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Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions.

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Old 30th Apr 2005, 12:08 pm   #1
oldeurope
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Smile making of the London Birmingham modulator

Hi,
I want to show how this thing growes.
If you are interested, it will be continued.

Kind regards
Darius
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Old 1st May 2005, 12:02 am   #2
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Default Re: making of the London Birmingham modulator

Always interested in your projects Darius! It is so good to see original projects built to a very high standard.


Excellent work!!


Rich.
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Old 1st May 2005, 9:57 am   #3
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Default Re: making of the London Birmingham modulator

Quote:
Originally Posted by Richard_Newman
Always interested in your projects Darius! It is so good to see original projects built to a very high standard.


Excellent work!!


Rich.
Couldn't agree more! Keep us informed of your progresss...
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Old 2nd May 2005, 7:55 am   #4
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Wink Re: making of the London Birmingham modulator

Good morning

Hi Rich and Nickthedentist thanks for your interest.

I finished the modulator stages and the sound stage.
The 47K and the 0,47uF will be placed later.

Next thing is the vision stage. I want to test a new much easyer
stage with a MOS-FET that clamps the sync tips to the zero line.
I made this successfully in the MKII+III standard converter.

If the sync tips are on the zero line,
the only part you need is a pnp emitter follower to drive the modulator
transistor. No special biasing and agliment!

Kind regards
Darius
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Old 3rd May 2005, 3:28 pm   #5
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Thumbs up Re: making of the London Birmingham modulator

Hi,
I made the vision stage with the "clamp to zero" MOS-FET.
Please tell me what you think about it.

Kind regards
Darius
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Old 3rd May 2005, 8:22 pm   #6
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Exclamation Re: making of the London Birmingham modulator

Good evening, sorry I forgot to draw a BAT43 Schottky diode at Q3.
Maybe you noticed the fast rising edges at the output of Q3
and that the synctips do not reach the 5V rail.
This is caused by the BAT43. It is a "speed up" diode.
The sync seperator is very quick acting to make sure that the
BSN10 pulls down the sync tips in the right moment.

Kind regards
Darius
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Old 7th May 2005, 9:45 am   #7
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Default Re: making of the London Birmingham modulator

Hi,

I am very happy with the new vision stages of the London Birmingham
modulator.

Every carrier London sound London vision and Birmingham sound
Birmingham vision can be switched on and off.

The sound stage is finished and the channel filters are mounted.

Kind regards
Darius
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Old 7th May 2005, 9:49 am   #8
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Default Re: making of the London Birmingham modulator

Amazing, in every respect!
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Old 7th May 2005, 12:14 pm   #9
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Thumbs up Re: making of the London Birmingham modulator

Hi Nickthedentist,
I have just tested the "London/Birmingham at the same time" modulator.
Clear picture no noise I am very satisfied.
I have a clean signal from both channels on the spectrum analyzer.

Kind regards
Darius
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Old 7th May 2005, 12:22 pm   #10
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Default Re: making of the London Birmingham modulator

Clever stuff, Darius, I've never seen this done before.

I don't have any vintage TVs myself (just radios), but I can see that this kind of set-up would be very useful indeed for someone who does.

Nick.
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Old 7th May 2005, 8:21 pm   #11
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Default Re: making of the London Birmingham modulator

Once again Darius you have demonstrated a work of genius!! This sort of construction is of a very professional standard and I have only seen similar work by amateur radio designers who build VHF and UHF transmitting equipment. It is so professional it is almost suggesting to me that I should start collecting 405 TV's just so that I can use this modulator!


Excellent work and very well done
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Old 7th May 2005, 8:30 pm   #12
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Default Re: making of the London Birmingham modulator

Quote:
Originally Posted by Richard_Newman
This sort of construction is of a very professional standard and I have only seen similar work by amateur radio designers who build VHF and UHF transmitting equipment.
Yes, the layout and build of Darius' projects is certainly the best I've seen
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Old 8th May 2005, 10:20 am   #13
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Thumbs up Re: making of the London Birmingham modulator

"I have only seen similar work by amateur radio designers who build VHF and UHF transmitting equipment."

Yes, You are right! I am a radio amateur DD3ET and I have home made
VHF/UHF transmitting and receiving equipment.

In the next pics you can see the making of the filters for the London and
the Birmingham channel.

I made them last year. Before I mounted the filters, I painted them red.

Darius
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Last edited by oldeurope; 8th May 2005 at 10:22 am. Reason: Text
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Old 8th May 2005, 10:34 am   #14
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Default Re: making of the London Birmingham modulator

Quote:
Originally Posted by Darius
Before I mounted the filters, I painted them red.

Darius
That's a shame, I liked the fruity theme. Only joking...
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Old 8th May 2005, 10:38 am   #15
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Wink Re: making of the London Birmingham modulator

In the next pictures you can see some screenshots from my spectrum
analyzer HM 5011. It has a tracking generator that makes it possible to sweep
the filters. Please not that the y- axis is calibrated in decibells, not linear!!!
The filters are 75 Ohms and I made special adapters to adapt them to
the 50 Ohms in and output terminals of the analyzer.

I hope the labbles on the case are in correct Oxford english.

Kind regards
Darius
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Old 8th May 2005, 10:58 am   #16
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Default Re: making of the London Birmingham modulator

Quote:
Originally Posted by Darius
I hope the labbles on the case are in correct Oxford english.
Yes, the labels are correct in every respect
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Old 8th May 2005, 11:45 am   #17
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Default Re: making of the London Birmingham modulator

Thanks to Nickthedentist,
I got a book from Peter Scott " The principles of television reception- Keen".
It has a table of equivalent british and american terms.
Very interesting to see that the terms are very different.
For 405 I want to have british labels, of course.

Kind regards
Darius
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Old 8th May 2005, 1:06 pm   #18
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Default Re: making of the London Birmingham modulator

Hi Darius,

Just to be nit picking, or is that Nick picking, Nick missed the word
"center" when telling you that you had correct Oxford English. (OK, it
wasn't on the case. I'm just being a pedant.)

Center would go down well in the US but back in the old world we
spell it centre.

Peter.
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Old 13th May 2005, 2:54 pm   #19
oldeurope
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Smile Re: making of the London Birmingham modulator

https://www.vintage-radio.net/forum/...ead.php?t=1875

http://www.your-normwandler-page.de.vu/

Hello,
the London Birmingham modulator is (nearly) finished now.

The schematics of the sound and the oscillators and mixers are
the same as used in my first converter.

In the following pics you can see the schematic of the power supply
and the RF output.

Kind regards
Darius
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Last edited by oldeurope; 13th May 2005 at 2:59 pm. Reason: link
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Old 14th May 2005, 11:46 am   #20
oldeurope
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Question Re: making of the London Birmingham modulator

Good morning,

I hope there will be a discussion about this technologie and
the schematic here in the forum.

Every 405 line TV will work with this modulator, because it makes
a signal on the London and Birmingham channel at the same time.

So if you have a collection of TV's this is definatly the ultimate
solution, I think.

What do you think?

Kind regards
Darius
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