In article ,
"Paul_Morphy" writes:

"Uwe" wrote in message
...

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.

I think 200 V is enough.

Not really. The original design uses about 300-325 volts.

Someone here probably knows what the AC-1 design
voltage was, but I'm sure it wasn't 300 V, and may be have more like 150 V.

Check the power transformer - it gave at least 300 volts with the 6X5
rectifier specified.

The AC-1 was spec'd at 15 watts input, which means about 40 mA at 350 volts!

While the 6V6 can handle higher voltages, as a keyed crystal oscillator, you
don't want to overdo it. You could fracture a crystal, too.

I ran a similar transmitter as a Novice. 350 volts on the plate of a 6V6GT,
grid-plate circuit. Xtals were fine, both on 80 and 40 meters. Those were
FT-243s, though. Smaller xtals need a bit more care.

A 6AG7 is a lot easier on the xtal than a 6V6.

There's quite a bit of AC-1 lore online. Use
http://www.google.com/search?q=ameco+ac-1 to find it. I even found a copy of
the original AC-1 manual, but it doesn't show circuit voltages.

Congrats on getting your ticket and making your first QSO.

YES!

Now it's time to
put this antique away and build some safe, cool, solid-state gear!

Why? If it does the job, what's the problem?

As another poster commented, the next step is a classic 6AG7/807 MOPA design
(or similar tubes - lots of choices, like the 6BG6, 6DQ6, 1625, etc). With a
few more parts than the AC-1, you can get 40-50 watts output. And learn a lot
in the process.

73 de Jim, N2EY