Correct!
That is until the engineers at Ampex figured out the rotating helical-scan head.

 

So I wonder , what the op wants to do , what is their knowledge level ,what research have they done ?
I do hope this is not another one of those posts that goes everywhere !

 

Correct!
That is until the engineers at Ampex figured out the rotating helical-scan head.

Actually, what AMPEX (an acronym, so all caps) figured out is transverse scan. It was wildly impractical to move the tape past the heads at the necessary speeds, so they decided to move the heads past the tape.

The headwheel has four heads 90 degrees apart. The plane of rotation is 90 degrees from the direction of tape travel. Rotation is 14,400 RPM, so while tape speed is 15 inches per second, the head-to-tape speed is around 100x that. The track angle is very close to 90 degrees. One scan of a head across 2" of tape records/plays a little over 16 lines of video. The tape is sucked up against a circular guide that matches the radius of the headwheel. A VTR requires a vacuum pump to operate.

AMPEX uses rotary transformers to couple the record and play signals, while RCA (the meatball) uses brushes. RCA and early AMPEX machines have high-impedance video heads that require frequency and Q compensation adjustments for each tape. 3rd and 4th gen AMPEX machines use low impedance heads that eliminate both adjustments.

Another thing AMPEX figured out was that even the best ball bearings had too much play, which showed up as an amplitude modulation of the FM carrier caused by radial movement, plus a phase modulation caused by axial movement. Both of these were almost completely eliminated by going to compressed air bearings, so besides the vacuum pump, a quadraplex video recorder also requires compressed air. We eliminated the vacuum pumps by picking off some of the compressed air for a venturi vacuum generator for the female guide.

https://en.wikipedia.org/wiki/Quadruplex_videotape

Various companies in Japan worked out the early helical scan system, turning it into the EIAJ standard. In the US, IVC developed the 9000 helical scan machine. It pulled 2" tape and made broadcast-legal video in both regular and still-frame playback. It did not do well in the US market, but better in Europe.

ak

 

Actually, what AMPEX (an acronym, so all caps) figured out is transverse scan. It was wildly impractical to move the tape past the heads at the necessary speeds, so they decided to move the heads past the tape.

The headwheel has four heads 90 degrees apart. The plane of rotation is 90 degrees from the direction of tape travel. Rotation is 14,400 RPM, so while tape speed is 15 inches per second, the head-to-tape speed is around 100x that. The track angle is very close to 90 degrees. One scan of a head across 2" of tape records/plays a little over 16 lines of video. The tape is sucked up against a circular guide that matches the radius of the headwheel. A VTR requires a vacuum pump to operate.

AMPEX uses rotary transformers to couple the record and play signals, while RCA (the meatball) uses brushes. RCA and early AMPEX machines have high-impedance video heads that require frequency and Q compensation adjustments for each tape. 3rd and 4th gen AMPEX machines use low impedance heads that eliminate both adjustments.

Another thing AMPEX figured out was that even the best ball bearings had too much play, which showed up as an amplitude modulation of the FM carrier caused by radial movement, plus a phase modulation caused by axial movement. Both of these were almost completely eliminated by going to compressed air bearings, so besides the vacuum pump, a quadraplex video recorder also requires compressed air. We eliminated the vacuum pumps by picking off some of the compressed air for a venturi vacuum generator for the female guide.

https://en.wikipedia.org/wiki/Quadruplex_videotape

Various companies in Japan worked out the early helical scan system, turning it into the EIAJ standard. In the US, IVC developed the 9000 helical scan machine. It pulled 2" tape and made broadcast-legal video in both regular and still-frame playback. It did not do well in the US market, but better in Europe.

ak

Actually, what AMPEX (an acronym, so all caps) figured out is transverse scan. It was wildly impractical to move the tape past the heads at the necessary speeds, so they decided to move the heads past the tape.

The headwheel has four heads 90 degrees apart. The plane of rotation is 90 degrees from the direction of tape travel. Rotation is 14,400 RPM, so while tape speed is 15 inches per second, the head-to-tape speed is around 100x that. The track angle is very close to 90 degrees. One scan of a head across 2" of tape records/plays a little over 16 lines of video. The tape is sucked up against a circular guide that matches the radius of the headwheel. A VTR requires a vacuum pump to operate.

