[Coco] [OT] Analog computer from Radio Shack

[Gene Heskett]

On Wednesday 20 December 2006 03:55, Kevin Diggs wrote:
>Gene Heskett wrote:
>> One of the real ones could be quite a bit more accurate than than you
>> folks have estimated them to be.  When I first went to work for
>> KOTA-TV in Rapid City, circa 1964, the Chief, Elmer Nelson, had made
>> himself one of them, ISTR it had an output meter and 8 input dials
>> plus
>> a .1,.2,.5,1,2,5 style of range switches over about 5 decades for the
>> input dials.  Using the then magic and expensive op-amps, and .1%
>> precision resistors and 10 turn .1% Beckman pots for input, he
>> estimated the overall accuracy at maybe .25%.  He used it to design
>> all the tuned circuits in his microwave equipment he was building, and
>> which worked quite well.
>>
>> They had tried several makes of microwave gear for their dual channel,
>> bi-directional back to Hays Springs/Alliance (KDUH-TV), 6 hops to
>> Lookout Mountain (KLZ-TV then) in Colorado for their network
>> microwave, but none of it could have the door slammed on the
>> mountaintop shacks for more than 30 days, a rather important
>> consideration when you might have to hire a helicopter to get you
>> there in the wintertime.  So he built one using all millspec tubes,
>> mostly 6922's that could go a year between visits to the shacks.  And
>> that was his computer at the time, but he eventually graduated to an
>> HP-85 in about 1965 or 66.  That HP-85 used a spark discharge printer,
>> and that's the first time I ever saw a smith chart actually plotted. 
>> I hope Elmer still lives, the last time I was in Rapid City was in
>> 1994, and I stopped at his shop, "Tepco Inc" and shot the breeze for
>> an hour or so.  But, he was in his mid 70's then, not as spry but
>> still as sharp as ever, so I've no idea if he is still working or has
>> sold it to the help, one of which had been with him for at least 30
>> years then.  Tepco's main product is tv translators at the 10 watt
>> power level, good for shadow fills & such. See at
>> <http://www.rapidnet.com/~tepco/>
>>
>>
>> I had fun with Elmer, he was a 'papered' engineer, and was always
>> amazed at just how much this 8th graduate knew about electronics.
>
>Gene,
>
>	I'll bet you could tell us all kinds of interesting TV station stories.
>Anything on digital tv (aka ATSC)?
>
>					kevin

Yeah, so far, after helping to install 5 Superior Broadcast digital 
transmitters, we finally have one with lip sync here at WDTV.  Generally, 
the mpeg encoder/modulator they originally used allowed the audio to get 
as much as 2 seconds behind the video but this one has a new all in one 
integrated unit in it that seems to be doing quite well in that regard.  
The only thing I have around here that can receive it is a pcHDTV-3000 
card I have in this computer, and xine, with the xine-hd additional 
modules seems to be able to run it just fine.  Basicly though, these are 
100 and 200 watt units that are designed to get a signal into the city of 
license, and we haven't built the antenna facilities to get much farther 
than that.  I'm 3 miles from it and the signal does glitch occasionally, 
but usually, on checking with the tx operators, its been glitching there 
too because the input signal isn't clean enough.  Doing digital demands a 
clean signal because you can't compress random noise without driving the 
mpeg encoders out of their minds.  And this is noise that, generally 
speaking, isn't visible to the average viewer who is used to the quality 
of signal he gets from his cable provider, or his vcr/dvd.  Its also 
something that won't get fixed until the GM can see it on his office tv, 
and its 16.5 air miles away in the opposite direction.  Out of range & 
not on the cable system, so engineering-wise we're doubly handicapped.  
Money will not be spent to fix it till he can see it.  In the meantime, 
its less than impressive to the 1 or 2 other local Joe Sixpacks who've 
bought something that could get it, looking no better than a poorly 
aligned "Dish" system in bad weather.  This of course is running as SDTV 
since we don't have the HDTV ability other than coming out of a CBS 
receiver we put in up there so we could stay on the air even without 
power at the studio.  I don't believe we've considered hooking that up 
yet.  But its a thought...

Then to top that off, my dual card audio system hasn't properly configured 
itself after the last reboot 3 or 4 days ago and the tv audio is being 
routed thru the onboard nvidia ac97 stuff instead of my Audigy 2 card.  
More Fedora Core 6 screwups to sort.

I'm going to buy something today that can get it as the little 9" GE 
portable the missus has been using in her room is showing signs of a 
fading crt after about 10 years of nearly 24/7 and it never was that 
sharp, she's always trying to read what it says onscreen and failing.  
Tain't her eyes, I can't read it either.

A Christmas present so to speak.  That's IF I can talk to a sales type at 
Circuit City, the place was a madhouse last night when I was there.  I 
saw a lot of folks going out the door empty-handed because there weren't 
enough sales staff.

Yeah, war stories.  This recent Mt. Hood disaster reminds me of what could 
have been a similar situation for me, but the mountain was only 10,800 
feet high.  Middle of February, it had several feet of fresh powder on it 
that was moving east at about 10 mph in a 30 mph wind.  I got out of the 
Bronco at about the 7,500 foot mark and hauled a dual trace scope, a tube 
caddy full of stuff to fix microwaves with, and a smallish hand toolbox, 
and waded on up to the site about 3 miles above where I spent about 4 
hours replacing and tuning up a fresh klystron in the relay gear there.  
Coming back out of the shack about midnight, the temps were down in the 
zero range and the wind was up to 40 or so.  My tracks were filled in in 
5 seconds, but above it was crystal clear with the stars as bright as 
possible at those altitudes.  The starlight was literally as bright as a 
1/4 moon would have been but it wasn't up till the wee hours.  My only 
saving grace was that the trail had a set of 20 foot high snow poles 
planted beside it at about 50 foot intervals, designed to guide plow 
operators when they can't find the road in the snow.  No idea why because 
I never saw any evidence of a plow ever being used up there on North 
Mountain.  I literally walked from snow pole to snow pole & eventually 
got back down to the Bronco.  I'd left it pointed down the hill so from 
there on down to the highway was only about another half hours slogging 
through the powder which was drifting like crazy, but never started to 
pack, too cold I guess.  I was dressed for the weather so I wasn't in 
danger of frostbite or worse unless I got lost and I'd been there many 
times.  Had I been injured, the story would have been quite different of 
course as I didn't even have a bottle of water with me, let alone any 
food other than a candy bar I ate before getting out of the Bronco & 
heading up.

-- 
Cheers, Gene
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Copyright 2006 by Maurice Eugene Heskett, all rights reserved.