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 --
Re: [drakelist] T4X Final RF Tubes
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 --
Re: [drakelist] T4X Final RF Tubes
john [EMAIL PROTECTED] made an utterance to the drakelist gang -- Eddy Take a look at 6GJ5s ! John K5MO At 08:32 AM 1/20/2008, you wrote: Good Morning All, I'm curious as to the results anyone may have had by substituting 12JB6 tubes in place of the stock 6JB6 bottles in their T4X transmitters... Glancing at the filament wiring in the schematic, such a transformation certainly looks like it'd be easy enough to execute, relatively harmless, AND simple to return the rig back to normal at any future time, should the need arise. I thought I was SO smart here, by convincing myself that a pair of my spare 6LQ6's would be a rugged, rough ready primo substitute for a 6JB6 --- until I saw the comparative physical heights between the two, AND took a peek inside the tight quarters of the RF cage of my T4X, that is! 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 --
Re: [drakelist] T4X Final RF Tubes
EP Swynar [EMAIL PROTECTED] made an utterance to the drakelist gang -- Hi John, Without a base diagram of the 6GJ5 directly in front of me --- and correct me if I'm wrong! --- isn't the suppressor grid connected directly to the cathode inside of that particular tube...? ~73~ Eddy VE3CUI - VE3XZ ** - Original Message - From: john [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Sunday, January 20, 2008 9:15 AM Subject: Re: [drakelist] T4X Final RF Tubes john [EMAIL PROTECTED] made an utterance to the drakelist gang -- Eddy Take a look at 6GJ5s ! John K5MO At 08:32 AM 1/20/2008, you wrote: Good Morning All, I'm curious as to the results anyone may have had by substituting 12JB6 tubes in place of the stock 6JB6 bottles in their T4X transmitters... Glancing at the filament wiring in the schematic, such a transformation certainly looks like it'd be easy enough to execute, relatively harmless, AND simple to return the rig back to normal at any future time, should the need arise. I thought I was SO smart here, by convincing myself that a pair of my spare 6LQ6's would be a rugged, rough ready primo substitute for a 6JB6 --- until I saw the comparative physical heights between the two, AND took a peek inside the tight quarters of the RF cage of my T4X, that is! 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 --
Re: [drakelist] T4X Final RF Tubes
EP Swynar [EMAIL PROTECTED] made an utterance to the drakelist gang -- Hi John, Without a base diagram of the 6GJ5 directly in front of me --- and correct me if I'm wrong! --- isn't the suppressor grid connected directly to the cathode inside of that particular tube...? ~73~ Eddy VE3CUI - VE3XZ ** - Original Message - From: john [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Sunday, January 20, 2008 9:15 AM Subject: Re: [drakelist] T4X Final RF Tubes john [EMAIL PROTECTED] made an utterance to the drakelist gang -- Eddy Take a look at 6GJ5s ! John K5MO At 08:32 AM 1/20/2008, you wrote: Good Morning All, I'm curious as to the results anyone may have had by substituting 12JB6 tubes in place of the stock 6JB6 bottles in their T4X transmitters... Glancing at the filament wiring in the schematic, such a transformation certainly looks like it'd be easy enough to execute, relatively harmless, AND simple to return the rig back to normal at any future time, should the need arise. I thought I was SO smart here, by convincing myself that a pair of my spare 6LQ6's would be a rugged, rough ready primo substitute for a 6JB6 --- until I saw the comparative physical heights between the two, AND took a peek inside the tight quarters of the RF cage of my T4X, that is! 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 --
Re: [drakelist] T4X Final RF Tubes
EP Swynar [EMAIL PROTECTED] made an utterance to the drakelist gang -- Hi John, Without a base diagram of the 6GJ5 directly in front of me --- and correct me if I'm wrong! --- isn't the suppressor grid connected directly to the cathode inside of that particular tube...? ~73~ Eddy VE3CUI - VE3XZ ** - Original Message - From: john [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Sunday, January 20, 2008 9:15 AM Subject: Re: [drakelist] T4X Final RF Tubes john [EMAIL PROTECTED] made an utterance to the drakelist gang -- Eddy Take a look at 6GJ5s ! John K5MO At 08:32 AM 1/20/2008, you wrote: Good Morning All, I'm curious as to the results anyone may have had by substituting 12JB6 tubes in place of the stock 6JB6 bottles in their T4X transmitters... Glancing at the filament wiring in the schematic, such a transformation certainly looks like it'd be easy enough to execute, relatively harmless, AND simple to return the rig back to normal at any future time, should the need arise. I thought I was SO smart here, by convincing myself that a pair of my spare 6LQ6's would be a rugged, rough ready primo substitute for a 6JB6 --- until I saw the comparative physical heights between the two, AND took a peek inside the tight quarters of the RF cage of my T4X, that is! 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 --
Re: [drakelist] T4X Final RF Tubes
