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Apple II and Sup'R'Mod II

H

Holmes

Experienced Member
Joined
Dec 13, 2010
Messages
313
Location
Marietta, GA
Hi All:

So I'd like to connect my Apple II to a nice Sony Trinitron KV9200 that I just picked up. The Sony only has UHF and VHF screws on it (a pair of screws for each). So I'm looking at using the Sup'R'Mod II that is in the Apple II, which I guess is an RF modulator.

I've never used one of these before, so I figured I'd check before I blew anything up. The Sup'R'Mod II is stuck to the inside of the Apple II case, and is attached to the motherboard with a cable with a 4-pin header. There are 2 RCA-type phono plugs on the Sup'R'Mod.

My understanding is that I'll need to connect this somehow to the UHF/VHF screws on the tv. So first of all, which RCA port do I use? Also, what sort of cable will allow me to do this? Do I need to make a custom cable? What did people do in 1977?

It doesn't make sense to me. I'd think if you were connecting to TV, they would put a coax plug on the RF modulator, not an RCA-type connector (which to me says composite output).

Can someone help? I tried googling everything I could think of, but couldn't find anything helpful.
 
It's not composite video. It's the same signal you'd get as broadcast TV (before we switched from analog to digital broadcast, that is) except instead of being carried over the air, it's being carried by an RCA cable.

If you have the book The New Apple II User's Guide, there's a photo that shows how to configure it.

Basically there are two components: the RF modulator and the TV-antenna switch. The modulator sits in your Apple II and you connect its cable to the 4 Molex pins at the upper-right corner of the motherboard. Then connect an RCA phono cable to the female connector that is on top of the gray box. Connect the other end of this RCA cable to your TV-antenna switch.

The TV-antenna switch should have two leads coming out. These leads need to be screwed to the screws on the back of your TV. Your TV will have two sets of screws, one for UHF and one for VHF.

There is some variation in RF modulators as to what channel/frequency they use. Try both sets if you're unsure. You'll know which set of screws is correct because the video quality will be significantly better than the other one.

My RF modulator uses channel 33.
 
Oh, thank you!

OK, I see now. I thought those TV boxes with the 2 leads WAS an RF modulator. I thought they took a composite video signal in (because of the RCA-type input), and converted this to work through the UHF/VHF wire connectors!

That's why I can't see why they designed these Sup'R'Mods to output their UHF/VHF signal with an RCA cable. It makes it all very confusing. If it was a coaxial cable/F-type connector, it would be clearer, right? I guess there's a reason that someone knows.

Thank you both. This has been driving me nuts. I actually have one of the old TV switches, but I was plugging the composite video out into that and plugging that to the VHF/UHF leads on the TV, which produced a beautiful snowy blizzard scene. Also, my TV switch doesn't say what channel to tune to, so I was going all the way up to channel 80 each time I tested a new configuration!

So one more question, while were on the subject. What's the other RCA plug used for on the Sup'R'Mod (the one on the side)? Is it a composite video input, so the Sup'R'Mod can be used with other computers?
 
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I have the exact same TV on my rev-0 Apple II with a Sup'R'mod. I tried the 300 ohm converter with the adapter but found I got a cleaner signal just using an RCA jack and soldered two wires which I put directly on the screws at the back of the TV. I also have a similar setup on my Rev-4 Apple II but a different modulator but the same model TV and it works the same.

Cheers,
Corey
 
Corey986 said:
I have the exact same TV on my rev-0 Apple II with a Sup'R'mod. I tried the 300 ohm converter with the adapter but found I got a cleaner signal just using an RCA jack and soldered two wires which I put directly on the screws at the back of the TV. I also have a similar setup on my Rev-4 Apple II but a different modulator but the same model TV and it works the same.

Cheers,
Corey
Click to expand...

I've been wondering if that would work! It always seems like a good idea to cut out unnecessary connectors and components, so it's cool to hear it's actually better. I think I'll give that a try on my setup as well.

Thanks!
 
Holmes said:
I've been wondering if that would work! It always seems like a good idea to cut out unnecessary connectors and components, so it's cool to hear it's actually better. I think I'll give that a try on my setup as well.

Thanks!
Click to expand...

In theory, using an impedance matching circuit or transformer would improve the signal reception by the TV. Results will vary in practice. Those TVs were designed to take 300 ohm impedance twin lead antenna cables. Typical COAX impedance is 50 to 100 ohms depending upon the particular cable.

