RCA TRK-5

[Panrock]

Like many others I expect, I have entered the ETF Sweepstake in the hope of winning an example of this pre-war American receiver. No, don't let's consider the cost of shipping it over here! 

The grandiose styling is very much to my taste. The contrast between having a massive 12-inch loudspeaker and a 5-inch screen is rather fun. Restoring this behemoth would be a suitable way to keep me occupied.

Being from 1939, it would probably have been a 441-line set. I believe the 525-line standard had FM sound from the start... but what about the 441-line standard?

Steve

[Mike Watterson]

Wikipedia says AM sound and public from 1938 to 1941.
https://en.wikipedia.org/wiki/441-line_t...ion_system

FM Audio was quite new. USA FM was touted as hi-fi, hence no 1950s valve portable sets like in Europe.

FM Audio changed band after WWII in USA
TV ran during the war but TV production stopped in 1941 when USA entered the war. After the war they changed to 525 lines as goal was to be equivalent quality to 16mm film and 441 lines wasn't, though the adoption of the 525 line system was in 1941, I believe the 441 line transmissions continued till 1945 or 1946.

[peter scott]

Yes, I think it was AM.
https://www.earlytelevision.org/pdf/comm..._11-37.pdf

Peter

[Panrock]

Thanks, both.

From Peter's document, this used negative vision modulation... and it seems there were Band III allocations planned as early as 1937! Though of course the band wasn't called that at the time.

I believe the French 441-line standard, also used by Nazi Germany in Paris, used positive modulation with AM sound. Please feel free to correct me.

Someone sent me the Owner's Manual. I shall now try to attach it.

Steve

[Geordie McBoyne]

The video channel bandwidth was fine for 441 lines but a bit narrow for 525. The active video part is about the same as the 625 line systems in use in Europe. I believe the active video is 50microseconds or so. So the 525 pictures have better vertical definition but the trade off was a loss of horizontal definition. 441 had negative video modulation, equalising pulses and AM sound. I guess the frame blanking period robbed the 441 line system of a good number of lines.
Possible to realign the sound IF response to operate as an FM slope demodulator?
The 441 line TV service from the Paris Eiffel Tower transmitter had positive video modulation, AM sound and no equalising pulses. Eight broad frame pulses just like our 405 line system.
The number of active lines was 385, the same as 405.

Geordie McBoyne.