5MK9 rectifier valve. Spares or equivalents?? - UK Vintage Radio Repair and Restoration Discussion Forum

jascha · 1st Mar 2007, 4:28 pm

Hi,
I have 4 similar tape machines from the 50s that were made in Japan and all use a 5MK9 valve rectifier. I am beginning to wonder how rare this valve might be and would like to stock up on a few spares. They have not gone wrong for all these years but who knows!!!! I would like to know if there are any equivalents one can use for this valve or where i can find replacements in the uk please?
The other valves they use are quite common so no worries about that. if it helps anyone i can always post the circuit diagram of this machine.
You can have a look at what they look like on this thread below:

https://www.vintage-radio.net/forum/...ad.php?t=14892

many thanks indeed

Ed_Dinning · 1st Mar 2007, 6:24 pm

Hi Jascha, any chance of a picture or the valve and some circuit details.
It may be that a common type such as an EZ80/81 or 5Z4 will do. If we know the base type and ratings it should be easier to advise.

Ed

jascha · 1st Mar 2007, 8:35 pm

Hi Ed,

The valve i am talking about is a 7 pin valve that is slightly longer in size than an ECC83. I shall attach a circuit diagram of my tape machine so you can see what this valve does. I also attach a few other pictures related to this valve. I have found a supplier who had 4 in all and i am buying them but it is worth knowing more about it. So i look forward to your replies.
many thanks

again

PJL · 1st Mar 2007, 8:48 pm

http://www.mif.pg.gda.pl/homepages/f...33/5/5M-K9.pdf half wave rectifier 5V heater - I think you maybe wise to stock up.

ppppenguin · 1st Mar 2007, 8:51 pm

You could probably get an EY91 to work with a bit of fiddling. Would need a resistor to correct the heater current.

Ed_Dinning · 1st Mar 2007, 9:03 pm

Hi Jascha, it is a bit of an oddball. There are plenty of rectifiers of this size around but very few that don't have 6.3 or higher voltage heaters. As Jeffery says, you may do it with an EY91 (not that common either), or you may need to look at adding turns to the rectifier heater winding and getting a 6.3 volt valve (plenty of these about).

Ed

jascha · 1st Mar 2007, 9:13 pm

Hi everyone,
Thanks for your replies....it sounds wise to stock up i think!!!! I will be in japan in April and i will definitely have alook around there to see if i find any lurking around too. I was told these are rare and were used for some japanese tape machines. If i can stick to the original i think it would be the safest bet.

Thanks once again

paulsherwin · 1st Mar 2007, 9:38 pm

If you rectify and smooth the 5V AC supply you'll get more than enough volts to use something like a 6X4/EZ90, but obviously this isn't an ideal solution. Or you could just use a silicon diode

Paul

Ed_Dinning · 2nd Mar 2007, 10:21 pm

Hi Jascha, If you are in Tokyo the Ahiharbra(?) market under the station is like certain areas of London in the 50's for radio spares, you should be lucky there.

Ed

jascha · 2nd Mar 2007, 11:19 pm

I go there every time i am in Tokyo (for work!!!). I love those tiny shops full of components....and the quality of the components is just very high quality too. It's called Akihabara.

MANY THANKS

1st Mar 2007, 4:28 pm	#1
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	5MK9 rectifier valve. Spares or equivalents?? Hi, I have 4 similar tape machines from the 50s that were made in Japan and all use a 5MK9 valve rectifier. I am beginning to wonder how rare this valve might be and would like to stock up on a few spares. They have not gone wrong for all these years but who knows!!!! I would like to know if there are any equivalents one can use for this valve or where i can find replacements in the uk please? The other valves they use are quite common so no worries about that. if it helps anyone i can always post the circuit diagram of this machine. You can have a look at what they look like on this thread below: https://www.vintage-radio.net/forum/...ad.php?t=14892 many thanks indeed

1st Mar 2007, 6:24 pm	#2
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: 5MK9 rectifier valve. Spares or equivalents?? Hi Jascha, any chance of a picture or the valve and some circuit details. It may be that a common type such as an EZ80/81 or 5Z4 will do. If we know the base type and ratings it should be easier to advise. Ed

1st Mar 2007, 8:35 pm	#3
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: 5MK9 rectifier valve. Spares or equivalents?? Hi Ed, The valve i am talking about is a 7 pin valve that is slightly longer in size than an ECC83. I shall attach a circuit diagram of my tape machine so you can see what this valve does. I also attach a few other pictures related to this valve. I have found a supplier who had 4 in all and i am buying them but it is worth knowing more about it. So i look forward to your replies. many thanks again Attached Thumbnails

1st Mar 2007, 8:48 pm	#4
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: 5MK9 rectifier valve. Spares or equivalents?? http://www.mif.pg.gda.pl/homepages/f...33/5/5M-K9.pdf half wave rectifier 5V heater - I think you maybe wise to stock up.

1st Mar 2007, 8:51 pm	#5
ppppenguin Retired Dormant Member Join Date: Dec 2003 Location: North London, UK. Posts: 6,168	Re: 5MK9 rectifier valve. Spares or equivalents?? You could probably get an EY91 to work with a bit of fiddling. Would need a resistor to correct the heater current.

1st Mar 2007, 9:03 pm	#6
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: 5MK9 rectifier valve. Spares or equivalents?? Hi Jascha, it is a bit of an oddball. There are plenty of rectifiers of this size around but very few that don't have 6.3 or higher voltage heaters. As Jeffery says, you may do it with an EY91 (not that common either), or you may need to look at adding turns to the rectifier heater winding and getting a 6.3 volt valve (plenty of these about). Ed

1st Mar 2007, 9:13 pm	#7
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: 5MK9 rectifier valve. Spares or equivalents?? Hi everyone, Thanks for your replies....it sounds wise to stock up i think!!!! I will be in japan in April and i will definitely have alook around there to see if i find any lurking around too. I was told these are rare and were used for some japanese tape machines. If i can stick to the original i think it would be the safest bet. Thanks once again

1st Mar 2007, 9:38 pm	#8
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,957	Re: 5MK9 rectifier valve. Spares or equivalents?? If you rectify and smooth the 5V AC supply you'll get more than enough volts to use something like a 6X4/EZ90, but obviously this isn't an ideal solution. Or you could just use a silicon diode Paul

2nd Mar 2007, 10:21 pm	#9
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: 5MK9 rectifier valve. Spares or equivalents?? Hi Jascha, If you are in Tokyo the Ahiharbra(?) market under the station is like certain areas of London in the 50's for radio spares, you should be lucky there. Ed

2nd Mar 2007, 11:19 pm	#10
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: 5MK9 rectifier valve. Spares or equivalents?? I go there every time i am in Tokyo (for work!!!). I love those tiny shops full of components....and the quality of the components is just very high quality too. It's called Akihabara. MANY THANKS