[Drakelist] L4 PS
Hello, Just acquired an L4B plus L4PS. First question: PS has a sn of 142X. This sn does not seem to match up to the ones on wb4hfn's site. Any history? The last Drake rig I ever saw with an X was a TR-6 prototype that I used back in the 70's. Second question: The caps in the power supply are blue sprague atoms with both leads on top of the cap and not axial. There also seems to be a skinny board at the base of these caps. I have'nt taken it apart to better understand the connections or modifications as yet. I'm assuming this is not original, since I understand Drake used axial capacitors. Am I correct here? And did Drake ever do any of the mod's outlined above? Looks like a pro job from looking at the tops of the capacitors and the little long skinny boards at the bottom? Before I picked this up, I had it in my head I'd need to get a upgrade board from the Heathkit Shop, but now I'm not sure that will be necessary, at least in the short run. Oh, I have'nt fired it up yet, so I cannot comment on the smell or anything else. I'm planning on bringing it up slowly on a variac. I was told it had been in storage for around 8 years. Thanks, David Wd9cmd___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] L4 PS
Dave, Ask Jeff Weinberg W8CQ, He jusr went through my L4B power supply with a fine tooth comb and fixed it and is sending it back. He can tell you and sell you what you need! 73 Bill K9BuB --- On Sun, 8/10/08, David Chris Drake [EMAIL PROTECTED] wrote: From: David Chris Drake [EMAIL PROTECTED] Subject: [Drakelist] L4 PS To: drakelist@zerobeat.net Date: Sunday, August 10, 2008, 5:09 PM Hello, Just acquired an L4B plus L4PS. First question: PS has a sn of 142X. This sn does not seem to match up to the ones on wb4hfn's site. Any history? The last Drake rig I ever saw with an X was a TR-6 prototype that I used back in the 70's. Second question: The caps in the power supply are blue sprague atoms with both leads on top of the cap and not axial. There also seems to be a skinny board at the base of these caps. I have'nt taken it apart to better understand the connections or modifications as yet. I'm assuming this is not original, since I understand Drake used axial capacitors. Am I correct here? And did Drake ever do any of the mod's outlined above? Looks like a pro job from looking at the tops of the capacitors and the little long skinny boards at the bottom? Before I picked this up, I had it in my head I'd need to get a upgrade board from the Heathkit Shop, but now I'm not sure that will be necessary, at least in the short run. Oh, I have'nt fired it up yet, so I cannot comment on the smell or anything else. I'm planning on bringing it up slowly on a variac. I was told it had been in storage for around 8 years. Thanks, David Wd9cmd___ 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] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness
Gene McCalmont [EMAIL PROTECTED] made an utterence to the drakelist gang -- Hello Jason; From your email, it appears that one of your 3-500z tubes has bit the dust. It would be difficult to say what caused the problem, but these tubes, while robust to a fault, are not indestructible and do have a definable life cycle. It is entirely normal for the tube plates to have a dull reddish glow while the amp is keyed, however, from your description, I would say you are correct that one tube was under full load while the other was not. While color descriptions are mostly subjective, an orangey glow means the remaining tube was pulling a lot of current when observed. Depending on how long this condition existed, it too is probably exhausted. There is practically no way an average amateur can check a 3-500z unless the tube is put into service and observed. Fortunately, you had enough presence of mind to observe the tubes while switching off the power. Bravo! This is the way I would proceed: 1. You will, of course, have to open the PS to replace R12. If at all possible, replace R12 with an exact value 2w carbon resistor. If unavailable, get as close as you can using only what is available in a 2 watt configuration metal oxide composition resistor. Remember, R12 is kind of like a thermal fuse so any condition that causes excessive current draw exceeding its 2w dissipation rating, will blow the fuse. Metal oxide resistors will be slower to give it up than carbon, so carbon is the choice. The value of R12 is important and fortunately, it is a commonly manufactured part. 2. Observe the other PS components paying close attention to the filter capacitors, bleeder resistors and all three dropping resistors. These components may need attention as well. 3. Go to the bottom of the RF deck and observe the components and socket around the tube that was not conducting. Look for obvious problems such as swollen/cracked capacitors and resistors, burnt wire etc. At this point, I would not start wholesale replacing components. It is likely that any component failure at this point was catastrophic and should be easily discovered. 