Lynn wrote:

"ken scharf" wrote in message
...
Lynn wrote:

"Tio Pedro" wrote in message
...

"ken scharf" wrote in message
...
Even with it's 'hard vacuum' the 01 didn't have as good a
'getter' as later tubes and would arc over with more than 130 volts
or so. It was used as a transmitter before the type 202 tube
became widely available, but was a QRP thing, less than a watt input.

Will it have enough output to drive a 245?
I doubt it very seriously. I suppose if perfection was achieved in
matching
the 01's output to the 245's grid was possible (I, for one cannot do
it),
the losses would be enough to tickle it into the beginning of class C.

Ken's idea of going to class A might work, but the 245 would be running
in a very inefficient mode. There is one website showing a couple of
45's running in AB2 (how do you make a sub 2?) . Another website
has some interesting stuff with 245 chatter...... (you may have already
seen it, but just in case..........

http://www.antiquewireless.org/otb/29amp.htm

Old Chief Lynn, W7LTQ and a couple commercials
Actually AB1 would be better. My point was that you don't need
driving power until you start drawing grid current. As long as the
final doesn't draw grid current you are not loading down the
oscillator tube.
The question was would the 01A be able to drive a '45. My answer is
yes, but probably not to full output....meaning you won't be able to
supply much grid current

Yor're correct (as qualified, and as usual)
But the 01A is NOT a suitable (satisfactory?) driver
for a 45.

Happy New Year! (Will I see any of you on "Straight Key Night?(

Old Chief Lynn
Well the original question was would it work, and the answer is yes, but
not very well.

If you want to use tubes from the same era, then I'd pick a '27 for the
oscillator. The 27 is probably the first tube in a chain of evolution
that led up to the 1626 which was used for the same purpose in the ARC-5
transmitters. (though the 1625 is a heck of a lot easier to drive than
a '45!).

"ken scharf" wrote in message
...
Lynn wrote:

"ken scharf" wrote in message
...
Lynn wrote:

"Tio Pedro" wrote in message
...

"ken scharf" wrote in message
...
Even with it's 'hard vacuum' the 01 didn't have as good a 'getter'
as later tubes and would arc over with more than 130 volts or so. It
was used as a transmitter before the type 202 tube became widely
available, but was a QRP thing, less than a watt input.

Will it have enough output to drive a 245?
I doubt it very seriously. I suppose if perfection was achieved in
matching
the 01's output to the 245's grid was possible (I, for one cannot do
it),
the losses would be enough to tickle it into the beginning of class C.

Ken's idea of going to class A might work, but the 245 would be running
in a very inefficient mode. There is one website showing a couple of
45's running in AB2 (how do you make a sub 2?) . Another website
has some interesting stuff with 245 chatter...... (you may have already
seen it, but just in case..........

http://www.antiquewireless.org/otb/29amp.htm

Old Chief Lynn, W7LTQ and a couple commercials
Actually AB1 would be better. My point was that you don't need driving
power until you start drawing grid current. As long as the final
doesn't draw grid current you are not loading down the oscillator tube.
The question was would the 01A be able to drive a '45. My answer is
yes, but probably not to full output....meaning you won't be able to
supply much grid current

Yor're correct (as qualified, and as usual)
But the 01A is NOT a suitable (satisfactory?) driver
for a 45.

Happy New Year! (Will I see any of you on "Straight Key Night?(

Old Chief Lynn
Well the original question was would it work, and the answer is yes, but
not very well.

If you want to use tubes from the same era, then I'd pick a '27 for the
oscillator. The 27 is probably the first tube in a chain of evolution
that led up to the 1626 which was used for the same purpose in the ARC-5
transmitters. (though the 1625 is a heck of a lot easier to drive than a
'45!).


Right again, Ken. Those ARC-5's were sure a lot of fun when new ones
were $5 a crack! Used one for VFO on a BC-375 when the'375 was
$45, new, complete with all tuning units, dynamotor, antenna tuner,
antenna switch with RF ammeter, etc! Glory days of radio. If one didn't
mind a little "yoooooop de yoooop yoooop" on CW, the 211 in the
'375 in MOPA mode made a nice oscillator tube as well!

