[Drakelist] L4B switch
Hi all, I've been told and have read where the power switch for an L4-L4B is unavailable. Does anyone have a replacement source or remedy? I have one that is always on, but the cw/ssb high plate switch works fine. Has anyone ever repaired one? I suppose I could rig up an external switch to retain the looks as a last resort. Thanks, David Wd9cmd___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4XB neutralization?
Thanks Bob!!! Now you have my curiosity up... I will look for dots and also try to adjust it lower and then move up to 10 Meters. 73 WA3Worn-Out-Mike - Original Message - From: Robert Ladden To: Drakelist@zerobeat.net Sent: Thursday, August 28, 2008 11:49 PM Subject: Re: [Drakelist] T-4XB neutralization? I use GE's in my T-4XC and they neutralized easily without modification, with the variable cap near half meshed (pretty good). Oddly, I had RCA's that I could not neutralize. But by the 1970s it was hard to tell who really made what tube. Look for a series of dots by the tube number stamp. Tubes with the dots probably were really made by GE, sometimes for other brands (I read this somewhere and I have a batch of GE's and off brands with dots). Sometimes it is hard to find the sweet spot on 10m. Try starting on 15m or 20m and then fine tune the neutralization on 10m. I read this tip on one of the Drake user web sites. 73, Bob WW3QB At 08:44 PM 8/28/2008, you wrote: A Drake technical bulletin issued when Drake could no longer get Sylvania 6JB6s and they had to begin substituting GE brand ones, says the following: The T-4X series transmitter uses a 6 pf @ 2KV padder capacitor (C-48) across the neutralization capacitor (C-49). You must experiment with a small value capacitor across the existing padder C-48 to achieve proper neutralization. I have several sets of matched GE and RCA brand 6JB6s that I am having trouble neutralizing. Anyone have any idea what small value capacitor means in this context? TNX ES 73 DE MIKE WA3WOM K ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist -- ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4XB neutralization?
I have 10 more matched sets of NOS 6JB6s to try. So far, I've tried one pair from Sylvania, 1 pair of RCAs and 1 pair of GEs and could not neutralize any properly. No obvious dip by the book. I have lots more to try, I just got frustrated after the third apparent failure... I will have to take a look at the manufacturer codes and see who made what. I was just hoping to get off easy with a little cap here or there. ;-) I will also get out the magnifying glass and check everything visually and also check voltage readings although it loads and seems to work perfectly on the air. Gary gave me an idea to try - disconnect the HV to the plates and adjust for minimum RF at the antenna jack. I will give that a shot next week while I'm off. Thanks, WA3Worn-Out-Mike - Original Message - From: Garey Barrell [EMAIL PROTECTED] To: WA3WOM [EMAIL PROTECTED]; drakelist@zerobeat.net Sent: Thursday, August 28, 2008 11:09 PM Subject: Re: [Drakelist] T-4XB neutralization? Mike - Before you expend too much effort in this, do you have ANY tubes that will neutralize? The RCA and Sylvania tubes were very close to the same and either should neutralize without difficulty or changes. I HAVE used GE tubes without difficulty also, aside the from fact that they seemed to fall off in output power more quickly from brand new than either Sylvania or RCA brands. I wonder if by the time that Service Bulletin was issued if the GE branded tubes may in fact not have been manufactured by GE. Back in the 60's, Sylvania 6JB6s (and all Zenith branded tubes) were manufactured by Sylvania. RCA 6JB6s were manufactured by RCA. By the mid 70's, tubes were being cross-manufactured and branded as tube manufacturing plants were being shut down. So a GE branded tube may in fact have been built by another company. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com WA3WOM wrote: A Drake technical bulletin issued when Drake could no longer get Sylvania 6JB6s and they had to begin substituting GE brand ones, says the following: /The T-4X series transmitter uses a 6 pf @ 2KV padder capacitor (C-48) across the neutralization capacitor (C-49). You must experiment with a small value capacitor across the existing padder C-48 to achieve proper neutralization./ I have several sets of matched GE and RCA brand 6JB6s that I am having trouble neutralizing. Anyone have any idea what _small value capacitor_ means in this context? TNX ES 73 DE MIKE WA3WOM K ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4XB neutralization?