4. It is most likely that the one tube you observed had reached its end of life and will need to be replaced. When you remove the tube, mark it with a felt tip marker. What caused it to fail, having not discovered any obvious failed components on the chassis underside, will be difficult to determine. At this point, you have several options. Replace that one tube with another USED tube and get on with life, or replace BOTH 3-500z tubes with fresh examples. Although this would be a lot of work, the most optimal approach, since the amp is already down for the count, would be to freshen the PS with new capacitors and diodes, and a few other components, do a really good cleaning of the amp, service the fan motor, replace any obviously defective under chassis components at the RF deck, plunk in some new Taylor 3-500z tubes from RF Supply and Rock and Roll. You will have an awesome amp, capable of 1,500watts out, that will last you another 20+ years. Good luck and please keep me informed. Gene W5DDW Gene McCalmont 270 Oak Ridge Ln. Argyle Texas 76226 -Original Message- From: Jason Buchanan [mailto:[EMAIL PROTECTED] Sent: Monday, December 06, 2004 6:42 AM To: [EMAIL PROTECTED] Subject: Re: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness Thank you VERY much for your EXCELLENT advice - I will do some checking inside the PS today. I did notice that one tube was dark while the other was red, almost orange, when this happened. I noticed a small pop sound coming from the power supply and when I turned my head to look at the supply and start reaching for the power switch I saw that one tube appeared to be handling the entire load while the other was not doing anything. Filaments were lit on both tubes. I will take a drive by the parts store today and dig up some of those resistors. And will take OUT that tube that went dark. No idea why it would go dark and the other pick up the load - would a grid-to-filament short cause this? Thanks, Jason -- On Behalf of Gene McCalmont [EMAIL PROTECTED] Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ --
Re: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness
Garey Barrell [EMAIL PROTECTED] made an utterence to the drakelist gang -- Gene Jason - One critique of your otherwise excellent advice. The 0.82 ohm resistor is actually a wirewound flameproof resistor. The wirewound is identified by the double width first color band. The value is also not particularly critical, since in this application it is really nothing more than a HV fuse that will explode on overload, clearing the circuit and protecting the power supply. NTE offers flameproof resistors in their replacement line, but anything under 1 ohm is difficult to find. A 1 ohm value is fine in the L-4B. The metal or ceramic oxide resistors are a second choice, at best. I don't know what they do under extreme overload. Some power supplies include a resistor in this circuit to protect the power supply against transient shorts, such as a tube flashover, but these are a larger value and size (multi-ohm and multi-watt) just to limit the short circuit current. Fuses DO have voltage ratings, which is the voltage they will interrupt when overloaded, which is why Drake used the resistor instead of a fuse. Small glass fuses are rated at 125V. The higher current automotive types are rated at 32 volts. I'm not sure, but I think that the reduced voltage rating is because the mass of the fusible link is enough to deposit on the inside of the small glass tube. Collins used a proper HV fuse in the 30S1, that is about 6 inches long. They are expensive, and take a lot of room. 73, Garey - K4OAH Atlanta Gene McCalmont wrote: Gene McCalmont [EMAIL PROTECTED] made an utterence to the drakelist gang -- Hello Jason; 1. You will, of course, have to open the PS to replace R12. If at all possible, replace R12 with an exact value 2w carbon resistor. If unavailable, get as close as you can using only what is available in a 2 watt configuration metal oxide composition resistor. Remember, R12 is kind of like a thermal fuse so any condition that causes excessive current draw exceeding its 2w dissipation rating, will blow the fuse. Metal oxide resistors will be slower to give it up than carbon, so carbon is the choice. The value of R12 is important and fortunately, it is a commonly manufactured part. Good luck and please keep me informed. Gene W5DDW Gene McCalmont 270 Oak Ridge Ln. Argyle Texas 76226 -Original Message- From: Jason Buchanan [mailto:[EMAIL PROTECTED] Sent: Monday, December 06, 2004 6:42 AM To: [EMAIL PROTECTED] Subject: Re: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness Thank you VERY much for your EXCELLENT advice - I will do some checking inside the PS today. I did notice that one tube was dark while the other was red, almost orange, when this happened. I noticed a small pop sound coming from the power supply and when I turned my head to look at the supply and start reaching for the power switch I saw that one tube appeared to be handling the entire load while the other was not doing anything. Filaments were lit on both tubes. I will take a drive by the parts store today and dig up some of those resistors. And will take OUT that tube that went dark. No idea why it would go dark and the other pick up the load - would a grid-to-filament short cause this? Thanks, Jason -- On Behalf of Garey Barrell [EMAIL PROTECTED] Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ --
