[patrick jankowiak]

This amp showed up. Gives an idea what it took to make 200 watts of
audio in 1940.

http://www.bunkerofdoom.com/Norton1/index.html

There is no model #, but if anyone knows where there's a manual with
specs and schematic, it would be useful. I have already drawn the shcem.
for the preamp and driver stage so you can see it.

All Kenyon iron too.

PJ

[Patrick Turner]

patrick jankowiak wrote:

This amp showed up. Gives an idea what it took to make 200 watts of
audio in 1940.

http://www.bunkerofdoom.com/Norton1/index.html

There is no model #, but if anyone knows where there's a manual with
specs and schematic, it would be useful. I have already drawn the shcem.
for the preamp and driver stage so you can see it.

All Kenyon iron too.

PJ

If you want to make 200W of power with tubes now,
and you wish to use triodes, then 4 x 845 is a nice way to do it
and you'd need a similar sized chassis for at least the power amp as in
1940 if you like to to things right.

I recently built a pair of class A 55W SET amps using 2 x 845 per amp,
and I used all the weight of iron they used in 1940 and perhaps more per
watt, being SE.

2 x 845 are also capable of giving 55W class A in PP,
with Pda at idle = 78W per 845, same as with SE use.
If one lowered the Pda to about 60W each tube, then you'd get about 40W
max of class A,
but maybe 100W in class AB1.

But today we'd use silicon rectifiers and voltage doublers to make the
B+
required for such amps, so the PSU chassis would be a lot smaller and
simpler than in 1940.
And the chokes for filters would now be smaller because we have reliable
electrolytic capacitors of enormous
capacitance values and small size, much better than the huge paper in
oil types they used.


Patrick Turner.

[patrick jankowiak]

Patrick Turner wrote:

patrick jankowiak wrote:
This amp showed up. Gives an idea what it took to make 200 watts of
audio in 1940.

http://www.bunkerofdoom.com/Norton1/index.html

There is no model #, but if anyone knows where there's a manual with
specs and schematic, it would be useful. I have already drawn the shcem.
for the preamp and driver stage so you can see it.

All Kenyon iron too.

PJ

If you want to make 200W of power with tubes now,
and you wish to use triodes, then 4 x 845 is a nice way to do it
and you'd need a similar sized chassis for at least the power amp as in
1940 if you like to to things right.

I recently built a pair of class A 55W SET amps using 2 x 845 per amp,
and I used all the weight of iron they used in 1940 and perhaps more per
watt, being SE.

2 x 845 are also capable of giving 55W class A in PP,
with Pda at idle = 78W per 845, same as with SE use.
If one lowered the Pda to about 60W each tube, then you'd get about 40W
max of class A,
but maybe 100W in class AB1.

But today we'd use silicon rectifiers and voltage doublers to make the
B+
required for such amps, so the PSU chassis would be a lot smaller and
simpler than in 1940.
And the chokes for filters would now be smaller because we have reliable
electrolytic capacitors of enormous
capacitance values and small size, much better than the huge paper in
oil types they used.


Patrick Turner.

I was given a bunch of NOS 838's with the amp. I think the PP 6B4 driver
can push a pair of the zero-bias class-B 838's, will be interesting to
find out if it can push two pair, I have my doubts since a pair takes
7.5 watts and there's a matching or driver xfmr turns ratio issue due to
peak g-g voltage requirement differences.

Right now I am ass-u-ming 1250V on the HV side, not tested the HVPS yet.
I am also ass-u-ming the amp takes 845's because it's what I was told by
an old fart, and they usually know.

I will probably apply some bias with 838's as the 845 wants these
conditions: 40mA resting per pair (4W/tube), -225V bias, 400V Pk. g-g- volts

The 838 at 1250V runs 148Ma per pair (93W/tube) at zero bias and 200V
Pk. g-g volts.

It's funny the tube manual calls the 845 operation class AB and the 838
class B, even though it's obvious the resting current is supposed to be
much lower with the 845's.

