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Hello everyone..

Finally my bitx, showing some audio signal, but the sound that I've got is FM Radio, at 89-90 MHz.. Any clue why this could happen?

I didn't attach the DDS.

Thankyou very much

Well, I don't know what you have done since you first posted having an issue with audio and perhaps microphone but it seems you have audio coming to the headphone jack from the audio amp and that's in general what you want, just not with an FM station providing the audio.

First this disclaimer - I am a math guy professionally, electronics is my hobby -so I am about to wildly guess. It seems that you are in close proximity to a strong commercial FM radio station. I wonder if the wires associated with the radio you are building are behaving like an antenna for the FM signal and allowing the FM signal to be injected into the system. Another possibility is the source of power that eventually feeds the radio is not well grounded and acting as the FM signal's antenna thus allowing the FM signal into your rig.

So, I am thinking - if you give the FM signal an easier path to follow other than through your audio amp will the issue? disappear? Maybe, so how would you do this? I am thinking try these ideas:

Make sure that the source you use for power is well grounded. If you can't do this switch to a battery for power to the rig and ground its negative terminal to a cold water pipe.

If the rig is in a metal enclosure ground the chassis too.

Good luck.

On May 28, 2018 5:55 AM, <qonita.salimah@...> wrote:

Hello everyone..

Finally my bitx, showing some audio signal, but the sound that I've got is FM Radio, at 89-90 MHz.. Any clue why this could happen?

I didn't attach the DDS.

Thankyou very much

Thank you for your reply,
Sorry if my post seems confusing.

The real thing I tried to do is building bitx40. After I soldered and configured all the component, I tried the receive system.
At first, I receive nothing just a "zzz" sound, because I use the Baofeng speaker.
After I connect to other audio speaker, I heard FM radio broadcast station.

So, it probably because the audio amp stage? The signal didn't even go through the IF amplifier? For power source, I use an adapter with 12V, 2 Amp..
Why I didn't receive the signal from another ham radio? Sorry for asking to many question

Thank you?

Thank you for your reply,
Sorry if my post seems confusing.

The real thing I tried to do is building bitx40. After I soldered and configured all the component, I tried the receive system.
At first, I receive nothing just a "zzz" sound, because I use the Baofeng speaker.
After I connect to other audio speaker, I heard FM radio broadcast station.

So, it probably because the audio amp stage? The signal didn't even go through the IF amplifier? For power source, I use an adapter with 12V, 2 Amp..

Thank you?

I just searched this forum for Baofeng, got dozens of hits from people using it with *Bitx* rigs.
Here's one of many threads:? /g/BITX20/topic/4554574

The microphone element is electret, just like the element suppied with the *Bitx*.
If the Baofeng element doesn't sound quite right, could patch in the one supplied with the rig.
Such a tiny speaker is bound to be a compromise, I wouldn't expect much from that.
The PTT switch arrangement looks pretty good, that alone is well worth $3.
Some of the Baofeng mikes on ebay are apparently even cheaper cones, there are some differences.

There is a bunch of stuff in that mike you don't need.
I'd replace the cable, using one with 3 wires for ground, ptt, and mike into a 3.5mm phone jack.
The ground goes to the ground side of the mike, also to one side of the ptt switch.
And of course the mike wire goes to the other side of the mike, the ptt wire goes to the other side of the ptt switch.



On Mon, May 28, 2018 at 01:33 pm, Mike aka KC2WVB wrote:

I just googled the Baofeng speaker. I see it is a combination microphone/speaker that is probably used on VHF portables.

?

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 :?/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?
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

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 :?/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?
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

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 :?/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?
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

If you don't have a scope, perhaps you have or can borrow a receiver that can tune those oscillators in.
The oscillators are an unmodulated carrier, so best if the receiver is in SSB mode so you can year a tone.
But an AM receiver can be used, it should go quiet as you get near the signal.

If you have a 12mhz crystal filter for the IF, the BFO should be 2 or 3 khz below 12mhz.

Jerry



On Tue, May 29, 2018 at 01:34 am, Raj vu2zap wrote:

First check if your VFO and BFO are working correctly.

Put an oscilloscope to C100 and see if you have a good voltage of your BFO frequency. Check the frequency of
BFO with a frequency counter.