Can someone explain why on a 1955 Zenith
 

Can someone explain why on a 1955 Zenith the channel selector goes
2-4-5-7-9-11-13-3-6-8-10-12 ?? its not like you can change them to an order you would like since the channel selector knob is made like this ???
Kenny

Someone explained this once but I can't remember exactly why.
I think it has something to do with adjacent channels, in other words your area would more likely have a channel lineup in this order rather than 2-3-4-5 and so on.

Only thing I could guess is the knob has removable
numbers that got jumbled up. IIRC there is a kit on
e-bay now for UHF strips with a numbers set. Much
like for the 70's 12 & 18 channel selectors.
As far as the tuner goes if its a turret tuner you can
put the strips in any order you want.

73 Zeno:smoke:

I have read that the strange numbering on the tuner was to make for quick tuning in most areas by skipping over adjacent channels that would not be assigned in a given area. Of course, cable changed that by using adjacent channels. For example the 2,4,5,7,9,11,13 group would be perfect for the Seattle area in the 50s, while 3,6,8,10,12 would be well suited further south in Portland. Remember, 4 and 5 are not considered adjacent channels because of the 4 mHz wide aircraft locater band situated between the two channels.

jr

I had always wondered why as well! In my teens, I had a '55 Zenith console that a teacher gave to me, and it's channel selector was odd-numbered like that as well. My set was VHF only, and the channels in my area then were 2,4,7,9.

thanks for the reply as to changing the numbers on the knob well this one you cant do that the numbers are printed on the knob I posted a picture

sorry here it is

Philco did something cheaper with an 8 detent tuner using pairs that were locally tuned behind the selector by the installer for that market. PHL had 3, 6, 10 in the day (1950 or so). NY had 2, 4, 5, 7, 9, 11. I think the Philco possibles were 2, 3-4, 5, 6, 7-8, 9-10, 11-12, 13. Corrections gladly accepted. Zenith just did it with full tuning in sections.

Never seen a Philco like that, but the Motorola VT-71 did basically that...Though the numbers varied with the NUMEROUS production changes.

IIRC, Zenith did that from the very begining, with the Mayflower model. In order to adjust the fine tuning, the back had to be removed. The fine tuning was located in front of the tuner, as a spring return knob and shaft. You had to use a mirror to set the fine tuning. The Port-hole models were that way.

Back when I was about ten years old I was wondering why TV sets had empty channels: 3, 6, 8, 10 12. NYC had 2, 4, 5, 7, 9, 11, 13. Only reason I could think of was that the government (FCC) mandated it, for no other reason beyond that they could. I thought that the TV stations in NYC covered the entire country. My family never traveled. At the time my teachers in my grammar school were making us do pointless and stupid things, like memorizing poems. I figured that this would also be true in adult life...
I don't know how I would have made it thru life without knowing that Henry Hudson's ship was named the "Half Moon"... :D

My 12 inch (late 40s-early 50s) Philco has an 8 detent tuner that is marked 2, 3, 4, 5, 6 - 7, 8 - 9, 10, 12 - 13 . The 6 - 7 position makes no sense to me at all as it seems as if the gap between 6 and 7 (approx 86 mHz) would be too large to span with a simple slug adjustment. :scratch2:

Sorry 'bout the poor picture, but the dial is in poor condition.

Maybe Zenith did it for their Chicago buyers. Chicago had channels 2,5,7 and 9 and later 11. Some other locales had odd numbered channels, as stated previously.
Milwaukee had to change their first TV channel from channel 3 to 4, to avoid co-channel interference from channel 2, Green Bay and Chicago, depending on the weather.

OThis sounds to me like someone at Zenith saw a picture of a British telly and thought it would be a good idea here.

As other posters here mentioned, first choice for more populated areas was not to assign channel 3, since doing so would condemn that area to having only two stations on the lowband. Likewise, assigning channel 8, 10 or 12 would limit a market to three or fewer channels on the highband.

Note that channel 2 got assigned to cities like NYC, LA, Chicago (later), San Francisco, Detroit, Houston, Boston and Pittsburgh, while channel 3 went to places like Eufaula, OK, Escanaba, MI, and Portales, NM. (Notable exceptions are for a reason - Philadelphia was too close to NYC and Cleveland was too close to Detroit, at least after the FCC realized that tropospheric refraction over Lake Erie would case too much interference).

The Detroit area was assigned 2-4-7, with Windsor across the river eventually getting 9. Toledo got 11 and 13 because and channel adjacent to Detroit's would be too close since the Toledo stations wanted their transmitters northeast of the city because TV antennas were aimed at Detroit.

Many British sets had channel 1 next to channel 9 on the dial. A single click to go from BBC to Rediffusion was not only convenient, it took a lot of mechanical wear off of the tuner.

I've seen and worked on the sets, but never realized that channels 6 & 7 were one the same position, fully knowing that the entire FM band was located between those channels.
I can't see how the channel six strip could be tuned for channel seven. It's a possibility, that if channel seven is used, it was tuned on the channel eight strip and Philco furnished a corrected indicator disc. :scratch2:

Minneapolis/ St. Paul used channels 2, 4, 5, 9, and 11. So that system would have been convenient there.

