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Radioddity PAX100 RF Power Amplifier | 100W | Portable | Plug and Play | for Xiegu G90 X5105

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SKU: 28-715-PAX100
  • $179.99
  • Regular price $199.99 SAVE $20.00

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United States
Limited Quantity

Radioddity PAX100 is a mini RF power amplifier DIY kit using MOSFETS and is specially designed for Xiegu G90 and X5105 radios. It can achieve 100W power output with an input power under 10W. The design is extremely compact and light-weight. Nothing like it is available in its power vs. size rating.

Must Know

1. A power supply capable of delivering 20 Amps current at 13.8 Volts is required.

2. When using PAX100, please turn off the built-in antenna tuner of G90, otherwise PAX100 will be damaged. (External tuner is allowed to use.)

3. The PAX100 requires a resonant antenna on every frequency it can operate on. If the antenna is not resonant, you will need an external Antenna Tuner. The tuner must be able to present an SWR to the output of the amplifier of less than 2.0:1. The lower the SWR is, the less chance of damage to the amplifier. Anything above 1.5: should be used with caution. The final transistors specifications recommend not exceeding 2.0:1. The internal tuner of the radio will not be useful then the amplifier is in use. If the SWR of the antenna in use is much higher than 1.5:1, after sustained operation, the amplifier may be damaged. At 2.5:1 or higher, the amplifier will be damaged and unusable until repaired.
If needed, the final transistors are available from general parts suppliers and are low-cost.

4. The input power (from the G90) to the amplifier should never exceed 10 Watts; even on SSB peaks. Driving the amplifier with an output from the G90 higher 10 watts will result in damage to the amplifier.

5. Amplifier’s gain is large on 160 meters. Please reduce drive to 5 watts on 160 meters.

6. Output with an open circuit or short circuit is prohibited.


What's New?

• Upgraded red PCB board & protective case

• Upgraded fuse box for the power cord

• Better soldering design


Up to 100W Power Output pecially Built for Xiegu G90 & X5105 Solid Material & Accessories

Up to 100W Power Output

This amp is capable of up to 100W output on 20 meters and below. 70 watts is typical in the higher bands. The amplifier connects to the G90 or X5105 to perform RX/TX switching. It uses two inexpensive 55-watt IRF 350’s as the final amplifier devices.

Specially Built for Xiegu G90 & X5105
Radioddity PAX100 is specially designed for Xiegu G90 & Xiegu X5105. It covers the 3 MHz~30MHz frequency range and modes including A1A (CW), J3E (SSB), A3E (AM), F3E (FM), F7M (C4FM), F1B (FSK).


Solid Material & Accessories
The PCB uses a double-layer immersion gold finish providing long and stable operational life.  It comes with an XT60 power supply connector which can easily handle its max current draw. Any type of power connector can be mated to it. Since it uses gold-plated SMA connectors, it comes with input and output adapter cables to male and female PL-259/PL-239 connectors. We also provide the PTT trigger cable. It can be used with ours and many other QRP radios.


Heat Dissipation Details Plug and Play Portable & Non-slip Design

Heat Dissipation Details

The amp uses a large aluminum heat sink. The whole PCB secures directly to this heat sink. High-conductivity interface materials are used to dissipate maximum heat and provide stable operation. A cooling fan is installed on one side of the heat-sink with 2 cooling modes. It is a low-noise model that provides excellent CFM.

Plug and Play

Different from other amplifier kits, Radioddity PAX100 comes with a PTT Trigger Cable connecting to the G90/X5105. Simply press the PTT key of G90/x5105 to transmit and PAX100 will automatically amplify the output power to 80-100W without any other operation.


Portable & Non-slip Design

It’s dimensions are (4.33 x 1.97 x 1.57 in). This DYI power amplifier kit only weighs 0.5lb. It is surprisingly small and has 4 non-skid pads on the bottom of the heat-sink. A beautiful clear poly-carbonate top mounts above the circuit board to protect it.



Frequency Range: 3 MHz~30MHz
Supported Modes: A1A (CW), J3E (SSB), A3E (AM), F3E (FM), F7M (C4FM), F1B (FSK)
Power Supply Voltage: DC 12V ~ 18V
Power Supply Current: Standby 0.2A | Transmit 12A maximum
Input SWR: <2.0: 1
Input / Output Impedance: 50 ohms (± 10%)
Through Loss: less than 0.5dB
Power Gain: greater than 15dB (± 2dB)
Maximum Input Power: 10W
Maximum Output Power: Input 5W, frequency <21MHz, power supply 15V = 100W
            Input 5W, frequency> 21MHz, power supply 15V = 70W

Low-pass Filter: Built-in 10, 15 and 17 meter band filters
Low-pass Filter Frequency: 33MHz (-6dB)
Harmonic Output: greater than -50db (even order), greater than -30dB (odd order)
Spurious Output Suppression: greater than 40dB
Input / Output Connector: SMA-K
Working Temperature: 0-50 ℃
Storage Temperature: -20-70 ℃
Storage Humidity: less than 55%
PTT Trigger Level: + VCC-2V (low trigger), GND + 5V (high trigger)
PTT Trigger Current: 2Ma
Product Size: 110 x 50 x 40mm | 4.33 x 1.97 x 1.57in
Product Weight: 230g | 0.51lb


