Smallest most compact RF modulator?

[lnx64]

Correct, the little metal box in the back (and yes it's composite video..). In fact, I have a Genesis system here where I don't use the RF, and would be willing to remove it to send for you. I'll test the RF out to make sure it works, and if the picture looks good enough, I'd be happy to sell it to you.

Mine is from the US, so it's NTSC with channel 3 and 4 selection. I'll post pictures of the RF out quality from it.

[Trekintosh]

Originally Posted by lnx64

Correct, the little metal box in the back. In fact, I have a Genesis system here where I don't use the RF, and would be willing to remove it to send for you. I'll test the RF out to make sure it works, and if the picture looks good enough, I'd be happy to sell it to you.

Hey, works for me! Even if I don't end up using it in this project I have been wanting to make a tiny TV test box and the RF can would be useful for that, too.

[lnx64]

Originally Posted by Trekintosh

Hey, works for me! Even if I don't end up using it in this project I have been wanting to make a tiny TV test box and the RF can would be useful for that, too.

Cool, shoot me a PM and I'll see what we can work out. I'm modifying my Genesis for RGB video, and with how I'm trying to get the best picture and sound out of it (even replaced the sound chip with something better--but compatible), I have been wanting to get rid of the RF modulator in it, to remove any noise it may be injecting back on the system.

[Findm-Keepm]

I have some Astec modulators from old 70s and 80s stuff, but my favorite is the little Alps modulators used in later VCRs and DVDs. 2X1x1/2 inch or so. You can find larger VCR, Cable and Satellite box modulators for 2 bucks each new, so I no longer scrounge. They even have RF pass through, so I use them on my daily driver with my DTT900 to test video units.

Worst modulator? Some of the early game units (we're not talking Atari, Nintendo, or Sega, but the cheaper/California all-in-one start-up stuff) - all discrete components, and drift like you wouldn't believe.

[Findm-Keepm]

Originally Posted by lnx64

Cool, shoot me a PM and I'll see what we can work out. I'm modifying my Genesis for RGB video, and with how I'm trying to get the best picture and sound out of it (even replaced the sound chip with something better--but compatible), I have been wanting to get rid of the RF modulator in it, to remove any noise it may be injecting back on the system.

With the Saw-resonator based modulators (last 15 years or so from Alps, Matsushita, Murata, and Toshiba), they lock dead on, with zero harmonics - any noise is typically a ground loop or RF leakage. I like HVAC tin foil tape for RF leakage issues, although the last I've really experienced was with the old OAK and SciAtlanta Cable boxes. Once they went addressable, we no longer could repair them.

[lnx64]

Originally Posted by Findm-Keepm

With the Saw-resonator based modulators (last 15 years or so from Alps, Matsushita, Murata, and Toshiba), they lock dead on, with zero harmonics - any noise is typically a ground loop or RF leakage. I like HVAC tin foil tape for RF leakage issues, although the last I've really experienced was with the old OAK and SciAtlanta Cable boxes. Once they went addressable, we no longer could repair them.

Shouldn't be any RF leakage, but I think it's ground loop issues. On the Sega Genesis, it's VERY sensitive with these RF modulators (Sega was certainly reluctant to put adequate filtering on it). The modulator works great otherwise, even as simple as it is. Since removing it to prepare possibly sending it to OP, as expected, RGB video cleaned up and lost the jailbars I was seeing before.

This is what this tiny little RF modulator has inside: http://i.imgur.com/zY5KfdD.jpg

No idea what the POT does, I'm guessing output power, but I have no plans to mess with it.

[Electronic M]

Originally Posted by lnx64

No idea what the POT does, I'm guessing output power, but I have no plans to mess with it.

Neat to get a look inside that.

That adjustment is NOT a pot, it is a ferrite tuned inductor or transformer. It likely tunes the frequency of the modulator, or some filtering for the system. I agree, you don't want to mess with it casually.

[Findm-Keepm]

Originally Posted by Electronic M

Neat to get a look inside that.

That adjustment is NOT a pot, it is a ferrite tuned inductor or transformer. It likely tunes the frequency of the modulator, or some filtering for the system. I agree, you don't want to mess with it casually.

The saw resonator sets the Output frequency - the adjustable coil sets the Audio modulation center frequency, for the 4.5MHz offset.

I've got several hundred brand new SAW resonators for a later Toshiba chip - useless these days, as the chip is about 3 bucks, and a whole modulator is a buck less.