WTB: two OPT's for p-p EL84's

[Engineer]

I am looking for two new or used high quality OPT's for push-pull
EL84's (6BQ5's) for a pair of 10 -15 watt monoblocs I am planning to
build (the "Mullard 5-10" circuit.) 8,000 ohms plate to plate, UL
type preferred (43% screen taps), but others considered.
Please email me at "analogdino 'at' rogers 'dot' com" (formatted
correctly.)
Ideally, I'd like to find these in the Greater Toronto Area (GTA),
Ontario, Canada, to avoid shipping costs, also customs costs if from
outside Canada, but this may not work out.
Thanks for all replies
Cheers,
Roger
GTA (Toronto), Canada.

 

[martin griffith]

On Sun, 29 May 2005 15:47:35 -0400, in sci.electronics.design
"Engineer" <fakeaddress@nowhere.net> wrote:

I am looking for two new or used high quality OPT's for push-pull
EL84's (6BQ5's) for a pair of 10 -15 watt monoblocs I am planning to
build (the "Mullard 5-10" circuit.) 8,000 ohms plate to plate, UL
type preferred (43% screen taps), but others considered.
Please email me at "analogdino 'at' rogers 'dot' com" (formatted
correctly.)
Ideally, I'd like to find these in the Greater Toronto Area (GTA),
Ontario, Canada, to avoid shipping costs, also customs costs if from
outside Canada, but this may not work out.
Thanks for all replies
Cheers,
Roger
GTA (Toronto), Canada.

try http://www.prodigy-pro.com/

they do Sowter stuff (excellent), and since they are US based they
probably arn't too expensive to ship from.

Old Doc Sowter was a cool guy, I'm think he invented Mumetal in the
days of Flash Gordon, and Tom& Jerry

martin

"Wales is a big welsh-shaped rain collection device"

 

[Pooh Bear]

martin griffith wrote:

On Sun, 29 May 2005 15:47:35 -0400, in sci.electronics.design
"Engineer" <fakeaddress@nowhere.net> wrote:

I am looking for two new or used high quality OPT's for push-pull
EL84's (6BQ5's) for a pair of 10 -15 watt monoblocs I am planning to
build (the "Mullard 5-10" circuit.) 8,000 ohms plate to plate, UL
type preferred (43% screen taps), but others considered.
Please email me at "analogdino 'at' rogers 'dot' com" (formatted
correctly.)
Ideally, I'd like to find these in the Greater Toronto Area (GTA),
Ontario, Canada, to avoid shipping costs, also customs costs if from
outside Canada, but this may not work out.
Thanks for all replies
Cheers,
Roger
GTA (Toronto), Canada.

try http://www.prodigy-pro.com/
they do Sowter stuff (excellent), and since they are US based they
probably arn't too expensive to ship from.

Old Doc Sowter was a cool guy, I'm think he invented Mumetal in the
days of Flash Gordon, and Tom& Jerry

I'll second Sowter for transformers ( if you really have to use them -
which valves do for output ! ). First class product. Probably the UK
equivalent of Jensen for low level stuff too. I've found their audio
'line level' transformers amongst the very best.

Another couple of names of old - now long gone I think - are Partridge
and Gardner transformers in the UK. I forget wich brand 'Orange' valve
amps used but it was one of them.

Did Jensen ever do OPTs ?

Btw - if you know your stuff you can design your own OPTs. Go for a
toroidal core and you'll get amazing bandwidth compared to EI and better
linearity IIRC.

Graham

 

[legg]

On Sun, 29 May 2005 15:47:35 -0400, "Engineer"
<fakeaddress@nowhere.net> wrote:

I am looking for two new or used high quality OPT's for push-pull
EL84's (6BQ5's) for a pair of 10 -15 watt monoblocs I am planning to
build (the "Mullard 5-10" circuit.) 8,000 ohms plate to plate, UL
type preferred (43% screen taps), but others considered.
Please email me at "analogdino 'at' rogers 'dot' com" (formatted
correctly.)
Ideally, I'd like to find these in the Greater Toronto Area (GTA),
Ontario, Canada, to avoid shipping costs, also customs costs if from
outside Canada, but this may not work out.
Thanks for all replies
Cheers,
Roger
GTA (Toronto), Canada.

Hammond Mfg still does these, available out of the 'Sonic catalogue
with a ~2wk lead time.

1608, 1650f, all have 40% screen taps.

Larger and potted types may also be available - never ordered them.

RL

 

[martin griffith]

On Mon, 30 May 2005 02:17:01 +0100, in sci.electronics.design Pooh
Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
snip

Btw - if you know your stuff you can design your own OPTs. Go for a
toroidal core and you'll get amazing bandwidth compared to EI and better
linearity IIRC.

I'm not a Toobe man, (although I *must* get my Quad II's up and

running one day.and rebuild my ESL's)

Any ref's on using a torroid for a OPT?

martin

"Wales is a big welsh-shaped rain collection device"

 

[Pooh Bear]

martin griffith wrote:

On Mon, 30 May 2005 02:17:01 +0100, in sci.electronics.design Pooh
Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
snip
Btw - if you know your stuff you can design your own OPTs. Go for a
toroidal core and you'll get amazing bandwidth compared to EI and better
linearity IIRC.

I'm not a Toobe man, (although I *must* get my Quad II's up and
running one day.and rebuild my ESL's)

I'm not really a toob man myself actually - but I learnt my early electronics
on them. Well.. kinda half and half with transistors too.

Any ref's on using a torroid for a OPT?

I knew someome who wound them. Having looked into it, the basic equations for
practical transformer design are quite simple but rarely well known.

Graham

 

[legg]

On Mon, 30 May 2005 06:52:04 +0200, martin griffith
<martingriffith@XXyahoo.co.uk> wrote:

On Mon, 30 May 2005 02:17:01 +0100, in sci.electronics.design Pooh
Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
snip
Btw - if you know your stuff you can design your own OPTs. Go for a
toroidal core and you'll get amazing bandwidth compared to EI and better
linearity IIRC.

I'm not a Toobe man, (although I *must* get my Quad II's up and
running one day.and rebuild my ESL's)

Any ref's on using a torroid for a OPT?

Check out Plitron, also in the GTA.

http://www.plitron.com/

RL

 

[Joerg]

Hello Graham,

Btw - if you know your stuff you can design your own OPTs. Go for a
toroidal core and you'll get amazing bandwidth compared to EI and better
linearity IIRC.

Or use pot cores. I also prefer toroids but that gets old when you have
to wind a gazillion turns onto them for the tube side.

Any ref's on using a torroid for a OPT?

I knew someome who wound them. Having looked into it, the basic equations for
practical transformer design are quite simple but rarely well known.

DC saturation is one concern, must stay away from that or things become
non-linear. Even in a push pull configuration there can be a residual DC
imbalance. Then there is the old habit of shooting for four times the
impedance at the lowest desired frequency. Doesn't always work if you
can't get enough BW for the upper end but with ferrites I found that to
be quite easy.

A good starting point is to see how much inductance a commercial OPT
with a good reputation affords.

Regards, Joerg

http://www.analogconsultants.com