Some places, like Princeton, NJ, were halfway between NYC and Philly, there you'd have TV stations on all the VHF channels except channel 8, IIRC. So you'd need a complete VHF dial.

The old zenith knob would still be useful since stations from either city would separated from eachother...You could search one city, turn your antenna rotor then sweep the other city.

I bet those Zeniths didn't sell well in northeastern Ohio or other areas with mixed high- and low-band TV stations; here's why. The city of Cleveland has channels 3, 5 and 8. To go from channel 3 to channel 5, for example, would mean turning the tuner knob at least one revolution, and from channel 5 to 8 would require another complete switch through most of the channels. Depending on how much the set was used and how often channels were changed, the tuner could wear out within a year.

These sets were obviously made for markets like New York, Los Angeles, Philadelphia, Seattle, Portland, Oregon and others with channel lineups that matched (or were very close to) the channel arrangement of the tuner.

New York and Los Angeles are the only two TV markets with seven VHF channels that exactly match the Zenith's channel knob. As VK member wa2ise mentioned, this tuner would work perfectly in areas between New York and Philadelphia stations, since the former would be in the 2-4-5-7-9-11-13 range and the latter in the lower 3-6-8-10-12 range. The only blank channel in the latter range would probably be channel 8, unless the set owner were in an area that could receive all New York stations; channel 8 would be in New Haven, Connecticut, near NYC if I remember correctly. Channel 12 would likely be blank in Philadelphia in 1955, depending on when the educational TV station in Wilmington, Delaware on that channel went on the air.

I've only seen one Zenith TV with a tuner arranged like this. Was this TV very popular in markets outside the ones I mentioned above? I would think not, due to the way the channels are arranged. This set may have had a great picture and all, but I would think most set owners in cities with more than three channels in a straight line, i. e. 3, 5, 8 or 2, 4, 7 (Cleveland, Detroit, Buffalo), would quickly get tired of having to flip through unused channels just to get to the local channel they wanted to watch.

You weren't going to wear out that tuner that easy. They were overbuilt and seldom, if ever needed cleaning.
In the 1956 model year, Zenith switched to an Oak or Standard Coil tuner.
The bandswitch tuner was used in the UHF equipped sets and the Standard Coil was used in the UHF strip equipped sets. There was a lot of those in Milwaukee.

The earlier Zeniths had this arraignment also, the 1949 models like the Mayflower Porthole used it, but on those the numbers are on a rotating plate inside the cabinet, not on the knob.

You can re arrange the strips inside the tuner any way you want, I wonder if they sold different knobs or indicators for different areas?

Models with the 'projection knob' (numbered transparencies that would appear lit in the knob center when in front of the dial light) allowed you to replace sections of the transparency with UHF numbers when using UHF strips, so you could probably re-order the transparency and channel strips any way you wanted on those sets....Even make them not match for April Fool's Day. :D

Here is a YouTube video of a Zenith Film that deals with UHF reception issues, but also explains Zenith philosophy regarding tuner design.

https://youtu.be/7lu5jqXaHRE

I don't understand the argument being presented here. Are some of you saying that the 1955 Zenith sets would not be able to succesfully receive directly adjacent vhf channels, unless the strips were arranged such that adjacent channels had to be separated such as the sequence 2,4,6,8,3,5,7,9 ?

Making a single-conversion tuner that could get more than say 20 dB rejection of adjacent channels was an expensive proposition. Interference 20 dB down (10% amplitude) is enough to ruin an analog picture. Overall best economy for the public was to not use adjacent channels in a given market. On UHF, the restrictions were worse. The so called "taboos" due to image frequencies required UHF stations in the same market to be spaced 6 channels apart. With digital, reception is fine if the total interference is below -15 dB, plus the digital broadcasts required lower power and could be slipped into empty channels while analog was still on the air, and then eventually packed more tightly, including even adjacent channels in the same market. Plus, tuners for digital receivers were gradually improved to provide more rejection of out-of-band signals.

Excellent, thanks for the additional detail! 😀

This is also possible within minutes in my vintage Austrian sets even though there was only one TV station back in the 50s :scratch2:
Maybe this was caused by the manufacturing process and mixing up the channels was just a side effect...

Greetings
Josef

Here is the Table of Allotments; 73.606 that the FCC used to assign television channels. This was developed to minimize interference from out of town stations, by staggering channels, and also minimize local interference by NOT assigning adjacent channels in a given city.
Note: channel 4 and 5 are not considered to be adjacent channels due to a 4 mHz wide aircraft locater band between the two channels.

http://www.ecfr.gov/cgi-bin/text-idx..._1606&rgn=div8

The funny skip channel tuning layout of the mid 50s Zenith sets makes perfect sense considering FCC channel assignments made in that era, although in hindsight, it seems weird, and likely met with some customer resistance.

jr