[Elecraft] Ameritron Pulser

[Vic K2VCO]

Stephen W. Kercel wrote:
> Does anyone on the list have any experience using an Ameritron pulser 
> (ATP 100 or ATP 102) to tune an amplifier.

No, but...

> Is there a practical way to connect both the pulser and a regular keyer 
> to the K2 key jack so that you can use either device, but avoid having 
> one device affect the other?

Probably you could simply parallel the output of the pulser device with 
a straight key. If you are using a paddle and the K2's internal keyer, 
then you could use the K2's 'autodetect' feature (look this up in the 
manual).

> Can you get the same effect as the ATP by simply sending a string of 
> dots from the keyer?

Probably the pulser would generate relatively shorter pulses than the 
50% duty cycle of keyer dits. But you could probably get away with using 
a keyer. See below.

> If so, is there a particular combination of dot spacing and code speed 
> that is best suited to get a K2 to generate the waveform necessary to 
> tune an amplifier by the "pulser" method?
> 
> Are these pulsers just a gimmick, or is this really a good way to tune 
> an amplifier?

The idea is this: to tune an amplifier properly for SSB, you need to 
tune it so it will be loaded properly under peak power conditions. One 
way to do this would be tune it in CW mode, increasing drive to produce 
a CW signal equal to the SSB peak power level.

But continuous operation at this level would exceed the tube's 
dissipation ratings; so by sending a series of short pulses, you can 
adjust the amplifier at peak plate current without excessive heating due 
to the low duty cycle.

When tuning for CW, it isn't necessary since you are only loading the 
amplifier to its rated CW plate current, which is lower than the peak 
SSB current. Of course, many amplifiers are not rated for 100% key-down 
output for any length of time, so tuning should be kept short. Or you 
can use a keyer or pulser to reduce the dissipation further.

When using a keyer, speed doesn't matter since duty cycle is determined 
by dot/space ratio. But if you can reduce the weight, that would reduce 
the duty cycle.
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco