I recently put together the old AC-1 tube transmitter for the 40 m band.
And it works, kind of.

It oscillates nicely but does not have any power.
I know, it is not supposed to have much power but this one is weaker than
weak, the output couldn't drive any antenna.

I was wondering if there are AC-1 owners/builders around here who could
suggest a few things to try, who are knowlegable about this thing.

73 Uwe

It oscillates nicely but does not have any power.
I know, it is not supposed to have much power but this one is weaker than
weak, the output couldn't drive any antenna.

I was wondering if there are AC-1 owners/builders around here who could
suggest a few things to try, who are knowlegable about this thing.

Did you do any voltage or current measurements? While I haven't played with a
real AC-1, I've built many similar 6V6 single tube transmitters. I have the
circuit for the AC-1, and it looks pretty similar to some I've built. First
thing to do is measure the B+ to the plate and screen. Next, open the plate
feed where it connects to the filter capacitor and insert a milliameter. With
the "load" capacitor at maximum, adjust the "tune" capacitor for minimum
current. Take a set of readings and get back to me.

Doug Moore KB9TMY (Formerly K6HWY)

It oscillates nicely but does not have any power.
I know, it is not supposed to have much power but this one is weaker than
weak, the output couldn't drive any antenna.

I was wondering if there are AC-1 owners/builders around here who could
suggest a few things to try, who are knowlegable about this thing.

Did you do any voltage or current measurements? While I haven't played with a
real AC-1, I've built many similar 6V6 single tube transmitters. I have the
circuit for the AC-1, and it looks pretty similar to some I've built. First
thing to do is measure the B+ to the plate and screen. Next, open the plate
feed where it connects to the filter capacitor and insert a milliameter. With
the "load" capacitor at maximum, adjust the "tune" capacitor for minimum
current. Take a set of readings and get back to me.

Doug Moore KB9TMY (Formerly K6HWY)

In article , Uwe
writes:

I recently put together the old AC-1 tube transmitter for the 40 m band.

From a kit, or from your own collection of parts?

It oscillates nicely but does not have any power.
I know, it is not supposed to have much power but this one is weaker than
weak, the output couldn't drive any antenna.

How are you tuning it up and measuring the output power?

I was wondering if there are AC-1 owners/builders around here who could
suggest a few things to try, who are knowlegable about this thing.

First thing is the voltages and currents, as already suggested. Then there's
the size of the coil and your tuneup technique.

What sort of load do you have connected to the output?

73 de Jim, N2EY

In article , Uwe
writes:

I recently put together the old AC-1 tube transmitter for the 40 m band.

From a kit, or from your own collection of parts?

It oscillates nicely but does not have any power.
I know, it is not supposed to have much power but this one is weaker than
weak, the output couldn't drive any antenna.

How are you tuning it up and measuring the output power?

I was wondering if there are AC-1 owners/builders around here who could
suggest a few things to try, who are knowlegable about this thing.

First thing is the voltages and currents, as already suggested. Then there's
the size of the coil and your tuneup technique.

What sort of load do you have connected to the output?

73 de Jim, N2EY

Doug, thank you soo much for your email, you just fixed my transmitter.
Well, sort of.

As I tried to do what you had suggested I noticed that someone (I could
never have done such a thing) had connected the 18k resistor (which is
connected to grid # 2 on one end) on the wrong end of the choke.
I guess that choked it.

Now we don't just have oscillations, there is even a little bite to it.

I am relatively new to all this and I am just putting together the necessary
equipment. So a 50 resistor serves as my dummy load and a meter connected to
the dummy load indicates around 10 volts RMS. If I did my homework that
would indicate around 2 watt output. All this at B+ of 200v and an anode
current of about 35mA (I am running the transmitter off an adjustable bench
tube power supply at this point).

Does all this compare with the numbers you get with your transmitter??
I will need to build a power supply for the final version and would be
interested to know what you use for B+. In order to get 5 Watts I would have
to crank up the B+ quite a bit.

