Six 1940 Philco tv's giveaway

[tubesrule]

Originally Posted by decojoe67

It was not so much about the operation of the sets being a problem, but their reception. I've definitely read of annoying interference problems that pioneer TV watchers dealt with in the day that were eliminated in the post-war years. The general performance of pre-war sets was adequate, but with huge leaps made in electronics due to the war-effort, many bugs were worked out and advances made for post-war TV's. It is definitely noted that the 1946 RCA 630TS is a superior set compared to the 1939 TRK-12. Between the circuity improvements and the timing being right for the public to accept the new technology, TV in the USA was basically re-introduced in the post-war years.

The only interference problems due to the design of the reciever I am aware of is from an anecdotal tale of the local oscillators in nearby sets interfering with each other. Other external interference sources would have been the same before and after the war. (ICE ignitions, diathermy, brushed motors, etc.) This in no way inferrers a lack of understanding on the part of the pre-war engineers or a limitation of the technology available to them. Most pre-war receivers lack an RF amp in front of the tuner, just like many post-war sets, as this was deemed unnecessary given most sets would be sold and used in a major metropolitan area.

There were really no technologies developed during the war that advanced the basic operation or performance of the receivers immediately post-war. The advances came in the form of miniaturization and cost reductions. While a 630TS is probably the pinnacle of immediate post-war design, it contains no technology that was not known, or could have been built pre-war for the right amount of money. Mass production and building to a certain price/performance target is what drove the technology. For instance, having a flyback power supply while technologically advanced and known before the war, provides no tangible operational advantage to the user over a mains derived supply. It does provide a cost and size advantage.

All this is to say a pre-war receiver like the TRK12, while not as technically advanced as a 630TS, will perform as good or better than many immediate post-war sets from the users point of view. Take for instance the ubiquitous VT71. These represent probably the most common design of post-war sets and their performance pales to many pre-war sets.

[Eric H]

One of the San Fransisco winners was Gilson Willets, probably this guy:

http://www.joshuablubuhs.com/blog/gi...s-as-a-fortean

And some more info here, apparently the winners who weren't in range of a TV station could take a Philco Radio instead.

http://onetuberadio.com/2015/01/27/t...uite-so-lucky/

[dtvmcdonald]

As late as the 9T-246 sets lacked RF amps and good image rejection ... and
even good rejection of low band signals when tuned to the high band ...
or vice versa.

The RF design of the TRK-12, while generating absolutely beautiful
frequency sweeps, is an ABYSMAL design that the engineers
MUST have known had coils and wire that were FAR too big.

When the band changes happened, they had to rewind the coils,
and it wasn't pretty. My set was never sold, being apparently used
as a test bed for changes by the RCA engineers, and it has
rather klunky looking change places. Maybe they though that bigger coils would have better Q.

And oh yes ... the fine tuning barely has enough range to tune the FM
signal acorss the split carrier IF discriminator over 200 kHZ!
Yet the final response at the video detector output is identical
to that of a properly tuned CT-100.

[Electronic M]

Originally Posted by tubesrule

The only interference problems due to the design of the reciever I am aware of is from an anecdotal tale of the local oscillators in nearby sets interfering with each other. Other external interference sources would have been the same before and after the war. (ICE ignitions, diathermy, brushed motors, etc.) This in no way inferrers a lack of understanding on the part of the pre-war engineers or a limitation of the technology available to them. Most pre-war receivers lack an RF amp in front of the tuner, just like many post-war sets, as this was deemed unnecessary given most sets would be sold and used in a major metropolitan area.

There were really no technologies developed during the war that advanced the basic operation or performance of the receivers immediately post-war. The advances came in the form of miniaturization and cost reductions. While a 630TS is probably the pinnacle of immediate post-war design, it contains no technology that was not known, or could have been built pre-war for the right amount of money. Mass production and building to a certain price/performance target is what drove the technology. For instance, having a flyback power supply while technologically advanced and known before the war, provides no tangible operational advantage to the user over a mains derived supply. It does provide a cost and size advantage.

All this is to say a pre-war receiver like the TRK12, while not as technically advanced as a 630TS, will perform as good or better than many immediate post-war sets from the users point of view. Take for instance the ubiquitous VT71. These represent probably the most common design of post-war sets and their performance pales to many pre-war sets.

I disagree with your point. One example I can give is intercarrier audio IF. It was a WWII invention that reduced the tube count greatly, and stabilized relative fine tuning of sound and picture...So they would drift together and in the same direction as the set warmed up.

[decojoe67]

Originally Posted by Electronic M

I disagree with your point. One example I can give is intercarrier audio IF. It was a WWII invention that reduced the tube count greatly, and stabilized relative fine tuning of sound and picture...So they would drift together and in the same direction as the set warmed up.

