昨天又测试了一次，uv8dplus差转覆盖面积，乡下有少数矮房子，平原。直线距离5公里，518+天线能打开，但已经断续，信号46左右。想换玻璃钢天线，有两个疑问 1、如果1.2米的华鸿，是不是效果和770h差不多？之前听ham说过，差不多长度的棒子和苗子基本一样。 2、几个牌子，华鸿、任丘天悦、任丘北方，这几个推荐选哪个？或者还有别的更有性价比的推荐没？暂时不考虑钻石，贵了点。 ……………… 说一下uv差转选频率的事情。刚才是随便选了两个本地不冲突的频率就用了。这两天看论坛，有ham提到机器内部干扰的问题。说U段收V段发，U段灵敏度会下降 V段收U段发，则影响不大。于是仔细思考下，发现自己差点儿犯错误了。本地有大佬发视频抓非法差转，把V段频率搞到卫星上行，导致卫星过境时整个四川都能从卫星下行抄到地面中继。然后是倍频干扰的问题，业余V段的3倍频刚好是432-444。在先排除业余V段里的卫星频点后，开始计算3倍频，既不能是地面中继频率，也不能是业余卫星U段频率。又要3倍频和自己U段有足够的频差，防止内部干扰。所以暂时选了144.7775 X 3=434.3325，和439.9975，u段和v段3倍频有5.665M频差，目前没有发现干扰和自激，但肯定又影响只是不那么明显。和地面中继也至少有50k的频差，不干扰地面中继台。

不太清楚你要多长的天线，如果是长天线，类似基地台那种，我推荐去小黄鱼搜一下“任丘”天线，也是老牌子

买过一根任丘的2.4米玻璃钢，驻波测下来436能有1.3左右，但是同样功率高度位置居然还不如1.2米的华鸿，任丘还是淘宝比较靠前的几家店里买的。说实话还是攒攒上钻石吧

@"BD4UJA"#p55315 看中1.9米的华鸿了。小贵，240元。现在我用770h架在楼顶，手台打中继背噪大，怕1.2米的棒子还这样。所以想买长点儿的，又怕太长不好安装。现在770h，5瓦差转，v段下行，能覆盖8公里。证明天线没有问题，想换增益更高的玻璃钢天线

别买国产的了，用不了多久就坏了，一步到位钻石，770都比华鸿棒子好太多了，

@"tudoubocai"#p55390 话说你馈线多粗？到电台几米？细的话可以买粗馈线，减少功率损耗

要不弄个CJU天线，其实指向性也没那么强，对着中继的方向😆

@"BD4UJA"#p55315 我就买的2.4米任丘百来块钱用着也还凑合不过没对比过同位置上1.2米华鸿

@"BA7OLV"#p55473 是没有用两者进行过对比，还是任丘2.4不如华鸿1.2？

经过实战考验，综合耐用性、性能做出以下主观结论： 1.2米双段选华鸿 2.4米双段选任丘 5.2米双段选钻石x520m

@"BA7OLV"#p55473 我用下来确实1.2的华鸿好，不过后面还是升级成x520了，去年夏天苏州有个台风路过，我距离台风眼20km，后面520一点事没有

Please recommend some glass fiber antenna options.

tudoubocai

I tested it again yesterday, and the uv8dplus coverage area was still insufficient. There are a few small houses in the countryside, and a flat plain. The straight-line distance is 5 km, and with the 518 antenna, I can get a signal of around 46, but it's intermittent.
I'm considering replacing my existing antenna with a glass fiber one, and I have two questions.
1. If a 1.2-meter Hua Hong is similar to a 770H, would the effect be comparable? I previously heard from someone who uses ham that rods and shafts of approximately the same length are essentially the same.
2. Several brands, including Hua Hong, Renqiu Tianyue, and Renqiu Beifang, are recommended. Which one should I choose? Or are there any other brands that offer better value for money? Currently, I'm not considering diamond-rated products, as they are more expensive.

………………
Please explain the process of selecting the frequency based on the UV difference.
I just used two local frequencies that didn't conflict with each other. I saw a post on the forum where someone mentioned internal interference from the device.
Say transmit on V band, and receive on U band, the sensitivity of U band will decrease.
If you are transmitting on VHF and receiving on UHF, there will be minimal impact.

After careful consideration, I realized that I had almost made a mistake.
A local expert has been uploading videos to capture illegal shortwave transmissions, transmitting the V-band frequency to the satellite uplink, which then allows signals to be received from ground repeaters across Sichuan when passing through the satellite.

