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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 7th Dec 2022, 7:25 am   #1
German Dalek
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Arrow HELP! Need a UHF-SECAM modulator

Hello folks,

I just bought in France an old Grundig TV receiver.
It is a 1960/61 model dedicated to France .
That means 819 lines/VHF and 625 lines/UHF.

I have a lot of converters from old VCRs, but I need AM-sound
and positive picture modulation.

Is there anybody out there, who has a simple schematic with a
minimum of ICs and without SMD-junk to use a VCR-modulator or
know how to construct a complete new one?

Thanks in advance!
German Dalek
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Old 7th Dec 2022, 7:51 am   #2
inaxeon
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Default Re: HELP! Need a UHF-SECAM modulator

Quote:
Originally Posted by German Dalek View Post
Hello folks,

I just bought in France an old Grundig TV receiver.
It is a 1960/61 model dedicated to France .
That means 819 lines/VHF and 625 lines/UHF.

I have a lot of converters from old VCRs, but I need AM-sound
and positive picture modulation.

Is there anybody out there, who has a simple schematic with a
minimum of ICs and without SMD-junk to use a VCR-modulator or
know how to construct a complete new one?

Thanks in advance!
German Dalek
This will do your positive modulation and AM sound:

https://www.ebay.com/itm/31409354197...Bk9SR-LayrWdYQ

Sadly looks like it's missing quite a few bits...
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Old 7th Dec 2022, 8:10 am   #3
inaxeon
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Default Re: HELP! Need a UHF-SECAM modulator

Oh here's another option: https://www.ebay.co.uk/itm/164735212...oAAOSwYjdgPhk-

According to your criteria it might be junk though. I think those have SMD components inside.

Last edited by inaxeon; 7th Dec 2022 at 8:21 am.
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Old 7th Dec 2022, 10:19 am   #4
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Default Re: HELP! Need a UHF-SECAM modulator

That PM5580 is interesting. The IF looks not to be spectrally inverted so I guess that up-converter (which clearly has been nicked) would be a low-side heterodyne converter.

Anyone know if that is standard for French systems? I have never seen that before! Or am I reading all of this upside-down?

I do have the manual and schematics for the PM5580 but unfortunately it looks like it was printed before that variation was developed so doesn't cover it. It does cover all other types.

Last edited by inaxeon; 7th Dec 2022 at 10:24 am.
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Old 7th Dec 2022, 1:02 pm   #5
German Dalek
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Default Re: HELP! Need a UHF-SECAM modulator

Thanks for your replies!

But sorry, these "machines" are much bigger than all my Auroras together.
Anyway, I have no more Ebay account and doesn´t want it anymore.
I am searching for a 1-2 vero-board solution.
A channel 8a converter needs only one vero-board.

Regards,
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Old 7th Dec 2022, 1:08 pm   #6
inaxeon
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Default Re: HELP! Need a UHF-SECAM modulator

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Originally Posted by German Dalek View Post
Thanks for your replies!

But sorry, these "machines" are much bigger than all my Auroras together.
Anyway, I have no more Ebay account and doesn´t want it anymore.
I am searching for a 1-2 vero-board solution.
A channel 8a converter needs only one vero-board.

Regards,
German Dalek
That PM5580 is well priced. If it has the vision and sound modulator PCBs in it, you can chuck the rest away leaving you with very little left over. You'll save yourself an awful lot of time designing one (assuming no-one else has a pre-cooked design). It would then just be a case of coming up with a suitable up-converter which is pretty easy given that you just want to plug into the TV's antenna socket.

Anyway just a thought.
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Old 7th Dec 2022, 1:51 pm   #7
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Default Re: HELP! Need a UHF-SECAM modulator

Look out for a Canon TC-21SP. It’s a PAL to secam transcoder with a system L RF output around ch 36. French eBay maybe?
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Old 7th Dec 2022, 3:15 pm   #8
inaxeon
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Default Re: HELP! Need a UHF-SECAM modulator

Drawings of vision and sound modulator PCBs attached. Nothing scary about them.
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Old 7th Dec 2022, 7:04 pm   #9
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Default Re: HELP! Need a UHF-SECAM modulator

If you don't want to buid it yourself, you have the Terra MT47 modulator which covers all standards, including the L standard (french 625 lines standard).
With some tricks it can even be used to attack a VHF 819 lines TV (on some band III channels only).

