1936 RCA RR-359B Restoration

[tubesrule]

A few corrections:

Their 343 line standard was 2.25MHz. From the "TEST INSTRUCTIONS FOR THE R.F. ALIGNMENT OF THE RC-199 TELEVISION RECEIVER" document attached.

The resolution was 1.5MHz not 2.5MHz as listed and graphed in the "HIGH DEFINITION TELEVISION RECEIVER NINE INCH MIRROR LID CONSOLE TYPE RR-359" manual. A copy of my manual can be found here: https://www.earlytelevision.org/pdf/...359_manual.pdf

Dr Kell devised the "Kell Factor" in 1934 well before the design of these sets so it was in use when these sets were designed. The RR-359A's have a Kell Factor of about 0.6.

The vid/aud spacing was changed to 4.5MHz in 1937 when the sets were upgraded to the 12" RR-359B's. All the video IF's and mixer were swapped out for the "B" upgrade per the "CHANGE FOR CONVERTING RC-199 TO RC-199B" engineering document. This doc also outlines various component value changes throughout the chassis.

No changes to the horizontal sweep needed to be made. They run efficiently from 240 to 625 lines with full width and good linearity.

All pre-war television run fairly well on FM audio using slope detection. RCA put out a letter to all registered owners after the change in 1941 that they would align their sets for slope detection at no cost.

[Penthode]

2.25 MHz sound spacing was used in 1933-34 not for the 1936 343 line and 441 line broadcast tests from July 1936. It is described in the volume 1
Television.

Do not confuse this with the earlier 240 tests described.

Goldsmith described that RCA engineers arrived at a 6MHz channel without the details of the video-aural carrier frequency spacing. You have to dig a bit to find the information.

But think logically about this: they identify the carrier frequencies which would fit nicely in the 44MHz to 50MHz channel. The RCA Volume 1 Television explicitly lists the sound carrier as 49.75MHz and the video carrier at 46.5MHz. The difference.is 3.25MHz.

The video aural carrier spacing could not be moved to 4.5MHz until after the modification from double sideband to vestigial sideband which RCA made immediately before the 1939 World's Fair. Your documentation identifying the change must be from 1939 not 1937..
I know this is correct. I encourage you to look for it. If you require further evidence I will dig it out for you.

[Penthode]

Find attached pg 17 from volume 2 of Television, "Recent Developments in Television". Note how the 343line 3.25MHz video aural carrier spacing was also used for 441 lines.

Next I will look for evidence of the 4.5MHz video aural carrier spacing switch. 4.5MHz spacing could not be used for the AM double sideband transmissions prior to April 1939.

[Penthode]

I found the transition to 4.5MHz spacing was done in March 1939, a month ahead of the 1939 New York World's Fair. It was published in Television volume 3 (1938 to 1941) in the paper " A Vestigial Side-Band Filter for use with a Television Transmitter", pages 251-2. Page 253 Fig. 1 depicts the interim 1939 VSB channel with 3.25MHz Video-Aural spacing and the 1939 to 2009 VSB channel with 4.5MHz Video-Aural spacing.

The added video channel bandwidth allowed by the increase in the video-aural carrier spacing from 3.25MHz to 4.5MHz certainly would have improved the horizontal resolution. It was in the spring of 1941 that the horizontal resolution would be somewhat sacrificed to facilitate the 525 line NTSC standard.

[tubesrule]

What I've stated was not guesses or extrapolations. I am very familiar with all of RCA's television development from 1928 thru the TRK sets as I have most of the original manuals, engineer notebooks, schematics, photographs, etc., part of which I have shared with Bob. I have quoted from my original RR-359 service manual and RF alignment engineering supplement and the RR-359B engineering change log. I have provided Bob with the schematics and photographs of his set. All these documents came from the original RCA engineers, DeHaven, Holmes, Carlson, etc.

I am familiar with the specifications, performance and operation of my own RR-359A1 and RR-359B and other prototype sets. I enjoy looking through the Television series books, but there are many deliberate misdirections, like the LO being coupled through the tuning capacitor shaft on the continuous 359 tuner. I'll stick with the original engineering documents and the actual sets

Darryl