Zenith Phonevision: Let's explore this
 

Caught a lucky BIN on eBay of two complete Phonevision units and one faceplate that appear to have been used in the two year trial run at WHCT in Hartford CT. I don't think that the seller knew what these were :)

Here's some pics from the auction:

Package received at home today. Two Phonevision units and one complete faceplate. Weight: 66 lb :eek: . If I had to pack these suckers for a $20 sale less ebay commissions I'd have thrown them out! :D LOL.

Well let's see what they look like inside! Seems this one's got a seal on it. Hm, hope Subscription TV doesn't get too angry with me.....

Built like a tank! Tubes topside are 6BQ5 and a 6BF8, underneath are 6HW8 and 6AW8. In the underside you can see one hell of a big line delay, adjustable too, as shown in one of the other pics

Now as far as operation, here's some info that I've found....and there's not much of it online. In fact, nothing at all when it comes to circuitry or hookup.

http://www.kylebookholz.com/whct3.html

Been chatting with Doug in his Facebook TV group about it too, he's never seen one and has no info on it at all.

Figuring all of this out is going to be interesting....though it was obviously in use for a short period of time, the system remains largely a mystery.

I'll be watching this thread ;)

Doug seems to think that this *might* be prototype stuff, but we're not sure at this point. The large connector on the box more than likely plugged into a billing processor unit of some kind.

From research I've done, some prototypes had a printer of some kind...I've even seen a reel to reel prototype that collected data somehow. I've also seen where some proposed models had billing through the customer's phone bill.

At this point, it's anyone's guess how this actually worked.

Wow. No idea that was ever made!

Zenith owner's manuals back in the day mention Phonevision in the last few pages.

In the past there were owners manuals on e-bay for
these.
It is the first OTA pay TV system. IIRC the signal was
sent without the hoz sync & the audio on a second
channel. Decoding the audio gave the sync signal.
In Boston area we had 2 OTA pay TV's in the late 70's
One was a Zenith service from ch 27 in Worcester
( Wistah ) The other ch 68 Boston, used a same but
different method. Dont remember who built it, BT maybe ?
Anyhows the Zenith used a 9-151 module from a System 3
along with another board. No hoz sync, you got that from decoding
the "stereo" audio. The off air audio was the NWS from Worcester.
A Sanyo LM1800 IC was used by hackers. One pin
outputted the needed H sync.
Both featured skin flicks after 10 PM so quite popular !

73 Zeno:smoke:

Neat find!

I guess you can start puzzling out the multi-pin connector, to see if you can identify the AC power input, as well as the phone line interface. I wonder if there was a separate phone line interface box, as this unit was from the days of the Ma Bell monopoly, where nothing but approved gear could be connected to the phone network.

I think this needed internal connections to the sync and video circuits in the receiver, as well.

Not an item that is ever likely to work again without a source of scrambled content, but a very cool bit of TV history.

This is waaaay before my time at Zenith, and the people who originally worked on it are probably all dead. I will see if I can find anyone I know from the Cable division who knows something about it.

I do know that the long delay line was switched in and out during multiple segments of the field interval, causing the picture to be scrambled into displaced horizontal strips. The code is part of determining which segments are delayed. I don't know if the switches were wired differently on each box to prevent code sharing, but that would have required some data memory per box, which would be hard to provide at that time. I suspect the phone call simply enabled the delay line switching with some simple on-line signal.

I never knew these existed (at least they weren't used here in Omaha) until Jamie (jstout) told me about this post yesterday. I assume it was analog video over a phone line, but when I have more time, I will research it some more, just out of curiosity. I remember a microwave link in which there was a movie channel (maybe 2), that used a dish aimed toward a tall building in central Omaha, transmitting mainly movies. (Early HBO?) of course this was before cable ever came to Omaha. Don't remember what the service was called anymore.

The system was scrambled analog video OTA, with a decoding signal (and audio) sent to subscribers via phone line. Worked by switching a delay line in and out of the transmitted signal path, producing a "venetian blind" kind of effect unless the delay was compensated for on the receiving end, in step with the decoding signal.

Sweet find! This system always intrigued me, way ahead of it's time.

That microwave system was here in Milwaukee too. One of my professors used to pirate it. He used a round metal sled for a dish, and an oscillator to hetrodyne it down to the broadcast band...Supposedly he got a clearer picture than those in his area, but he had to periodically adjust the osc. to compensate for drift.

There is no way you could get NTSC video quality over a phone line at an acceptable frame rate for TV back then.

I think, just about anyone that had any electronics knowledge built one! The one, I built was an octagonal PC board soldered to one pound coffee can. In the old neighborhood, I lived in, you could see the building where the signal came from, so it was real easy to receive it.