https://shopdelta.eu/modulator-tv-mt-47_l2_p3967.html
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Old 7th Dec 2022, 7:28 pm   #10
inaxeon
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Default Re: HELP! Need a UHF-SECAM modulator

You sure about that? I have one similar which claims to support L but doesn't actually do positive modulation and AM sound. Nothing in the specs for that positively state that one does?
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Old 7th Dec 2022, 8:09 pm   #11
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Default Re: HELP! Need a UHF-SECAM modulator

Hi to all,
Hi Inaxeon & German Dalek,

Believe Marceljack from France, for us French TV collectors E Standard (819) & L (625), both AM audio & Positive video modulation are a nightmare in the modern world.
French ex-forum member Clopos did extensive research 2 years ago & wound up with the Terra MT-47 which we have been buying in droves.

Unfortunately, models sold under a bewildering onslaught of Chinese brands have the exact same physical appearance (blue) & sometimes orange have nearly all standards, but NOT L. Also most sellers know nothing about analogue-era TV standards (= don't know what you're buying).

The Terra MT-47 with the link above is guaranteed to work on system L and with some tweaking to offset frequencies (A or V depending on channel) , on many of the upper channels of
system E.

For your pleasure, please see the attached Terra MT-47 English user manual.

If you want PAL to SECAM transcoding + RF modulation, the Canon TC-21 is a very good choice.
Tip: search "leboncoin.fr" auction site for cheap used units.

Best Regards
jhalphen
Paris/France
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Old 7th Dec 2022, 8:34 pm   #12
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Default Re: HELP! Need a UHF-SECAM modulator

Quote:
Originally Posted by jhalphen View Post
Unfortunately, models sold under a bewildering onslaught of Chinese brands have the exact same physical appearance (blue) & sometimes orange have nearly all standards, but NOT L.
Well that might be what I have got here and I have just found something rather interesting. The chip inside it doing the modulation is a Philips MC44BS373CA. I just looked at the datasheet, and it supports System L. (attached).

The only reason it doesn't work is because the firmware in the microcontroller (written by whatever cowboys designed the modulator) doesn't have any facility to activate it.
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Old 7th Dec 2022, 8:43 pm   #13
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Default Re: HELP! Need a UHF-SECAM modulator

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Originally Posted by inaxeon View Post
Well that might be what I have got here and I have just found something rather interesting. The chip inside it doing the modulation is a Philips MC44BS373CA. I just looked at the datasheet, and it supports System L. (attached).
MC44BS373CA does not resemble a Philips semiconductors reference but a Motorola reference.
The data sheet is very strange because it has the NXP logo (successor of Philips semiconductors) on the upper left corner of pages and Freescale (successor of Motorola) on some pages, in particular the last one.
Maybe NXP has bought Freescale in the meantime ...
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Old 7th Dec 2022, 8:46 pm   #14
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Default Re: HELP! Need a UHF-SECAM modulator

Quote:
Originally Posted by marceljack View Post
Quote:
Originally Posted by inaxeon View Post
Well that might be what I have got here and I have just found something rather interesting. The chip inside it doing the modulation is a Philips MC44BS373CA. I just looked at the datasheet, and it supports System L. (attached).
MC44BS373CA does not resemble a Philips semiconductors reference but a Motorola reference.
The data sheet is very strange because it has the NXP logo (successor of Philips semiconductors) on the upper left corner of pages and Freescale (successor of Motorola) on some pages, in particular the last one.
Maybe NXP has bought Freescale in the meantime ...
Yes, looking online Freescale has indeed merged into NXP.
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Old 7th Dec 2022, 9:04 pm   #15
inaxeon
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Default Re: HELP! Need a UHF-SECAM modulator

Quote:
Originally Posted by dglcomp View Post
Quote:
Originally Posted by marceljack View Post
Quote:
Originally Posted by inaxeon View Post
Well that might be what I have got here and I have just found something rather interesting. The chip inside it doing the modulation is a Philips MC44BS373CA. I just looked at the datasheet, and it supports System L. (attached).
MC44BS373CA does not resemble a Philips semiconductors reference but a Motorola reference.
The data sheet is very strange because it has the NXP logo (successor of Philips semiconductors) on the upper left corner of pages and Freescale (successor of Motorola) on some pages, in particular the last one.
Maybe NXP has bought Freescale in the meantime ...
Yes, looking online Freescale has indeed merged into NXP.
My mistake. I skimmed past the front page. Correct.
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Old 8th Dec 2022, 11:14 pm   #16
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Default Re: HELP! Need a UHF-SECAM modulator

Quote:
Originally Posted by inaxeon View Post
That PM5580 is interesting. The IF looks not to be spectrally inverted so I guess that up-converter (which clearly has been nicked) would be a low-side heterodyne converter.