As if to recant this, the TT-3 RCA manual does give as an afterthought a
set of "special" conditions for the 838 for "low distortion 4%" of
1250V plate, -15V bias, 50mA resting current(pair). 210V peak g-g volts.
TT-3 has no curves for the 838's but refers the designer to the 805 curves.

From the curves, the 200mA max-signal plate current of the 845's might
be obtained from 838's with the -15V bias conditions by driving only
150V pk g-g volts.

Well my suppositions above my all be hogwash. The proof if any will be
in the test hopefully in a couple weeks. I have to replace a few caps in
the driver and then check the other two chassis out.

;;

If building new I still might use 866's or the like with a FWCT
transformer but I am certainly open to options. I like the way MV
rectifiers look and they are also still alive after lightning etc. I
prefer FWB or FWCT for my large RF stuff because it has better
regulation when old iron is used than with doublers+old_iron. For me it
depends on what's available and I don't mind old parts as long as they
are good. I like the way it looks with lots of iron and oil caps. I
don't mind doing it the old way if space and weight is not a critical
issue. I would have no objection to exchanging the small-value oil cap
for a big stack of electrolytics since the voltage is certainly less
than 1500 in the Norton.

Another piece of gear uses a mercury FWCT with 8uF/4H/32uF oil filter
for a pair of 3-500Z's at 3000VDC now (in a transmitter) and have only
6V p-p ripple at 600mA which is close to the full load condition. The
bleeder draws about 120mA of this. The regulation is also better with
the choke and a small input capacitor than with just a big C bank out
there.

I am not disputing the value of modern components. Certainly if I had a
modern PWD or equivalent 2500V 1A plate transformer with a secondary
resistance of 30 ohms instead of the old 240 ohm 5KVCT pole pig core
then it might be as good or better. But you know what they say, ham
radio operators are the cheapest people alive and also like to use what
is on hand or otherwise free/cheap.

Patrick Jankowiak

[Patrick Turner]

patrick jankowiak wrote:

Patrick Turner wrote:

patrick jankowiak wrote:
This amp showed up. Gives an idea what it took to make 200 watts of
audio in 1940.

http://www.bunkerofdoom.com/Norton1/index.html

There is no model #, but if anyone knows where there's a manual with
specs and schematic, it would be useful. I have already drawn the shcem.
for the preamp and driver stage so you can see it.

All Kenyon iron too.

PJ

If you want to make 200W of power with tubes now,
and you wish to use triodes, then 4 x 845 is a nice way to do it
and you'd need a similar sized chassis for at least the power amp as in
1940 if you like to to things right.

I recently built a pair of class A 55W SET amps using 2 x 845 per amp,
and I used all the weight of iron they used in 1940 and perhaps more per
watt, being SE.

2 x 845 are also capable of giving 55W class A in PP,
with Pda at idle = 78W per 845, same as with SE use.
If one lowered the Pda to about 60W each tube, then you'd get about 40W
max of class A,
but maybe 100W in class AB1.

But today we'd use silicon rectifiers and voltage doublers to make the
B+
required for such amps, so the PSU chassis would be a lot smaller and
simpler than in 1940.
And the chokes for filters would now be smaller because we have reliable
electrolytic capacitors of enormous
capacitance values and small size, much better than the huge paper in
oil types they used.


Patrick Turner.

I was given a bunch of NOS 838's with the amp. I think the PP 6B4 driver
can push a pair of the zero-bias class-B 838's, will be interesting to
find out if it can push two pair, I have my doubts since a pair takes
7.5 watts and there's a matching or driver xfmr turns ratio issue due to
peak g-g voltage requirement differences.

Right now I am ass-u-ming 1250V on the HV side, not tested the HVPS yet.
I am also ass-u-ming the amp takes 845's because it's what I was told by
an old fart, and they usually know.

I will probably apply some bias with 838's as the 845 wants these
conditions: 40mA resting per pair (4W/tube), -225V bias, 400V Pk. g-g- volts

The 838 at 1250V runs 148Ma per pair (93W/tube) at zero bias and 200V
Pk. g-g volts.