1. Transmitting with an open circuit or short circuit will damage the amplifier.
2. Antenna standing wave ratio of under 2.5 to 1 is required
3. Maximum power input is 10 watts

Compatible Models:

Xiegu G90, Xiegu X5105

Available Accessories:

• 1. Radioddity LPFX7 low pass filter (plug and play | full-band low pass filter)

• 2. Radioddity LPMX2-1 & LPMX2-2 filter model DIY kits (need to be soldered by yourself)


1. This amplifier does not have an antenna tuner.
2. Hardwired connection for PTT is required for functioning.

Installation Guidance


Q & A:

Q: What is the difference on yours, yours is quite expensive I have seen similar amp going for cheaper on eBay.
A: It's a totally different product from what you saw on eBay or Alibaba. We made so many efforts to improve it. This version on eBay is not stable with only 50W sometimes and different performance for different radio (said compatible with many radios). We abandon the compatibility of ICOM and KW23.

What are the differences
1. Built-in 10, 15 and 17 meter band filters
2. Data adjustment for G90 & X5105 only (even not G1M)
3. Trigger cable/connector for G90 & X5105
4. Copper core feeder added
5. Plug and play for G90 & X5105, stable output
6. Circuit optimization
7. We improve some soldering parts for safety
All of the above have made its cost way more expensive than other versions you can see on eBay and Ali.

Q: Is soldering surface mount components needed? How long would it take to put together?
A: No, plug and play for PAX100 + LPFX7 + G90. If you've already had a DC power, 2 minutes.
If you prefer the filter model LPMX2 instead the LPFX7 with single-band filtering, you need to solder.

Q: Does the LPFX7 filter sit alongside the amp or does it fit inside the amp housing? If it goes alongside, do you include the cables needed to do all the connections? If I buy both, is anything missing that I need to connect it all?
A: It goes alongside. Both of them are with all the connectors and cables you need to install (except for the power plug). Refer to the following images to install. What you need is a DC power source.

Q: Is the power to the amp always on? Is there a switch?
A: For the amp, there is no power button. For the LPFX7 filter, it's with a power button, and 4 switches with LED to help you select the band you need.

User Manual:

Click Here to download.

What's in the box

1 x Radioddity PAX100
1 x Power Cable
1 x SMA to PL-259 adapter cable
1 x SMA to SQ-239 adapter cable (female)
1 x G90/X5105 PTT Trigger Cable
1 x Installation Guide

1 Year and 6 months
Manufacturer's Warranty.
• Radioddity's limited warranty applies to all BRAND NEW items sold by and other authorized dealers.
• This warranty is non-transferable and proof of purchase from us or an authorized dealer is required for warranty service.

What Does This Limited Warranty Cover?

We warrant that the Products are free from defects in materials and workmanship under normal use and use in accordance with the respective Product user manual, during the Warranty Period. Please refer to the Instructions inside each package for a description of proper use and care of the unit.

What Does This Limited Warranty Not Cover?

This limited warranty does not cover damages directly or indirectly arising or resulting from or during:

(1) accident, misuse, abuse, vandalism or acts of God (including lightning and other weather conditions)

(2) use with another product or other damage or loss suffered by the use or combination of any other item

(3) improper or inadequate maintenance

(4) repairs by an unauthorized service technician

(5) normal wear and tear

If you are satisfied with our products and service, please kindly leave us a positive product review. Any problem, be free to contact us
We strive to answer all emails as quickly as possible, but due to high email volume, it may take time for us to reply. Thanks in advance for your patience!

Order Processing

All orders will be processed within 1 business day after full payment is received. The tracking number will be updated as soon as it's available and be sent to the Radioddity Members. So We strongly suggest you register as a Radioddity Member (CLICK HERE). If the item you ordered is temporarily out-of-stock, you will be contacted by our customer service representatives. You can choose to wait for restocking or cancel the order.

Flat Shipping Rates



Express (free)

Flat fee

$9.99 for US & EU

Free when order amount ≥ $99.99 for US & EU

Ship from

➤ United States warehouse (Las Vegas, New Jersey)
➤ Germany warehouse (Berlin)
➤ US/DE/IT/FR/ES Amazon warehouse

➤ United States warehouse (Las Vegas, New Jersey)
➤ Germany warehouse (Berlin)
➤ US/DE/IT/FR/ES Amazon warehouse

Delivery time

5-7 days
AFTER the handling time

5-7 days
AFTER the handling time


1. Customs fee included for US & EU countries.
2. US Shipping does not include Alaska, Hawaii and Puerto Rico area. Please contact us for detailed shipping fee.
3. For Canada, items will be shipped from the US warehouse, thus customs fee may occur, which won't be covered. Shipping fee would be higher.


How Do I Change The Shipping Address Or Cancel My Order
Contact (
CLICK HERE) immediately if you need to change the shipping address or cancel your order. Please be advised that some orders are shipped very soon after placement and it will not always be possible to make changes to the shipping address and/or cancel the order.


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