[Coco] Re: Composite Video - Compared to "modern" composite - EASY!

[farna at att.net]

The old 300 ohm composite TV antenna input boxes never worked very well. They are designed to be connected to screw type TV antenna leads, which no TV made today has. As noted, the video is bad with that cheap 300 ohm lead! What you need is a length of 75 ohm cable (plain cable TV cable) and an RCA plug ("F" plug?) adapter for the CoCo end. Then you will have nice clear video on the TV. At least compared to that lightly shielded 300 ohm cable.

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Frank Swygert
Publisher, "American Independent 
Magazine" (AIM)
For all AMC enthusiasts
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 -------------- Original message ----------------------

> Message: 1
> Date: Mon, 30 Jan 2006 10:36:23 -0300
> From: "Mat¡as Guti‚rrez Reto" <matiasar at tournet.com.ar>
> Subject: [Coco] Re: [Color Computer] Re: TRS-80 CoCo Group Color
> 	Computer	Composite Video - Compared to "modern" composite - I 
> don't
> 	get it
> To: "Neil Morrison" <neilsmorr at hotpop.com>,
> 	ColorComputer at yahoogroups.com
> Message-ID: <43DDEC27.23984.1418C680 at localhost>
> Content-Type: text/plain
> 
> My case is similar to Ben's.
> 
> Related to this subject I've a little question.
> I've found this groups some time ago and I decided to reconnect again my Coco 
> 2, which I did not use from the late 80s.
> Back in the 80s I used to connect my Coco to a 300 ohms impedance tv antenna 
> input.
> 
> Nowadays the antenna input from my tv is 75 ohms. The right impedance to 
> connect the coco is 300 ohms, right? In that case I imagine that an impedance 
> adaptor will by necessary.
> 
> Regards from Argentina,
> Matías
> 
> On 29 Jan 2006 at 21:55, Neil Morrison wrote:
> 
> > 
> > 
> > You have to connect to the ANTENNA, not the video in. Note that it has a 
> > channel 3/4 switch - the TV has to be set to the same channel. You may need 
> > an adaptor plug, but you can't use the RF modulator - return it.
> > 
> > (Other lists - copy this guy please, he's only on 
> > TRS80CoCo at yahoogroups.com )
> > 
> > Neil
> > 
> > ----- Original Message ----- 
> > From: "benwillis" <benwillis at verizon.net>
> > 
> > 
> > > Hello, I'm new to this board and hope that there's somebody out
> > > there who can help me understand something.
> > >
> > > I've loved the Coco for years, used one in college back in the early
> > > 80's for my degree. It was cool to hookup to the TV, had a 300 baud
> > > modem, cassette drive, loved it, but always had screen interference
> > > problems with the RF modulator. Oh well.
> > >
> > > Now I've purchased one on eBay, even got a floppy drive (I just had
> > > cassette in college, couldn't afford the $500 drive!).
> > >
> > > Anyway, I want to hook it up, and get a good picture. Bought an RF
> > > modulator, disappointing to say, it still has a crappy picture.
> > >
> > > Then I was wondering - the Coco (this is a Coco 2) has a composite
> > > video out, but what confuses me is it has _both_ video and audio
> > > over one cable. Newer TV's with composite input have just the video
> > > on the composite cable, and the sound is separate. Plus if I plug
> > > the composite from the Coco into the TV composite input, it (of
> > > course) doesn't work.
> > >
> > > What I don't get is, why doesn't it work? Why is the sound/video
> > > together on the Coco composite, but separate on "modern" TV's? Is
> > > it possible to separate the 2 somehow and plug directly into a TV
> > > without an A/B switch? All I want is to display the video crisp and
> > > sharp and also have sound. Should I just buy a Coco monitor?
> > >
> > > Any advice on improving the Coco picture, and making it work well
> > > with a TV, would be appreciated.
> > >
> > > Thanks,
> > > Ben