Sunday, November 21, 2010

CZH-05B 500mW FM transmitter

I like to listen to the VK2WI Sunday broadcast. It's part of my weekly routine. This week I was able to listen to it lying in a hammock thanks to a new arrival, a small FM transmitter purchased on eBay.


It's synthesised for frequency stability. At 500mW it saturates the house but doesn't go much past the neighbours. On the back there is a BNC connector and it comes with a little antenna. No doubt an external antenna would extend the range.

Internally, construction is of a very high standard:


It came with an over the top switched giant power supply. There is some hum evident in the signal but no doubt that could be improved with a regulated supply.

Over the years I've built many little FM transmitters but they always drift to some extent. It's nice to have something stable like this.

I think there could be a market for a radio station that broadcasts selected podcasts, my latest discovery is The Changelog. Now I can just make my own.


Unknown said...

I have recently received the CZH-05B and for "Audio" input it works great. My question is how to use the "Mike" input correctly. I bought and tested a microphone, but cannot get it to work on the CZH-05B "Mike" input socket. When I connect the "Mike" input to an audio source it barely comes through, but with lots of static and crackle. Could I have inadvertently damage the "Mike" input by feeding into it an audio source???? Rob

Anonymous said...

when I ordered it I was really. skeptical but it sounds very good.
The Audio input works great but is very sensitive: a careful setup of input level is required.
I also tested the Mic input (unuseful for my purposes) but... believe me... forget it.
with the short antenna I receive receive the audio up to 1 km. For sure better results with an external antenna.

Lighthouser said...

I bought one of these specifically for the mic input, with the intention of using it in my van when I give tours. When I plugged in a mic I get absolutely nothing. Has anyone gotten the mic input to work at all?

Lighthouser said...

I bought one of these specifically to use with a microphone, but I can't get the mic input to work. Has anyone had any luck with this?

Peter Marks said...

I've only used the line input but I'll try the mic and let you know.

Peter Marks said...


I tried it out and the mic input does work - but not very well (at least with the mic I tried).

Two things might trip you up: First the socket is stereo and if your mic plug is mono it could be shorting one side to ground, second you might be using a PC mic which requires DC power (normally provided by a sound card). I don't think this unit provides that.

Best wishes,


Anonymous said...

about 3 out of 100 the mic jack will work I got in side of them its
not the jack it its in the board they make in the far east for about $3.00 and the U.S. dealer mark them
up from $15.00 tp $100+
If you buy the ST-7A 7 WATT OUTPUTT
the mic jack work real good
+ you can turn the power up and down
just hold the power button down
and plug the power jack in and thin you will see low and high power

Anonymous said...

The Mic input on the CZE-05B takes a "Computer" type that needs power from the unit to work.