Aurora standard converter mode 819/25i - UK Vintage Radio Repair and Restoration Discussion Forum

oldeurope · 15th Jun 2005, 2:54 pm

http://converter.home.comcast.net/User_Manual_3.9.pdf
Hi,
I noticed that the french system has a very different V- sync against
the british and the american standard.
The V puls is only one puls 0,4 x 1 line.

Reading page 10 of the manual it looks like the 819 V sync is the same
kind like the 405 V sync.

My question is: Does the aurora generate this special V- puls in 819 ?

Please excuse me for this question not depending in the british standard.
The aurora was discussed here, that's why I ask here.

Kind regards
Darius

ppppenguin · 15th Jun 2005, 3:11 pm

Why not ask Darryl directly? He designed the Aurora converter so he will know why he chose a particular sort of V sync for 819. I suspect he chose a more complex V sync to give better V lock and interlace. He also made EQ pulses switchable so that you can choose between authenticity and best interlace.

oldeurope · 15th Jun 2005, 4:58 pm

"Why not ask Darryl directly? "

Hi Jeffrey, Darryl is a forum member and some people in the forum
have an aurora. Maybe this is interesting
for them too.

That's why I asked here.

Kind regards
Darius

tubesrule · 15th Jun 2005, 11:14 pm

Hi Darius,
I've been reading with fascination your postings about re-flashing a getter on a crt, but that's another thread

On the converter, the original 819/25i, 441/25i, 405/25i and 343/30i standards did not have equalization pulses. Since this did not provide for the best possible interlacing, I included an option to add eq pulses to these standards. If you turn this option on, eq pulses will be added to the original waveform. If you turn it off, they will not be added, and each waveform will match the original spec, in the case of 819, one small broad pulse per field.
The four formats still always follow their orignal specifactions, they were just grouped together for this feature since they were the only original interlaced waveforms that did not use eq pulses.

Darryl

oldeurope · 16th Jun 2005, 8:09 am

"in the case of 819, one small broad pulse per field."

Good morning Darryl,

thanks for your answer. I am very impressed about your aurora again!

From your discription on page 10 I thaught it is like the other V- syncs.
I did not know about this special V sync and I was
very sureprised about it!
There is only one 20us V- pulse.

This makes possible to build a TV set without any H and V oscillators.
My friend Michael got one of these strange sets

Time ago, one forum member showed us a screenshot of a 819
signal he received in England on a 405 line set.
The result was two small pics on the screen.
You get the same if you switch your DVD to progressive scan and watch
it on a 15,625KHz monitor.

The interesting thing is how his 405 set syncs on this small V-puls.
I think the answer is the V- sync sep from PYE described in
"The principles of television reception- Keen".

Kind regards
Darius

oldeurope · 16th Jun 2005, 8:44 pm

Here is the french 819 standard:
(from "Philips Fernsehen 1951)

819 Zeilen 819 lines

Kind regards
Darius

tubesrule · 17th Jun 2005, 1:11 am

It's quite amazing looking at the VBI area in the 819 standard. I don't know of any other standard that used just a single broad pulse for the vertical sync. It would be interesting to see the sync seperator that was used on these sets.

Darryl

oldeurope · 17th Jun 2005, 7:51 am

Hi Darryl,

here is the schematic of Michaels Ducretet TL1468.
Please note, the deflection stages are not working without signal

.

I know this from simple monochrom display monitors

.

Look at the Sony CVM-90UM ( dual standard)
it uses the PYE circuit with D701 D702.
Because of dual standard it has oscillators.

To get all the advantages of the 819 standard you must find a
819 only telly

.

At the moment Michael runns his set provisorial with a 7BP7 crt.
(It was spare for my SSTV monitor)
And with 625/25i. The EQ pulses and the long V sync causes trouble,
they pull down the booster voltage. You can hear this

.

Kind regards
Darius

tubesrule · 17th Jun 2005, 9:45 pm

Hi Darius,
Thanks for all the information. I am surprised that the TL1468 doesn't use line or frame osc's, but only integrators! It certainly made for a simple design. I was also surprised by the minimal difference between the line and frame sync pulses that the seperator had to deal with. This is definitely one of the more cleaver systems I have seen, and I appreciate finally being able to see how the original sets worked.

Darryl

oldeurope · 23rd Jun 2005, 9:37 am

https://www.vintage-radio.net/forum/...5&page=2&pp=20

Hi,
the forum member who made this screenshot was Peter Scott!

I found it in the forum archiv! It is #36.

It seems to me that the H sync is locked but the V sync not.
Do you remember this Peter?