I would like to add further from an article by Jack Davis in A.R.C. Here is an excerpt:
".....the 630TS was the first set to use a 13 channel turret tuner. The video IF's were stagger tuned to give a video bandwith of 4 MC and the horizontal sync was automatic frequency controlled allowing the set to lock-in on a signal as weak as 50 microvolts, thus expanding reception to so-called "fringe" areas. The 10BP4 picture tube, designed for the 630TS, operated with an anode voltage of 9,000 volts, developed through the now familiar fly-back method, doing away with the lethal 60 cycle power supplies that were used in the pre-war sets. The high definition picture that was produced was about sixty foot lamberts, almost ten times brighter than the TRK's. In addition, the area contrast of a maximum of 90 to 1 was the best ever. The set was simple to operate because of the drift-free circuitry...."
Also from Ray Bintliff, from an article about the 630TS in A.R.C.:
"....it is apparent that the 630TS was vastly superior to the TRK-12. It's picture size was slightly smaller, by about roughly one inch in width and height, but it produced better quality pictures and sound...."
I may also add of the addition of the ion-trap on the 630TS to prevent ion burn that plagued the pre-war CRT.
Joe

[Sandy G]

Yeah, winning a pre-war TV did not do the recipient any favors. Unless you lived in one of the handful of cities that had a transmitter, & hopefully had a neighbor who was a ham or something, you had a ginormous box that gave you a nice picture of-Snow, and/or interference..

[Eric H]

Originally Posted by Sandy G

Yeah, winning a pre-war TV did not do the recipient any favors. Unless you lived in one of the handful of cities that had a transmitter, & hopefully had a neighbor who was a ham or something, you had a ginormous box that gave you a nice picture of-Snow, and/or interference..

That depends, if they kept it long enough, their Grand kids could sell it and buy a decent Car with the proceeds.

[David Roper]

Intercarrier sound has definite advantages as well as arguable disadvantages, but it didn't affect a set's tube count. Period.

[tubesrule]

Originally Posted by decojoe67

I would like to add further from an article by Jack Davis in A.R.C. Here is an excerpt:
".....the 630TS was the first set to use a 13 channel turret tuner. The video IF's were stagger tuned to give a video bandwith of 4 MC and the horizontal sync was automatic frequency controlled allowing the set to lock-in on a signal as weak as 50 microvolts, thus expanding reception to so-called "fringe" areas. The 10BP4 picture tube, designed for the 630TS, operated with an anode voltage of 9,000 volts, developed through the now familiar fly-back method, doing away with the lethal 60 cycle power supplies that were used in the pre-war sets. The high definition picture that was produced was about sixty foot lamberts, almost ten times brighter than the TRK's. In addition, the area contrast of a maximum of 90 to 1 was the best ever. The set was simple to operate because of the drift-free circuitry...."
Also from Ray Bintliff, from an article about the 630TS in A.R.C.:
"....it is apparent that the 630TS was vastly superior to the TRK-12. It's picture size was slightly smaller, by about roughly one inch in width and height, but it produced better quality pictures and sound...."
I may also add of the addition of the ion-trap on the 630TS to prevent ion burn that plagued the pre-war CRT.
Joe

Joe,
The 630TS was a well designed chassis. I have not argued that point. My original post was in response to your assertion that pre-war receivers suffered from interference and poor designs that were improved by technological advances during the war. I have yet to see anything to support this assertion. Flybacks, ion traps, staggered IF's... had nothing to do with technologies developed during the war and were all known before the war. The RR359 used staggered IF's, the pre-war Philco's used ion traps, the Telefunken E1 used a flyback... The 630TS is simply the culmination of value engineering to create a smaller, well performing receiver. While many innovations certainly were in the works and came over the following years, my point was the technology advances of the war did not result in immediate advances to the underlying design of receivers.

While I never had the pleasure to meet Mr Davis, I believe the excerpt you posted is simply his opinion and not in any way a technical evaluation of the two sets. My 630TS has sat next to my TRK12 for 15 years, and in my subjective opinion, they both produce images of excellent quality (being fed directly from a modulator), are equally easy to operate, and neither one requires any readjustments do to drift. The TRK12 has a strong, original crt and is nearly as bright as the 630TS. There is simply no technical reason the 10BP4 at 9KV would be 10 times brighter than the 12AP4 at 7KV.
In my engineering opinion, while there are certainly parts of the design that make the 630TS superior to the TRK12, the TRK12 is not inferior due to a lack of knowledge by the pre-war engineers, or by the "advances" made during the war.

Intercarrier sound was developed post-war and is one of those technological advances that is double edged as David pointed out. From an engineering standpoint, it's great as it simplifies the design (cost) and offers better drift performance (tangible benefit to the user), but can cause problems of it's own.

The original topic I was replying to was technologic advances created directly or indirectly by advances during the war, yet no instances of such advances have been presented.

Darryl

[tubesrule]

Originally Posted by dtvmcdonald

The RF design of the TRK-12, while generating absolutely beautiful
frequency sweeps, is an ABYSMAL design that the engineers
MUST have known had coils and wire that were FAR too big.