Then there's the issue of frequency interference, specifically the 3x frequency in the V band used by amateur radio operators, which falls within the range of 432-444.
After excluding satellite frequencies in the amateur V-band, I began calculating the 3x frequency, which must not be a ground repeater frequency or an amateur satellite U-band frequency.
Also, it needs a frequency three times higher than its own U-band and sufficient frequency difference to prevent internal interference.
Therefore, for now, I've chosen 144.7775.
X 3 = 434.3325
The frequency difference between the u-segment and v-segment is 5.665 MHz, which is three times the frequency of 439.9975 Hz. Currently, there are no signs of interference or self-excitation, but it is definitely affecting the system, although the effect is not very obvious.
The frequency difference between the aerial and ground repeater should be at least 50 kHz, to avoid interference with the ground repeater.

BH2VYJ

1、棒子稳定性比苗子好，尤其是天线在车载的情况下，行驶状态的改变会导致天线发生形变，微小的形变就会导致天线的指标发生偏移，就会造成通信效果不稳定，如果使用棒子，其稳定性要比苗子好很多，稳定性就会更好，但是在家用的情况下，天线是固定架设，情况就好很多，几乎只有刮大风等恶劣天气会造成天线发生形变，所以有ham说，差不多长度的情况下，棒子和苗子基本一样。
不过，由于苗子是振子外露，棒子是将振子藏在内部，风霜雨雪对天线造成的影响更小，条件允许的情况下，最好还是用棒子。
2、UV天线这玩意技术已经非常成熟了，价格差不多的情况下，指标基本上没有太大差别，只要正常使用，别长时间高驻波发射，放到室外风吹雨打几年也基本上不会有啥问题。
我好像知道有不少中继台都使用健博通的天线，楼主也可以考虑考虑。

BG9PDU

I'm not sure how long of an antenna you need. If it's a longer one, like a base station type, I recommend searching for "Renqiu" antennas on Xiaohongshu (Little Yellow Fish). It's a well-established brand.

BD4UJA

I bought a 2.4-meter glass steel antenna from Renqiu, and the SWR measurement was around 1.3 at 436 MHz. However, even with the same power level and height, it performed worse than a 1.2-meter Hua Hong antenna. I purchased the Renqiu antenna from one of the most reputable stores on Taobao. Honestly, I think saving up for a Diamond antenna would be a better option.

tudoubocai

BD4UJA I'm considering a 1.9-meter Hua Hong antenna. It's relatively inexpensive at 240 yuan. Currently, I'm using a 770h antenna mounted on the roof, and the noise level from the repeater is quite high. I'm concerned that a 1.2-meter antenna might also produce excessive noise. Therefore, I'm looking for a longer antenna, but I'm worried about the difficulty of installation with a very long one.
Currently at 770 hours of use, with a 5-watt difference in power consumption, operating in the V segment downwards, and covering a distance of 8 kilometers.
I've confirmed that the antenna isn't faulty and I want to replace it with a higher-gain glass fiber antenna.

BA7OLV

BD4UJA I bought a 2.4-meter Renqiu for around 200 yuan, and it's okay to use. However, I haven't compared it to a 1.2-meter Hua Hong at the same location.

BD4UJA

tudoubocai By the way, what's the diameter of your coax cable? And how long is it? If it's thin, you could buy a thicker coax cable to reduce power loss.

dxs660

Don't buy domestic products anymore, they will break down in a short time. The 770 is much better than the Hua Hong brand.

BD8DFK

Alternatively, we could get a CJU antenna; however, its directional performance isn't that strong when pointed towards the repeater.😆

tudoubocai

BA7OLV Was there no comparison made between the two? Or is the Huahong 1.2 better than the Renqiu 2.4?

BD4UJA

BA7OLV I found that the Hua Hong 1.2 was actually quite good, but I eventually upgraded to the X520. Last summer, there was a typhoon that passed near Suzhou, and I was about 20 km away from the eye of the storm. The X520 didn't experience any problems.

BG5VCU-VK2VCU-AK6CU

After practical testing and evaluation of overall durability and performance, the following subjective conclusions were reached:
1.2-meter double-segment selection for Hua Hong
2.4m double-section, selectable from Qiu
5.2-meter double-segment selection, Diamond X520m

BA7MAT

The Renqiu I'm using is 2.4 GHz, and according to the specifications, it's not much different from Hua Hong's Renqiu. It costs around 100-200 yuan, but as long as it works, that's fine. The main thing to consider is the loss caused by the cable; if you can use a cable with a good signal and connect it to a receiver, or use a -7 dB attenuator, then you can get at least -5 dB attenuation, otherwise all the signal will be lost.

YangZifan-BA7KVH

I have a 1.2m glass fiber and a 770S, a V-band repeater, the glass fiber can reach S9 but the 770S only reaches S6-S7. I feel that the glass fiber is better because it's more power tolerant, with a 100W output, the antenna for Miaozi is only 20W, which is inconvenient.

I connected the high-power D9000 to the glass fiber, and then used the 770S with the 778UV. It works well; I use the 778UV as a backup, but I switch to the D9000 because it gets too hot (although the D9000 has good cooling, so I don't use the 778UV very often).

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