Fuzzy Audio problem

[+rbairos]

Hi Everyone.

I have a light sixer, that the image is okay, but the sound has some static.
When I switch from channel 3 to 2,  the image goes staticky, but the sound is very clear.

Am I right in concluding I need to adjust the vertical red/pink choke piece to adjust the audio carrier ?

If so, it just requires a *plastic* screwdriver to carefully adjust?
Any online recommendations for one?

Thanks,
Rob.
 

[+rbairos]

For anyone interested, I ended up buying a set of nylon anti-static adjustment  tools from amazon for about $15.
Unfortunately, none fit properly.

So I **carefully** inserted a 3/32 hex allen key through the audio coil, so that it traveled all the way through, making contact with the bottom of the unit,
I then was able to turn carefully to adjust the audio level.

I think I got it better, but unfortunately never quite got rid of the buzz entirely.
Channel 2 however (instead of channel 3) has no static or buzz on the audio at all it seems.

Maybe that's a different issue, but I may just go with channel 2 for a while.

Cheers,
Rob.

[nick3092]

I'm not an EE, so I might misspeak slightly. But I'm pretty close with my description.

 

An inductor is a ferrite rod in the middle of a coil. And that creates a magnetic field that changes the frequency as you move the rod up or down through the coil. Which fine tunes the RF signal to your TV. 

 

The reason for the plastic tool isn't because a regular Allen wrench will wreck it. It's because the metal from the wrench will change the adjustment. And when the wrench is removed, the magnetic field changes causing the frequency to shift. 

 

You could experiment with adjusting past the ideal setting or backing off from the ideal setting. So that when the wrench is removed, the magnetic field "moves" to the ideal setting. 

[ChildOfCv]

Nick is correct about why we use mostly plastic alignment tools.  But I'm surprised that none of them fit.  I got a 9-piece one that has had a tool for pretty much anything I've needed to adjust (unless the ferrite rod has already been destroyed by a previous ham fist).

 

As for channel tuning, that happens inside the RF modulator.  There's a hole in the modulator case for adjustment of the tuner in there.  The red tuner outside of the modulator is indeed for audio subcarrier.

[+rbairos]

Yah, I was aware the metal would change the adjustment while inserted, but I read some strongly worded old posts here that any metal edge could introduce cracks into the brittle core.
I did all my measurements several times with the tool removed to make sure it was where I needed it.

One thing to note, I did this on an analog TV with its own manual fine tuning, so Im not 100% sure I adjusted this optimally for actual channel 2/3 frequency.
Cheers,
Rob.