Actually I don't care at this point since I am still practicing for my code
exam, so I can't even use the transmitter right now.

How do you monitor your transmitting tone with a device like this.


Doug, thanks again, I am quite happy now


Uwe

KB1JOW





in article , Troglodite at
wrote on 3/11/04 14:26:

It oscillates nicely but does not have any power.
I know, it is not supposed to have much power but this one is weaker than
weak, the output couldn't drive any antenna.

I was wondering if there are AC-1 owners/builders around here who could
suggest a few things to try, who are knowlegable about this thing.

Did you do any voltage or current measurements? While I haven't played with a
real AC-1, I've built many similar 6V6 single tube transmitters. I have the
circuit for the AC-1, and it looks pretty similar to some I've built. First
thing to do is measure the B+ to the plate and screen. Next, open the plate
feed where it connects to the filter capacitor and insert a milliameter. With
the "load" capacitor at maximum, adjust the "tune" capacitor for minimum
current. Take a set of readings and get back to me.

Doug Moore KB9TMY (Formerly K6HWY)

Doug, thank you soo much for your email, you just fixed my transmitter.
Well, sort of.

As I tried to do what you had suggested I noticed that someone (I could
never have done such a thing) had connected the 18k resistor (which is
connected to grid # 2 on one end) on the wrong end of the choke.
I guess that choked it.

Now we don't just have oscillations, there is even a little bite to it.

I am relatively new to all this and I am just putting together the necessary
equipment. So a 50 resistor serves as my dummy load and a meter connected to
the dummy load indicates around 10 volts RMS. If I did my homework that
would indicate around 2 watt output. All this at B+ of 200v and an anode
current of about 35mA (I am running the transmitter off an adjustable bench
tube power supply at this point).

Does all this compare with the numbers you get with your transmitter??
I will need to build a power supply for the final version and would be
interested to know what you use for B+. In order to get 5 Watts I would have
to crank up the B+ quite a bit.

Actually I don't care at this point since I am still practicing for my code
exam, so I can't even use the transmitter right now.

How do you monitor your transmitting tone with a device like this.


Doug, thanks again, I am quite happy now


Uwe

KB1JOW





in article , Troglodite at
wrote on 3/11/04 14:26:

It oscillates nicely but does not have any power.
I know, it is not supposed to have much power but this one is weaker than
weak, the output couldn't drive any antenna.

I was wondering if there are AC-1 owners/builders around here who could
suggest a few things to try, who are knowlegable about this thing.

Did you do any voltage or current measurements? While I haven't played with a
real AC-1, I've built many similar 6V6 single tube transmitters. I have the
circuit for the AC-1, and it looks pretty similar to some I've built. First
thing to do is measure the B+ to the plate and screen. Next, open the plate
feed where it connects to the filter capacitor and insert a milliameter. With
the "load" capacitor at maximum, adjust the "tune" capacitor for minimum
current. Take a set of readings and get back to me.

Doug Moore KB9TMY (Formerly K6HWY)

So a 50 resistor serves as my dummy load and a meter connected to
the dummy load indicates around 10 volts RMS. If I did my homework that
would indicate around 2 watt output. All this at B+ of 200v and an anode
current of about 35mA (I am running the transmitter off an adjustable bench
tube power supply at this point).

Does all this compare with the numbers you get with your transmitter??
I will need to build a power supply for the final version and would be
interested to know what you use for B+. In order to get 5 Watts I would have
to crank up the B+ quite a bit.

Actually I don't care at this point since I am still practicing for my code
exam, so I can't even use the transmitter right now.

How do you monitor your transmitting tone with a device like this.

