On May 14, 2004, at 3:01 AM, Angel Vilaseca wrote:
Hi,
To ensure screen protection, how about connecting a string of diodes
between
plate and screen with its cathode connected to the plate?
The screen and the anode/plate are at greatly different potentials
during the RF cycle. Putting a string of diodes between the two
elements would cause a serious problem when they conducted. A simpler
way of protecting the screen would be to put a string of zener diodes
from the screen to the ground, with the zener bias obtained from the
high voltage bleeder resistor. This would limit screen current to a
safe value and also provide a sink for reverse screen current.
cheers.
If the plate supply fails, then the extra diodes will put the plate at
the
same voltage as the screen, so most (not all) of the electrons should
hopefully continue flowing to the plate.
I have never actually tried this. I saw it in a german magazine some
years
ago.
Any opinions?
Angel Vilaseca HB9SLV
"R.Measures" wrote:
On May 12, 2004, at 11:34 AM, Thomas Hoeppe wrote:
Hello guys,
I am new on this reflector, so may be I am asking a question whitch
has been discussed before.
I am looking for a simple design for the regulation of a screen
supply. I need 800V and about 50 mA. I will have to take care of some
negative current, so the supply has to be able to do that or I will
use a 100mA supply and allow 50 mA of current through a resistor to
ground. My anode voltage is 5 KV, so I don't want to get the G2
voltage from the anode voltage.
For my current tetrode-with-handles A/AB1 project, I am using a
semi-simple 1500v resonant-choke filter screen supply with a 50k-ohm
100w bleeder and No electronic V regulator -- such as:
http://www.somis.org/D-a-08.GIF
- The logic is that with a resonant-choke filter, the screen
regulation will be good enough and that 30mA of shunt-current will
handle negative/reverse screen current during tune-up. Collins used a
resonant-choke filter screen supply on the 30L-1, so I thought I might
give it a go. If it's not good enough, there's a 1600V tap on the
transformer to allow for the series pass regulator circuit above.
good luck, Tom
I am looking for easy and rugged solutions. (KISS.......keep it
simple
and stupid!)
Any ideas?
Thanks in advance.......
Tom, DJ5RE (DL0AO crew)
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|
