22 Jan
2015
22 Jan
'15
2:54 p.m.
I picked up a little Atari 800XL bundle the other day (system, pair of 1050
drives, and an 850 expansion box) - cheap because it was missing cables and
power supplies.
1) When hooking this up to a TV via the RF input - is there any "magic"
involved, or will a suitable braided co-ax TV cable with a phono connector
added at the Atari end do? I know it "works" because I lashed one up
quickly (and I do mean quickly, no soldering involved) and ran the machine
from a stray +5V PSU, which obviously resulted in a
fuzzy picture - but
then when it came to making a good one, I got to thinking about
those
little antenna switch boxes that US machines often seemed to come with, and
wondering if there were a bunch of passive components in there which make a
difference to the signal quality.
2) Does anyone have any spare I/O cables, or know of a source of the
connectors so I can make my own?
(I suppose while I'm here I may as well ask if anyone just happens to know
what voltage power supplies the 1050's and 850 need, but I'm sure I can dig
the answers to that up online if needed)
cheers
Jules
22 Jan
22 Jan
3:09 p.m.
1) When hooking this up to a TV via the RF input - is
there any "magic"
involved, or will a suitable braided co-ax TV cable with a phono connector
added at the Atari end do? I know it "works" because I lashed one up
quickly (and I do mean quickly, no soldering involved) and ran the machine
from a stray +5V PSU, which obviously resulted in a fuzzy picture - but
then when it came to making a good one, I got to thinking about those
little antenna switch boxes that US machines often seemed to come with,
and wondering if there were a bunch of passive components in there which
make a difference to the signal quality.
Forget the RF output, use the composite monitor connection, there are
schematics for the cable on the web. Anyways, a proper 75 ohms coaxial cable
from the computer to the tv (with adequated connectors)
should work
2) Does anyone have any spare I/O cables, or know of a
source of the
connectors so I can make my own?
Mostly impossible to find the connectors alone. Best electronics.ca has
the cables at a fair price. Or you could use ebay.
(I suppose while I'm here I may as well ask if
anyone just happens to know
what voltage power supplies the 1050's and 850 need, but I'm sure I can
dig the answers to that up online if needed)
Sure :) While you're on google, get the schematics and build a SIO2SD
device, you'll need it! ;o)
4:14 p.m.
On 01/22/2015 05:09 PM, Alexandre Souza wrote:
Yeah, I figured it would be! If finding the genuine cables turns into a big
deal, I suppose I could run some 13-way IDC cable out of the
system/drive/850 cases and use DA15 connectors (there's enough clearance
around the existing connectors to do so without harming anything), but it
would be nice to find at least one real cable first and verify that my
drives work.
;-) I like using real floppies for as long as I can, though! One of the
1050 drives has some kind of speed-doubler widget fitted internally, so
although I heard that the drives can be slow, that one might not be too bad.
J.
Forget the RF output, use the composite monitor
connection, there are
schematics for the cable on the web. Anyways, a proper 75 ohms coaxial
cable from the computer to the tv (with adequated connectors) should work
Yes, I think it will possibly work with my Commodore 1702, but I'm not sure
if I have a suitable spare connector in the junk pile at the moment - plus
it feels a bit weird using a Commodore display with an Atari :-)
2) Does anyone
have any spare I/O cables, or know of a source of the
connectors so I can make my own?
Mostly impossible to find the connectors alone. (I suppose
while I'm here I may as well ask if anyone just happens to
know what voltage power supplies the 1050's and 850 need, but I'm sure I
can dig the answers to that up online if needed)
Sure :) While you're on google, get the schematics and build a SIO2SD
device, you'll need it! ;o) 
5:06 p.m.
Yeah, I figured it would be! If finding the genuine
cables turns into a big deal, I suppose I could run some 13-way IDC cable out of the
system/drive/850 cases and use DA15 connectors (there's enough clearance around the
existing connectors to do so without harming anything), but it would be nice to find at
least one real cable first and verify that my drives work.
I bought some of the SIO cables off eBay a few months back, intending to cut them and
stick DA-15 connectors on them. Before I did that, I took apart the connectors to look at
how they were made to see if I could come up with any ideas for reproducing them. The
design is fairly simple and I think the shell could be easily reproduced on a 3D printer
or hobby CNC.
Instead of hacking up the cables that I bought I ended up making a brand new cable using
the original shell and I used 0.156 crimp pins as a substitute. They were just a little
tight, but I had no problems fitting them into the original housing.
Here?s some photos: http://imgur.com/a/F0WUD
--
Follow me on twitter: @FozzTexx
Check out my blog: http://insentricity.com
6:09 p.m.
Yes, I think it will possibly work with my Commodore
1702, but I'm not
sure if I have a suitable spare connector in the junk pile at the moment -
plus it feels a bit weird using a Commodore display with an Atari :-)
If it works, you're lucky (and use it)! :D
Mostly
impossible to find the connectors alone.