Since they are so inexpensive, I personally would at least try using a matching transformer. My experience in the old days with those modulators isn't all that good. They work, but it's hard to get a picture that you love, when you are staring at the result for hours on end.

regards,
Mike Willegal
 
Mike,

You bring up a good point. My cable itself could be matching the impedance close to what the TV needs and then adding a transformer makes it worse. I'll check later what cables I'm using.

Cheers,
Corey
 
Holmes said:
I've been wondering if that would work! It always seems like a good idea to cut out unnecessary connectors and components, so it's cool to hear it's actually better. I think I'll give that a try on my setup as well.

Thanks!
Click to expand...

So I just gave the game-switch method a try (this is connecting the Sup'R'Mod to the vintage TV-game-switch connected to the UHF pins on the TV): terrible, barely visible, lots of interference/snow.

I tried the direct method you outlined (connected the Sup'R'Mod via RCA cable directly to the UHF pins on the TV) - pretty clear image, except it's missing all the text! No text prints out, and all I can see is the cursor square. The cursor moves along the screen as I type, but no text appears (just black space).

Interesting. I have a modern inexpensive matching transformer on order, so I'll give that a try.

Any thoughts on what I was seeing above?
 
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Hey, to all who are interested. A few posts back I noted wondering why they didn't just put an F-type (coaxial) jack on the Sup'R'Mod. I did some more research and found this interesting page where the author discusses this topic:

http://saundby.com/atari7800mod/hookup.html

http://saundby.com/atari7800mod/hookup2.html

The first link is page 1, and here he talks about the hookups you need, and it's just like others on this thread have talked about. The 2nd link is for page 2, and here he asserts that when the early computers came out, there was no video cable standard, which is why the early machines had RF outputs on RCA-type jacks. He also discusses other interesting potential factors for the decision. Anyway, it's a bit before my time, but was an interesting read for me.
 
What if you print inversed text? Does that show up?

IMHO, RCA is nicer than F any time you don't need a weathertight or strainproof connection.
 
Oh, I never thought of that. I didn't know the Apple II could do inverted text. I did a quick search, and I guess I type "INVERSE" in Applesoft basic?

I'll give it a try. Thanks!
 
Yes, that's correct.

]INVERSE
]
:)

Incidentally, FLASH will make the text flash inverse/normal, and NORMAL will turn off INVERSE and FLASH.
 
KC9UDX said:
Yes, that's correct.

]INVERSE
]
:)

Incidentally, FLASH will make the text flash inverse/normal, and NORMAL will turn off INVERSE and FLASH.
Click to expand...


No, it didn't work. I also tried flash. Nothing but a clear view of my cursor moving around as expected.

I guess I'll wait for the matching transformer to arrive and try it out again. Thanks.
 
Are you sure your system works regardless of monitor. I can think of a few bad chips that can cause that problem.

Have you tried a generic color composite monitor?

Also what version Apple II. Is it a rev 0 or does it have the color killer transistor?

Cheers,
Corey
 
Corey986 said:
Are you sure your system works regardless of monitor. I can think of a few bad chips that can cause that problem.

Have you tried a generic color composite monitor?

Also what version Apple II. Is it a rev 0 or does it have the color killer transistor?

Cheers,
Corey
Click to expand...

Yes, I tested it with an Apple color composite monitor and it works fine.

It's a rev 0.
 
Did you test it with the composite monitor after testing it with the modulator?
 
I'm not sure I understand your question. The composite monitor was the last thing I tested, so naturally it was after testing it with the modulator (which was several days ago). I think I'm missing something in your question, though.

I switched off between reconnecting everything.
 
I think he's basicily saying double check it still works with a monitor. Sometimes things go bad and we think it's the new item we introduced but it's not always. Had this last week with my Altair. I added a cassette adapter and the system wouldn't load basic off paper tape anymore and the cassette adapter wasn't working. Turned out a had a memory chip go on another unrelated board.

Cheers,
Corey
 
Corey986 said:
I think he's basicily saying double check it still works with a monitor. Sometimes things go bad and we think it's the new item we introduced but it's not always. Had this last week with my Altair. I added a cassette adapter and the system wouldn't load basic off paper tape anymore and the cassette adapter wasn't working. Turned out a had a memory chip go on another unrelated board.

Cheers,
Corey
Click to expand...

OK, just checking. It seems like sometimes this stuff is very particular about the specific sequence of events.

Thanks to all.

I'll post back once I get my matching transformer and test the RF output through that.
 
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