Electronic – How to send out 60khz signal from antenna

BACKGROUND

In Japan there are radio-controlled clocks. Time is synchronized by 40khz (in west Japan) and 60khz (in east Japan) radio, which is broadcast from transmission towers. The signal is known as JJY:

https:/ /en.wikipedia.org/wiki/JJY

After the earthquake in 2011, the tower in the east Japan was collapsed. Time synchronization in the east Japan is affected. Hence, someone Japanese has made a simulators and shared on the Internet.

I am from Hong Kong. I have a radio-controlled watch and clock bought from Japan. I want my devices to be synchronized. There are iOS and Android app JJY-simulators. I have tried some of them. This one works well:

https:/ /play.google.com/store/apps/details?id=jp.houryo.jjyemulator&hl=ja

The principle behind is, using time from NTP server, emulating the JJY signal, sending out through 3.5mm audio port.

Now I want to implement the emulator on a Raspberry-Pi. There are some tutorials found on the Internet. Below is the one I am following to:

http://itpro.nikkeibp.co.jp/atcl/column/14/093000080/093000002/?ST=oss&P=1 (Japanese)

Instead of the source-code in the tutorial, I use this one:
https://github.com/snt/rpi_jjy_server

PROBLEM

I have made the circuit following the tutorial:

However, most of the time my watch does not read any signal.
If there is signal, the signal status is "low", and eventually the time-sync is failed. (For the Android-app one, my watch can read a "high" signal.)

Note: I am using Toshiba 2SC1815-GR transistor, 30k ohm resistors, which are suggested in the Git-hub article. And a telephone-line made antenna.

I have tried using a 9V battery replacing the 5V Raspberry-Pi power source. But it does not help.

My knowledge on electronic is very limited. Please kindly forgive me if I have asked silly questions or made silly mistakes. Could anyone please point out if I am made anything wrongly? Or, by what means could I boost the signal from the antenna?

Great appreciation for any help!