Re: The Duggled Method of using PP OPT to give SE outpur was pentode amplifiers

In article <1194309189.479990.68830@xxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Multi-grid <pentode@xxxxxxxxxxxx> wrote:


Well John I've made it plain that I am not going to hand this out. It
isn't any fun for you, and it is too much work for me. So get with it
if you can. Just remember, I know your belief or understading isn't
required, I've seen it in action.

You have yet to do anything which deserves my indulgence of your lazy
and closed mind. Behave yourself.
cheers,
Douglas

I'll give you a hint: Think about the power, you've come to an
incorrect conclusion. See if you can find it.


Since you are not naming the tube used in your amplifier, let's run the
numbers for a popular audiophile tube, the 300B, to see how unworkable
your idea is.

The filament supply for the following calculations is assumed to be a
5.0 volt DC source and no inductor is assumed in the filament circuit.

The 300B filament has the following Characteristics

Vf = 5.0 volts
If = 1.2 amps

This gives the following for the filament resistance.

Rf = 5.0/1.2 = 4.1667 Ohms

For the example I choose the following operating point from the 300B
data ***.

Va = 350 volts
Vg = -71 volts
Ia = 80 mA
Rl = 2,200 Ohms
Po = 9.6 Watts

With the 1.2 amp filament current and the quiescent anode current of 80
mA, the required turns ratio between the primary and the "special
winding" becomes.

1,200/80 = 15:1

With a filament resistance of 4.1667 Ohms and a turns ratio of 15:1, the
filament resistance reflected to primary side of the transformer becomes.

4.1667 x (15^2) = 937.5 Ohms

Without even connecting a loudspeaker load to the transformer secondary,
the load on the 300B tube is already only half of the desired load
resistance of 2,200 Ohms. The lower than desired load reduces the audio
power the tube can generate, and a large percentage of the audio power
actually generated by the tube is shunted into the tubes heater, with
little left over for the loudspeaker. Other operating conditions give
slightly better results, but the audio load from the filament alone was
still less than the desired load for the tube with all the operating
points I tried.

The results with the hypothetical transmitting tube I tried, which could
easily supply 50 Watts in a normal SE circuit, were essentially
identical to the 300B results presented above.

The above example should illustrate to anyone still following this
discussion that the idea as you have described it simply doesn't work.

The obvious conclusion is that you have something to hide and are
playing some kind game with your claim that this is a workable scheme,
while at the same time refusing to give even the simplest details of the
circuit, like what tube was used.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
.