Firstly could someone confirm it is a CuO rectifier
http://home.graffiti.net/diverse:gra...et/CuO_rec.jpg
steel bolt mount is horizontal,
from a mid 30s Avo, "Mark 1" valve/tube tester, discs about 3/4 inch
diameter, gives only about 4V dc.
Assuming functional replacement with a 1N4007, what value of sag resistor?
Is the functional part just the 6 central discs and the outer discs are just
insulators/strain relief, they seem a bit more than that ?

N_Cook wrote:

Firstly could someone confirm it is a CuO rectifier
http://home.graffiti.net/diverse:gra...et/CuO_rec.jpg
steel bolt mount is horizontal,
from a mid 30s Avo, "Mark 1" valve/tube tester, discs about 3/4 inch
diameter, gives only about 4V dc.
Assuming functional replacement with a 1N4007, what value of sag
resistor? Is the functional part just the 6 central discs and the
outer discs are just insulators/strain relief, they seem a bit more
than that ?

Yes I can confirm that it is a Copper Oxide rectifier ! If I can find
the right box probably have a new one kicking around. Made by Ferranti
if I recall. Antique Radio may have some data on it !

--
Best Regards:
Baron.

On Wed, 8 Apr 2009 12:46:00 +0100, "N_Cook" put
finger to keyboard and composed:

Firstly could someone confirm it is a CuO rectifier
http://home.graffiti.net/diverse:gra...et/CuO_rec.jpg
steel bolt mount is horizontal,
from a mid 30s Avo, "Mark 1" valve/tube tester, discs about 3/4 inch
diameter, gives only about 4V dc.

See http://www.xcvcorp.com/PIC00035.jpg

.... and ...

http://www.xcvcorp.com/PIC00039.jpg

.... at ...

http://www.xcvcorp.com/Electronics%20Museum%20HTML.html

Assuming functional replacement with a 1N4007, what value of sag resistor?
Is the functional part just the 6 central discs and the outer discs are just
insulators/strain relief, they seem a bit more than that ?

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

If the reverse capability of CuO is only 6 volts how can a 6 disc one be
used for anode/plate supply?

On Apr 8, 2:19*pm, "N_Cook" wrote:
If the reverse capability of CuO is only 6 volts how can a 6 disc one be
used for anode/plate supply?

Copper oxide was used for low voltage rectifiers. For anode supply
rectifiers they used selenium. Selenium rectifires were most commonly
seen with cooling fins, but if the dissipation was low, conduction
cooling through the mounting stud was adequate. What you showed could
easily be a selenium type, and selenium has a rating of about 30-50V
per plate so a 6 plate would be good for 180-300V.

The rectifier in the Heath V7-A VTVM was a tiny stud mounted block [~
5/8" cube] and it was rated, IIRC, for 50mA and 150V.

Neil S.

nesesu wrote in message
...
On Apr 8, 2:19 pm, "N_Cook" wrote:
If the reverse capability of CuO is only 6 volts how can a 6 disc one be
used for anode/plate supply?

Copper oxide was used for low voltage rectifiers. For anode supply
rectifiers they used selenium. Selenium rectifires were most commonly
seen with cooling fins, but if the dissipation was low, conduction
cooling through the mounting stud was adequate. What you showed could
easily be a selenium type, and selenium has a rating of about 30-50V
per plate so a 6 plate would be good for 180-300V.

The rectifier in the Heath V7-A VTVM was a tiny stud mounted block [~
5/8" cube] and it was rated, IIRC, for 50mA and 150V.

Neil S.

There is no HT capacitor associated with the anode/plate HT, what is the
result of feeding high voltage ac to the anode/plate of a tube/valve? and
then just rectify a small ac voltage for feeding the meter , for testing
purposes

N_Cook wrote:

nesesu wrote in message
...
On Apr 8, 2:19 pm, "N_Cook" wrote:
If the reverse capability of CuO is only 6 volts how can a 6 disc one be
used for anode/plate supply?

Copper oxide was used for low voltage rectifiers. For anode supply
rectifiers they used selenium. Selenium rectifires were most commonly
seen with cooling fins, but if the dissipation was low, conduction
cooling through the mounting stud was adequate. What you showed could
easily be a selenium type, and selenium has a rating of about 30-50V
per plate so a 6 plate would be good for 180-300V.

The rectifier in the Heath V7-A VTVM was a tiny stud mounted block [~
5/8" cube] and it was rated, IIRC, for 50mA and 150V.

Neil S.

There is no HT capacitor associated with the anode/plate HT, what is the
result of feeding high voltage ac to the anode/plate of a tube/valve? and
then just rectify a small ac voltage for feeding the meter , for testing
purposes


Copper rectifiers were used to convert DC meters to AC meters. Look
at the schematic of old VOM with AC/DC functions. Copper rectifiers
have a very low forward drop, and the use of another type of rectifier
will change the calibration. A silicon diode is not a good replacement
in most circuits. A modern replacement would be an 'Ideal Rectifier'
circuit, using an opamp to offset the forward voltage drop.

http://en.wikipedia.org/wiki/Precision_rectifier has a brief
description. Several semiconductor OEM cover the details in their
application notes. My collection is on another computer right now, but
ON, national, or anyone who makes opamps should have one in their list
of application notes.


--
And another motherboard bites the dust!

Lynn wrote:
On Apr 9, 2:39 am, "Michael A. Terrell" wrote:
Copper rectifiers were used to convert DC meters to AC meters.

You're full of ****. **** You.

Nice response Lynn, we all learned something today.

So who **** in your Wheaties this morning?

Jeff

"Jeffrey D Angus" wrote in message
...
Lynn wrote:
On Apr 9, 2:39 am, "Michael A. Terrell" wrote:
Copper rectifiers were used to convert DC meters to AC meters.

You're full of [deleted]
Nice response Lynn, we all learned something today.

Jeff, look at the headers, another troll... "Let It Be", to quote the
Beatles...

seems these testers drove the valves to be tested with ac as very difficult
to get a regulated DC supply over the required ranges, wheras for well
enough regulated ac, only required different taps on the mains transformer.

In "N_Cook" writes:

There is no HT capacitor associated with the anode/plate HT, what is the
result of feeding high voltage ac to the anode/plate of a tube/valve?

They only work half the time. Here's a (not the best) schematic as
far as I've gotten things traced for an old piece of medical gear:

http://www.gothicdigital.com/wappler/Wappler.png

I'm not sure what you would call this topology; a self-rectifying oscillator?

--
Tim Mullen
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