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Hi Rolf,
I use the same tube for an 144 MHz amp. 2.1KV gives ~ 350W+ for 20W in =
in GG configuration. I use one 18W 120x120 fan and have no problems with =
overheating.
My best guess is that you have an oscillation problem (the tube can =
operate at up to 3GHz). Have you looked at anode current? (I draw =
about 300mA for full PO)
Vy 73 de OZ1PIF, Peter
Sound clips from OX2K operation "off the air": =
http://hjem.get2net.dk/oz1pif/OX2K-sound.htm
********** OZ1PIF **************
email: oz1pif(no-spam-filler)@get2net.dk
http://hjem.get2net.dk/oz1pif
Shack Ph. +45 4619 3208
Snailmail:
Peter Frenning
Ternevej 23
DK-4130 Viby Sj.
Denmark
***********************************
----- Original Message -----=20
From: Roelof Bolhuis=20
To: Amps newsgroup=20
Sent: Thursday, March 01, 2001 8:24 PM
Subject: [AMPS] GI-7b power question
Hello OM,
I have build a 50 MHz amplifier with a GI-7b tube. It give about 200 =
watt with 2000 volt. I use two coolers from 12 x 12 cm. The problem is =
that when the power comes up, it goes to about 200 watt, it stay there =
for about two at three seconds, then the power drop down to about 20 =
watt, and then it comes up to about 200 watt again. This cycle happens =
in about 3 seconds. The powersupply, including the heater supply from 12 =
volt is okay, it doesn't drop down. I have the same result with an other =
tube.
Do you know what the cause can be ? Every hint is welcome !
Thanks in advance.
Regards,
Roelof (PE5TS)
E-mail: pe5ts@amsat.org
=20
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<DIV><FONT size=3D2>Hi Rolf,</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=3D2>I use the same tube for an 144 MHz amp. 2.1KV gives =
~ 350W+=20
for 20W in in GG configuration. I use one 18W 120x120 fan and have no =
problems=20
with overheating.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=3D2>My best guess is that you have an oscillation =
problem (the=20
tube can operate at up to 3GHz). Have you looked at anode =
current? =20
(I draw about 300mA for full PO)</FONT></DIV>
<DIV> </DIV>
<DIV>Vy 73 de OZ1PIF, Peter</DIV>
<DIV> </DIV>
<DIV><BR>Sound clips from OX2K operation "off the air": <A=20
href=3D"http://hjem.get2net.dk/oz1pif/OX2K-sound.htm";>http://hjem.get2net=
.dk/oz1pif/OX2K-sound.htm</A></DIV>
<DIV> </DIV>
<DIV>********** OZ1PIF **************<BR>email:=20
oz1pif(no-spam-filler)@get2net.dk<BR><A=20
href=3D"http://hjem.get2net.dk/oz1pif";>http://hjem.get2net.dk/oz1pif</A><=
BR>Shack=20
Ph. +45 4619 3208<BR>Snailmail:<BR>Peter Frenning<BR>Ternevej =
23<BR>DK-4130 Viby=20
Sj.<BR>Denmark<BR>***********************************</DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: =
0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A href=3D"mailto:rbolhuis@worldonline.nl"; =
title=3Drbolhuis@worldonline.nl>Roelof=20
Bolhuis</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
href=3D"mailto:amps@contesting.com"=20
title=3Damps@contesting.com>Amps newsgroup</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Thursday, March 01, 2001 =
8:24=20
PM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> [AMPS] GI-7b power=20
question</DIV>
<DIV><BR></DIV>
<DIV><FONT face=3DArial size=3D2>Hello OM,</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>I have build a 50 MHz amplifier with =
a GI-7b=20
tube. It give about 200 watt with 2000 volt. I use two coolers from 12 =
x 12=20
cm. The problem is that when the power comes up, it goes to about 200 =
watt, it=20
stay there for about two at three seconds, then the power drop down to =
about=20
20 watt, and then it comes up to about 200 watt again. This cycle =
happens in=20
about 3 seconds. The powersupply, including the heater supply from 12 =
volt is=20
okay, it doesn't drop down. I have the same result with an other=20
tube.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Do you know what the cause can be ? =
Every hint is=20
welcome !<BR>Thanks in advance.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Regards,<BR>Roelof =
(PE5TS)</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>E-mail: <A=20
href=3D"mailto:pe5ts@amsat.org";>pe5ts@amsat.org</A></FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial =
size=3D2></FONT> </DIV></BLOCKQUOTE></BODY></HTML>
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