Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- Eddy -
Nope, no cigar.......
NO modifications are needed to either the T-4(any) or the TR-4(any) to use the 6GJ5s.Pin 3 in the Drake 4 Line transmitters is the cathode of the final tubes. Pin 8 in the transmitters is grounded at the socket.With 6JB6s, K is connected internally to Pin 3, and G3 is connectedinternally to Pin 8.With 6GJ5s, K AND G3 are connected internally to Pin 3, AND there is _NO_ connection to Pin 8.So everything works the same, except G3 is connected directly to K rather than via a 15 ohm and 3.3 ohm resistor.The only difference is the interelectrode capacitance, which is small enough (0.5 pF) that the neutralization circuit is able to take care of it.NOTE: RCA Tube Manual for Class A Operation states "G3 connected tocathode at socket".73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B & C-Line Service Supplement CDs <www.k4oah.com> EP Swynar wrote:
"EP Swynar" <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- On Sunday 20th January, Garey wrote... "...True, the G3 is brought out to Pin 8 in the 6JB6, and that socket pin IS grounded in the T-4... However, in the 6GJ5 G3 is brought internally to the cathode Pin _3_. There is NO connection to Pin 8 in the 6GJ5. Simple!..." *************************************** Hi Garey, I think I'm beginning to understand all this, at last...! What's been missing all along here, is the mandatory execution --- right from the get-go --- of TWO crucial operations, i.e.: (1) The wire from pin #8 to chassis ground at the final amplifier sockets in the T4X must first be snipped, and, (2) A new wire has to be added, jumpering pin #3 to pin #8 at both sockets. What will be accomplished thusly is the following: (1) The pin #3 cathode "break-out" of the 6GJ5 will now effectively be at the pin #8-cum-pin #3 of the T4X socket, and, (2) For better or worse, the suppressor grids of the 6GJ5 tubes will be at the exact same potential as the cathodes (NOTE: is that an especially good --- or bad --- thing?). Failure to first execute the "...nip & tuck" at the sockets will leave the current meter reading "zero" all the time, and the finals will be "on" constantly...correct? I wonder if it wouldn't be simpler to just re-wire the filaments for 12.6 VAC, & a pair of 12JB6's, Hi Hi! ~73~ Eddy VE3CUI - VE3XZ
---------------------------------------------------------------------- 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 ----------------------------------------------------------------------
PRTG Network Monitor
Lake Harriet Lodge #277 AF & AM
Scottish Rite Masonry in MN
Lake Harriet OES #202 Chapter
GoldWing Riders group
No comments:
Post a Comment