Date: Sun, 4 Jun 2017 05:20:01 -0400
From: Markus Vester <markusvester@aol.com>
To: rsgb_lf_group@blacksheep.org
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References: <15c725d9c9b.marcocadeddu@tin.it>
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Subject: Re: LF: For today the FETs survived... and are working!
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> The gates now are switched with a square wave (a bit smoothed in the risi=
ng side) swinging from + 20 to -10 V with respect to ground.

Why are these so unsymmetrical? With 50% duty cycle and DC-free output from=
 the transformer, the two polarities should have the same amplitude.


> Unfortunately I cannot rise the supply continously from 50V to the final =
180V.. so will let it to be used to eat 50V and later give 180V

Oh man, that's going to be a tense moment! Take care, and be sure to protec=
t yourself against bits flying around!

Best 73,
Markus

-----Urspr=C3=BCngliche Mitteilung-----=20
Von: marcocadeddu <marcocadeddu@tin.it>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: So, 4. Jun 2017 11:11
Betreff: LF: For today the FETs survived... and are working!


Good morning LF &VLF :-)

I had not a big choice among available cores for the driver xfmr.. and=20
finally I choose a BN43-202 with a lower AL but higher cross section.=20
Now the driver xfmr is wound 10T primary and 22T+22T of sec (it had to=20
be 20T but the cutted wire allowed a couple of turns more ;-) )
Now have provided much confortable test points for the gates too.
So I wired everything and replaced the original 150=C2=B5H coil with=20
4x2200pF in the output tank and have again available(but not yet=20
connected) the 25T for the guard circuit.

the gates now are switched with a square wave (a bit smoothed in the=20
rising side) swinging from + 20 to -10 V with respect to ground.

The tx is running since about half an hour at 50Vdc and only the dummy=20
load is warming a bit.
With 7T/19T xfmr on the output it is puring 35Wout with 45W input

Unfortunately I cannot rise the supply continously from 50V to the=20
final 180V.. so will let it to be used to eat 50V and later give 180V

Cross your fingers!

Marco IK1HSS

...
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<div style=3D"font-size:10pt;font-family:arial,helvetica,sans-serif;color:b=
lack;"><div style=3D"color: black; font-family: arial,helvetica,sans-serif;=
 font-size: 10pt;">&gt; The gates now are switched with a square wave (a bi=
t smoothed in the rising side) swinging from + 20 to -10 V with respect to =
ground.<br><br>Why are these so unsymmetrical? With 50% duty cycle and DC-f=
ree output from the transformer, the two polarities should have the same am=
plitude.<br><br><br>&gt; Unfortunately I cannot rise the supply continously=
 from 50V to the final 180V.. so will let it to be used to eat 50V and late=
r give 180V<br><br>Oh man, that's going to be a tense moment! Take care, an=
d be sure to protect yourself against&nbsp;bits flying around!<br><br>Best =
73,<br>Markus<br><br>-----Urspr=C3=BCngliche Mitteilung----- <br>Von: marco=
cadeddu &lt;marcocadeddu@tin.it&gt;<br>An: rsgb_lf_group &lt;rsgb_lf_group@=
blacksheep.org&gt;<br>Verschickt: So, 4. Jun 2017 11:11<br>Betreff: LF: For=
 today the FETs survived... and are working!<br><br></div>Good morning LF &=
amp;VLF :-)<br><br>I had not a big choice among available cores for the dri=
ver xfmr.. and <br>finally I choose a BN43-202 with a lower AL but higher c=
ross section. <br>Now the driver xfmr is wound 10T primary and 22T+22T of s=
ec (it had to <br>be 20T but the cutted wire allowed a couple of turns more=
 ;-) )<br>Now have provided much confortable test points for the gates too.=
<br>So I wired everything and replaced the original 150=C2=B5H coil with <b=
r>4x2200pF in the output tank and have again available(but not yet <br>conn=
ected) the 25T for the guard circuit.<br><br>the gates now are switched wit=
h a square wave (a bit smoothed in the <br>rising side) swinging from + 20 =
to -10 V with respect to ground.<br><br>The tx is running since about half =
an hour at 50Vdc and only the dummy <br>load is warming a bit.<br>With 7T/1=
9T xfmr on the output it is puring 35Wout with 45W input<br><br>Unfortunate=
ly I cannot rise the supply continously from 50V to the <br>final 180V.. so=
 will let it to be used to eat 50V and later give 180V<br><br>Cross your fi=
ngers!<br><br>Marco IK1HSS<br><br>...<br><br><br><br><br><br><br><br></div>
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