Yeah, I figured it would be! If finding
the genuine cables turns into a
big deal, I suppose I could run some 13-way IDC cable out of the
system/drive/850 cases and use DA15 connectors (there's enough clearance
around the existing connectors to do so without harming anything), but it
would be nice to find at least one real cable first and verify that my
drives work. ;-) I like using real floppies for as long as I can,
though! One of the
1050 drives has some kind of speed-doubler widget fitted internally, so
although I heard that the drives can be slow, that one might not be too
bad.
Well, some people pay to suffer :oD Kidding aside, it is great to use
disks! But in Brazil, 5 1/4 disks are rare and expensive now. I still use
them, but only in my Apple II :)
And if someday you will to leave your 850 unit know a (too much) sunny
place called Brazil, let me know :D
3:13 p.m.
Hey Jules - a great place to start for various questions is the official
Atari 8-bit FAQ:
http://faqs.cs.uu.nl/na-dir/atari-8-bit/faq.html
You should find port pinouts, PSU info, etc. for each model.
One thing you'll notice right away is that, besides the coax RF hookup,
there is also a monitor port with 5 pins. You will get better picture and
sound using the composite video and audio outputs from that port on the
800xl.
From the various vendors, I recommend a couple
specifically:
B&C ComputerVisions
http://www.myatari.com/
Best Electronics
http://www.best-electronics-ca.com/
With some looking and contacting, you may find a lot of things you want. Of
course, eBay will have lots of stuff. Also, check and use the marketplace
forum on AtariAge. The folks in the 8-bit forum will also provide a wealth
of knowledge for future questions.
http://atariage.com/forums/
It's possible I might have spares of some of the things you'll be looking
for, so feel free to contact me offlist if you like to go into any detail.
James
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Jules
Richardson
Sent: Thursday, January 22, 2015 5:55 PM
To: and Off-Topic Posts' <cctalk at classiccmp.org>
Subject: Atari 800XL RF cable (and I/O cable availability?)
I picked up a little Atari 800XL bundle the other day (system, pair of
1050
drives, and an 850 expansion box) - cheap because it
was missing cables
and
power supplies.
1) When hooking this up to a TV via the RF input - is there any "magic"
involved, or will a suitable braided co-ax TV cable with a phono connector
added at the Atari end do? I know it "works" because I lashed one up
quickly
(and I do mean quickly, no soldering involved) and ran
the machine from a
stray +5V PSU, which obviously resulted in a fuzzy picture - but then when
it
came to making a good one, I got to thinking about
those little antenna
switch boxes that US machines often seemed to come with, and wondering
if there were a bunch of passive components in there which make a
difference to the signal quality.
2) Does anyone have any spare I/O cables, or know of a source of the
connectors so I can make my own?
(I suppose while I'm here I may as well ask if anyone just happens to know
what voltage power supplies the 1050's and 850 need, but I'm sure I can
dig
the answers to that up online if needed)
cheers
Jules
9:47 p.m.
1) When hooking this up to a TV via the RF input - is
there any "magic"
involved, or will a suitable braided co-ax TV cable with a phono connector
added at the Atari end do? I know it "works" because I lashed one up
Maybe... The modulator output is nominally 75 ohm, and should be linked to
such a piece of coax. European TVs have a 75 ohm aerial input, often on what
we call a 'Belling-Lee coax socket', so it's just a cable. US TVs, I am told,
may have
either a 75 ohm coax input, often on an F connector, or a 300 ohm balanced input
(for parallel twin feeder cable) on a pair of screw terminals. For the former, just
connect it up. For the latter you may need a matching transformer, aka a 'balun'
(BALanced to UNbalanced converter). I am pretty sure you can buy these, but
it must be possible to wind one if you can get a suitable core
The European switch box is just a switch. The US one I have somewhere has
screw terminals for the aerial input, a bit of twin feeder for the output and
IIRC a phono socket for the computer RF input. There is a balun inside.
The switch is special too. It is designed to minimise RF leakage from the
computer to the aerial, since linking an aerial to the computer modulator
output would make a very low power TV transmitter. How far it would be
detectable I do not know, but the FCC (or whoever) take a dim view of
such things.
-tony
10:34 p.m.
On Fri, 23 Jan 2015, tony duell wrote:
Doing such a thing would have an appreciable chance of causing damage to
the modulator because it's feeding into something that's probably not
tuned to precisely the right frequency. Antennas designed only to receive
tend to be very poor for transmitting.
