UHF Modulators

[lnx64]

Would using a UHF modulator improve my picture quality and reduce interference I get from incandescent light bulbs? If so, what is the best cheap UHF modulator I can get.

Also, what would be the best balun to use?

[ChrisW6ATV]

The best cheap modulators you can get, for multiple channels, are used commercial "agile modulators" on Ebay, such as the Blonder-Tongue AM40-550, AM60-550 or similar.

I have not heard of interference from incandescent bulbs. What exactly do you see?

Regarding baluns, I typically get better performance from physically larger ones versus smaller ones (if you are referring to 75-to-300-ohm transformers).

[old_tv_nut]

Interference from light bulbs? Are you wired to the tuner input or trying to broadcast locally? If wired, you should be swamping out any radiated interference.

[lnx64]

These are old Mazda bulbs. They mess up the low VHF stations in my room.

[lnx64]

Here's what it looks like. More noisy on channel 3, less on 4, but still there.

http://img.photobucket.com/albums/v3...n/vhfnoise.jpg

This happens on the Hitachi too, not just this Samsung.

[jr_tech]

Are the Mazda bulbs vintage (ca 1910) carbon filament ?

jr

[lnx64]

They are vintage, but tungsten. But as far as I know, I thought all mazdas were tungsten.

[jr_tech]

The interference that you pictured really looks like that that can be generated by an old carbon filament bulb... if your bulb is indeed tungsten filament, i would check the soldering at the base of the bulb for signs of arcing... or perhaps look for arcing at the two points that the filament attach to the header wires from the base... or perhaps the switch in the fixture is bad, or a corroded socket?

jr

[lnx64]

Hmm, doesn't appear to be arcing, but I don't know, maybe it is filament.. Let me get a closeup of the bulb.. If I use a dimmer switch and turn it down a notch, the noise goes away.

[lnx64]

Here's the bulb.

http://img.photobucket.com/albums/v3...n/IMG_0612.jpg
http://img.photobucket.com/albums/v3...n/IMG_0614.jpg

It looks like tungsten to me..

[jr_tech]

NICE!
I would agree... tungsten. For nostalgia lighting, I generally use one of these:

http://www.amazon.com/Bulbrite-13401...8699646&sr=8-1

Looks prettymuch like the "real deal", does not cause RFI, and I will not feel bad when it burns out.

jr

[lnx64]

Originally Posted by ChrisW6ATV

The best cheap modulators you can get, for multiple channels, are used commercial "agile modulators" on Ebay, such as the Blonder-Tongue AM40-550, AM60-550 or similar.

I have not heard of interference from incandescent bulbs. What exactly do you see?

Regarding baluns, I typically get better performance from physically larger ones versus smaller ones (if you are referring to 75-to-300-ohm transformers).

I looked up the price of these Blonder Tongue's, way out of my price range. I'm seeing like $700 for those. I don't need a clear picture that bad.

I was thinking about under $100..

Perhaps this? http://www.amazon.com/CHANNEL-5415-S...pd_sim_sbs_e_1

[old_tv_nut]

Originally Posted by lnx64

Here's what it looks like. More noisy on channel 3, less on 4, but still there.

http://img.photobucket.com/albums/v3...n/vhfnoise.jpg

This happens on the Hitachi too, not just this Samsung.

You still didn't say if you are wired to the set or broadcasting to the rabbit ears.

If you are wired to the tuner input, then make sure the antenna is disconnected. If you still have interference when directly wired with the antenna disconnected, a third party consumer modulator probably will not be any better than the channel 3/4 modulator in the VCR/DVD player. In this case, the interference may be conducted rather than emitted, and a line filter could help.

[lnx64]

Oh, sorry. It's wired into the cable. The antennas are just there for show, they aren't actually wired in to anything.

[earlyfilm]

Originally Posted by lnx64

Hmm, doesn't appear to be arcing, but I don't know, maybe it is filament.. Let me get a closeup of the bulb.. If I use a dimmer switch and turn it down a notch, the noise goes away.

Sheesh!

I have not seen that problem since the 1950's when those lamps were aggressively replaced.

Try it on a circuit without the dimmer switch. If that cures the problem, then it is the dimmer switch.

If not, try a 600 volt .01 mfd (better yet, a line bypass) condenser across the line in the lamp.

For gosh sakes, keep the antique bulb and use a reproduction, as they are replaceable.

(Another very unlikely possibility is that whoever installed the dimmer switch wired it into the wrong side of the line.)

James