Kind regards
Darius

peter_scott · 23rd Jun 2005, 10:15 am

Quote:

Originally Posted by oldeurope

It seems to me that the H sync is locked but the V sync not.
Do you remember this Peter?

Hi Darius,

Given that it's about 40 years since I took the photo my memory of it is a little
vague. However looking at the image I see that the frame flyback lines are black
which makes me think that 819 must have been negative modulated. The set I used was an unmodified 405 line Ekco so it was probably not synch'ed in either line or frame. I will just have adjusted the free running rates to get the semblence of a picture.

Peter.

turret_tuner · 23rd Jun 2005, 3:57 pm

Maybe Peter Scott was unlucky not to get a locked picture on his Ekco. The Pye VT4 (a British 405-only set c1955) used to lock to 819 giving 2 narrow pictures without changing the vertical or horizontal hold controls from the 405 settings. There was a pre-set line hold trimmer capacitor on the side of the chassis whose adjustment range was so great that the line frequency could be doubled and a true 819 picture could be displayed. Pity about the horizontal resolution being spoilt by the 405 IF bandwidth. And a second TV was needed to tune into the sound because of the wider sound/vision spacing!

oldeurope · 23rd Jun 2005, 4:52 pm

Very interesting to hear this.
The PYE vertical sync sep is able to handle this short V pulse.
I expected this.

I am sure Peter's EKCO locked in horizontal but he had a H-phase shift.
The EKCO has a flywheel H sync.
The V separator did not react on the short V puls (integrator).
The picture is moving up or down slowly.

The dark lines comes from the V blanking stages in the set. It is a late 50th
EKCO like mine I think.
The modulation is definatly AM positiv like in GB.

In the 819 system you must use positiv modulation.
With negativ modulation noise generates a V -sync I think!

Maybe someone here has an aurora and can switch it to 819.
Let us see what happens on a 405 set!

Kind regards
Darius

PS: Where are Michaels screenshots from the 819 set with the 7BP7
radar "tube" ?

turret_tuner · 23rd Jun 2005, 6:02 pm

The Pye VT4 also has flywheel line sync.

15th Jun 2005, 2:54 pm	#1
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Aurora standard converter mode 819/25i http://converter.home.comcast.net/User_Manual_3.9.pdf Hi, I noticed that the french system has a very different V- sync against the british and the american standard. The V puls is only one puls 0,4 x 1 line. Reading page 10 of the manual it looks like the 819 V sync is the same kind like the 405 V sync. My question is: Does the aurora generate this special V- puls in 819 ? Please excuse me for this question not depending in the british standard. The aurora was discussed here, that's why I ask here. Kind regards Darius Last edited by Dave Moll; 4th Jun 2007 at 3:07 pm. Reason: update URL link

15th Jun 2005, 3:11 pm	#2
ppppenguin Retired Dormant Member Join Date: Dec 2003 Location: North London, UK. Posts: 6,168	Re: aurora standard converter mode 819/25i Why not ask Darryl directly? He designed the Aurora converter so he will know why he chose a particular sort of V sync for 819. I suspect he chose a more complex V sync to give better V lock and interlace. He also made EQ pulses switchable so that you can choose between authenticity and best interlace.

15th Jun 2005, 11:14 pm	#4
tubesrule Hexode Join Date: Jul 2004 Location: Michigan USA Posts: 325	Re: aurora standard converter mode 819/25i Hi Darius, I've been reading with fascination your postings about re-flashing a getter on a crt, but that's another thread On the converter, the original 819/25i, 441/25i, 405/25i and 343/30i standards did not have equalization pulses. Since this did not provide for the best possible interlacing, I included an option to add eq pulses to these standards. If you turn this option on, eq pulses will be added to the original waveform. If you turn it off, they will not be added, and each waveform will match the original spec, in the case of 819, one small broad pulse per field. The four formats still always follow their orignal specifactions, they were just grouped together for this feature since they were the only original interlaced waveforms that did not use eq pulses. Darryl

16th Jun 2005, 8:09 am	#5
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: aurora standard converter mode 819/25i "in the case of 819, one small broad pulse per field." Good morning Darryl, thanks for your answer. I am very impressed about your aurora again! From your discription on page 10 I thaught it is like the other V- syncs. I did not know about this special V sync and I was very sureprised about it! There is only one 20us V- pulse. This makes possible to build a TV set without any H and V oscillators. My friend Michael got one of these strange sets Time ago, one forum member showed us a screenshot of a 819 signal he received in England on a 405 line set. The result was two small pics on the screen. You get the same if you switch your DVD to progressive scan and watch it on a 15,625KHz monitor. The interesting thing is how his 405 set syncs on this small V-puls. I think the answer is the V- sync sep from PYE described in "The principles of television reception- Keen". Kind regards Darius Attached Thumbnails Last edited by oldeurope; 16th Jun 2005 at 8:20 am. Reason: text and picture

