I've always been curious as to why most UHF tuners prior to the 70's or so were the continuous-tuning radio-type (which were notoriously difficult to fine-tune and "lock-in" a signal) as opposed to the traditional VHF tuners, which were detent (click on each individual channel) from early on. Was it a manufacturing thing; e.g., were they not able to manufacture small enough parts to make a mechanical detent tuner to cover 70 channels back in the day? Or was it some combination of economics (the radio-type tuners were perhaps cheaper to make) and/or the short shrift given UHF for so long?
-
Get involved.
We want your input!
Apply for Membership and join the conversations about everything related to broadcasting.
After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
If you use a disposable or false email address, your registration will be rejected.
After your membership is approved, please take a minute to tell us a little bit about yourself.
https://www.radiodiscussions.com/forums/introduce-yourself.1088/
Thanks in advance and have fun!
RadioDiscussions Administrators
Old UHF Tuners: Continuous vs. Detent
- Thread starter Stanislav
- Start date
Economics was the major reason, untill the FCC mandated UHF tuners there was little demand for them. (That is in markets with VHF stations, in all UHF markets TV sets with UHF sold just as well as VHF only sets)
The problem was without the "click" it was necessary to keep the UHF stations in the same market six channels from each other.
Like in Chicago
20, 26, 32, 38, 44, 50...
With "clickable tuners" you could have the spacing closer
It was one of those if the demand was there we'd make it. But without the improvement in technology there'd be no demand.
Even on VHF tuners which did "click" the mechanism was clumsy and that is why you had a "fine tuner" that went around the VHF dial so you could "fine tune" the VHF dial to get the frequency
You have to think of it like a radio, most radios on cheap sets you have to move the dial. On the better ones you can tune them directly or hit a button to move from one frequency to the next
It wasn't till the 70s when the FCC mandated TV sets have UHF tuners just as easy to tune as VHF.
The problem was without the "click" it was necessary to keep the UHF stations in the same market six channels from each other.
Like in Chicago
20, 26, 32, 38, 44, 50...
With "clickable tuners" you could have the spacing closer
It was one of those if the demand was there we'd make it. But without the improvement in technology there'd be no demand.
Even on VHF tuners which did "click" the mechanism was clumsy and that is why you had a "fine tuner" that went around the VHF dial so you could "fine tune" the VHF dial to get the frequency
You have to think of it like a radio, most radios on cheap sets you have to move the dial. On the better ones you can tune them directly or hit a button to move from one frequency to the next
It wasn't till the 70s when the FCC mandated TV sets have UHF tuners just as easy to tune as VHF.
on some of the old RCA televisons from the late sixties had only one knob on the set. The center of the knob was to tune the VHF channels, while the the outside sleeve on the knob was the fine tuning for the for the VHF. To tune to UHF you would tune to "U" and use outer sleeve knob to change uhf stations. I'm glad they eventually went to seperate knobs because those old tuners had a bad habit of getting stuck between channels and you had to call the TV man to fix it. Besides, the single knob type tuners always confused the old people. They never could figure out how to get UHF. My grandmother only watched channel 3 and 12 and sometimes 16 if nobody had changed the UHF channel, she would panic if someone changed it. Luckily Lawrence Welk was on 12. On some tuners you had to push the channel knob in and turn to fine tune.
Interesting topic--first off the old spacing of UHF channels 6 apart that Mark spoke of had nothing to do with click vs. continuous tuners. The FCC used to allocate UHF channels according to what they called "UHF Taboos." Certain spacing of UHF channels resulted in interferrence between the channels---a spacing of 7 channels was never allowed as it would cause interferrence and I think there were other spacing which wouldn't work, so out of convienence spacing in many cities were every 6, but sometimes it was 10---for example, in Columbia SC the early UHF's was 19, 25, and 35, but in nearby Sumter there was a channel 27, which came in perfectly fine on a continuous tune UHF, with no interferrence from 25. I'm reminded of my elderly neighbor back in the early 70s. We lived about 40 miles out from Columbia and she just loved the sole VHF, channel 10, and watched it all the time on her late 60s RCA set, which had a continuous tune UHF dial under the VHF dial. Every once in while she would want to watch something on CBS or ABC, so she would call me to come over and tune it in for her. She NEVER COULD understand that the VHF dial had to be tuned to "VHF" in order to tune to 19 or 25. She got very good reception on 19 and 25 (she had a good outside UHF antenna), but as far as she was concerned, those two channels were only for special occasions. Yes, life was rough for UHF stations in those days--even though the first stations in Columbia in 1953 were UHF, channel 10 came along later. I remember once, about 1980, channel 10 had a serious transmitter problem and was off the air for 4 days--meanwhile 19 and 25 continued to broadcast as usual. When the Arbitron ratings came out for those 4 days, channel 10 continued to be the highest rated station--event though they were completely off the air! Unbelievable!
fortmill said:
Yes but once clickable tuners came in the spacing issues went out the window. This was a combination of a lot of things, including better UHF transmitters which didn't bleed over. You're right about the "magic 7" as they called it, the UHF would interfer on each other.
Everything I've ever read has indicated the six or more spaces was due to the non-clickable tuners and that would cause the bleed-ins.
As people have noted it could be more or less depending on things like exact transmitter location. I have heard that is one of the reasons why WPWR-TV changed from 60 -> 56 -> 50 as even in the 80s the transmitters on the Sears and John Hancock towers wouldn't allow channel 56 there do to spacing.
Mark said:
The FCC mandated that UHF tuners "click" in the early seventies, but they didn't change the six channel spacing requirement until the start of the digital transition -- ten years ago. Considering the 25 years separating these two occurrences, it doesn't seem that the spacing issues "went out the window" when clickable UHF tuners came along.
And, really, the spacing requirements aren't impacted by whether a tuner "clicks" or not. The real determing factors are things like a tuner's IF frequency (which is the reason for the seven channel spearation prohibition) and the quality/bandwidth of the IF filters in the tuner.
Mark said:
Looking at those numbers reminded me old Sears Silvertone televisions had those channel numbers on its UHF dials. Sears of course is based....well you know that by now.
I grew up in a UHF market, Lexington, KY. A good UHF tuner was everything along with multiple outdoor antennas. The TV stations were in three direction and later four in 1986. Until 1980 the ABC affiliate was on Channel 62 and many UHF tuners had issues. KET/PBS affiliate suffered the most since it was rare to see an outdoor antenna pointed towards that location.
- Status