Uwe wrote in message ...
With the help of some folks here I did troubleshoot my AC-1 tube transmitter
(using a 6V6) and got it working somehow. Since I passed my code test and
had my first QSO using the transmitter and boy was that exciting.

But questions remain.

I monitor the output signal on my scope and notice that right after key down
the waveform contract just a bit and the tone changes pitch. I guess this is
called chirp. I normally use B+ 200V.
If I increase the voltage lets say to 300V this effect becomes much more
pronounced.
I still use an external bench supply capable of much higher currents and I
don't think it is a power supply weakness. In fact putting a VOM on the
supply line shows no sag in my supply voltage.

How can I minimize this and especially keep it from becoming more severe at
higher outputs.


Also, the circuit diagram for the tranmitter did not state the coil diameter
of the pi network. The pi network still has me scratching my head. Coils
with slight variations in diameter give dramatically different results.

Also changing the air cap with one of an identical range can have a vast
effect, which surprised me. Is this the "real world components" versus the
theory???

Uwe

----------------

Congratulations!

I still have my original Ameco AC-1 15-Watt CW transmitter, completely
intact with all original parts and accessories, all in perfect
like-new condition, and a copy of the whole manual. If you want me to
look at or measure anything for you (e.g. the coil you mentioned?),
just let me know. I am at tomg AT fullnet.com .

By the way, I think that I paid $14.98 for the Ameco AC-1 kit, new,
back in about 1969. I built it, tested it, and then never used it. And
I HAVE had people offer me hundreds of dollars for it, "out of the
blue", several times over the last few years. There's a picture of it
on my webpage (see URL, below).

Good luck!

Regards,

Tom Gootee

http://www.fullnet.com/u/tomg

-----------------------------

Only now do I have a chance to react to some of the suggestions...

I guess one poster here is right, I will just have to fiddle a bit more
with the pi network (since at the B+ voltages suggested here my plate
current would be way high) and I will have to live with the chirp. Nobody
has complained yet anyways and maybe the chirp is worse in my receiver than
on the air, as someone here suggested. By the way I use a Icom R75 for a
receiver and switch the antenna off during transmit-still plenty of a signal
seems to get into the receiver anyways.

By the way, I see suggestions how to just "stretch" crystal controlled
oscillators a bit by adding a suitable coil and capacitor in series with the
crystal. Has anybody tried that with the AC-1??
Would be nice to be able to get out of the ways of some of the big power
guys.
Any suggestion would be welcome.

Uwe

Only now do I have a chance to react to some of the suggestions...

I guess one poster here is right, I will just have to fiddle a bit more
with the pi network (since at the B+ voltages suggested here my plate
current would be way high) and I will have to live with the chirp. Nobody
has complained yet anyways and maybe the chirp is worse in my receiver than
on the air, as someone here suggested. By the way I use a Icom R75 for a
receiver and switch the antenna off during transmit-still plenty of a signal
seems to get into the receiver anyways.

By the way, I see suggestions how to just "stretch" crystal controlled
oscillators a bit by adding a suitable coil and capacitor in series with the
crystal. Has anybody tried that with the AC-1??
Would be nice to be able to get out of the ways of some of the big power
guys.
Any suggestion would be welcome.

Uwe

"Uwe" wrote in message
...

By the way, I see suggestions how to just "stretch" crystal controlled
oscillators a bit by adding a suitable coil and capacitor in series with
the
crystal. Has anybody tried that with the AC-1??
Would be nice to be able to get out of the ways of some of the big power
guys.
Any suggestion would be welcome.

An rf choke or variable inductor of between 7 and 20 uH in series with a
variable cap of about 200 pF in series with a crystal, will pull the
frequency. It's called a variable crystal oscillator or VXO. You're probably
using FT-243 crystals, though, and they don't pull very far.

I have to say this again: Time to put this thing on the shelf. For the time
and trouble you are putting into it you could build a solid-state rig that
would put out as much power, have a VFO and not contain life-threatening
voltages.

73,

"PM"

"Uwe" wrote in message
...

By the way, I see suggestions how to just "stretch" crystal controlled
oscillators a bit by adding a suitable coil and capacitor in series with
the
crystal. Has anybody tried that with the AC-1??
Would be nice to be able to get out of the ways of some of the big power
guys.
Any suggestion would be welcome.

