过，设备本身的发射功能都正常，天线也换过好几个不同的（见下）。❓我的问题是：1. **5 楼高度没办法通联 15km 是正常的吗**？我问了一圈 AI，有说可以、有说不行、也有说勉勉强强的，比较困惑。2. **有什么方法改善通联质量吗**？比如换天线？如果没办法，这种环境有什么通联的希望吗？考 B 证玩短波？短时间内我估计不会搬家，每次通联都要跨城去公园，也挺麻烦的。📡我的设备有：**手台**（2 个）：泉盛 UV-K1（5W）；冠星 GX8500（标称 20W，实际 15~18W 左右）**天线**（4 个）：手台自带天线；SRH771；老鹰 RH770S；BD6JPS 的 Moxon 便携八木提前谢谢各位台友！

排版发出来咋全乱了。各位看这张图吧🙏

是只有在宿舍发射才没回波，同样机器在近一点的地方就有是吗，如果这样的话可能刚好直线到中继被挡住了，如果其他地方也没回波，你就要考虑是不是写频错了，比如发射亚音没设置对

中继发射功率大，手台功率低，所以接受发射不对等情况是正常的玩UV段，我觉得高度因素远大于天线/设备（更何况，城市里的五楼高度遮挡肯定会很严重），所以我会建议你到楼顶或者更高的地方打中继，或者想办法把天线架设到更高的地方～

得看是否刚刚好有楼遮挡住了信号路径，V段折射能力不如U段强，城市环境里如果被遮挡了就可能比较难了，尤其在学校公寓这种楼密集的地方。你可以找同一栋楼其他楼层试试

有防盗网吧?严重影响信号.

天线换八木，挂窗外，找合适的方向

5楼高度没办法通联15KM是正常的吗？很正常。你能“听见”对方，说明的“耳朵”没啥问题，你换了多个手台也证明了这点。上行不通，首先得排除设置问题，确认上行频率与哑音都设置正确。如果都设置正确还没回波，那应该是你的信号到达中继的强度，低于打开中继的“阈值”，也就是没有到达中继“听力”的下限，他听不见，自然也不可能有反馈。有什么方法改善通联质量？你首先需要找个尽量高的地方，来验证手台设置正确，能顺利打开中继。然后你需要确定中继的地理位置，看看中继在你阳台一面，还是在你背后。最快改善通联质量的方法就是想办法提高高度，如果无法提高高度，你需要面向中继，移动位置尽量减少自己与中继之间的阻挡。Moxon可以多试试，注意要垂直极化，也就是方框要垂直于地面，上下左右摆动天线，找到最佳的位置。如果阳台环境允许，且Moxon天线能顺利打开中继，可以考虑4单元左右的八木天线，能较为明显的改善通联质量。当然，如果Moxon都打不开中继，换八木效果可能也不会有太大的改善。供参考

太正常了，你是在哪个区啊hhh，我在普陀天安千树6F（大于居民楼6F）阳台打协会中继也是能听打不上，V段传播本来就差，天线受限于尺寸也很难有很大增益（不过顺道说我觉得ioo老师的天线比钻石厉害，八木之下大概能与之匹敌的不多）。同时我从来没有打通过据说位于徐家汇的AA中继，协会中继在长宁附近还是打上过几次的。听点名的时候，我记得有一个QRP大佬，每次都用很小的功率发射，还是要高度高，可以去4800cm人造上海第一高山（不是）双子山和佘山去试试，我还没时间去测试

有没有铁栅栏防盗窗之类的这个类似法拉弟笼对信号影响很大另外检查一下发射亚音设置是否正确再有上楼顶天台试试

Is it possible to use a high-power VHF repeater in an urban environment with good signal strength, and still be able to communicate?

BI4BHI

Hello everyone, I'm a new ham radio operator who recently obtained my license this month. My QTH is in Shanghai, and I currently live in the university dormitory. I'm trying to use a handheld repeater to communicate, with the repeater located approximately 15km across the city center.

The apartment has an open balcony, and both the rooftop and high-floor windows are sealed (for safety reasons), so I would like to be able to connect directly from my own room's balcony.

The receive is very clear (even with a thumb drive antenna, I can hear 59), but **I'm not getting any response when transmitting.** I have already verified the functionality of both handheld radios with each other, and the devices themselves are functioning normally. I have also tried several different antennas (see below).

❓ My question is:

1. **Is it normal that the height of the 5th floor cannot be connected over a distance of 15 km?** I asked several AIs, and their responses were mixed – some said it was possible, others said it wasn't, and some offered vague or uncertain answers, which left me confused.
2. **Are there any ways to improve the communication quality?** For example, by changing the antenna? If that's not possible, is there any chance of establishing a connection in this environment? Should I take the B license and use shortwave radio? Given my current situation, I don't think I can move anytime soon. Every time I try to communicate, I have to travel across town to the park, which is quite inconvenient.

