RTL2832U Direct Sampling
8bit ADC 28.8MHz clock.
3kHz to 24MHz with precise OP amp
above 14.4MHz is over sampling.
second RF amp for 15MHz to 24MHz
4band Filter by rotary selector
common mode choke for USB supply
+-1.0PPM 28.8MHz TCXO replacement(option)
(over sampling mode is silightly low sensitivity.
practical reception frequency is around 24MHz)
New version 3kHz to 1.7GHz.(slide swict on back panel)
3kHz to 24MHz = direct sampling Q channel
above 24MHz R820T2 tunner

set Q input on EXIO.DLL. Check RTL AGC on high band.


internal noise in 0kHz to 1100kHz. original RTL dongle has a lot of noise.
Soft66Q has common mode choke and big capacitor.


soft66q.jpgFilter selector
4 -> 3kHz to 1MHz   red + green
5->1MHz to 5MHz    red
6->5MHz to 15MHz  green
7->15MHz to 28.8MHz   no led
8->R820T2 tunner(Q2)


Turn right RF GAIN to increase.
USE SMA connector to ANTENNA

New version of Soft66Q

change BPF for suitable position

red+green -> channel4
red -> channel 5
green--> channel 6
blank -> channel 7



Q2.JPG BPF rotary swicth
4 -> 3kHz to 1.1MHz
5->1.1MHz to 5MHz
6-< 5MHz to 15MHz
7-> 15MHz to 24MHz

set slide switch
left -> above 24MHz
change EXIO.DLL to direct sampling disable.

right -> under 24MHz
change EXIO.DLL to Q input direct sampling

Inside of Soft66Q2
28.8Mhz TCXO +-1.0ppm replacement(option)
Reception with 80m long wire

15m band reception with dipole antenna

Q  I can not receive on SDR# with link of your site.
A Please change Direct Sampling to Q input on DLL.

Q There is not enough sesitivity above 10MHz.
A There is two gain control. you need to increase RF gain trimmer on Soft66Q. also try to check RTL AGC on EXTIO.DLL

Q There is a lot of noise under 100kHz.
A try to reduce RF gain. also you need suitable antenna for VLF. magnetic loop antenna is good.

Q.USB Dongle is very hot.
A. it is normal. R820T is becomming hot. Soft66Q have new TV dongle. no thermal problem.

Q I can not receive. nothing is comming.
A. Please read installation and explain your setting details. I am not god. I need your informations.

Q HF is working. But VHF is not working.
A. Please check SMA connector conection.

Q. Soft66 may be working. But it is not enough sensitive.
A. check antenna connection. if you connect only SMA center PIN, it is bad. Please use SMA connector.

Q  My PC does not recongnise Soft66RTL.
A. There is bad USB cable. If your USB cable does not connected GND pin to outer shield, please change it.

Q installation is succes. but no signals.
A  some user can not connect SMA corectly. please check SMA contact. check center pin reach to jack center.

VLF stations LIST.