--
David Griffith
dgriffi at cs.csubak.edu
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
1) When hooking this up to a TV via the RF input
- is there any "magic"
involved, or will a suitable braided co-ax TV cable with a phono connector
added at the Atari end do? I know it "works" because I lashed one up
Maybe... The modulator output is nominally 75 ohm, and should be linked to
such a piece of coax. European TVs have a 75 ohm aerial input, often on what
we call a 'Belling-Lee coax socket', so it's just a cable. US TVs, I am told,
may have
either a 75 ohm coax input, often on an F connector, or a 300 ohm balanced input
(for parallel twin feeder cable) on a pair of screw terminals. For the former, just
connect it up. For the latter you may need a matching transformer, aka a 'balun'
(BALanced to UNbalanced converter). I am pretty sure you can buy these, but
it must be possible to wind one if you can get a suitable core
The European switch box is just a switch. The US one I have somewhere has
screw terminals for the aerial input, a bit of twin feeder for the output and
IIRC a phono socket for the computer RF input. There is a balun inside.
The switch is special too. It is designed to minimise RF leakage from the
computer to the aerial, since linking an aerial to the computer modulator
output would make a very low power TV transmitter. How far it would be
detectable I do not know, but the FCC (or whoever) take a dim view of
such things.
23 Jan
23 Jan
12:41 p.m.
Doing such a thing would have an appreciable chance of causing damage to
the modulator because it's feeding into something that's probably not
I think that's unlikely. The modulator has a very low RF output (after all, it is
designed to
connect to an input that typically gets microvolt signals from an aerial) so there is not
enough RF power around to do damage no matter where it ends up. Certainly
running a modulator into an open circuit or short circuit does no harm (These are
big no-nos for radio transmitters)).
For that matter, I am not convinced that the aerial input of a TV is going to be tuned
to the modulator output frequency. Particularly not if the TV is tuned to a different
channel :-). And I have never seen warnings about making sure the TV is correctly
tuned before powering up.
tuned to precisely the right frequency. Antennas
designed only to receive
tend to be very poor for transmitting.
How come? The elementary books on aerials suggest that a good transmitting
aerial is a good receiving aerial and vice versa.
-tony
9:30 a.m.
On 01/22/2015 11:47 PM, tony duell wrote:
Aha, thanks. I think that whatever equipment I might ever want to connect
the machine to will be using an F connector, so straight-through will do
the job. I did find a lead at a shop yesterday though with DIN connectors
at the end (original purpose unknown), so I can butcher that and make
myself up a composite lead.
Oddly, I never saw a TV switch box in the UK back in the day - everyone I
knew with any kind of machine that used a TV for a display simply unplugged
the regular antenna and plugged the computer in when they wanted to use it.
1) When hooking this up to a TV via the RF input
- is there any "magic"
involved, or will a suitable braided co-ax TV cable with a phono connector
added at the Atari end do? I know it "works" because I lashed one up
Maybe... The modulator output is nominally 75 ohm, and should be linked to
such a piece of coax. European TVs have a 75 ohm aerial input, often on what
we call a 'Belling-Lee coax socket', so it's just a cable. US TVs, I am told,
may have
either a 75 ohm coax input, often on an F connector, or a 300 ohm balanced input
(for parallel twin feeder cable) on a pair of screw terminals. For the former, just
connect it up. For the latter you may need a matching transformer... (BALanced to UNbalanced converter). I am pretty sure
you can buy these, but
it must be possible to wind one if you can get a suitable core
I do see ones for old video game consoles every once in a while, I've just
never picked one up as I have monitors (CBM, Apple etc.) that will work
with the other machines I have over here. Maybe I'll grab one at some
point, just in case I ever need it for some reason.
cheers
Jules
1:34 p.m.
Oddly, I never saw a TV switch box in the UK back in
the day - everyone I
knew with any kind of machine that used a TV for a display simply unplugged
the regular antenna and plugged the computer in when they wanted to use it.
I never saw one with a computer, they were more commonly used with TV games
consoles. I have one somewhere. Actually I think I've seen them in pound shops
(equivalent of dollar stores) recently, next time I am going around such places I
will have another look
I got a US one (300 ohm aerial I/O, 75 ohm computer input on an RCA phono
socket with internal balun) with my CoCo 3, which is the US NTSC version (it was
never sold in the UK, and trying to find the PAL version sold in Australia was
impossible). I have never used it, I use the CoCo 3 with an RGB monitor.
-tony
24 Jan
24 Jan
10:45 a.m.
[TV Aerial switchboxes]
I never saw one with a computer, they were more
commonly used with TV games
consoles. I have one somewhere. Actually I think I've seen them in pound shops
(equivalent of dollar stores) recently, next time I am going around such places I
will have another look
I was right. The pound shop next to Woolwich Arsenal station has a 3-way aerial
switchbox, sold as a 'TV game switch'. 3 Belling-Lee sockets, a switch (which
doesn't
look as though it will provide much RF isolation) and a short cable ending in a
Belling-Lee plug.
-tony
3573
days inactive
3575
days old
11 comments
6 participants
participants (6)
-
alexandre.tabajara＠gmail.com -
ard＠p850ug1.demon.co.uk -
dgriffi＠cs.csubak.edu -
fozztexx＠fozztexx.com -
james＠slor.net -
jules.richardson99＠gmail.com