Too much static in BA1404 FM Transmitter.

Thread Starter

Utkarsh Verma

Joined Oct 30, 2016
102
So, I made this circuit:
http://electronics-diy.com/BA1404_Stereo_FM_Transmitter.php
After struggling for some time acquiring the rare components. Finally, I was able to make it. Since I did not have a ferrite core variable inductor, so like always, I used a 0.1uH inductor along with 20-40pf varicap. But for some reason, the frequency of my transmitter is spread over 1Mhz range, eg. I have set it such that I have several transmissions between 88-90Mhz, all with varying qualities but not one of them is clear. Is this causing the static? Please solve this problem of mine quickly as I am quite a maniac in making circuits and my mind doesn't get peace until my proceeding work is finished. Lastly, would like to add that there are no such frequency drifts.
 

Thread Starter

Utkarsh Verma

Joined Oct 30, 2016
102
Just noticed something. For some reason, when I move around my hand near the antenna and inductor randomly, at some position, if I keep my hands still, the reception clarifies greatly. I want to achieve that reception. Any idea why that is happening?
 

ScottWang

Joined Aug 23, 2012
7,397
Just noticed something. For some reason, when I move around my hand near the antenna and inductor randomly, at some position, if I keep my hands still, the reception clarifies greatly. I want to achieve that reception. Any idea why that is happening?
I was modified the link in the first posted.
 

AlbertHall

Joined Jun 4, 2014
12,345
Is the prototype board of the single pad soldered type, or the plug-in solderless type. The latter, especially, is not a good idea for RF circuitry.
 

Thread Starter

Utkarsh Verma

Joined Oct 30, 2016
102
Is the prototype board of the single pad soldered type, or the plug-in solderless type. The latter, especially, is not a good idea for RF circuitry.
no it is not a breadboard. It is a one sided copper board. I know that breaboard's long rails hamper radio transmission.
 

BR-549

Joined Sep 22, 2013
4,928
"I used a 0.1uH inductor along with 20-40pf varicap."

Where?

Let's see your board. And the modified schematic.

I would suggest you get a 20 dollar SDR dongle and look at your signal.

I'll bet your modification has screwed up the oscillator.
 

Thread Starter

Utkarsh Verma

Joined Oct 30, 2016
102
"I used a 0.1uH inductor along with 20-40pf varicap."

Where?

Let's see your board. And the modified schematic.

I would suggest you get a 20 dollar SDR dongle and look at your signal.

I'll bet your modification has screwed up the oscillator.
The female header is for powering this circuit up. The rest parts are placed just as is described in the schematic.There are no modifications as such. All I have done is replace C6 with 18pf and L1 with 0.1uH and 2-18pF varicap in parallel. The rest wiring and components are untouched.
 

Thread Starter

Utkarsh Verma

Joined Oct 30, 2016
102
"I used a 0.1uH inductor along with 20-40pf varicap."

Where?

Let's see your board. And the modified schematic.

I would suggest you get a 20 dollar SDR dongle and look at your signal.

I'll bet your modification has screwed up the oscillator.
In place of L1. The inductor and varicap were placed in parallel.
 
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