"EP Swynar" <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- Hi Garey,
...At long last, the clouds (in my mind) are beginning to part, & I believe I can see the light, at long last...! You'd never know that I'm a college graduate, would you...?! Hi Hi Thanks for the info...I'll be watching for those bottles at the next Hamfest that I might attend here... ~73!~ Eddy VE3CUI - VE3XZ ******************************************* ----- Original Message ----- From: "Garey Barrell" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, January 21, 2008 9:15 AM Subject: Re: [drakelist] T4X Final RF Tubes > > 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 connected > internally 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 to > cathode 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 > ---------------------------------------------------------------------- ---------------------------------------------------------------------- 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 ----------------------------------------------------------------------
