Transformation of jadine modulator 819 lines for 405 lines telly

[wiwior]

Hello everyboby,

Also sorry for my awfull english but I will try to explain what I do

The 405 lines modulator who fernseh oofer me was out of order so I decide to make another 405lines modulator for my english television set.

I decide to realize a new jadine modulator witch work on my 819lines television set but the frequencies is not the same jardine is on 185.25 vision carrier and 174.10 sound carrier.

As this modulator is easy to understand I just remplace the two coils on the video section oscilator and after adjustements you have just to copy in the sound sectiond and

the two coils are in the original of 3 whorls and approximaly 2 for "reject" with a 1mm cable so I decide to make 13 whorls and half and eight for "reject" with a 0.2mm cable.The first time I've plug it works.For the sound it's the same thing except that adjustement is more delicate to obtain but you can solve the problem with a fixed caps to enlarge adjustement.

I will post picture but it actualy seems to have a problem with attachement

sincerely as all

wilfrid

[wiwior]

pictures of the modulator now !

kinds regards

wilfrid

[FERNSEH]

Hello Wilfrid,
This is good news. Originally, Mr. Jardines modulator was designed for operation on Band 3 to supply 819 line receivers.

However, it is proving to be a versatile modulator. the oscillator coils can be wound for channell B1 and I see no reason why the unit should not work well on the other 405 Band channels. Also, it could be considered for the Paris 441 line frequencies, 42mhz sound and 46mhz vision.

The unit has the advantage of low component count, it's a lot easier to construct than the 1984 David Looser design.

The more 405 line equipment we have available, the better it is.

DFWB.

[wiwior]

Hello David,

thanks to contribute to explanations I hope my message was understanding and once again all my thanks to offer me my first 405 lines in working order who gave me desire for repairing other television sets 405 after being tomb in love with this standard.

I hope french 819lines found also a new home in england .

I would like if I've time enought this summer to realize a modulator has multiple bands .The idea is to use a rotactor and make the diffrents channel on each position like that you have just to turn to have a "multi-modulator".

all the best

wilfrid

[Kat Manton]

Hi,

Are boards and other details available somewhere? I'd like to build one of these for 819, System E.

Currently I feed the Sondyna TV (kindly provided by Wilfrid via David) with a hybrid 819-line System B signal.

What's the vision bandwidth of this modulator like? I get very high video bandwidth from my computer system; if the modulator manages the full 10MHz then the limiting factor is just the set. A modern high-definition digital source scaled down to 819-line could show this system working very well.

Wilfrid, I like your idea of making it switchable, I might do that myself. My first idea was to tune one of the Band I System A modulator designs up in frequency. I wasn't confident that it'd work given they were designed for 3MHz vision bandwidth and usually no higher than Channel 4/Birmingham.

This seems like a better idea, a multi-purpose modulator covering several channels and standards which used AM sound and positive vision modulation would be useful. I have a few 405-line sets, an 819-line one; I'd like a 441-line set as well, some day.

Cheers, Kat

[FERNSEH]

Hi Kat and Wilfrid,
The concept of a switchable modulator is a very good idea.
However, switches always do introduce problems at high freqencies. How about using varicap diodes to alter the frequency? One modulator unit could take of the band 1 frequencies and another for Band 3. I'm sure that many 405 line enthusiasts would like the idea of operating their sets on Band 3 in order to display vintage ITV programs.

DFWB.

[ppppenguin]

The 1496 based designs (David Looser's, the one in Domino, mine, maybe others) are not really useful in Band III.

One answer for multistandard work is David Robinson's design using the programmable Motorola/Freescale chips. A similar design is also used in the Aurora. I have no idea if these chips will do 10MHz bandwidth but AFAIK they have no specific bandwidth limiting.

[wiwior]

Hello everybody,

For respond to david: (I hope I will be understanding)

I was thinking using a switched varicap for final ajustement with a commutation on/off and also a video inverter for using in negative but I've actually no television set using this mode.

As you say the problem is on high frequency above 80mhz with a bandwidth around 180mhz It will be necesarry to make coils with protection but I've idea about in fact draw the coil in the "mika" I hope you'll understand my idea.

For Kat same thing )

Hi kat I've the diagram if necessary but you can ask to David he has the completed instruction to build one I had built for him a 8a channel modulator when he came in france a few month ago with all instruction so I think is more easier to communicate with him not like me who very very bad pratice of english.

I'm very interesting by your computer lines converter and it's the same thing as understand english is hard I let it down.The funny thing is like I'm not good in new technologie I was several times ask in france about 5 years how to convert with a computer but I wasn't on internet regulary.

about 441lines it's very very very rare because in fact there is a limited production just for Paris and several production was ever in 819lines.

But just a point of tecnologie view 441lines is nearly similar to 405lines.The only interest will to see a color 819lines witch never exist.

I stop here my brain is very too hot

kind regards

wilfrid

[maitiustandun]

Originally Posted by wiwior

Hello everybody,

For respond to david: (I hope I will be understanding)

I was thinking using a switched varicap for final ajustement with a commutation on/off and also a video inverter for using in negative but I've actually no television set using this mode.

As you say the problem is on high frequency above 80mhz with a bandwidth around 180mhz It will be necesarry to make coils with protection but I've idea about in fact draw the coil in the "mika" I hope you'll understand my idea.

For Kat same thing )

Hi kat I've the diagram if necessary but you can ask to David he has the completed instruction to build one I had built for him a 8a channel modulator when he came in france a few month ago with all instruction so I think is more easier to communicate with him not like me who very very bad pratice of english.

I'm very interesting by your computer lines converter and it's the same thing as understand english is hard I let it down.The funny thing is like I'm not good in new technologie I was several times ask in france about 5 years how to convert with a computer but I wasn't on internet regulary.

about 441lines it's very very very rare because in fact there is a limited production just for Paris and several production was ever in 819lines.

But just a point of tecnologie view 441lines is nearly similar to 405lines.The only interest will to see a color 819lines witch never exist.

I stop here my brain is very too hot

kind regards

wilfrid

stop worrying wilfrid your doing great and everybody understands your text ,regards maitiu.