特易通 TYT TH-9800 车载四频对讲电台 -1

TH-9800 是我台目前的主力车载/基地台。选它的理由很直接：四波段全模拟 FM，带真正的跨段中继，而且机头可拆分离——这一点后来成了整个 ESP32 改造项目的前提。

为什么是这台

同价位里能同时满足这三条的机器并不多：

• 29 / 50 / 144 / 430 MHz 四段收发，10m 和 6m 在澳洲的开放条件下很有用
• 双段双收，主副频段可以分别守听不同的通话组
• 跨段中继（Cross-Band Repeat），UHF 手台经它转发到 VHF，覆盖范围立刻不一样

发射功率 VHF 50W、UHF 35W，800 信道，13.8V 直流供电。

机头分离带来的可能性

TH-9800 的机头和主机之间是一根 8 芯线，走的是自定义串行协议。这条线原本只是为了让你把主机塞进后备箱、机头放在仪表台上。

但既然机头和主机之间的全部交互都从这根线上过，那么在中间插一个设备，就能同时做到两件事：

1. 监听主机上报的状态（频率、S 表、发射指示）
2. 伪造机头的按键指令注入给主机

这正是 elfRadio Box 的工作原理——一个 ESP32 做的中间人控制盒。

ESP32 控制盒

硬件装在机头和主机之间，对两端都透明：机头照常能用，主机也不知道多了个东西。ESP32 一边解析协议，一边通过 WiFi 把状态推给手机 App 和网页。

实现的功能：

• 频率、音量、静噪、功率档位的远程读写
• S 表与信道忙状态实时上报
• 机头本体仍可独立操作，两边不冲突

协议是完整逆向出来的，没有留下未解码的字段。详细的逆向过程和硬件设计在 项目栏目 里有单独一篇。

实际使用感受

作为日常守听台，它的短板也很明确：只有模拟 FM，没有任何数字模式。DMR 那部分的活儿交给了 AnyTone 和 MMDVM 热点。

另外四段里 29MHz 段的实用性取决于太阳活动，大部分时间是摆设。真正每天在用的还是 144 和 430。

媒体演示

正文里插入媒体只有一种写法：独占一行的 ![说明](地址)。地址指向什么，就渲染成什么。

YouTube 链接自动变成播放器：

音频文件直接出播放条（这是本站 MMDVM 的一段真实通联录音）：

图片照旧：

这篇正文是占位示例，用来确定版式。内容可以在后台随时替换。

The TH-9800 is the primary mobile/base rig at this station. The reasoning was straightforward: four bands of analogue FM with genuine cross-band repeat, plus a detachable head — that last point turned out to be the foundation of the whole ESP32 project.

Why this rig

Not many radios in this price bracket tick all three boxes:

• 29 / 50 / 144 / 430 MHz, and 10m/6m are genuinely useful under Australian band openings
• True dual receive, so main and sub can monitor different talkgroups
• Cross-band repeat, letting a UHF handheld reach far beyond its own coverage via VHF

Output is 50W on VHF, 35W on UHF, 800 channels, 13.8V DC.

What the detachable head makes possible

The head and the main unit are joined by an 8-conductor cable carrying a proprietary serial protocol. Its intended purpose is simply to let you hide the body in the boot and mount the head on the dash.

But since every interaction between head and body travels down that cable, inserting a device in the middle gives you two things at once:

1. Visibility into everything the body reports — frequency, S-meter, TX state
2. The ability to inject fabricated keypresses back into the body

That is exactly how the elfRadio Box works: an ESP32-based man-in-the-middle controller.

The ESP32 controller

The hardware sits between head and body and is transparent to both. The head keeps working normally; the body never knows anything was added. The ESP32 decodes the protocol and pushes state over WiFi to a phone app and a web page.

What it does:

• Remote read/write of frequency, volume, squelch and power level
• Live S-meter and channel-busy reporting
• The physical head remains fully usable — the two never fight each other

The protocol was reverse engineered in full, with no undecoded fields left. The teardown and hardware design have their own write-up under Projects.

Living with it

As a daily monitoring rig its weakness is equally clear: analogue FM only, no digital modes whatsoever. DMR duty falls to the AnyTone and the MMDVM hotspot.

Of the four bands, 29 MHz is only as useful as solar conditions allow — most of the time it sits idle. The bands that actually earn their keep are 144 and 430.

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