making of the London Birmingham modulator - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

brianc · 17th May 2005, 11:37 am

Hi Darius

The modulator looks great! I have been attempting to build one using your methods but with copper-clad laminate instead of tinplate - it is not as easy as it looks! Perhaps I need much more practise.

One question though: What does the 8.2V zenner in the sync-sep collector do? The supply voltage is only 5V so how does the diode ever "zenner" or am I missing something?

Cheers

Brian

oldeurope · 17th May 2005, 1:33 pm

Hi Brian,
the 8V2 is a protection against ESD for the gate-source oxyde of the
BSN10. This MOS-FET is a very sensitive thing be very carefull with the
gate!!!

Kind regards
Darius

brianc · 17th May 2005, 3:46 pm

Hi Darius

Thanks for the advice! I will be very careful.

Brian

oldeurope · 17th May 2005, 7:23 pm

"with copper-clad laminate instead of tinplate - it is not as easy as it looks! Perhaps I need much more practise."

I think Peter Scott made it this way.

Kind regards
Darius

oldeurope · 3rd Jul 2005, 9:24 am

https://www.vintage-radio.net/forum/...ead.php?t=3723

Good morning

In the pics you can see how the "sound modulation > 100%" detect
stage is build in.

I want to point out that both channels can be switched on without
any inteference.

Kind regards
Darius

oldeurope · 4th Jul 2005, 3:58 pm

Hi,
I just got the summer Bulletin. Jeffrey Borinsky's article about the aurora
is very interesitng. Please look at page 34:

"Some minor problems

DC offset
This is... This has now be changed to a simple DC coupled output
leaving sync tips at 0V and black level at +300mV."

This is exactly what we need to drive Q5.

So if you use the aurora, the modulator schematic is much easyer.

Kind regards
Darius

oldeurope · 18th Sep 2005, 11:31 am

Hi, sorry
I forgot an importand resistor in the sync separator Q3.
A 220K Ohms goes from its base to ground.

Here is the completed schematic:

Kind regards
Darius

Sean Williams · 19th Sep 2005, 10:11 pm

Hi All,

Well, Seeing as Darius has posted such excellent diagrams and pictures, I thought I would knock one up for a laugh!!

Addictive this television lark!

Still a fair amount to do - the Video amps need buliding, as do the filters - the oscillators are not clean enough to use without them, still, so far my congrats to Darius for an easily repeatable design!!

Sean

oldeurope · 20th Sep 2005, 9:42 am

Hi Sean, looks good, I like what you are doing there.

Please let us see your progress here.

Kind regards
Darius

Sean Williams · 20th Sep 2005, 3:49 pm

Hi Darius,

A simple question really - Do you use the same sound and vision amp for both London and Birmingham, or do you have two of each, and split the input signal??

Thanks
Sean

oldeurope · 20th Sep 2005, 5:40 pm

"Do you use the same sound and vision amp for both London and Birmingham"

Good evening,
yes of course.

Please look at the schematic in thrad 27 for vision and
thrad 25 for sound.

Kind regards
Darius

DoctorWho · 24th Sep 2005, 3:53 pm

I'd love one of these modulators when they are available Darius. I use an extremely old (1980's) modulator which, whilst it works incredibly well, causes interference on UHF and only covers Channel 1. I'd love one of your modulators as I have not been able to have a Channel 4 signal before now. Any idea when they will be available?

All the best,

Peter.

oldeurope · 24th Sep 2005, 5:10 pm

https://www.vintage-radio.net/forum/...ead.php?t=3045

At the moment I have not enough time to build them for sale.
It takes several hours to build one and making it to earn some money
would make it too expensive.

The one I have is still available for swap.

Kind regards
Darius

DoctorWho · 24th Sep 2005, 6:31 pm

Well I'd love it Darius, but sadly I don't have anything suitable to offer you as a swap, unless there is anything else you may be looking for to add to your collection? Alternatively would you sell it?

Peter.

