"Chuck Grandgent" <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- Wow.
In this case I'm suspecting that the tube itself had problems, as the "new" one behaves much different. However, I will certainly check R100, R101, etc., and generally poke around. Thanks ! Chuck, K1OM On Sat, Mar 29, 2008 at 7:07 PM, Dennis Monticelli <[EMAIL PROTECTED]> wrote: > > "Dennis Monticelli" <[EMAIL PROTECTED]> made an utterance to the drakelist > gang > ---------------------------------------------------------------------- > Overload occurs after the entire cathode (inside of the cylinder) has > been lit. At this point the tube is saturated and any additional > current will cause the regulated voltage to significantly rise and > thus overheat the tube shortening its life. But your tube had some > flicker. Flicker is caused by small regions of negative resistance in > the current vs voltage curve ("pips")that develop over time. The > discharge jumps from one region to the other on the cathode, hence the > flicker. I have seen this before and there are two solutions. One, > change the current through the tube to a different level (higher of > lower) to get away from the negative resistance region. Be sure to > stay within current ratings if you do this.. Two, just replace the > tube as you did. Flicker causes noise in a receiver and can give an > interesting light dance in a dark room. I had this occur in my TO > Keyer. > > I have also seen the flicker accompanied by a bright localized > discharge (just like you described); not to be confused with the > localized dull orange region of a tube operating just above minimum > current. I don't know what causes that but I'm guessing gas has > intruded or been internally outgassed and that gas has contaminated > the pure existing gas causing the ionization path to become > concentrated (ie. bright). I experienced this in my R4B, and let me > tell you, it was quite a light show. It scared me enough to abruptly > kill the power thinking there was a tube that had developed an > internal short. A new regulator tube fixed the problem. > > So these simple regulator tubes are not so simple after all when it > comes to failure mechanisms. > > Dennis AE6C > > > > On Sat, Mar 29, 2008 at 2:58 PM, Chuck Grandgent > <[EMAIL PROTECTED]> wrote: > > > > "Chuck Grandgent" <[EMAIL PROTECTED]> made an utterance to the drakelist > gang > > ---------------------------------------------------------------------- > > > > I'd noticed my OB2 in my R4A starting to flash or flicker bright > > orange, maybe a little reddish tint. First only at startup, then more > > and more. > > > > So I got a "new" OB2 and now have only a continuous orange glow from > > the base area, without any flickering. > > > > What precisely are the failure modes of these regulator tubes ? > > > > Chuck, K1OM > > > > > > ---------------------------------------------------------------------- > > Submissions: [EMAIL PROTECTED] > > Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body > > Hopelessly Lost: [EMAIL PROTECTED] - help in body of message > > Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net > > ---------------------------------------------------------------------- > > > > ---------------------------------------------------------------------- > Submissions: [EMAIL PROTECTED] > Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body > Hopelessly Lost: [EMAIL PROTECTED] - help in body of message > Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net > ---------------------------------------------------------------------- > ---------------------------------------------------------------------- Submissions: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net ----------------------------------------------------------------------