EP Swynar [EMAIL PROTECTED] made an utterance to the drakelist gang -- Hi John, Without a base diagram of the 6GJ5 directly in front of me --- and correct me if I'm wrong! --- isn't the suppressor grid connected directly to the cathode inside of that particular tube...? ~73~ Eddy VE3CUI - VE3XZ ** - Original Message - From: john [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Sunday, January 20, 2008 9:15 AM Subject: Re: [drakelist] T4X Final RF Tubes john [EMAIL PROTECTED] made an utterance to the drakelist gang -- Eddy Take a look at 6GJ5s ! John K5MO At 08:32 AM 1/20/2008, you wrote: Good Morning All, I'm curious as to the results anyone may have had by substituting 12JB6 tubes in place of the stock 6JB6 bottles in their T4X transmitters... Glancing at the filament wiring in the schematic, such a transformation certainly looks like it'd be easy enough to execute, relatively harmless, AND simple to return the rig back to normal at any future time, should the need arise. I thought I was SO smart here, by convincing myself that a pair of my spare 6LQ6's would be a rugged, rough ready primo substitute for a 6JB6 --- until I saw the comparative physical heights between the two, AND took a peek inside the tight quarters of the RF cage of my T4X, that is! 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 --
Re: [drakelist] T4X Final RF Tubes
john [EMAIL PROTECTED] made an utterance to the drakelist gang -- Exactly, but Drake does that at the socket, so no diff! JB At 09:26 AM 1/20/2008, you wrote: EP Swynar [EMAIL PROTECTED] made an utterance to the drakelist gang -- Hi John, Without a base diagram of the 6GJ5 directly in front of me --- and correct me if I'm wrong! --- isn't the suppressor grid connected directly to the cathode inside of that particular tube...? ~73~ Eddy VE3CUI - VE3XZ ** - Original Message - From: john [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Sunday, January 20, 2008 9:15 AM Subject: Re: [drakelist] T4X Final RF Tubes john [EMAIL PROTECTED] made an utterance to the drakelist gang -- Eddy Take a look at 6GJ5s ! John K5MO At 08:32 AM 1/20/2008, you wrote: Good Morning All, I'm curious as to the results anyone may have had by substituting 12JB6 tubes in place of the stock 6JB6 bottles in their T4X transmitters... Glancing at the filament wiring in the schematic, such a transformation certainly looks like it'd be easy enough to execute, relatively harmless, AND simple to return the rig back to normal at any future time, should the need arise. I thought I was SO smart here, by convincing myself that a pair of my spare 6LQ6's would be a rugged, rough ready primo substitute for a 6JB6 --- until I saw the comparative physical heights between the two, AND took a peek inside the tight quarters of the RF cage of my T4X, that is! 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 -- -- 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 --
Re: [drakelist] T4X Final RF Tubes
Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Eddy - The cathode is almost grounded at the socket by a 470 pF cap, (a little feedback for linearization,) then through the 15 ohm cathode resistor to equalize the current between the tubes, and then RF Ground by a 0.005 uF cap. Then it's off through an RF choke for keying and cathode current monitoring, etc., essentially a 3.3 ohm resistor to DC ground. In the T-4(any), G3 is DC grounded at the socket, but in the TR-4(any), G3 is bypassed to the bottom of the 15 ohm cathode resistors. Bottom line is, the 6GJ5 works just fine in the T/TR-4(any) with the same caveats as the 6JB6, i.e., not ALL brands work well. The same reliable brands, (Sylvania, Zenith, RCA and GE ALWAYS work,) Westinghouse, Raytheon, Standard and a few of the late term rebranders sometimes work. The tube was designed to work at ~16kHz, and only Sylvania actually characterized and published data for use in linear service at 2-30 MHz. 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 -- Hi Again John, Interesting...! I can't honestly say that I've had the bottom cover off of my ...new/old T4X here yet, but the schematic in the manual, at least, definitely shows that pin #8 (suppressor grid) of each tube is directly grounded, whilst pin #3 for each is connected to resistors, capacitors, etc., i.e. NO direct ground connection... This merits further investigation on the part of yours truly, 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 --
Re: [drakelist] T4X Final RF Tubes
Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Close, but not quite. 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! :-) The tube manuals all say Pin 8 is IC for Internal Connection, but after looking at many 6GJ5s of various brands, I have yet to find one with anything connected to Pin 8. There may be one, but so far 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... ...Bottom line is, the 6GJ5 works just fine in the T/TR-4(any) with the same caveats as the 6JB6, i.e., not ALL brands work well... *** Hi Garey, Many thanks for that FB note... However, I must say, I still remain skeptical and confused (both!) by the notion of employing a 6GJ5 tube as a direct replacement for the 6JB6 in the T4X transmitter... Specifically, because pin #8 in the rig is directly connected to ground, and in the 6GJ5 the suppressor grid is connected directly to the cathode internally AND both the cathode suppressor come out at pin #8 in that tube, wouldn't you effectively have the finals in constant key down mode with the substitutes plugged in...? As well, you'd have no cathode/plate current meter readings, either --- correct? What have I missed here...? I dearly DO want to be a believer, but there must be some Missourian doubting Thomas deep within me! Hi Hi. That, or my proverbial enquiring mind just NEEDS to know... ~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 --
