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Old 17th Oct 2017, 6:33 pm   #1
cjwhoishe
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Join Date: Jun 2016
Location: Grantham, Lincolnshire, UK.
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Default Dulci FMT/2 information request

I have recently been looking for and acquiring potential FM tuners for use with a pair of Leak amplifiers, these were predominantly different versions of the Leak tuners. I did though see and buy this unit (see pics).
It is a separate tuner and is of about the period. I cannot though find much information for it.
It is mechanically fairly well built but the addition of the stereo decoder does not look original as the bracket for the output connectors is an add-on with the original plate that was there cut off.
This extra bracket is of the same finish as the rest of the case and the wiring for the decoder is very neat so I suspect that it was a factory retrofit after initial manufacture.
The front plate is copper with white silk screen printing on it, which is again interesting.

The valve line-up is:
ECF82, EF89, EF80, EF80, ECC85
mains rectifier potted selenium? (will get code when I can)
The only indication of an age is the label on the stereo decoder module which is 1968 (I think)

I have not powered it yet but have worked out the main power supply caps and so will do something to reform them. There is though a second large can dual capacitor of which only one is used. This appears to be connected around the FM discriminator but seems to be a bit of 'over-kill' for this job.

Does anybody know anything about it and have any circuit details?
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Old 17th Oct 2017, 7:36 pm   #2
Edward Huggins
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Default Re: Dulci FMT/2 information request

These certainly are well built. The factory made decoder was a extra as most of these were sold as Mono tuners. It may have a cathode follower output. I think the tuners proper were built earlier than 1968.
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Old 17th Oct 2017, 8:10 pm   #3
ms660
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Default Re: Dulci FMT/2 information request

Circa 1960 for the FMT/2.

The FMT/5 was Circa 1962 and covered 88MHz to 108MHz.

Lawrence.

Last edited by ms660; 17th Oct 2017 at 8:33 pm. Reason: addition
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Old 17th Oct 2017, 8:12 pm   #4
Nickthedentist
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Default Re: Dulci FMT/2 information request

Not listed (let alone pictured) on Radiomuseum, so you could send them some snaps.
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Old 2nd Nov 2017, 9:52 pm   #5
cjwhoishe
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Default Re: Dulci FMT/2 information request

A progress report.
I have managed to find some time to look at this a bit closer, and compare it with a couple of Leak tuners I have obtained and since repaired (which is another story).
The stereo decoder module has the same pinouts and looks very similar to the unit in a troughline stereo (only comparing with photos).

I took time to try and re-form the capacitors but they did not re-form fully and draw a little more current than I am happy with. The case of the capacitors also gets warm to touch (but not hot) after about 1 hour.
After checking all of the resistors, which were just within their original tolerance, I then slowly powered it up (via a variac) carefully monitoring the power supply to the stereo decoder module which stabilised well below the 25V working voltage of the capacitor decoupling it.

With an aerial connected it was quiet sensitive and gave a nice clear stereo output at what seemed to be a low level.
It sounded very comparable with a mono leak troughline but the amplifier had to be turned up to get the same volume level.
It was connected to a leak varislope pre-amp and 2 x TL12+ amplifiers.

I don't think that it will be the tuner I use with this setup for 3 reasons:
1. It has a lower output level and so will need the volume changing (a lot) when switching from records to radio on the leak pre-amp. (I don't need to do that with the leak tuners)
2. It does not cover up to 108Mhz.
3. You cannot force mono only and so need a good signal for everything you want to receive.

This exercise has prompted a few questions:
1. When was the stereo module developed for the Leak troughline (and probably used in this) relative to the first BBC stereo broadcasts?
2. When was some level of standardisation for input signal levels established?
3. Was there some form of monopoly ie buy 1 leak product and you had to buy all Leak etc. ?

I don't know what I am going to do with this now, probably just add to the collection and keep for curiosity.
It will not be used long term unless I change the decoupling capacitors.
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