An rf choke or variable inductor of between 7 and 20 uH in series with a
variable cap of about 200 pF in series with a crystal, will pull the
frequency. It's called a variable crystal oscillator or VXO. You're probably
using FT-243 crystals, though, and they don't pull very far.

I have to say this again: Time to put this thing on the shelf. For the time
and trouble you are putting into it you could build a solid-state rig that
would put out as much power, have a VFO and not contain life-threatening
voltages.

73,

"PM"

"Paul_Morphy" wrote in message
...

"
I have to say this again: Time to put this thing on the shelf. For the
time
and trouble you are putting into it you could build a solid-state rig that
would put out as much power, have a VFO and not contain life-threatening
voltages.

73,

"PM"

I suggest he put all his radios on a shelf, and get a cell phone. No
dangerous
RF levels, no deadly voltages...

NOT

"Paul_Morphy" wrote in message
...

"
I have to say this again: Time to put this thing on the shelf. For the
time
and trouble you are putting into it you could build a solid-state rig that
would put out as much power, have a VFO and not contain life-threatening
voltages.

73,

"PM"

I suggest he put all his radios on a shelf, and get a cell phone. No
dangerous
RF levels, no deadly voltages...

NOT

" Uncle Peter" wrote in message
news:vQnbc.9210$pM1.6556@lakeread06...

I suggest he put all his radios on a shelf, and get a cell phone. No
dangerous
RF levels, no deadly voltages...

NOT

Gee, Unc, have a tough week? : I don't want him to give up radio, I just
don't think an Ameco AC-1 is worth the trouble. I didn't want one when I was
15 and they were new, and I wouldn't waste my time fiddling with one now.

73,

"PM"

" Uncle Peter" wrote in message
news:vQnbc.9210$pM1.6556@lakeread06...

I suggest he put all his radios on a shelf, and get a cell phone. No
dangerous
RF levels, no deadly voltages...

NOT

Gee, Unc, have a tough week? : I don't want him to give up radio, I just
don't think an Ameco AC-1 is worth the trouble. I didn't want one when I was
15 and they were new, and I wouldn't waste my time fiddling with one now.

73,

"PM"

in article ,
Paul_Morphy at wrote on 4/2/04 19:37:


"Uwe" wrote in message
...

By the way, I see suggestions how to just "stretch" crystal controlled
oscillators a bit by adding a suitable coil and capacitor in series with
the
crystal. Has anybody tried that with the AC-1??
Would be nice to be able to get out of the ways of some of the big power
guys.
Any suggestion would be welcome.

An rf choke or variable inductor of between 7 and 20 uH in series with a
variable cap of about 200 pF in series with a crystal, will pull the
frequency. It's called a variable crystal oscillator or VXO. You're probably
using FT-243 crystals, though, and they don't pull very far.

I have to say this again: Time to put this thing on the shelf. For the time
and trouble you are putting into it you could build a solid-state rig that
would put out as much power, have a VFO and not contain life-threatening
voltages.

73,

"PM"




Thank you Paul, since I have a crystal socket on the front of the little box
it ought to relatively simple to try out this scheme and see if I can't get
a "range" out of this one frequency device.
And yes you are right, I have a few FT 243 but others are on order.

It is my experience that whatever I do around the crystal it stops it from
oscillating but I will try your suggestion nevertheless.


As to high voltages I grew up in Europe where I got used to (and sometimes
shocked by) 220V and now I can't let go ...

Paul, your concern for a new ham is very much appreciated, but ever since I
wanted to be a ham I wanted to know code and I wanted to build my own gear,
preferably tube gear.
It gets cold in Maine and these at least warm your hands in between QSO's.
I will probably never own an SSB or a phone radio and as somebody mentioned
here, for communication we have other solutions. For me being a new ham
opens a world of learning and tinkering possibilities with the side effect
of being able to communicate with others via code.

And I think I can learn a whole lot by working on this transmitter. And I
will need all the learning I can get because someone mentioned a different,
slightly more sophisticated tube transmitter using two 807's in the final. I
would love to build that and appreciate more info on the device.

And Paul, lest you get the impression I hate silicon, I just finished a
Rockmite-very cute.


Thanks again and keep the advice and help coming.

Greetings from Maine

Uwe