Old Chief Lynn

"ken scharf" wrote in message If you
want to use tubes from the same era, then I'd pick a '27 for the
oscillator. The 27 is probably the first tube in a chain of evolution
that led up to the 1626 which was used for the same purpose in the ARC-5
transmitters. (though the 1625 is a heck of a lot easier to drive than a
'45!).


I agree Ken. A lot of the early 30s rigs used a tetrode driving a 45.
I'll have to dig deeper. (Looking for retirement projects!)
I saw a neat design using a pair of 30s to drive a P-P pair of 33s in
one battery TX QST ran in 32 or so.

Pete

Tio Pedro wrote:
"ken scharf" wrote in message If you
want to use tubes from the same era, then I'd pick a '27 for the
oscillator. The 27 is probably the first tube in a chain of evolution
that led up to the 1626 which was used for the same purpose in the ARC-5
transmitters. (though the 1625 is a heck of a lot easier to drive than a
'45!).


I agree Ken. A lot of the early 30s rigs used a tetrode driving a 45.
I'll have to dig deeper. (Looking for retirement projects!)
I saw a neat design using a pair of 30s to drive a P-P pair of 33s in
one battery TX QST ran in 32 or so.

Pete


The 27 is an indirectly heated triode.
Except for the Kellog tube, it was the first one ever made.
(not talking prototypes though).

The 24A is a tetrode. Than might make a nice xtal oscillator to drive
the '45.

I've noticed a lot of the early designs from the late 20s
and early 30s used cathode bias (resistors to B- off the
directly heated filaments) on triode RF power
amplifiers. Were they adding a small amount of
bias to make them easier to drive? Or, for what reason?

One other thing, I don't remember seeing parasitic
suppressors on early rigs; did the need become
evident when TV became popular in the late
40s? I know those early TXs could take off in
the nether regions

Pete

Tio Pedro wrote:
I've noticed a lot of the early designs from the late 20s
and early 30s used cathode bias (resistors to B- off the
directly heated filaments) on triode RF power
amplifiers. Were they adding a small amount of
bias to make them easier to drive? Or, for what reason?

One other thing, I don't remember seeing parasitic
suppressors on early rigs; did the need become
evident when TV became popular in the late
40s? I know those early TXs could take off in
the nether regions

Pete


Cathode bias resistors on rf power amps were a safety measure.
If the tube lost drive with no bias it could draw enough plate current
to MELT the plate, especially if run with a high voltage near (or OVER!)
the maximum ratings. Of course, using a C- supply would serve the
same purpose. Many rigs actually used batteries. Since the grid
current flowed in the reverse direction from the battery, a C battery
would actually be RECHARGED in normal use, so they tended to last a long
time.

Parasitic suppressors were not used in the early days since no one was
on the vhf frequencies there wasn't anybody to interfere with!

Actually, parasitic oscillation might show up in other ways making the
amplifier hard to load, and if detected this way the builder would take
steps to stabilize the circuit.

"ken scharf" wrote in message
...

Cathode bias resistors on rf power amps were a safety measure.
If the tube lost drive with no bias it could draw enough plate current to
MELT the plate, especially if run with a high voltage near (or OVER!) the
maximum ratings. Of course, using a C- supply would serve the
same purpose. Many rigs actually used batteries. Since the grid current
flowed in the reverse direction from the battery, a C battery would
actually be RECHARGED in normal use, so they tended to last a long time.

Parasitic suppressors were not used in the early days since no one was on
the vhf frequencies there wasn't anybody to interfere with!

Actually, parasitic oscillation might show up in other ways making the
amplifier hard to load, and if detected this way the builder would take
steps to stabilize the circuit.


The reason I asked this that Bill (Exray) ran
into some problems with his early TX project.
The old neon lamp trick showed
the presence of VHF parasitics, and adding suppressors
improved a few of the problems he was having.

We were discussing the use of cathode bias resistors, and
I couldn't quite grasp the reason for using them, but
tube protection makes sense.

Pete