My equipment includes:

**Handhelds** (2): QuanSheng UV-K1（5W）; Crownstar GX8500 (rated at 20W, actual output around 15-18W)
**Antennas:** (4) – Handheld radio with integrated antenna; SRH771; Eagle RH770S; BD6JPS Moxon portable Yagi.

Thank you in advance to all our listeners!

BI4BHI

The formatting seems to have messed everything up when I posted it. Could you please take a look at this image? 🙏

BG5JKZ

If only transmitting from the dorm results in no return signal, and if the same equipment at a closer location also fails to receive a return signal, it's possible that the direct path to the repeater is being blocked. If you don't get any return signals anywhere else, you should consider whether the frequency might be incorrect, for example, if the transmit frequency isn't set correctly.

BG5CVB

The repeater has a high transmit power, while handheld radios have low transmit power, so receiving a signal from a powerful transmitter when using a weak receiver is normal.
When operating in the UV band, I believe that antenna/equipment factors are far less important than height (especially since buildings on city streets can significantly block signals). Therefore, I would recommend setting up your repeater at a higher location, such as on the roof or even higher, or finding a way to raise your antenna.

natsumikka_BA7OPF

Whether the signal path is just blocked by a building, V-band has weaker refraction ability than U-band, and if it's obstructed in an urban environment, especially in densely populated areas like university dormitories, it can be more difficult. Try looking at other floors within the same building.

BG5WDZ

Are there any bars with security fences? This significantly affects the signal.

BG8LKT

Replace the existing antenna with a Yagi-Uda antenna, and mount it outside the window, finding the appropriate direction.

BG5LU

Is it normal that a 5-story building cannot be connected wirelessly over a distance of 15 km?
That's perfectly normal.
If you can "hear" the other person, it indicates that your "ears" are functioning properly, and switching to multiple handheld radios confirms this. If the uplink is not working, the first step is to rule out any setting issues and ensure that both the uplink frequency and the silent tone are set correctly. If these settings are correct but you still don't receive a response, it means that the strength of your signal reaching the repeater is below the "threshold" required to activate the repeater, meaning it hasn't reached the minimum level that the repeater can detect. Therefore, the repeater cannot hear you, and there will be no feedback.

What methods can be used to improve communication quality?
First, you need to find a location as high as possible to verify that your handheld radio is properly configured and can successfully connect to the repeater. Then, you need to determine the geographical location of the repeater and see if it's located on your balcony or behind you. The fastest way to improve communication quality is to try to increase the height. If increasing the height isn't possible, you need to position yourself so that you are facing the repeater and move around to minimize obstructions between you and the repeater. You can experiment with different Moxon antennas, but be sure to use a vertically polarized antenna, meaning the square frame should be vertical relative to the ground. Adjust the position of the antenna to find the optimal location. If your balcony environment allows it and the Moxon antenna can successfully connect to the repeater, consider using a Yagi-Uda antenna with approximately 4 elements, which can significantly improve communication quality. However, if the Moxon antenna cannot connect to the repeater, switching to a Yagi-Uda antenna may not result in significant improvements.

For reference

Carlos

It's perfectly normal. Which district are you in? I was able to hear and transmit through the club repeater on the balcony of my apartment at Puthu Tianan, Building 6F (above the residential building), but it wasn't very strong. The V-band propagation is already poor, and antennas with limited size also have difficulty achieving high gain (although, by the way, I think IOO's antenna is better than the Diamond one; there aren't many that can match it). I also haven't been able to contact the AA repeater supposedly located in Xujiahui. The club repeater near Changning was sometimes reachable. When they called out specific stations, I remember a QRP expert who always used very low power and needed a high antenna; you could try testing at the 4800cm artificial Shanghai's first mountain (not really), Shuangzi Mountain and佘山. I haven't had time to test yet.

BI4BHI

Carlos 我在杨浦区五角场这边，两个中继都打不到欸😂

BA4QBK

Are there any iron fences or anti-theft windows like a Faraday cage? This significantly affects the signal. Also, check if the sub-audio transmission settings are correct. Finally, try going to the rooftop to see if it helps.

BI4BHI

我去啊，这小程序收到回复一点通知都没有，我给忙忘了，过了几个月才想起来看😵感谢楼上各位大佬回复！看来不换位置是不行了，不知道之后短波有没有机会在家发射，哈哈😂

tudoubocai

高度才是硬道理，到楼顶去试试，说不定有惊喜。
无法提升高度，就用八木，3单元不行就5单元，5单元不行就8、12单元（虽然V段的体积有点大）。
v段天线，相对来讲，效率比u段低太多。尤其是手台天线，全都是“负增益”。
还有那个“摩克森便携八木”其实它仅仅相当于两单元八木天线，仅仅是倍噪小一点而已。

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