UHF Set-Top Converters for early UHF broadcasts
 

These are pretty rare IMO. Only saw one in person. Seems like most TVs had an integrated UHF section by the mid-50s. Too bad these will have no uses after the DTV transition. Suppose they simply aren't needed anymore, and that's the end of it.

Anyone have one?

If I still have one of those kicking around I'm not aware of it.

But I seldom remember going to any flea market--such as the ones held a few times a year in Brimfield, MA (east of Springfield) where I didn't see at least one Mallory TV-101 UHF converter waiting for a home. They were extremely popular starting in the early '50s, and were in common use until the mid '60s, just after the government mandate for all set makers to include built-in UHF provisions in '64 model sets.

As for today's outboard digital converters for older sets what I have seen look pretty grim; they don't lock in worth a bucket of warm spit, and some of them die altogether after about 6 months. They're all cheap Chinese garbage from what I can see. I ended up buying a Sony flat screen that pulls the digitals in very well. As for available converters I invite any of you to come forth with one with which you've had good experience--especially in fringe areas.

I saw many of these at secondhand stores and hamfests in the early 1980's, and used one regularly back in those days.

They actually found new popularity after the all-channel act was passed, as new UHF stations came on the air and people were stuck with VHF-only sets.

Most UHF converters had a very simple circuit. A power supply powered a 6AF4 oscillator (in later models, a transistor or tunnel diode) which, 76 or 82 MHz below the frequency of the desired station, mixed, in a germanium diode with the station's signal, converting the UHF station to channel 5 or 6.

As one might imagine, this essentially passive conversion took a LOT of UHF signal to produce a usable picture.

One good question: Is it legal to possess a UHF converter today, post-ECPA? (since it is a device designed to receive frequencies that have since been reallocated to Part 22).

Now that cell phones using narrow band FM are obsolete and no longer supported by the phone companies, that issue of violating ECPA with a UHF converter would today be moot. As the signal is now encrypted as digital bits.

I suppose you could use a UHF converter to feed a DTV set or converter box set to channel 5 or 6. I don't know how fussy an ATSC DTV receiver is, though.

we had a set-top UHF add-on tuner when I was a kid. The set was a CTC-4; the converter was (I think) a JFD.
The CTC-4 was pretty elderly when we had it (the mid-1960s); our first color TV.

I have one down in the basement, still in the box. It's a Granco. It works but sucks.

I have a high end LS LST-3410A unit (HD digital tuner with DVR and TV Guide On-Screen). I got it about 5 years ago (yeah, many folks have NO IDEA how long digital broadcasts have been around). I was receiving free over-the-air (OTA) signals about a year earlier when I tried a new HD satellite service called VOOM (the STB tuned in both OTA and satellite signals), but the service (I blame the hardware) had lots of bugs, so I gave up and went for my own tuner/DVR (works like TIVO, but all free to me :D).

Anyway, my unit has a real good tuner section, too bad everything else on it has bugs. I did my research though being in a fringe/hilly area, and discovered I needed the largest type antenna type to pull in the far away stations. This is a big problem with many folks, not knowing what antenna to get for their area. Go to antennaweb.org to find help in selecting the right antenna. I still giggle when people think they need a special digital or HD antenna, when in reality all they need is a plain old UHF antenna because all digital signals are broadcast on UHF. It can be difficult to know if your digital tuning issues are tuner or antenna related.

I will soon try a DTV Pal Plus tuner to see if it is of any improvement in signal acquisition. Too bad our government, in their infinite wisdom, only allows the $20 coupon to be used on low end (read: non-HD) tuners. I am not sure why they care what digital tuner I would get.

Unfortunately for most areas it's not this simple. The FCC allowed the broadcaster to choose channels between 2 and 51, so many are staying in, or returning to VHF. I also thought I could ditch the VHF part of my roof antenna, but in Detroit there will be VHF digital stations so I still need both :-( You can see how your area shakes out here:
http://hraunfoss.fcc.gov/edocs_publi...C-07-138A2.pdf

I have a NIB Radio Receptor converter.

http://www.antiqueradio.org/RadioReceptor.htm

It works well, although I bought it just for fun.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Very interesting, I am in the LA area, and my tuner captures all digital stations down to Ch 2, but none of the lower number channels has yet to be utilized. All of the normal VHF stations (Ch 2 - 13) have a previously assigned digital UHF channel, and this is where they transmit digital stations.

I did some research, and one website says that "most of our UHF antennas will capture high frequency VHF signals (Channels 7-13), we typically only recommend using VHF antennas to capture the low end of the VHF band (Channels 2-6)". This would explain why most of the low number channel assignments on the list in your link seem to be 7-13 (few in the Ch 2-6 range).

I am old enough to remember when the first uhf channels in our area came out. We had to have one to receive more than the one channel wrgb (ge schenectady) that was broadcasting in our area.

I have a couple in the basement, the last one I picked up was about 10 years ago, at a garage sale marked "old radio needs tube" $1.00

If you study the schematics of any television's built in UHF tuner you'll find they work in much the same way. IIRC the succeeding "IF" stage is the VHF mixer stage, with the VHF oscillator disabled and that stage tuned to the same frequency as the remaining pixIF chain.

With an outboard converter you add the benefit of the RF stage of the VHF tuner and the VHF mixer and oscillator are working as they normally do, making for an additional stage over the built in configuration, and "dual conversion" to boot.

I could be wrong about all this, as it has been a long time since I've delved into this stuff, but that's how I remember it.

The outboard converters seemed to work very well for me on pre '64 sets I've had. I suppose that there are some that are better than others. The only gripe I'd had was that there were often spurious image signals. But as long as they didn't share the same frequency with a desired station one was OK.

I probably have a dozen UHF converters, from the old Mallorys, Blonder-Tongue, etc., up to some crappy later models. I have a couple small ones that attach to the back of the set. My wife brought one home for me just a couple weeks ago, someone at work gave it to her-I forget the brand but it's cheaper, from the 50s. Come to think of it, I probably have more than a dozen! Lotta good they will do me this summer! Out of the ones I've tried the old Mallory does the best. We were at a radio meet early in this decade and were browsing the silent auction tables; Kim put a bid in on it, thinking it was a radio! Around here the first real local station came on the air in '54, on UHF, and that made for brisk sales of converters. Surprisingly I don't see many sets from the 50s with built-in UHF; guess the option cost too much for most people.

If you want to see and read a bit about the "grand daddy" of UHF converters:

http://www.myvintagetv.com/1948%20UHF%20Converter.htm

http://www.myvintagetv.com/1950%20UHF%20Converter.htm


Chuck

ChuckA, that's a great site you have there. :thmbsp: I especially liked the Philco Prototype color set and the huge 20" DuMonts.