When the band changes happened, they had to rewind the coils,
and it wasn't pretty. My set was never sold, being apparently used
as a test bed for changes by the RCA engineers, and it has
rather klunky looking change places. Maybe they though that bigger coils would have better Q.

And oh yes ... the fine tuning barely has enough range to tune the FM
signal acorss the split carrier IF discriminator over 200 kHZ!
Yet the final response at the video detector output is identical
to that of a properly tuned CT-100.

Doug,
Just to clarify, I believe you are referring to the oscillator coils in the tuner and not the IF's. I don't want people thinking RCA rewound IF's or anything else.

The changes that created that "mess" in the tuner LO section cannot fully be blamed on the engineers or on the original design of the set. The sets were designed for the original channel assignments and if you look at a set that has not been modified, they are clean and sweep extremely well. When presented with the change, the engineers did the best they could. The fact that the channel order had to be swapped from low to high to high to low (requiring those black channel labels) could not have been easy for the engineers, but was a clever solution. I have been faced with similar challenges many times during my career and you don't always end up with a solution you are fully happy with, or proud of, but such is engineering. You rarely get everything you want and make the best of what you have.

The narrow fine tuning of the RCA pre-war sets compared to every other manufacturer also puzzled me at first, but I have to give credit to the RCA engineers that their sets, when fed with a proper AM audio signal, never need trimming by the user. Their LO stage is just that stable. The other manufacturers, mainly GE and Dumont, do require the fine tuning to be touched up periodically by the user, which may explain why they are so wide on these sets.

Darryl

[dtvmcdonald]

I am referring to the coils, both oscillator and signal, in the tuner.

Yes, they really are that stable. Considering the stiffness, its not
surprising. I would not dare try to reset mine to all current channels.
On my TRK-12 only 3 and 4 match current channels. 2, 5, and 6 exist but are
neither 1939 nor postwar channel frequencies. All sweep quite well,
and all work perfectly if fed the proper signal (made by downconverting
a signal on a cable-only channel 34-40 MHz higher). But getting them
all to tune EXACTLY right was a chore ... I had to add a piece of
copper strip to one of the "loop" inductors. (There was a sticker with the
frequencies.) I put the 1939 channel
labels on when the set was being refinished.

The TT-5 was spot on as I got it.

To say it once again, the IF strips are marvels of good design and stability!
NOT CHEAP!

I would dispute anyone who says a 630 has a better picture than my TRK12,
at least with a good signal. Modern solid state B&W monitors, with some sort
of table-lookup gamma correction are the only way to get better.

[init4fun]

Originally Posted by Electronic M

I disagree with your point. One example I can give is intercarrier audio IF. It was a WWII invention that reduced the tube count greatly, and stabilized relative fine tuning of sound and picture...So they would drift together and in the same direction as the set warmed up.

Originally Posted by David Roper

Intercarrier sound has definite advantages as well as arguable disadvantages, but it didn't affect a set's tube count. Period.

David , I'm curious as to why you think eliminating the sound IF strip and running the sound through the video IFs didn't reduce tube count ?

[Electronic M]

Originally Posted by init4fun

David , I'm curious as to why you think eliminating the sound IF strip and running the sound through the video IFs didn't reduce tube count ?

By all rights it should reduce tube count. The average split sound set had 4 video IF tubes and ~4 audio IF tubes for a total of 8. Contrast that with an intercarrier sound set that had 4 video IF tubes (that doubled as sound IF amps) and one 'sound IF' tube, for a total of 5. That is three tubes saved...Nearly a %10 reduction in a ~40 tube TV.

Perhaps David was in need of coffee, or feeling contrarian when he posted...

[tubesrule]

Originally Posted by Electronic M

I disagree with your point. One example I can give is intercarrier audio IF. It was a WWII invention that reduced the tube count greatly, and stabilized relative fine tuning of sound and picture...So they would drift together and in the same direction as the set warmed up.

Tom,
You got me curious about the development of intercarrier sound. I haven't been able to find a definitive source of the early history of it's developments, but did come across this well researched thread:
http://www.forum.radios-tv.co.uk/vie...php?f=5&t=3824

From this source it would appear to be a post-war development. I also found several patents dating from 1950. Does anyone else have a source for the history of intercarrier sound?

Darryl

[Electronic M]

Originally Posted by tubesrule

Tom,
You got me curious about the development of intercarrier sound. I haven't been able to find a definitive source of the early history of it's developments, but did come across this well researched thread:
http://www.forum.radios-tv.co.uk/vie...php?f=5&t=3824

From this source it would appear to be a post-war development. I also found several patents dating from 1950. Does anyone else have a source for the history of intercarrier sound?

Darryl

I'm by no means an expert, but I seem to recall reading probably on the ETF website or in a 50's publication that the experimental TV guided bombs of WWII were the first use of intercarrier sound...I'm fairly attached to the notion that it was a WWII military development.