16th Jun 2005, 8:44 pm	#6
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: aurora standard converter mode 819/25i Here is the french 819 standard: (from "Philips Fernsehen 1951) 819 Zeilen 819 lines Kind regards Darius Attached Thumbnails

15th Jun 2005, 4:58 pm	#3
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: aurora standard converter mode 819/25i "Why not ask Darryl directly? " Hi Jeffrey, Darryl is a forum member and some people in the forum have an aurora. Maybe this is interesting for them too. That's why I asked here. Kind regards Darius

17th Jun 2005, 1:11 am	#7
tubesrule Hexode Join Date: Jul 2004 Location: Michigan USA Posts: 325	Re: aurora standard converter mode 819/25i It's quite amazing looking at the VBI area in the 819 standard. I don't know of any other standard that used just a single broad pulse for the vertical sync. It would be interesting to see the sync seperator that was used on these sets. Darryl

17th Jun 2005, 7:51 am	#8
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: aurora standard converter mode 819/25i Hi Darryl, here is the schematic of Michaels Ducretet TL1468. Please note, the deflection stages are not working without signal. I know this from simple monochrom display monitors. Look at the Sony CVM-90UM ( dual standard) it uses the PYE circuit with D701 D702. Because of dual standard it has oscillators. To get all the advantages of the 819 standard you must find a 819 only telly. At the moment Michael runns his set provisorial with a 7BP7 crt. (It was spare for my SSTV monitor) And with 625/25i. The EQ pulses and the long V sync causes trouble, they pull down the booster voltage. You can hear this. Kind regards Darius Attached Thumbnails

17th Jun 2005, 9:45 pm	#9
tubesrule Hexode Join Date: Jul 2004 Location: Michigan USA Posts: 325	Re: aurora standard converter mode 819/25i Hi Darius, Thanks for all the information. I am surprised that the TL1468 doesn't use line or frame osc's, but only integrators! It certainly made for a simple design. I was also surprised by the minimal difference between the line and frame sync pulses that the seperator had to deal with. This is definitely one of the more cleaver systems I have seen, and I appreciate finally being able to see how the original sets worked. Darryl

23rd Jun 2005, 9:37 am	#10
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: aurora standard converter mode 819/25i https://www.vintage-radio.net/forum/...5&page=2&pp=20 Hi, the forum member who made this screenshot was Peter Scott! I found it in the forum archiv! It is #36. It seems to me that the H sync is locked but the V sync not. Do you remember this Peter? Kind regards Darius

23rd Jun 2005, 3:57 pm	#12
turret_tuner Retired Dormant Member Join Date: Jul 2003 Location: S. W. Midlands, UK. Posts: 36	Re: aurora standard converter mode 819/25i Maybe Peter Scott was unlucky not to get a locked picture on his Ekco. The Pye VT4 (a British 405-only set c1955) used to lock to 819 giving 2 narrow pictures without changing the vertical or horizontal hold controls from the 405 settings. There was a pre-set line hold trimmer capacitor on the side of the chassis whose adjustment range was so great that the line frequency could be doubled and a true 819 picture could be displayed. Pity about the horizontal resolution being spoilt by the 405 IF bandwidth. And a second TV was needed to tune into the sound because of the wider sound/vision spacing!

23rd Jun 2005, 4:52 pm	#13
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: aurora standard converter mode 819/25i Very interesting to hear this. The PYE vertical sync sep is able to handle this short V pulse. I expected this. I am sure Peter's EKCO locked in horizontal but he had a H-phase shift. The EKCO has a flywheel H sync. The V separator did not react on the short V puls (integrator). The picture is moving up or down slowly. The dark lines comes from the V blanking stages in the set. It is a late 50th EKCO like mine I think. The modulation is definatly AM positiv like in GB. In the 819 system you must use positiv modulation. With negativ modulation noise generates a V -sync I think! Maybe someone here has an aurora and can switch it to 819. Let us see what happens on a 405 set! Kind regards Darius PS: Where are Michaels screenshots from the 819 set with the 7BP7 radar "tube" ?

23rd Jun 2005, 6:02 pm	#14
turret_tuner Retired Dormant Member Join Date: Jul 2003 Location: S. W. Midlands, UK. Posts: 36	Re: aurora standard converter mode 819/25i The Pye VT4 also has flywheel line sync.