flipper wrote:
On Fri, 5 Aug 2005 14:45:06 -0400, "Eike Lantzsch, ZP6CGE"
wrote:
flipper wrote:
On Fri, 05 Aug 2005 16:40:30 GMT, (Don Pearce)
wrote:
On Fri, 05 Aug 2005 11:15:17 -0500, flipper wrote:
I just received a pair of SE OPTs that were claimed to be from a
stereo console with 6BQ5 outputs. So far so good as that's precisely
what I wanted to build.
Problem is, when I put 120.7 AC on the primary I get 1.9VAC out for a
ratio of 63.5/1, which comes to roughly 32k/8 ohms, or 16k/4 ohms, and
from what little I know of 6BQ5 characteristics that doesn't make any
sense to me. I mean, 8K would be good but a console with 2 ohm
speakers?
Physically, the core is gapped with (actual core) dimensions of 2.25
inch wide by 1.74 inch high and .75 thick. Mounting is 2.75 centers
with 10A15-10 marked on the frame. Primary and secondary, 4 wires
total. No taps.
Does anyone have information, or an educated guess, on what these
transformers may really be or what I'm missing about 6BQ5s with such a
high OPT impendence?
These transformers sound an awful long way from optimum for a 6BQ5. I
think you were fed some duff gen.
That was my first impression too but I wondered if maybe there's some
'secret' I'm unaware of.
Is there some other tube these things would be a fit for?
ECL80 Ra~17k, B+=250V, but it only produces 1.4W
It can be had cheap however.
Kind regards, Eike
Thanks. I made a note of it.
I'm wondering, wouldn't the 6BQ5 do about the same thing with the same
Ra and B+?
I'm also wondering if I could run the 6BQ5 with a much higher B+ and
correspondingly lower Ia through that transformer. Say 550 and 17ma.
(Actually 5V6 or 12AQ5 is what I had in mind as I can get those for 2
bucks and I already have the sockets)
Well, here we have to draw a line! - a loadline that is ;-)
AFAIR 6BQ5 can be used with far higher Ra and up to 400V. Less Pout
less THD. That is left as an exercise for the reader. At least until
I have time to draw the line.
If it *sounds* good - I can't tell.
Kind regards, Eike
--
Lions go to absurd lengths to retain the posession of their skins.
- Stewart Edward White 1913