RE: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness
[EMAIL PROTECTED] made an utterence to the drakelist gang -- On Mon, 6 Dec 2004, Gene McCalmont wrote: From your email, it appears that one of your 3-500z tubes has bit the dust. It would be difficult to say what caused the problem, but these tubes, while robust to a fault, are not indestructible and do have a definable life cycle. It is entirely normal for the tube plates to have a dull reddish glow while the amp is keyed, however, from your description, I would say you are correct that one tube was under full load while the other was not. While color descriptions are mostly subjective, an orangey glow means the remaining tube was pulling a lot of current when observed. Depending on how long this condition existed, it too is probably exhausted. Many thanks again - I checked inside the L4 cabinet and also have checked through the power supply cabinet and do not find any other problems (no burned components, etc.) so it appears I got off lucky by this single resistor being the only thing needing replacement. I did notice that it appears this resistor has been replaced once before by the apperance of the other wires soldered to the lug strip terminals. No telling how long it had been since it had been replaced though. I am going to take a trip to the local electronics store in a few days (wx supposed to be bad up here in Beantown tomorrow) and look for a replacement. I think i'll buy a few extras and tape them to the inside of the cover plate! Will keep you updated after I replace the part. vy 73 Jason N1SU -- On Behalf of [EMAIL PROTECTED] Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ --
Re: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness
[EMAIL PROTECTED] made an utterence to the drakelist gang -- On Mon, 6 Dec 2004, Garey Barrell wrote: The 0.82 ohm resistor is actually a wirewound flameproof resistor. The wirewound is identified by the double width first color band. The value is also not particularly critical, since in this application it is really nothing more than a HV fuse that will explode on overload, clearing the circuit and protecting the power supply. NTE offers flameproof resistors in their replacement line, but anything under 1 ohm is difficult to find. A 1 ohm value is fine in the L-4B. The metal or ceramic oxide resistors are a second choice, at best. I don't know what they do under extreme overload. Good to hear that NTE makes these resistors. I hope to get to the local parts store on Wednesday to buy a few replacements. The resistor that blew was blue in color and each end was fluted out, no wide color bands as the value of the resistor was stamped on the side of it. But I will look for the wirewound variety first and then carbon. I think the one that was in there probably was the slower type as it didn't pop and quit working - I heard a pop and then noticed some light coming out from underneath the L4 PS through the ventilation holes, all while I was transmitting. The resistor currently has a value of 400K ohms - hi Thanks for the help - will keep you updated. vy 73 Jason N1SU -- On Behalf of [EMAIL PROTECTED] Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ --
Re: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness
Garey Barrell [EMAIL PROTECTED] made an utterence to the drakelist gang -- Jason - That sounds like a description of a carbon film or perhaps a ceramic composition resistor. Sounds like someone may have been here before! :-)Also why you got the light show. 73, Garey - K4OAH [EMAIL PROTECTED] wrote: On Mon, 6 Dec 2004, Garey Barrell wrote: The 0.82 ohm resistor is actually a wirewound flameproof resistor. The wirewound is identified by the double width first color band. The value is also not particularly critical, since in this application it is really nothing more than a HV fuse that will explode on overload, clearing the circuit and protecting the power supply. NTE offers flameproof resistors in their replacement line, but anything under 1 ohm is difficult to find. A 1 ohm value is fine in the L-4B. The metal or ceramic oxide resistors are a second choice, at best. I don't know what they do under extreme overload. Good to hear that NTE makes these resistors. I hope to get to the local parts store on Wednesday to buy a few replacements. The resistor that blew was blue in color and each end was fluted out, no wide color bands as the value of the resistor was stamped on the side of it. But I will look for the wirewound variety first and then carbon. I think the one that was in there probably was the slower type as it didn't pop and quit working - I heard a pop and then noticed some light coming out from underneath the L4 PS through the ventilation holes, all while I was transmitting. The resistor currently has a value of 400K ohms - hi Thanks for the help - will keep you updated. vy 73 Jason N1SU -- On Behalf of Garey Barrell [EMAIL PROTECTED] Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ --
RE: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness
