"Jim F." <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- Good advice Garey...And very well taken
Happy New Year ! Jim / W1FMR --- Garey Barrell <[EMAIL PROTECTED]> wrote: > > Garey Barrell <[EMAIL PROTECTED]> made an > utterance to the drakelist gang > ---------------------------------------------------------------------- > Jim - > > Loss of control bias in ANY transmitting tube is a > problem. > > The problem here (as in so much electronic > equipment) is that > electrolytic capacitors have a finite lifetime. > Unfortunately it's > WIDELY variable, and just about impossible to > predict which cap is going > to last 50 years, and which will only last five > years. Or less.! > > The capacitors that are causing "most" of these > failures are all over 25 > years old, well past even the most optimistic > reliability expectations. > Hams being hams, they will use them until they fail, > rather than take > any sort of preventative maintenance steps. > > Fusing is not quite that simple, since the short > term peak currents > associated with off-resonance operation during > tuning can be pretty > large. As with most fused circuits, it's a narrow > line between blowing > when you lose bias and blowing every time you're a > little slow tuning up! > > Another problem is that the fuse may have to clear > up to 700 VDC > depending upon the condition of the tube. > > Bottom line is, keep your power supply in good > condition (update ANY > "original" AC-4 with an AC-4R upgrade kit) and make > sure your Cinch > connector is plugged in firmly and doesn't have to > support the weight of > the entire power cable. You're good for another > 10-20-30 years, > probably longer than you're gonna need the > T-4X(any)!! > > 73, Garey - K4OAH > Glen Allen, VA > > Drake 2-B, 4-B & C-Line Service Supplement CDs > <www.k4oah.com> > > > > Jim F. wrote: > > "Jim F." <[EMAIL PROTECTED]> made an utterance to > the drakelist gang > > > ---------------------------------------------------------------------- > > I see that tube bias is a big problem in these > > sets. > > > > Any chance of fusing the cathode resistors > > to would help stem the bias problem ? > > > > Do you think a couple of cathode wired-in-series > fuses > > work ? > > > > Jim > > > > > > ---------------------------------------------------------------------- > 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 ----------------------------------------------------------------------
