12 Jun
2024
12 Jun
'24
6:55 p.m.
So, I recently salvaged a pair of ASR 33s and a PDP-8/I from a research lab where I work.
A few folks chimed in on the "anybody want this" thread, but I happened to be
the lucky winner (not lucky for my back or my basement, but they will be fun restoration
projects.)
One of the engineers here asked if there were any teletype rolls along with these and if
so that they be salvaged because "...it is broadly lossy to rf and can be used as an
rf termination load."
When asked a little further if this was teletype rolls in particular, she replied yes, and
that this was something she had picked up in former work as an RF engineer at Varian, from
a previous generation of crafty engineers.
I thought this was pretty interesting, and that the list here might have a cross-section
of folks who might comment. Anybody heard of this before?
Hmmm, teletypes *and* RF -- sounds like something Marc might want to check out... :-)
cheers,
--FritzM.
12 Jun
12 Jun
8:18 p.m.
"teletype rolls" what, like rolls of paper? They are not effective as dummy
loads.
Sent from Nine<http://www.9folders.com/>
________________________________
From: Fritz Mueller via cctalk <cctalk(a)classiccmp.org>
Sent: Wednesday, June 12, 2024 6:56 PM
To: General Discussion: On-Topic and Off-Topic Posts
Cc: Fritz Mueller
Subject: [cctalk] teletype roll as an RF termination load
So, I recently salvaged a pair of ASR 33s and a PDP-8/I from a research lab where I work.
A few folks chimed in on the "anybody want this" thread, but I happened to be
the lucky winner (not lucky for my back or my basement, but they will be fun restoration
projects.)
One of the engineers here asked if there were any teletype rolls along with these and if
so that they be salvaged because "...it is broadly lossy to rf and can be used as an
rf termination load."
When asked a little further if this was teletype rolls in particular, she replied yes, and
that this was something she had picked up in former work as an RF engineer at Varian, from
a previous generation of crafty engineers.
I thought this was pretty interesting, and that the list here might have a cross-section
of folks who might comment. Anybody heard of this before?
Hmmm, teletypes *and* RF -- sounds like something Marc might want to check out... :-)
cheers,
--FritzM.
9:28 p.m.
Yeah, something’s missing here, teletype paper is for sure not good as a dummy load.
9:39 p.m.
Maybe they are thinking that because it is oil it will work like an oil
can load.
Sound to me like the originator of this is a big load of dummy🙂
On 6/12/2024 8:28 PM, mark audacity romberg via cctalk wrote:
Yeah, something’s missing here, teletype paper is for
sure not good as a dummy load.
13 Jun
13 Jun
1:45 a.m.
On 6/12/2024 8:28 PM, mark audacity romberg via cctalk
wrote:
Yeah, something’s missing here, teletype paper is for sure not good as a dummy load.
<shrug>
Sounded pretty strange to me, but the commenter is a fairly accomplished person in the
accelerator electronics and detector division, and the audience (on a general channel) was
the entire staff of the lab. So I assume there was *something* to the tale...
I wonder what might be missing or lost in translation down the years? I figure if anybody
had heard of such a thing, it might be some of this lot :-)
--FritzM.
2:11 a.m.
could early rolls have been on graphite or metal instead of cardboard? Or a metal
reusable core with a hollow cardboard tube holding the paper, like paper towels?
<pre>--Carey</pre>
On 06/13/2024 12:45 AM CDT Fritz Mueller via cctalk
<cctalk(a)classiccmp.org> wrote:
On 6/12/2024 8:28 PM, mark audacity romberg via
cctalk wrote:
Yeah, something’s missing here, teletype paper is for sure not good as a dummy load.
<shrug>
Sounded pretty strange to me, but the commenter is a fairly accomplished person in the
accelerator electronics and detector division, and the audience (on a general channel) was
the entire staff of the lab. So I assume there was *something* to the tale...
I wonder what might be missing or lost in translation down the years? I figure if
anybody had heard of such a thing, it might be some of this lot :-)
--FritzM. 
1:54 p.m.
On Jun 12, 2024, at 9:39 PM, Mike Katz via cctalk
<cctalk(a)classiccmp.org> wrote:
Maybe they are thinking that because it is oil it will work like an oil can load.
But oil can loads use the oil for cooling; a resistor (typically made of carborundum) is
the actual load.
paul
4:44 p.m.
New subject: "Pentium" (by any other name?)
"What to use in place of 586?"
Unreliable sources told me that the name "Pentium" was chosen in a
contest; what was second place??
It was said that Intel chose to not use "586", because
competitors were competing and/or cheating on the numbers
a 386 level chip being called "486xx", 486 level chips being called
"586",
and 586 level chips being called "686"
. . . and "you can not "trademark" a number."
(sorry for an automotive analogy, but what about the Oldsmobile "442"?)
"Pentium" seemed to be safe from "look-alike"names/numbers.
BUT, they may not have noticed a serious risk on that.
Honeywell had purchased "Pentax" from Asahi.
If Honeywell wanted to jump into the fray, they could probably legally put
out a chip named "Pentaxium". Fortunately for Intel, Honeywell did not.
--
Grumpy Ol' Fred cisin(a)xenosoft.com
12 Jun
12 Jun
10:12 p.m.