Anyone know if that is standard for French systems? I have never seen that before! Or am I reading all of this upside-down?

The standard IF channel for French system L receivers was 32.7 MHz vision, 39.2 MHz sound, so that it was non-inverted, as it were, in contrast to most other standard IFs, which were inverted. (The exceptions were those for systems A, E and L.) Thus to the extent that standard receivers IFs were also used in modulators, it would not be so surprising to find the non-inverted channel used for system L.


Cheers,
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Old 9th Dec 2022, 9:48 am   #17
inaxeon
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Default Re: HELP! Need a UHF-SECAM modulator

Quote:
Originally Posted by Synchrodyne View Post
Quote:
Originally Posted by inaxeon View Post
That PM5580 is interesting. The IF looks not to be spectrally inverted so I guess that up-converter (which clearly has been nicked) would be a low-side heterodyne converter.

Anyone know if that is standard for French systems? I have never seen that before! Or am I reading all of this upside-down?

The standard IF channel for French system L receivers was 32.7 MHz vision, 39.2 MHz sound, so that it was non-inverted, as it were, in contrast to most other standard IFs, which were inverted. (The exceptions were those for systems A, E and L.) Thus to the extent that standard receivers IFs were also used in modulators, it would not be so surprising to find the non-inverted channel used for system L.

Cheers,
Ah that is really interesting. It's like everything about System L is the opposite to everything else.

On another note this doesn't appear to be something that (at least Philips) stuck with. I've got a PM5680 which also supports System L and the IF is inverted. Vision at 38.9 MHz and sound at 32.4 MHz. I suppose this would benefit of adding NICAM, certainly every suitable modulator I've seen has an inverted IF output @ 33.05 MHz.
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Old 9th Dec 2022, 4:57 pm   #18
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Default Re: HELP! Need a UHF-SECAM modulator

Ah. There are two versions.

"real" L and "pretend" L. Looks like I have the latter.
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Old 9th Dec 2022, 9:44 pm   #19
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Default Re: HELP! Need a UHF-SECAM modulator

The 38.9 MHz VIF, 32.4 MHz SIF combination was one of several non-standardized IFs used for system L (and for that matter systems D/K) in some later European multistandard receivers.

The system L standard IF was evidently chosen on the basis of having the same SIF as already established for system E, namely 39.2 MHz. That simplified the design of dual-standard (E/L) receivers. In that era, a common SIF was of greater benefit than a common VIF, given that the diode vision demodulators then in use were essentially untuned devices that could accommodate different VIFs without major switching. The later advent of tuned quasi-synchronous vision demodulators changed the equation somewhat, as did the use of SAWFs.

The standard system E IF channel was direct, i.e. non-inverted, so that correspondingly, so was the system L IF channel. That mandated infradyne conversion, no problem at UHF where system L was first placed, and still no problem when it was extended to Band III. However, the extension to Band I, where only supradyne conversion was practicable, was problematical. It was solved by using indirect, i.e. inverted transmission channels, with vision carrier high. As such, it was referred to as system L’, although as far as I can trace, that was never an official CCIR or ITU designation. Of course, whilst that suited French domestic receivers, it created a difficulty for the multistandard type, one solution to which being the use of double-Nyquist SAWFs.

Thus did decisions made in the 1950s (in this case for the system E standard IF) echo down to the end of analogue TV.


Cheers,
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Old 9th Dec 2022, 10:56 pm   #20
inaxeon
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That mandated infradyne conversion
Are you sure that is the correct use of that term? I looked up it and it appears to refer to scenarios where the IF frequency is higher than the signal frequency? That would not be the case for Band I

But in any case, going back to what I said earlier in this thread, "true" System L being non-inverted would have to use low side heterodyne conversion i.e. subtracting the IF frequency from the on-air frequency (I assume this is what you meant by infradyne, perhaps this is the correct term?)

Is the problem that local oscillator tone being used for the down-conversion ends up in the middle of the received signal for some band I frequencies with traditional system L?

And also, would moving to 38.9 MHz based inverted IF not just be a practically sensible choice because that is what most PAL systems use therefore that would simplify multi-standard receivers?
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