AMPEX uses rotary transformers to couple the record and play signals, while RCA (the meatball) uses brushes. RCA and early AMPEX machines have high-impedance video heads that require frequency and Q compensation adjustments for each tape. 3rd and 4th gen AMPEX machines use low impedance heads that eliminate both adjustments.

Another thing AMPEX figured out was that even the best ball bearings had too much play, which showed up as an amplitude modulation of the FM carrier caused by radial movement, plus a phase modulation caused by axial movement. Both of these were almost completely eliminated by going to compressed air bearings, so besides the vacuum pump, a quadraplex video recorder also requires compressed air. We eliminated the vacuum pumps by picking off some of the compressed air for a venturi vacuum generator for the female guide.

https://en.wikipedia.org/wiki/Quadruplex_videotape

Various companies in Japan worked out the early helical scan system, turning it into the EIAJ standard. In the US, IVC developed the 9000 helical scan machine. It pulled 2" tape and made broadcast-legal video in both regular and still-frame playback. It did not do well in the US market, but better in Europe.

ak

You have great knowledge on the professional video recorderes , the size of large fridge freezers.

Think consumer machines had heads at more like 45 degrees and used the speed of the head to hold the tape tight .

I assume the op has a consumer machine . Let's hope they get back to the forum .

 

You have great knowledge on the professional video recorders , the size of large fridge freezers.

In round numbers, 3 feet by 4 feet by 6 feet, 1/2 ton. Everything from grunt linear power supplies to a 10 MHz FM signal system, plus voltage-variable, baseband video analog delay lines, plus multiple overlapping servo systems, and two motor drive amplifiers. Except for high voltage transmission lines, it is the world of EE in one big analog box. This is where I worked my way through school - EE classes during the day, and a room with seventeen (!!!!!) video machines at night. Absolute EE candy-land.

Think consumer machines had heads at more like 45 degrees

VHS decks started out with two heads on the drum, but added more as quality improved - flying erase heads for editing, separate record and play heads, etc.

and used the speed of the head to hold the tape tight .

The speed of the head was used to create an air cushion; the head did not touch the tape, or touched it very lightly. Consumer machines (3/4" U-Matic, 1/2" VHS and BETA, etc.) all have mechanical tape tension systems. Toward the end of the quad era, AMPEX produced the AVR-1. This monster had dual vacuum columns to maintain tape tension, and ***no pinch roller***.

I assume the op has a consumer machine .

If the OP has a quad deck, I'm on the next plane out of here.

ak

 

At this point we should ask just what format of video the TS is actually wanting to amplify/record/playback.
Please consider that HAM RADIO folks have been sending and receiving video over voice-frequency links prior to transistors being commonly available. SLOW-SCAN video, but actual video.
AND consider the BELL SYSTEM "PICTURE PHONE" that also delivered video images.
I SUGGEST that the TS do more research and try to find a way to watch a current standards VHS video player actually operating, with the covers removed so that the tape path is visible. Once you understand what is happening, it is very impressive indeed!! All of the folks who are at all interested, really should do that! To achieve an effective head-across- tape speed fast enough for OK video playback at a bulk tape speed of about 2 inches per second is totally brilliant! AND to do it cheap but reliable and long lasting is AWSOME!!
The actual magnetic track is diagonal across the tape, because the tape is wrapped diagonally around the spinning cylinder with the writing part centered between the two ends of the cylinder. So instead of straight down across the tape, it is a much longer path with a higher speed because the tape speed adds to the spin speed. I have no clues as to how they synchronise for playback. Probaby magic, is my guess.

 

JVC licensed the original patents that became VHS from ----- AMPEX.

ak

 

I have actually SEEN one of thos e 60 inches per second video playbacks at a TV station, back in about 1961, I think. My recollection was about how exciting a tape spill would be.

 

My recollection was about how exciting a tape spill would be.

Death trap video.

ak