Amps
[Top] [All Lists]

[AMPS] Parasitics in Yaesu FL2100B

To: <amps@contesting.com>
Subject: [AMPS] Parasitics in Yaesu FL2100B
From: oz5dx@adr.dk (Hans Otto Pyndt)
Date: Sun, 8 Aug 1999 20:45:53 +0100

I have problems debugging a FL2100B after I installed a pair of Svetlana
572B.
It has blown several 33 ohm grid resistors with a big bang. The grid is not
directly grounded but decoupled with 200pF. Bias is supplied via the 33
ohm.
Bias supply has been modified to a voltage doubler a la Svetlanas
suggestions and the tubes are cut-off in stand by. No-signal current is
adjusted to 30 mA.
I have had this problem occasionally with the original Cetron USA tubes,
but after I changed the grid resistor to 47 ohm, 2w, I have not seen this
problem. However with Svetlana tubes the big bang occurs nearly
immediately. Luckily the tubes have survived so far.
Any suggestions?
73, 
Hans, OZ5DX




--
FAQ on WWW:               http://www.contesting.com/ampsfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm


<Prev in Thread] Current Thread [Next in Thread>