I run my 6V6's at about 325 volts on the plate, 250 on the screen. The plate is
loaded to about 40ma, which is about 13 watts input. You can push it beyond
this, but there's really no point since you have to quadruple your power to
gain one S unit on the receiving end. You'll get about 8 watts out which is
fine. If you want something heftier, you can go to a 6L6, 807 or 6146 tube.
There is a compromise with single tube transmitters though, as the power goes
up they tend to chirp, that is, the frequency slides a bit as they are keyed.
It's not objectionable on the 6V6 transmitters, which is why I favor this power
level.

I started out in 1954 with a surplus ARC-5 receiver and a simple 6V6
transmitter. With it I gained code proficiency and managed to work 28 states
before my Novice licence expired. (They were only good for a year back then.)

For monitoring, you can just use your receiver with the antenna disconnected,
or you can construct any number of monitor devices which you will find in the
ARRL handbook. You can get more sophisticated but you don't have to. There is a
special satisfaction in communicating with very simple equipment.

Doug Moore KB9TMY

So a 50 resistor serves as my dummy load and a meter connected to
the dummy load indicates around 10 volts RMS. If I did my homework that
would indicate around 2 watt output. All this at B+ of 200v and an anode
current of about 35mA (I am running the transmitter off an adjustable bench
tube power supply at this point).

Does all this compare with the numbers you get with your transmitter??
I will need to build a power supply for the final version and would be
interested to know what you use for B+. In order to get 5 Watts I would have
to crank up the B+ quite a bit.

Actually I don't care at this point since I am still practicing for my code
exam, so I can't even use the transmitter right now.

How do you monitor your transmitting tone with a device like this.

I run my 6V6's at about 325 volts on the plate, 250 on the screen. The plate is
loaded to about 40ma, which is about 13 watts input. You can push it beyond
this, but there's really no point since you have to quadruple your power to
gain one S unit on the receiving end. You'll get about 8 watts out which is
fine. If you want something heftier, you can go to a 6L6, 807 or 6146 tube.
There is a compromise with single tube transmitters though, as the power goes
up they tend to chirp, that is, the frequency slides a bit as they are keyed.
It's not objectionable on the 6V6 transmitters, which is why I favor this power
level.

I started out in 1954 with a surplus ARC-5 receiver and a simple 6V6
transmitter. With it I gained code proficiency and managed to work 28 states
before my Novice licence expired. (They were only good for a year back then.)

For monitoring, you can just use your receiver with the antenna disconnected,
or you can construct any number of monitor devices which you will find in the
ARRL handbook. You can get more sophisticated but you don't have to. There is a
special satisfaction in communicating with very simple equipment.

Doug Moore KB9TMY

Uwe wrote in message ...
So a 50 resistor serves as my dummy load and a meter connected to
the dummy load indicates around 10 volts RMS. If I did my homework that
would indicate around 2 watt output.

E squared over R, yes, two watts is about right.

All this at B+ of 200v and an anode
current of about 35mA (I am running the transmitter off an adjustable bench
tube power supply at this point).

Seven watts input, two watts output is a bit low. How are you
adjusting the controls?

Does all this compare with the numbers you get with your transmitter??
I will need to build a power supply for the final version and would be
interested to know what you use for B+. In order to get 5 Watts I would have
to crank up the B+ quite a bit.

IIRC that design called for 300 or 350 volts B+, which would work out
to 15 watts or so input. The output network is not optimized for 200
volts B+, and in addition the efficieny is better with more plate
voltage.

Actually I don't care at this point since I am still practicing for my code
exam, so I can't even use the transmitter right now.

What study methods are you using?

How do you monitor your transmitting tone with a device like this.

Several ways:

1) Connect an audio oscillator to the key so that both it and the
transmitter are keyed at the same time. This can be a bit tricky
because the two circuits must not interact.

2) Listen to the transmitted signal on your receiver when
transmitting. This requires that you have a way of reducing the
receiver gain while transmitting, but not completely silencing the
receiver. What sort of receiver do you have to go with the
transmitter?

73 de Jim, N2EY