It's funny the tube manual calls the 845 operation class AB and the 838
class B, even though it's obvious the resting current is supposed to be
much lower with the 845's.

As if to recant this, the TT-3 RCA manual does give as an afterthought a
set of "special" conditions for the 838 for "low distortion 4%" of
1250V plate, -15V bias, 50mA resting current(pair). 210V peak g-g volts.
TT-3 has no curves for the 838's but refers the designer to the 805 curves.

From the curves, the 200mA max-signal plate current of the 845's might
be obtained from 838's with the -15V bias conditions by driving only
150V pk g-g volts.

Well my suppositions above my all be hogwash. The proof if any will be
in the test hopefully in a couple weeks. I have to replace a few caps in
the driver and then check the other two chassis out.

1,250V for Ea is about right for class AB1 for 845, but
for 838? or 805 you'd need to drive grid current for AB2,
and Ra is higher.

845 is the best IMHO.

PP grid drive for 2 x 845 will need about 300Vrms g-g,
so usually ppl have used a couple of PP EL34 in triode with a 1:1
tranny, with two secs
for bias application to each 845 if fixed bias is used.



;;

If building new I still might use 866's or the like with a FWCT
transformer but I am certainly open to options. I like the way MV
rectifiers look and they are also still alive after lightning etc. I
prefer FWB or FWCT for my large RF stuff because it has better
regulation when old iron is used than with doublers+old_iron. For me it
depends on what's available and I don't mind old parts as long as they
are good. I like the way it looks with lots of iron and oil caps. I
don't mind doing it the old way if space and weight is not a critical
issue. I would have no objection to exchanging the small-value oil cap
for a big stack of electrolytics since the voltage is certainly less
than 1500 in the Norton.

If it doesn't cost much and you have the iron, may as well
stay with 1940 techniques.

Another piece of gear uses a mercury FWCT with 8uF/4H/32uF oil filter
for a pair of 3-500Z's at 3000VDC now (in a transmitter) and have only
6V p-p ripple at 600mA which is close to the full load condition. The
bleeder draws about 120mA of this. The regulation is also better with
the choke and a small input capacitor than with just a big C bank out
there.

Choke input reg depends on the 'on' resistance of the diodes, PT tranny
winding R,
and the choke winding R.

With modern Si diodes, its easy to have a capacitor input B+ rail that
has better
regulation between 100mA dc and 1A dc than anything with a choke input.
The choke input allows low peak charging currents to flow, so vacuum
tube rectifiers
can be used.




I am not disputing the value of modern components. Certainly if I had a
modern PWD or equivalent 2500V 1A plate transformer with a secondary
resistance of 30 ohms instead of the old 240 ohm 5KVCT pole pig core
then it might be as good or better. But you know what they say, ham
radio operators are the cheapest people alive and also like to use what
is on hand or otherwise free/cheap.

Those of us in hi-fi audio land like to see hum at the CT measured in
mV.
6Vp-p seems a lot.

But with ham gear, you are not looking for commercial broadcast station
standard
AM fidelity of say less than 2% THD at near full modulation for a 1kHz
signal.
So hams settle for a lot less with SSB etc.

The keenest hams don't cut corners, and build to the same standards as
the best broadcast stations.
Its a matter of pride.

These days if I tune into 80M or 40M, there are all these old guys of 80
yabbering on and bloody on about the operations they've had, and the
doctors, and how long they were
in hospital, and frankly, they are somewhat tiresome after awhile.
When they eventually finish talking, then they
let someone else hold forth for what seems like an eternity.

I like these very free telegrams we can type to each other though.

Somehow, the attractions of the Internet seem to have stolen what
interest young folks
might have had away from learning heaps about radio, and setting up a
radio station.
Then to build a decent rotating antenna in the middle of suburbia and
getting the approvals for it
and putting up with complaints from neighbours about TVI is all too
much, so to be a ham, its best
you live well out of town IMHO.

Patrick Turner.

Patrick Jankowiak