On 06/12/2024 5:55 PM CDT Fritz Mueller via cctalk
<cctalk(a)classiccmp.org> wrote:
One of the engineers here asked if there were any teletype rolls along with these and if
so that they be salvaged because "...it is broadly lossy to rf and can be used as an
rf termination load."
cheers,
--FritzM.
It's been almost 40 years since I saw a roll of teletype paper, but I think they were
rolled on cardboard? I can't imagine it would work very well in its native state, but
maybe soaked in water or salt water it would be conductive enough and could dissipate a
fair amount of power. I wouldn't think it would work much better than a light bulb,
though.
I know in the army they taught us to make a terminating resistor out of an ear plug case
filled with salt water, but that wasn't intended to be very accurate or dissipate much
power.
Will
Grownups never understand anything by themselves and it is tiresome for children to be
always and forever explaining things to them,
Antoine de Saint-Exupery in The Little Prince
11:08 p.m.
On 2024-06-12 8:17 p.m., Dennis Boone via cctalk wrote:
Wow the worlds cheapest RTTY setup, or is it fewest parts.
Does any one do RTTY or slow scan TV now days?
Ben.
I wouldn't
think it would work much better than a light bulb, though.
Load it up with a wide range tuner, and you could probably make contacts
across three states, though, just like the light bulb. :)
De
11:24 p.m.
Yes I do rtty and I use mechanical equipment. Several of us use military standards and
military equipment. I show some of this on my Youtube Channel which can be found at
@w2hx
Sent from Nine<http://www.9folders.com/>
________________________________
From: ben via cctalk <cctalk(a)classiccmp.org>
Sent: Wednesday, June 12, 2024 11:08 PM
To: cctalk(a)classiccmp.org
Cc: ben
Subject: [cctalk] Re: teletype roll as an RF termination load
On 2024-06-12 8:17 p.m., Dennis Boone via cctalk wrote:
Wow the worlds cheapest RTTY setup, or is it fewest parts.
Does any one do RTTY or slow scan TV now days?
Ben.
I wouldn't
think it would work much better than a light bulb, though.
Load it up with a wide range tuner, and you could probably make contacts
across three states, though, just like the light bulb. :)
De 
11:32 p.m.
Is it possible they were thinking about really old FAX paper which
might have been wet to support marking via an electric discharge
through it (and to (slightly) reduce the frequency with which the
receiving machine caught fire)?
On Wed, Jun 12, 2024 at 5:56 PM Fritz Mueller via cctalk
<cctalk(a)classiccmp.org> wrote:
So, I recently salvaged a pair of ASR 33s and a PDP-8/I from a research lab where I work.
A few folks chimed in on the "anybody want this" thread, but I happened to be
the lucky winner (not lucky for my back or my basement, but they will be fun restoration
projects.)
One of the engineers here asked if there were any teletype rolls along with these and if
so that they be salvaged because "...it is broadly lossy to rf and can be used as an
rf termination load."
When asked a little further if this was teletype rolls in particular, she replied yes,
and that this was something she had picked up in former work as an RF engineer at Varian,
from a previous generation of crafty engineers.
I thought this was pretty interesting, and that the list here might have a cross-section
of folks who might comment. Anybody heard of this before?
Hmmm, teletypes *and* RF -- sounds like something Marc might want to check out... :-)
cheers,
--FritzM.
13 Jun
13 Jun
11:46 a.m.
On 6/12/24 22:32, Gavin Scott via cctalk wrote:
Is it possible they were thinking about really old FAX
paper which
might have been wet to support marking via an electric discharge
through it (and to (slightly) reduce the frequency with which the
receiving machine caught fire)?
Yes, there was teledeltos paper, that had a silver top layer
and a carbon layer below that.
A high voltage spark burned away the silver layer and left a
black image.
Jon
12:05 p.m.
On Thursday (06/13/2024 at 10:46AM -0500), Jon Elson via cctalk wrote:
On 6/12/24 22:32, Gavin Scott via cctalk wrote:
The OP mentioned that the story may have originated at Varian, where they
historically did a lot of work on high power _microwave_ stuff. I could
imagine that a roll of paper might make an OK attentuator at the end
of a piece of waveguide, into which you can dump a bunch of power.
But it probably isn't going to be a very good impedance match.
I don't see it working well at all at HF, VHF or UHF frequencies if
the RF source (transmitter) is expecting any sort of normal impedance
like a 50 ohm termination-- because how are you connecting the feedline
to this roll of paper? What is the mechanical and electrical interface
between the unbalanced (or balanced) feeder and the roll of paper?
Maybe they put an actual dummy load resistor inside the roll of paper
and were using it as a heatsink-- you know, before it lit on fire ;-)
Seems like some important details of this story are missing...
Chris N0JCF
--
Chris Elmquist
Is it possible they were thinking about really
old FAX paper which
might have been wet to support marking via an electric discharge
through it (and to (slightly) reduce the frequency with which the
receiving machine caught fire)?
Yes, there was teledeltos paper, that had a silver top layer and a carbon
layer below that.
A high voltage spark burned away the silver layer and left a black image.
17
days inactive
18
days old
14 comments
13 participants
participants (13)
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ben -
CAREY SCHUG -
Chris Elmquist -
Dennis Boone -
Fred Cisin -
Fritz Mueller -
Gavin Scott -
Jon Elson -
mark audacity romberg -
Mike Katz -
Paul Koning -
W2HX -
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