Re: Receive FM Radio Station #bitx40

Mike aka KC2WVB <rb5363@...>
 

Since your building your rig from scratch this will be easy for you to accomplish.

Once everything is working. Modify the amp that the microphone feeds by doing this:

"I lhave changed just R63 so now it is 24 ohm (I added 2 ordinary 100ohms resistors in parallel) as suggested. I confirm it increases the average power to the right level given the stock mic element."

This is the fix people are using to increase the gain. Its the one that I can't do because my hands are not steady enough to pull it off. Hence I am going the route of adding a pre-amp which I intend to make variable. Apparently without this change the audio being mixed into the RF is too weak and one needs to speak rather loudly to be heard on receive.

Good luck and I am rooting for your success.

On Tue, May 29, 2018, 8:07 AM Mike aka KC2WVB <rb5363@...> wrote:
Incidentally, what is your call sign?? I want to listen for you once you have the bugs worked out and the rig up and running.

On Tue, May 29, 2018, 7:54 AM Mike aka KC2WVB <rb5363@...> wrote:
What ever the outcome you did great! Most people did not build from scratch and source their own parts.

Too bad my lack of knowing your language may make it difficult to be of much help. However, let me ask this simple question. What are you using for an antenna? If it is not something like a dipole cut to 40 meters or 20 meters or 80 meters...then you may hear nothing but noise and interference on the receiver. 
My version of the radio came to life when I connected a 40 meter dipole to the rig. The 40 meter dipole is two wires each 32.5 feet long connected at one end to either the center conductor or shield of 50 ohm coax cable. The other end of the coax runs to the rig. The feed point of this antenna, I.e. where the wires connect to the coax, is ideally elevated to 1/4 wave length in height or roughly 33 feet.
I could not elevate my 40 meter dipole so I built a compromise dipole. The issue that occurs when the dipole is not elevated to 1/4 wavelength is that the feedpoint impedance becomes terribly low to the point it is far short of 50 ohms and nearly nothing can then be heard. So, I made my dipole as a folded dipole that uses two wires on each leg. This raises the feedpoint impedance of the antenna to such an extent that it is actually spot on 50 ohms when it is barely off the ground. This of course changes the radiation pattern but not enough that I don't still pick up Dave, on or about 7.145 MHz, out of England whenever he keys up.

AgIn good luck, hope you get the bugs worked out.

On Tue, May 29, 2018, 4:12 AM <qonita.salimah@...> wrote:

Thank you for your reply.
I also tried to make the wire connectivity in Baofeng mic and speaker according to the post in this threads : https://groups.io/g/BITX20/topic/4554574

The PTT switch in Baofeng work perfectly, but not for the speaker and mic. I will try to make the modification like you've said.

But what about the RX system? It still not receiving any ham radio signal. I tried to follow the troubleshooting that Asshar Farhan made in https://www.youtube.com/watch?v=R8G8XAwq38A&t=456s
Here is what I've got

C107 (C13 in my schematic) makes noise when it's touched with cable.
C33 (C6) is also make noise
C31 (C9) is also make noise, but not very loud.
C53 (C5) I didn't hear any noise at all. 
C21 (C24) I didn't hear any noise at all. 

I also didn't hear any noise if the cable touched the antenna connector.

I made my own BPF and LPF because I want to make 8.456 MHz frequency as the center frequency.

Here is the schematic. To tell you the truth I didn't buy the kit from Asshar Farhan. I built in from scratch, like from the schematic, the PCB layout, and bought all the component by myself. I come from Indonesia. And this is for my final project. Still learning and this is my first time building a radio

Thank you very much for helping me

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