Inquiry regarding the function of UV differential measurement for chassis.

bh1cqz

为了扩大接收机发射范围，想再家中放置一个固定台，同时启动UV差转功能。考虑机制性价比的原因，不知道那些老设备具备此功能？有些说明书和介绍中都提质你单方向差转（说白了就是只能通过UV差转发射，但不能反向接收）。看的云里雾里的。所以想咨询各位，大家是否使用过这个功能？
想要了解的心仪机器包括 icom2720h，yaesu ft-8800和ftm-100dr，如果有这类机器的有台也可以分享自己的经验。

BG2GJJ

The Wi-NO 6600 PRO supports it, and I actually have one that I'm selling.

BG8KUQ

The following provides a comprehensive overview of the UV to HF/VHF conversion function for the ICOM IC-2720H, Yaesu FT-8800, and FTM-100DR mobile transceivers, combining key information on hardware modifications, operating steps, and usage limitations.

📻 1. UV differential transmission function of the ICOM IC-2720H

How to start it

Hardware modifications: Requires opening the laptop case and removing the component near the CPU.Patch diode(Located at the red box marker), otherwise the "differential switching" function cannot be activated.https://www.chinaham.cn/jishufenxiang/406.html)(https://www.hellocq.net/forum/read.php?tid=306166)。
Operating steps：
After sealing, simultaneously press both sides. M/CALL key + Power button Power on.
Independently set the transmit and receive frequencies for each frequency band (e.g., receive on the left V-band, transmit on the right U-band).
Press both buttons simultaneously. DUP + LOW + SET Three buttons. The screen displays two flashing "L" icons, indicating that the system has entered a differential mode.https://www.chinaham.cn/jishufenxiang/406.html)(https://www.hellocq.net/forum/read.php?tid=306166)。

Important notes

⚠️ Make sure to connect the load antenna during transmission to avoid damaging the amplifier.
Supports hearing aids（CTCSS）With DUP± setting, but requires manual adjustment.https://www.chinaham.cn/jishufenxiang/406.html)]。

📡 2. UV Difference Mode Function for Yaesu FT-8800

How to start it

No hardware modifications required.: Enable cross-band relay directly through menu operation; this is a convenient method.http://www.360doc.com/content/17/0130/08/27898355_625387291.shtml)。
Features and functionalities：
Supports bidirectional forwarding (A → B or B → A), for example, when segment A receives at 438.000 MHz, segment B can transmit at 145.000 MHz.
After enabling it, holding the microphone while using the device disables its functionality. Pressing PTT will display an "ERROR TX" error message.http://www.360doc.com/content/17/0130/08/27898355_625387291.shtml)。

Important notes

📶 3. UV Differential Transmit function of Yaesu FTM-100DR

How to start it

Hidden features: Similar to the FTM-400XDR (using the same technology), activation is achieved through a combination of keys:
Press and hold the following keys simultaneously when the device is turned off: DISP + F + GM Three-button power on; the screen displays "X-BAND Repeater" indicating that it has been turned on.http://www.360doc.com/content/17/0130/08/27898355_625387291.shtml)。
Function settings：
The AB frequency band frequencies, sub-audio, power, and other parameters must be pre-set.
Turn off the APRS MODEM Function to avoid conflictshttp://www.360doc.com/content/17/0130/08/27898355_625387291.shtml)。

Important notes

Also, it only supports FM simulation modeIn digital mode, differential steering is not possible.
⚠️ Microphone overheating issue: We recommend removing the handheld microphone when in use.
High cooling requirements; can be paired with the original fan (e.g., SMB-201 + SAD-11G power adapter).http://www.360doc.com/content/17/0130/08/27898355_625387291.shtml)。

💎 Summary of comparisons between three devices

Features	ICOM IC-2720H	Yaesu FT-8800	Yaesu FTM-100DR
How to start it	Requires disassembly of two diodes + combination keys.	Menu operations	Combination keys (hidden features)
Hardware modifications	⚠️ Required	No need	No need
Power limitation	Not specified; recommendation: mid-range to low-end.	Recommended ≤ 20W	Recommended ≤ 20W
Usage restrictions	Requires external load	Microphone disabled; only simulation mode available.	Microphone disabled; only simulation mode available.
Cooling requirements	Standard cooling	Suitable for low to medium power applications.	Requires an additional cooling fan (for long-term use)

⚠️ General Notes

Frequency rangeEnsure that the transmission frequency is within the device's valid range (e.g., FTM series must be between 400-480 MHz). If not, display "TX FREQ ERROR".http://www.360doc.com/content/17/0130/08/27898355_625387291.shtml)。
Thermal management: Recommended long-term case fan combinations, especially for the FTM series.http://www.360doc.com/content/17/0130/08/27898355_625387291.shtml)。
Mode compatibility: All three devices areDoes not support digital mode switching.(e.g., C4FM/DMR), only for FM simulationhttp://www.cqkexun.com/uploadfile/dxhcy.pdf)(http://www.360doc.com/content/17/0130/08/27898355_625387291.shtml)。

💎 Purchase recommendations

Striving for stability: Choose the FT-8800 (no modifications required, easy to operate).
Long-term differential rate demand: The FTM-100DR requires additional cooling, but supports both digital and analog modes (digital to analog conversion is limited to analog).
Strong practical skills: The IC-2720H has a low cost, but modifications carry risks, making it suitable for temporary deployments in different scenarios.

It is recommended to consult the device manual or community forums (such as Halo CQ) for further information.https://www.hellocq.net/forum/read.php?tid=306166) Confirm details, especially the stability of the hidden features in the FTM-100DR.

BG8KUQ

BG8KUQ The FT-8900R would also work. The price at the seafood market should be around 1000 yuan.

bh1cqz

100dr: If anyone can try it out, as many people say that 100dr is not supported.

dxs660

Both the 8900 and 8800 are suitable; you just need to configure them. They provide bidirectional frequency shifting, achieving the same effect as a repeater, but they only support UV (cross-band) frequency shifting, not UU or VV (same-band) frequency shifting.

bh1cqz

dxs660 Yes, this requires a simple setup, which allows for communication over long distances from the ground floor.

BG2EFX

D9000 2720 2730 100D I know it's okay, I've used it.

bh1cqz

BG2EFX Yes, the 2720 and 2730 should work. The d9000 also seems to have an internal repeater mode. Does it support transmitting when using a 100d? I'm concerned because there are conflicting opinions about this device; some people say it works, while others say it doesn't.

BG2EFX

bh1cqz 30 and 20 require a specific item to be disassembled. 100 requires activation of a specific mode using a particular key.

BA4SUA

bh1cqz The D9000 can be used with a UV antenna, and I use it to connect my handheld radio to the home base station to listen for distant repeaters while walking. I haven't tried using a UU antenna; the manual indicates that a duplexer is required.

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