Gene McCalmont [EMAIL PROTECTED] made an utterence to the drakelist gang -- Good evening Garey and Jason; Jason, I believe Garey to be correct in this and it's something I had not noticed in the past. I have another L-4B, left at my door in a wicker basket with a note from its previous owner, which is suffering from a blown R12. I had not been into this PS as yet, but opened it up just a few moments ago. Yup... Thar she blows (no pun intended)... A wirewound flameproof just as Garey had said and with the same markings (best I can tell), so I believe it was original. Interesting. However, I fear that this owner was not so lucky and it looks like one or more of the carbon bleeder resistors have cooked. I am somewhat reluctant to look further into this... before Christmas! Gary, I'm still working on my 30S-1 resolving some issues with unstable bias voltages on a 4CX1500B. I believe the fuse you referred to is almost unobtanium. Fortunately, I haven't had need of this beast! Good luck guys and keep those tubes glowing. Gene W5DDW Gene McCalmont 270 Oak Ridge Ln. Argyle Texas 76226 Garey Barrell [EMAIL PROTECTED] made an utterence to the drakelist gang -- Gene Jason - One critique of your otherwise excellent advice. snip -- On Behalf of Gene McCalmont [EMAIL PROTECTED] Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ --
Re: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness
Garey Barrell [EMAIL PROTECTED] made an utterence to the drakelist gang -- John - That's what I expected... Thanks for the info. 73, Garey - K4OAH Atlanta john wrote: One suggestion... if you're interested in fusing action, do not use Metal Oxide parts. I've tested these things with many times over their power dissipation. They'll get red hot and ignite cotton , but they won't open up! They're great replacements for carbon comps, in that their surge characteristics are great, but they're not a good fuse!:-) 73 John K5MO -- On Behalf of Garey Barrell [EMAIL PROTECTED] Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ --
Re: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness
[EMAIL PROTECTED] made an utterence to the drakelist gang -- On Mon, 6 Dec 2004, Garey Barrell wrote: That sounds like a description of a carbon film or perhaps a ceramic composition resistor. Sounds like someone may have been here before! :-) Also why you got the light show. I have not been successful at finding this resistor online - but perhaps i'm looking in the wrong places. Does anyone know where I can find some of these for sale? Long distance is cheap when using a cellphone - i'll call anywhere... my guess is i'm going to drive to the local parts store and not find them there so might as well start looking now. 73 jason N1SU -- On Behalf of [EMAIL PROTECTED] Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ --
RE: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness
Stu Greene [EMAIL PROTECTED] made an utterence to the drakelist gang -- At 04:52 PM 12/6/2004, Gene McCalmont wrote: Gene McCalmont [EMAIL PROTECTED] made an utterence to the drakelist gang -- I have another L-4B, left at my door in a wicker basket with a note from its previous owner, which is suffering from a blown R12. I had not been into this PS as yet, but opened it up just a few moments ago. Yup... Thar she blows (no pun intended)... A wirewound flameproof just as Garey had said and with the same markings (best I can tell), so I believe it was original. Interesting. However, I fear that this owner was not so lucky and it looks like one or more of the carbon bleeder resistors have cooked. I am somewhat reluctant to look further into this... before Christmas! If the B+ cord from the power supply to the amp had not been disconnected, that resistor is going West together with one or both of the 25K ohm bleeder resistors. More than likely the diode bank on the side where the bleeder resistor blew will have to be replaced. This is spelled out in the operator's manual. You have a bit of work awaiting. -- On Behalf of Stu Greene [EMAIL PROTECTED] Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ --
Re: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable har...
I have not been successful at finding this resistor online - but perhaps i'm looking in the wrong places. Does anyone know where I can find some of these for sale? Hi, Try Jeff. I believe he was the person selling them at Dayton Last year. Jeff Weinberg - W8CQ Harbach Electronics 468 County Road 620, Polk, OH 44866 Telephone Fax (419) 945-2359 73, John, W4AWM
Re: [drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness
[EMAIL PROTECTED] made an utterence to the drakelist gang -- Resistor is easy to find. Just go to W8CQ's website under Harbach Electronics... -- On Behalf of [EMAIL PROTECTED] Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ --
[drakelist] L4-PS R12 burned - .825 ohm 2W resistor on pin 6 of cable harness
Jason Buchanan [EMAIL PROTECTED] made an utterence to the drakelist gang -- hi all, R12 in my L4-PS burned to a crisp. Any ideas why and what I should look for as to why this happened? Amp was working fine when this happened - I powered it off as soon as I noticed the smell. 73 Jason N1SU -- On Behalf of Jason Buchanan [EMAIL PROTECTED] Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ --
