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From: Rolf Torvik <la2xpa@gmail.com>
Date: Sun, 8 Apr 2018 05:10:19 +0200
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To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: W1VD amp help
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Paul,

also had problems with the W1VD driver circuit (MF version).
The solution for me was to earth all the unused pins of the 74F74.


I can send you the input levels later if needed (not available now)

73 Rolf LA2XPA

2018-04-08 2:09 GMT+02:00 N1BUG <paul@n1bug.com>:

> 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
>
>


-- 
Rolf Torvik (LA2XPA)
Langveien 61
6510 Kristiansund
Norway
+47 91663050

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<div dir=3D"ltr">Paul,<div><br></div><div>also had problems with the W1VD d=
river circuit (MF version).<div>The solution for me was to earth all the un=
used pins of the 74F74.</div><div><br></div><div><br></div><div>I can send =
you the input levels later if needed (not available now)</div><div><br></di=
v><div>73 Rolf LA2XPA</div></div></div><div class=3D"gmail_extra"><br><div =
class=3D"gmail_quote">2018-04-08 2:09 GMT+02:00 N1BUG <span dir=3D"ltr">&lt=
;<a href=3D"mailto:paul@n1bug.com" target=3D"_blank">paul@n1bug.com</a>&gt;=
</span>:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bo=
rder-left:1px #ccc solid;padding-left:1ex">It seems I&#39;m in over my head=
 again. I&#39;m having difficulty getting my<br>
newly built W1VD kW 137 amp to run correctly. I think the problem<br>
may be with my driver board.<br>
<br>
Question 1:<br>
Could anyone with a known good W1VD kW deck send me a scope plot of<br>
your gate waveform please?<br>
<br>
<br>
Question 2:<br>
Using the driver circuit exactly as shown here<br>
<br>
<a href=3D"http://w1vd.com/137-500-KWRev3.0.pdf" rel=3D"noreferrer" target=
=3D"_blank">http://w1vd.com/137-500-<wbr>KWRev3.0.pdf</a><br>
<br>
what have you successfully driven it with? Please specify sine or<br>
square wave and drive level.<br>
<br>
<br>
<br>
Here are the problems I&#39;m having:<br>
<br>
Using the configuration shown in the pdf schematic above my amp will<br>
not drive with either sine or square wave input at any level up to<br>
+23 dBm from a HP 3325B at X2 frequency (275 kHz).<br>
<br>
When I add this X2 multiplier<br>
<br>
<a href=3D"http://w1vd.com/X2LinearClassDinterface2.pdf" rel=3D"noreferrer"=
 target=3D"_blank">http://w1vd.com/<wbr>X2LinearClassDinterface2.pdf</a><br=
>
<br>
between the 3325B and the amp, it works. Sort of. I changed the<br>
3325B to 137.5 kHz of course. I get about 65W with 13V on the drains<br>
and 250W at 25V. But, something goes into oscillation when RF drive<br>
is removed! Not the FETs. It&#39;s either the driver board or the<br>
multiplier or the combination of the two. I can see it oscillating<br>
when I probe the input to the driver board. Oscillation starts only<br>
after RF drive has been present and then removed. Neither the<br>
multiplier nor the driver board show evidence of oscillation when<br>
not connected to each other.<br>
<br>
I may have additional issues at high power but I think I should get<br>
the driver working correctly before proceeding further.<br>
<br>
73,<br>
Paul N1BUG<br>
<br>
</blockquote></div><br><br clear=3D"all"><div><br></div>-- <br><div class=
=3D"gmail_signature" data-smartmail=3D"gmail_signature">Rolf Torvik (LA2XPA=
)<br>Langveien 61<br>6510 Kristiansund<br>Norway<br>+47 91663050<br></div>
</div>

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