[Lowfer] W1VD amp help

[Chris Wilson]

Hello again Paul,

Just  to  be clear I used the tail end of this circuit originally as a
pre  amp  to  bump up the max 0dBm output of my TS-590 to a level that
would  run the X2 converter circuit. I had to run the 590 at much less
than  0dBm as its sine wave output was quite distorted run flat out. If
you  are  happy  to  use the U3S as the direct exciter it makes things
dead simple :)

http://w1vd.com/Phasingexciter.pdf

Sunday, April 8, 2018


> It seems I'm in over my head again. I'm having difficulty getting my
> newly built W1VD kW 137 amp to run correctly. I think the problem
> may be with my driver board.

> Question 1:
> Could anyone with a known good W1VD kW deck send me a scope plot of
> your gate waveform please?


> Question 2:
> Using the driver circuit exactly as shown here

> http://w1vd.com/137-500-KWRev3.0.pdf

> what have you successfully driven it with? Please specify sine or
> square wave and drive level.



> Here are the problems I'm having:

> Using the configuration shown in the pdf schematic above my amp will
> not drive with either sine or square wave input at any level up to
> +23 dBm from a HP 3325B at X2 frequency (275 kHz).

> When I add this X2 multiplier

> http://w1vd.com/X2LinearClassDinterface2.pdf

> between the 3325B and the amp, it works. Sort of. I changed the
> 3325B to 137.5 kHz of course. I get about 65W with 13V on the drains
> and 250W at 25V. But, something goes into oscillation when RF drive
> is removed! Not the FETs. It's either the driver board or the
> multiplier or the combination of the two. I can see it oscillating
> when I probe the input to the driver board. Oscillation starts only
> after RF drive has been present and then removed. Neither the
> multiplier nor the driver board show evidence of oscillation when
> not connected to each other.

> I may have additional issues at high power but I think I should get
> the driver working correctly before proceeding further.

> 73,
> Paul N1BUG




-- 
Best regards,
 Chris    2E0ILY                        mailto:chris at chriswilson.tv