For what it's worth, I have found the Sylvania by far are the best but I have found no matter whether its a Sylvania, RCA, or GE, they all will neutralize in the transmitter as the circuit was designed by Drake.I have found when a tube would not properly neutralize the tube was either bad or weak or on the verge of going bad.Also if your looking for a dip on 10 meters first put the loading to 0, or to the far left. This will give you the maximum dip effect. Advancing the loading from that point the dip becomes more shallow and less apparent on the meter. Regarding the final tubes stay with the above mentioned brand tubes. I have found most of the other brands have a tendency to not do well especially on the higher bands. I found the International brand tubes to be the absolute worst possible final tube to use in Drake. I acquired several brand new International and ended up tossing all of them because everyone appeared somewhat different, and forget trying to find a match pair. 73, Ron / WB4HFN _ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of WA3WOM Sent: Friday, August 29, 2008 1:39 PM To: [EMAIL PROTECTED]; drakelist@zerobeat.net Subject: Re: [Drakelist] T-4XB neutralization? I have 10 more matched sets of NOS 6JB6s to try. So far, I've tried one pair from Sylvania, 1 pair of RCAs and 1 pair of GEs and could not neutralize any properly. No obvious dip by the book. I have lots more to try, I just got frustrated after the third apparent failure... I will have to take a look at the manufacturer codes and see who made what. I was just hoping to get off easy with a little cap here or there. ;-) I will also get out the magnifying glass and check everything visually and also check voltage readings although it loads and seems to work perfectly on the air. Gary gave me an idea to try - disconnect the HV to the plates and adjust for minimum RF at the antenna jack. I will give that a shot next week while I'm off. Thanks, WA3Worn-Out-Mike - Original Message - From: Garey Barrell mailto:[EMAIL PROTECTED] [EMAIL PROTECTED] To: WA3WOM mailto:[EMAIL PROTECTED] [EMAIL PROTECTED]; mailto:drakelist@zerobeat.net drakelist@zerobeat.net Sent: Thursday, August 28, 2008 11:09 PM Subject: Re: [Drakelist] T-4XB neutralization? Mike - Before you expend too much effort in this, do you have ANY tubes that will neutralize? The RCA and Sylvania tubes were very close to the same and either should neutralize without difficulty or changes. I HAVE used GE tubes without difficulty also, aside the from fact that they seemed to fall off in output power more quickly from brand new than either Sylvania or RCA brands. I wonder if by the time that Service Bulletin was issued if the GE branded tubes may in fact not have been manufactured by GE. Back in the 60's, Sylvania 6JB6s (and all Zenith branded tubes) were manufactured by Sylvania. RCA 6JB6s were manufactured by RCA. By the mid 70's, tubes were being cross-manufactured and branded as tube manufacturing plants were being shut down. So a GE branded tube may in fact have been built by another company. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs http://www.k4oah.com www.k4oah.com WA3WOM wrote: A Drake technical bulletin issued when Drake could no longer get Sylvania 6JB6s and they had to begin substituting GE brand ones, says the following: /The T-4X series transmitter uses a 6 pf @ 2KV padder capacitor (C-48) across the neutralization capacitor (C-49). You must experiment with a small value capacitor across the existing padder C-48 to achieve proper neutralization./ I have several sets of matched GE and RCA brand 6JB6s that I am having trouble neutralizing. Anyone have any idea what _small value capacitor_ means in this context? TNX ES 73 DE MIKE WA3WOM K ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4XB neutralization?
Ron - No doubt that Sylvania was/is the best. Zenith branded tubes were ALL made by Sylvania as well, so they are fine. RCA tubes worked fine, and were often subbed in new production transmitters. The few times I used GE tubes in the 60's I found them to drop off about 10% from new output power levels in the first few hours of use, where the Sylvania tubes had a fairly smooth fall-off from new to worn out. I was using three T-4X/B transmitters in full power RTTY Autostart service then, and found that the Sylvania tubes would last about two years. Again, this was with full power output on 20M with transmissions often exceeding 30 minutes. There were small fans on each transmitter final cage of course. By the way, worn out was when the power output on 20M dropped to 100W. I find it much easier to first neutralize on 20M, where the sweet spot is considerably broader and easier to find with new finals. Once in the ballpark on 20M it is only a slight refinement to effect neutralization on 10M. Certainly keeping the LOAD control at 0 as you say sharpens the neutralization dip. The International brand tubes were toward the end of tube manufacture, and were made by MANY different manufacturers, which is the reason they vary all over the map from OK to dud. Raytheon is another brand that varies considerably along with Westinghouse. None of those companies actually made tubes, so you never knew what you would get, especially toward the end. The notice published by Drake was very late, in fact it referred to the inability to obtain production quantities of Phillips/Sylvania tubes which were the predecessor to ECG/Sylvania. By this time GE branded tubes were also quite possibly NOT manufactured by GE. This sourcing problem was also the reason for the change from 6EV7 to 6FQ7 and even to the 6AQ8 in the Relay Control spot. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Ron Baker wrote: For what it's worth, I have found the Sylvania by far are the best but I have found no matter whether its a Sylvania, RCA, or GE, they all will neutralize in the transmitter as the circuit was designed by Drake.I have found when a tube would not properly neutralize the tube was either bad or weak or on the verge of going bad.Also if your looking for a dip on 10 meters first put the loading to 0, or to the far left. This will give you the maximum dip effect. Advancing the loading from that point the dip becomes more shallow and less apparent on the meter. Regarding the final tubes stay with the above mentioned brand tubes. I have found most of the other brands have a tendency to not do well especially on the higher bands. I found the International brand tubes to be the absolute worst possible final tube to use in Drake. I acquired several brand new International and ended up tossing all of them because everyone appeared somewhat different, and forget trying to find a match pair. 73, Ron / WB4HFN ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4XB neutralization?
I also found that GE's will drop off more on the Hickock 6000 when dropping the filament voltage down a notch, Sylvanias and others barely move. 73, Gary___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4XB neutralization?
