Leak Through Line III Tuner

[persil]

I picked up this Leak Through Line Tuner in a junk shop last week for pennies, I have read about it on the web and it seems a good one. Its in good working order but I know that I will have to do work on it to bring it back to great condition. I tested the valves (tubes) and they are all low so I have managed to get the seven replacements off the web for good money, they are all Mullard nos. I have the circuit diagrams and I have the components lists. I have refurbed much solid state but never a tuner or indeed any tube gear but have researched on this forum and have a fair idea what has to be done, I have been inside and checked most of the resistors and a lot of them are well out of spec.

I think I am correct is saying that I should only change some of the caps? Should I re-tube before the component change or after? I have a local dealer who will align the tuner for me after the work is done.

I want to add a stereo decoder to it, it has the multiplex output, and I can get the original Leak decoder. or a new built one. Obviously the Leak decoder is very old (1962) and quite basic. the new built one is the best available in the UK, will adding solid state to this valve tuner take away the sweet sounds the tubes produce? My system is all valve.

Any help or comments would be appreciated.

 

[KentTeffeteller]

Get the new built MPX decoder for this one. The original Leak unit was only fair performance wise. Improves the performance in Stereo by miles upgrading the MPX decoder. It won't detract from the tube sound, mate. The signal path capacitors are fair game for replacement before it's aligned. Replace any weak tubes before it's aligned and recap it before it's aligned. A superb tuner, the best of the English tuners ever made and a classic unit. :tresbon:

 

[ModernClassic]

Yes, simply change those small capacitors, + change at least the first smoothing capacitor too. Check also the 2 switches on the front panel for good switchability. I would leave resistors and tubes alone until you get it in good working order first.
The Orginal MPX is a 2 transistor simple stereo decoder. The only good thing is it fits into the unit!!!!!

 

[persil]

Thanks for the info, I have ordered a new decoder and I have decided not to put it in the Leak tuner because it will be very tight and right next to a glowing valve! I have a custom built passive preamp and there is plenty of room inside for the decoder. Oh, its by One Thing Audio?
As the tuner (Through line 2) was working, but just managing to pick up a station! and the new valves arrived. I tested and subsituted the valves one at a time. each one was testing very weak and after they all got changed The thing has burst into life with avengence! It pickes up everything, and I mean "everything"! Its very sensitive, it hold the stations well and sounds so sweet! I have a feeling that the two switches are not working as they should? The local distant switch has no effect and in my location, I wish it did! The AFC switch is very stiff and I dont think the AFC side of it is working as it seems to me the AFC is permantly on, The switch does turn off the magic eye though.

I am getting the caps I am going to change, but with difficulty. Does anybody know a source for them in the UK (or elsewhere) and the one cap I cant seem to get any info on is the tripple elect. 40uf 200 volt smoothing cap
. I think I will have to get individual caps to replace it? How far away from the uf and voltage rating can I go? the HT rail is shown and meters at 148 volts.

I own and have owned some great tuners, but I can say this 1960 valve tuner sounds sweeter than any of them. Your correct when you said that its a superb tuner! And it looks good as well!