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Old 17th Jun 2021, 8:17 pm   #1
AdrianH
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Default Identifying vales help Mazda/brimar/?

I saw a post for a valve on the wanted thread and think I may have some of them but I would need to check some numbers.

The valves I have are both B8A one with a glass base and the other with the metal base. All normal printing on the side of the glass has long gone but there is a set of 4 digits and then 2 or 3 digits on the base.

These are on the metal base 1442 and C0 or CO.

On the glass base 1442 and what looks like a 3 digit 2C4. One has a stuck on label that suggests a UY41, is there anyway to confirm this. I have picked up from the internet several threads on Philips factory codes but have struggled to find anything with these codes?

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Old 17th Jun 2021, 8:42 pm   #2
kestrelmusic
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Default Re: Identifying vales help Mazda/brimar/?

1442 looks like a Brimar code, but I can't see what valve it applies to.
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Old 17th Jun 2021, 9:22 pm   #3
cathoderay57
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Default Re: Identifying vales help Mazda/brimar/?

It should be fairly obvious from the appearance whether it is a single anode i.e. half-wave rectifier or a pair of anodes in which case it could be an EZ40, both being on a B8A base. If definitely half-wave on a B8A I can't think it's likely to be anything but a UY41. If in doubt, put 6.3v on the heater and if it lights fully then it's not a UY41. If it fails to light at 6.3v, crank up the heater voltage in stages and if it will not light fully until it gets to 31v, it's a UY41. Cheers, Jerry
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Old 17th Jun 2021, 9:43 pm   #4
AdrianH
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Default Re: Identifying vales help Mazda/brimar/?

I do not have a PSU that would do up to 30 plus volts but the resistance of the heater is 50 Ohm cold.

From looking at the data sheet it seems to match the pin out

Heater on 1 and 8.
Pin 7 cathode
Pin 6 has an internal connection which appears to be just a support up through the two mica's
and after removing the paper label I can see that pin 2 has a similar connection that goes to the top of the valve, has the getter connected to it and a connection to the anode.

It would still be nice to find factory codes for the valve sequence, but I will have to assume that code 1442 is a UY41.

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Old 17th Jun 2021, 9:48 pm   #5
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Default Re: Identifying vales help Mazda/brimar/?

The metal based valve has a heater resistance of 44 Ohms cold so a slight difference between the two. This is more difficult to see into as the top is a lot darker from the getter firing.

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Old 18th Jun 2021, 2:48 am   #6
Maarten
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Default Re: Identifying vales help Mazda/brimar/?

1442 could also be a Mullard code. They continued the pre-1948 system a bit longer than continental Philips. Unfortunately I don't know to which valve it belongs.
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Old 18th Jun 2021, 7:57 am   #7
paulsherwin
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Default Re: Identifying vales help Mazda/brimar/?

There is no shortage of close-up photos of UY41s on the net if you search, e.g. http://www.r-type.org/exhib/aan0002.htm
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Old 18th Jun 2021, 11:08 am   #8
AdrianH
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Default Re: Identifying vales help Mazda/brimar/?

The sorting of the UY41 was to help confirm a valve for another member
I am also trying to confirm some other valves if I could find the codes.

Here is a few others within my box of acquired pulls.
These seem to be Mullard valves codes

B8A Valves

1439 UF41 Mullard printed valve
1405 UB41 Hand written
1451 or 1431 EZ40 Hand written
1328 UF42 Hand written

Some Mazda and Brimar old B8A's have no such extra markings on the base so if I loose the normal printed numbers I would be stuffed.

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