Sean Williams · 24th Sep 2005, 9:06 pm

Hi Peter,

Why not have a go at making one - the parts are fairly common, and the design is quite easy to build - just follow the photographs thatr Darius has kindly posted...

Im sure we can help you get one working.

Cheers
Sean

oldeurope · 25th Sep 2005, 10:04 am

Yes, I agree with Sean.
This is why I made this thrad. Thanks to Paul Stenning for making
this possible.

I am sure there are "ham's" in your neighbourhood who can help
you with the agliement.

Kind regards
Darius

DoctorWho · 26th Sep 2005, 8:23 am

Unfortunately it's rather beyond my abilities, I don't have the experience to tackle something like this. I have been hoping for some time that someone would be able to make a modulator available for Channels 1 & 4. Maybe a little later that may be possible?

Thanks again for the reply.

Sean Williams · 30th Sep 2005, 10:06 am

Hi Doctor Who,

I could build the RF and modulator stages for you - you could then fit it into a case and build the power supply, assuming there are no objections from Darius (it is his design after all).

What do you think?

Cheers
Sean

DoctorWho · 1st Oct 2005, 8:07 am

Hello Sean,

Many thanks for your kind offer. I would be very grateful if that is alright with Darius.

Thanks for the kind offer,

Peter.

Sean Williams · 1st Oct 2005, 8:33 pm

Darius has contacted me regarding the modulator build, and as a result of this I have decided that my offer was not fair to make, so I will not be building these on anyones behalf.

If anyone wants to make one I am happy to offer my time free of charge to assist in alignment/troubleshooting.

Cheers all
Sean

17th May 2005, 11:37 am	#21
brianc Rest in Peace Join Date: Jun 2004 Location: Burghfield, Reading, Berkshire, UK, Posts: 1,055	Re: making of the London Birmingham modulator Hi Darius The modulator looks great! I have been attempting to build one using your methods but with copper-clad laminate instead of tinplate - it is not as easy as it looks! Perhaps I need much more practise. One question though: What does the 8.2V zenner in the sync-sep collector do? The supply voltage is only 5V so how does the diode ever "zenner" or am I missing something? Cheers Brian

17th May 2005, 1:33 pm	#22
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: making of the London Birmingham modulator Hi Brian, the 8V2 is a protection against ESD for the gate-source oxyde of the BSN10. This MOS-FET is a very sensitive thing be very carefull with the gate!!! Kind regards Darius

17th May 2005, 3:46 pm	#23
brianc Rest in Peace Join Date: Jun 2004 Location: Burghfield, Reading, Berkshire, UK, Posts: 1,055	Re: making of the London Birmingham modulator Hi Darius Thanks for the advice! I will be very careful. Brian

17th May 2005, 7:23 pm	#24
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: making of the London Birmingham modulator "with copper-clad laminate instead of tinplate - it is not as easy as it looks! Perhaps I need much more practise." I think Peter Scott made it this way. Kind regards Darius

3rd Jul 2005, 9:24 am	#25
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: making of the London Birmingham modulator https://www.vintage-radio.net/forum/...ead.php?t=3723 Good morning In the pics you can see how the "sound modulation > 100%" detect stage is build in. I want to point out that both channels can be switched on without any inteference. Kind regards Darius Attached Thumbnails

4th Jul 2005, 3:58 pm	#26
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: making of the London Birmingham modulator Hi, I just got the summer Bulletin. Jeffrey Borinsky's article about the aurora is very interesitng. Please look at page 34: "Some minor problems DC offset This is... This has now be changed to a simple DC coupled output leaving sync tips at 0V and black level at +300mV." This is exactly what we need to drive Q5. So if you use the aurora, the modulator schematic is much easyer. Kind regards Darius Attached Thumbnails

18th Sep 2005, 11:31 am	#27
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: making of the London Birmingham modulator Hi, sorry I forgot an importand resistor in the sync separator Q3. A 220K Ohms goes from its base to ground. Here is the completed schematic: Kind regards Darius Attached Thumbnails

