looks like I found a "TR4 matched set" of 6JB6s in the garage that I got back in '99, looks like from WB2LHP. Two Sylvania's and an RCA. Slips of paper for each, two are marked 109, one is marked 110.
Those numbers are exactly what ? What is the typical variation seen among NON-matched 6JB6's ? What bad stuff might one see when not using matched sets ? Would be fun to know what I paid for them back then. Of course those dollars were worth more then than now. BTW RFParts didn't have any Sylvania/RCA last week, but did have GE's. Chuck, K1OM On Nov 25, 2007 10:30 AM, Garey Barrell <[EMAIL PROTECTED]> wrote: > > Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist > gang > ---------------------------------------------------------------------- > Hi Gary - > > Well the filament wiring in the TR-4/C is important because it's a > combination series/parallel arrangement. The three final tube filaments > are in parallel, and that is then in series with eight other tubes and > the SSB pilot lamps. The Dial and S-Meter lamps are in series across > the 12.6V filament supply. Ohm's opinion still works on series/parallel > resistance combinations! :-) > > Don's (N9OO) very nice LED replacements are not offered for the TR-4/C > for that reason. It would be possible to make a series/parallel/LED > arrangement to allow the proper LED current while maintaining the > appropriate current for the filament string, but would require two > resistors, one of which would have to dissipate most of a watt. Not > easy to build into a #47 bulb base. > > I have been using #755 bulbs for years. They are the same voltage and > current as the #47 but with a design life of 20,000 hours rather than > the 2,000 hours of the #47. Roughly 2-1/2 years instead of 1/4 year of > continuous use. The filament is also more rugged and is less prone to > vibration or turn-on surge failure. I probably have 50 of them in > various Drake gear, and have yet to replace one since about 1965! > > 73, Garey - K4OAH > Glen Allen, VA > > Drake 2-B, 4-B & C-Line Service Supplement CDs > <www.k4oah.com> > > > > Gary Poland wrote: > > > > "Gary Poland" <[EMAIL PROTECTED]> made an utterance to the > > drakelist gang > > ---------------------------------------------------------------------- > > Garey, > > I have heard that filament current balance is important and using > > incorrect pilot lamps can upset the balance of current distribution. > > Does this prevent the use of the LED replacements? I am just curious, > > I still use the #47 lamps. > > > > 73, Gary W8PU > > http://home.cinci.rr.com/w8pu > > > > > > ---------------------------------------------------------------------- > 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 > ---------------------------------------------------------------------- >