Thanks Ron. I have received several REALLY good suggestions from you * the other experienced Drake guys so I will experiment and let you all know what I find. Thanks a ton... WA3Worn-Out-Mike - Original Message - From: Ron Baker To: drakelist@zerobeat.net Sent: Friday, August 29, 2008 3:29 PM Subject: Re: [Drakelist] T-4XB neutralization? For what it's worth, I have found the Sylvania by far are the best but I have found no matter whether its a Sylvania, RCA, or GE, they all will neutralize in the transmitter as the circuit was designed by Drake.I have found when a tube would not properly neutralize the tube was either bad or weak or on the verge of going bad.Also if your looking for a dip on 10 meters first put the loading to 0, or to the far left. This will give you the maximum dip effect. Advancing the loading from that point the dip becomes more shallow and less apparent on the meter. Regarding the final tubes stay with the above mentioned brand tubes. I have found most of the other brands have a tendency to not do well especially on the higher bands. I found the International brand tubes to be the absolute worst possible final tube to use in Drake. I acquired several brand new International and ended up tossing all of them because everyone appeared somewhat different, and forget trying to find a match pair. 73, Ron / WB4HFN -- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of WA3WOM Sent: Friday, August 29, 2008 1:39 PM To: [EMAIL PROTECTED]; drakelist@zerobeat.net Subject: Re: [Drakelist] T-4XB neutralization? I have 10 more matched sets of NOS 6JB6s to try. So far, I've tried one pair from Sylvania, 1 pair of RCAs and 1 pair of GEs and could not neutralize any properly. No obvious dip by the book. I have lots more to try, I just got frustrated after the third apparent failure... I will have to take a look at the manufacturer codes and see who made what. I was just hoping to get off easy with a little cap here or there. ;-) I will also get out the magnifying glass and check everything visually and also check voltage readings although it loads and seems to work perfectly on the air. Gary gave me an idea to try - disconnect the HV to the plates and adjust for minimum RF at the antenna jack. I will give that a shot next week while I'm off. Thanks, WA3Worn-Out-Mike - Original Message - From: Garey Barrell [EMAIL PROTECTED] To: WA3WOM [EMAIL PROTECTED]; drakelist@zerobeat.net Sent: Thursday, August 28, 2008 11:09 PM Subject: Re: [Drakelist] T-4XB neutralization? Mike - Before you expend too much effort in this, do you have ANY tubes that will neutralize? The RCA and Sylvania tubes were very close to the same and either should neutralize without difficulty or changes. I HAVE used GE tubes without difficulty also, aside the from fact that they seemed to fall off in output power more quickly from brand new than either Sylvania or RCA brands. I wonder if by the time that Service Bulletin was issued if the GE branded tubes may in fact not have been manufactured by GE. Back in the 60's, Sylvania 6JB6s (and all Zenith branded tubes) were manufactured by Sylvania. RCA 6JB6s were manufactured by RCA. By the mid 70's, tubes were being cross-manufactured and branded as tube manufacturing plants were being shut down. So a GE branded tube may in fact have been built by another company. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com WA3WOM wrote: A Drake technical bulletin issued when Drake could no longer get Sylvania 6JB6s and they had to begin substituting GE brand ones, says the following: /The T-4X series transmitter uses a 6 pf @ 2KV padder capacitor (C-48) across the neutralization capacitor (C-49). You must experiment with a small value capacitor across the existing padder C-48 to achieve proper neutralization./ I have several sets of matched GE and RCA brand 6JB6s that I am having trouble neutralizing. Anyone have any idea what _small value capacitor_ means in this context? TNX ES 73 DE MIKE WA3WOM K -- ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] neutralization method using simple method, requires a receiver
Hello- I neutralize my Drake's by: 1. Disconnect screen voltage to finals. 2. Tune up transmitter PA as normal on 10 meters into a dummy load, although there is no discernable output on wattmeter. Listen to the signal on a receiver. Tune up transmitter for max signal in receiver. Adjust receiver gain to prevent overloading. 3. Adjust neutralizing trimmer for minimum signal as indicated on receiver S-Meter. 4. Reconnect screen voltage to finals. Hope this is of use, Byron WA5THJ. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] neutralization method using simple method, requires a receiver
Byron - This works well, just be VERY careful removing the screen voltage from the Final IF you are unsoldering from the feedthrough capacitor on the shield wall. They are susceptible to overheating, and cracking, if too much force is used when removing the wire. Not fun to replace, either! Of course if the transverter mod has been installed, just pull the plug! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Byron Tatum wrote: Hello- I neutralize my Drake's by: 1. Disconnect screen voltage to finals. 2. Tune up transmitter PA as normal on 10 meters into a dummy load, although there is no discernable output on wattmeter. Listen to the signal on a receiver. Tune up transmitter for max signal in receiver. Adjust receiver gain to prevent overloading. 3. Adjust neutralizing trimmer for minimum signal as indicated on receiver S-Meter. 4. Reconnect screen voltage to finals. Hope this is of use, Byron WA5THJ. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