19th Sep 2005, 10:11 pm	#28
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,513	Re: making of the London Birmingham modulator Hi All, Well, Seeing as Darius has posted such excellent diagrams and pictures, I thought I would knock one up for a laugh!! Addictive this television lark! Still a fair amount to do - the Video amps need buliding, as do the filters - the oscillators are not clean enough to use without them, still, so far my congrats to Darius for an easily repeatable design!! Sean Attached Thumbnails __________________ Engineers make things work and have spare bits when finished Last edited by Sean Williams; 19th Sep 2005 at 10:16 pm. Reason: addition

20th Sep 2005, 9:42 am	#29
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: making of the London Birmingham modulator Hi Sean, looks good, I like what you are doing there. Please let us see your progress here. Kind regards Darius

20th Sep 2005, 3:49 pm	#30
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,513	Re: making of the London Birmingham modulator Hi Darius, A simple question really - Do you use the same sound and vision amp for both London and Birmingham, or do you have two of each, and split the input signal?? Thanks Sean __________________ Engineers make things work and have spare bits when finished

20th Sep 2005, 5:40 pm	#31
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: making of the London Birmingham modulator "Do you use the same sound and vision amp for both London and Birmingham" Good evening, yes of course. Please look at the schematic in thrad 27 for vision and thrad 25 for sound. Kind regards Darius

24th Sep 2005, 3:53 pm	#32
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: making of the London Birmingham modulator I'd love one of these modulators when they are available Darius. I use an extremely old (1980's) modulator which, whilst it works incredibly well, causes interference on UHF and only covers Channel 1. I'd love one of your modulators as I have not been able to have a Channel 4 signal before now. Any idea when they will be available? All the best, Peter.

24th Sep 2005, 5:10 pm	#33
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: making of the London Birmingham modulator https://www.vintage-radio.net/forum/...ead.php?t=3045 At the moment I have not enough time to build them for sale. It takes several hours to build one and making it to earn some money would make it too expensive. The one I have is still available for swap. Kind regards Darius

24th Sep 2005, 6:31 pm	#34
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: making of the London Birmingham modulator Well I'd love it Darius, but sadly I don't have anything suitable to offer you as a swap, unless there is anything else you may be looking for to add to your collection? Alternatively would you sell it? Peter.

24th Sep 2005, 9:06 pm	#35
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,513	Re: making of the London Birmingham modulator Hi Peter, Why not have a go at making one - the parts are fairly common, and the design is quite easy to build - just follow the photographs thatr Darius has kindly posted... Im sure we can help you get one working. Cheers Sean __________________ Engineers make things work and have spare bits when finished

25th Sep 2005, 10:04 am	#36
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: making of the London Birmingham modulator Yes, I agree with Sean. This is why I made this thrad. Thanks to Paul Stenning for making this possible. I am sure there are "ham's" in your neighbourhood who can help you with the agliement. Kind regards Darius

26th Sep 2005, 8:23 am	#37
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: making of the London Birmingham modulator Unfortunately it's rather beyond my abilities, I don't have the experience to tackle something like this. I have been hoping for some time that someone would be able to make a modulator available for Channels 1 & 4. Maybe a little later that may be possible? Thanks again for the reply.

30th Sep 2005, 10:06 am	#38
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,513	Re: making of the London Birmingham modulator Hi Doctor Who, I could build the RF and modulator stages for you - you could then fit it into a case and build the power supply, assuming there are no objections from Darius (it is his design after all). What do you think? Cheers Sean __________________ Engineers make things work and have spare bits when finished

1st Oct 2005, 8:07 am	#39
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: making of the London Birmingham modulator Hello Sean, Many thanks for your kind offer. I would be very grateful if that is alright with Darius. Thanks for the kind offer, Peter.

1st Oct 2005, 8:33 pm	#40
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,513	Re: making of the London Birmingham modulator Darius has contacted me regarding the modulator build, and as a result of this I have decided that my offer was not fair to make, so I will not be building these on anyones behalf. If anyone wants to make one I am happy to offer my time free of charge to assist in alignment/troubleshooting. Cheers all Sean __________________ Engineers make things work and have spare bits when finished